Terima kasih. Pn. Vinny Jain, to please present the Prime Minister with a shawl now. And also to please come out here to give the welcome address. Prime Minister Sheenarayan Ramodi, ministers, ladies and gentlemen, on behalf of Economic Times, welcome to the Global Business Summit. This is the sixth edition of this summit, an event which has grown in scope and stature every year. Our honored guests and speakers have made it into the premier venue for debate and discussion on the big issues of our times. To kick off this summit, I would like to remind you of a very apt statement made just last week by President Donald Trump when he met PM Modi in Ahmedabad. He said that while India in the years since independence has come very far, it is nothing compared to how far India will go. We have indeed come far. Last year when we met, I mentioned that the Indian economy was poised to become the fifth largest in the world. The recent IMF World Economic Outlook report confirmed that India has indeed reached that position, overtaking France and the United Kingdom. Just ten years ago, India was ranked ninth. Let me take a moment to congratulate the Prime Minister and the Finance Minister for laying the foundations that let the country reach these commanding heights. It has been the ambition and drive of entrepreneurs and business leaders like yourselves that have propelled that growth with, of course, the support of a receptive and reformist government. The Prime Minister and his team have worked towards encouraging investment, enabling business and empowering Indian citizens from all sections of society. The results are clear. Even with global headwinds, the resilience of the Indian economy is apparent. We seem to have weathered the slowdown with green shoots of growth now visible in many sectors. Manufacturing and service PMI in January was at a six-year high and core infrastructure activity has also rebounded, aided by government's proactive measures on the infrastructure and tax fronts. Retail investors continue to repose their faith in Indian markets by investing in systematic investment plans. A pickup in earnings growth would vindicate their faith and provide more fuel for growth. The recent budget had many measures to boost investment and sentiments. These include giving more leeway to sovereign wealth funds to invest in infrastructure, the proposed listing of LIC, and the mapping of the dividend distribution tax among other measures. Ladies and gentlemen, what I have said so far deals with the business part of the summit's name. The global part is a rather different story. Last year, we talked about the challenges of a globalizing economy in which some of the leading economies, notably the US and Britain, seemed to be turning away from globalization. I'm sure that none of us imagine that a year later, it would be the coronavirus epidemic that is the main cause of global economic strife instead of Brexit or a US-China trade war. It goes to show that life can throw up unexpected surprises. You never know what can happen next. I can, however, tell you what you are going to get over the next two days of the Global Business Summit. We have an incredible lineup of speakers who will spur debate on the most important issues facing business and the economy and indeed, our planet. We have already heard Cherry Blair and Stephen Schwartzman. Our Defence Minister Rajnath Singh, Foreign Minister S. Jaishankar and Railways and Commerce Minister Mr. Piyush Goyal and some other ministers will take the stage. And in between, we have entrepreneurs, technocrats, economists and thought leaders, all of whom make this gathering truly the finest forum for ideas in India. And of course, setting the agenda for the summit is the Prime Minister who will speak about the next steps on the journey of the Indian economy as it moves towards the five trillion target that he has set. Thank you, ladies and gentlemen. Thank you, Prime Minister. Thank you, Vineet and yes, a great start to the summit and well, the PM is here. We'd all love to hear from him. Zorda Arthalian, for Mr. Modi. On the global summit, between all the experts who have come from all over the world, Economic Times has given me the opportunity to keep my word. From this morning, since we have been sitting or discussing many issues, the prominent people in the business world have started giving their ideas and will continue to do so. And the effect of these ideas is to collaborate to create. For sustainable growth, the vision to collaborate to create is also needed today and the foundation of the future. And we all know that this vision suddenly has come out of the thoughts of the past few years. It is not like that. What is the harm from the development is the experience of the world. And when it comes together, it's done. When it comes together, it's gone. Collaborate to create is the same as the past. The same as the future. In every era, new challenges we face.   Today, we all have to face this challenge. Collaborate to create and we must be victorious. Friends, even on the philosophy of the fractured world, we are going to do real fractures, over-imaging fractures, and even the responsibility of it I am sure there will be a discussion here. Along with that, when especially according to the predictions, we used to do the same final but because of the technological and the democratic discourse, today every generation of the society will make up their opinion. Today, our opinion is very strong compared to the so called wisdom, it is very strong. First of all, on the expectations and expectations of the people especially and the theories will be achieved. It was a very big reason that you guys had the opportunity to serve us for the first time in 2014 so a huge part of the nation toilets, electricity connection, gas connection, home, basic amenities and we had the idea that we should go to the same path or make up new approach and we decided to make up new approach and the biggest advantage for people during this election and we had a lot of work but I would like to share with you in today's global business I would like to sit in this hall and pay attention to what I say Friends I was talking to you and I have a great understanding of talking i.e always to say the right thing to say the right thing is not but to say i.e people hate and who do the right things and that's why when status is changed people like this and disruptions begin to be seen now pay attention those who who tell themselves the message of gender justice is to make law against three divorces those people to give the world the authority to give the authority the authority for that the world keeps giving the knowledge they for the authority when the law is made those people day and night give the authority that article 370 as status temporary status in Jammu and Kashmir completely to make law against the authority those people day and night speak of justice he he a decision of supreme court a decision if he didn't come to go against the law of the authority of the country question friends to ask this and in that where he went he is still relevant but the country is very happy but the country is very happy that the authority i.e it is very easy to give the authority but to act to act on the authority it is very difficult as long as status it is not difficult people like this and they think in action is the most convenient action but for us nation nation development good governance all these convenience is not for us it is a conviction conviction to do the right things conviction to break the status status friends who themselves become the prisoners of their thoughts prisoners of their thought process life these people they are happy they are happy to make them happy they are happy and in other words they make their life to be in status separated from their pressure our government all the state all the state to free prisoners of their thought to free one after the other take one step one by one we convenience convenience you dbt dbt direct benefit transfer dbt status status big change and thousands crore rupiah evil it is a habit it costs 15 money but not that much how to achieve 100 rupiah it needs action making real estate sector free of black money Ibu beritahu saya bahawa ia menyebabkan kata-kata besar. Dan kembali ke Madhyambar, ke rumahnya, ia menjelaskan kata-kata kita. Kami menjelaskan kata-kata kita. Ibu juga mempunyai penyelaskan Mugti di dunia korporat. Dengan IBC, kami mempunyai status, berubah, berubah, berubah, berubah, berubah, berubah. Oleh itu, kami mempunyai status, berubah, berubah. Ibu tidak mengenai penyelaskan. Ibu tidak mengenai penyelaskan. Ibu mempunyai status, berubah, berubah. Untuk kerja perlahan, ia membantu peluang beli. Inilah yang saya inginkan. Sebelumnya, saya menghidupkan kongsi terbaik. Saya inginkan sekali kerana kelebihan dan kerja. Saya menghadapi kerja kerja yang berlaku, membuat CDS dan membuat stetes yang menarik, dan membuat kelihatan yang lebih baik di dalam kerajaan saya. Colobration in action, and combination of ideas is moving forward. Today, India is creating a model of sustainable growth which will be beneficial for the entire world. The world's largest financial inclusion program, world's biggest sanitation program, world's biggest health assurance scheme, there are many such researches whose experience is helping in the development of the world. India of the 21st century is learning a lot and for the people of the country to achieve the benefit of development, it is at the same level. Friends, at different sectors, at different regions, the results of this are clearly visible. Six years ago in the country, the speed of highway construction per day was 12 km. Per day was 12 km. Today, per day is around 30 km. Six years ago, the situation was that in one year, the electrification of the 600 km railway line was going on. In one year, in the last year, the electricity of the 5300 km railway line was turned off. Six years ago, our airports were handling around 17 crore passengers. Now, they are handling more than 34 crore. Six years ago, our major port, cargo handling was around 550 million tonnes. Now, it has reached 700 million tonnes. And one important thing which you must pay attention to, is that major ports per turn-around time. Six years ago, ports per turn-around time was around 100 hours. 100 hours. Now, it has reached 60 hours. It is now working to reduce it. And these 5-6 examples are connected to connectivity. And the people sitting in this hall each person knows that connectivity is connected to infrastructure. Governors are connected to it. How deeply it affects economic activity. Now, I am asking you that such a big change has it happened? Has it happened in the routine? No. We have done a lot for the government who were not a part of a vertical silos. We have tried to finish those silos. We have done systematic efforts. And we have given strength to the collaboration. We have gone to the ground level to fix things. We have tried. The work that is being done at the airport today at the railway station I am sure that you are watching it. Do you listen to it? People in our country what they deserve and what they got the difference is it is very important. A few years ago the day the day on the railway crossing the news of accident was reported. Why? Because before 2014 in the country on the broad gauge line 9,000 9,000 unman level crossing unman level crossing after 2014 we have run the broad gauge railway line unman level crossing completely liberated. I do not know if there is news in the world there is news that happened in the last years in the last 3 years 9,500 unman level crossing three years in the railway the last 6 years in the railway crossing Sebaik-sebaik dolaq lebih biotoilit yang berlaku Bagaimana 9000 dan sebaik dolaq? Teman-teman, tak boleh kata-kata bahawa Bukankah Bukanya tak pernah Dan saya merasakan bahawa Ia tak berpengaruh di negara buddhichagat Sebab itulah bahawa Bukankah tak akan berlaku Ini tak cara berlaku Bukankah saya akan terdapat beberapa hari? Bukankah sebaiknya? Ia tak nya? Daripada bahawa Ia tak berlaku Bemaknya saya tidak faham Bukankah saya tidak faham Bukankah saya tak pernah Bukankah saya tidak faham Sangat terbelaru Sangat terbelaru Kami juga melihat Ia bermula. Tetapi, ia bermula. Sekarang, banyak orang berada di sini yang akan menggunakan aerolines dua kali hari ini. Semua aerolines juga tidak membuat rifun terlalu lewat. Tetapi, ia adalah negara yang akan membuat rifun terlalu lewat hari ini. Ia akan membuat rifun terlalu lewat. Dengan rifun terlalu lewat, atau ia akan membuat rifun terlalu lewat, jika kita membuat rifun terlalu lewat. Kita tahu bahwa kita membuat rifun terlalu lewat. Saya tahu itulah yang akan berlaku. Dan hari ini, risik akan berlalu lewat. Sebabnya, untuk antara, offices yang terlalu lewat, tetapi, ia akan membuat rifun terlalu lewat. Saya orang seperti bena. Saya tidak tahu jika llatah betul. Tapi saya sangat gembira berhak. Saya sangat secara gembira. Saya berkumpul dengan bahagia yang terjadi. Tetapi saya sangat gembira bagi orang-orang yang tidak mendapatkan bahagia saya. Bagi saya, bahagia saya sangat gembira. Saya sangat gembira bagi orang-orang yang tidak mendapatkan bahagia kami. Hanya Kamu hanya membeli perjumpaan untuk membeli perjumpaan. dan juga membuat perangkatan yang kuat. Tapi dengan cara yang berlaku, perangkatan tersebut adalah bahawa ekonomi global sedang berlaku dengan kejutan yang kecil dan kejadian yang kecil. Tetapi, kejadian ini berlaku dengan kejadian yang kecil dan kejadian yang kejadian yang kejadian yang kejadian dan kejadian yang kecil, untuk membuat perangkatan tersebut. Dan juga, kejadian yang kecil dan kejadian yang kejadian dan kejadian yang kejadian. Untuk membuat perangkatan tersebut, BTA, berlaku dengan kejadian yang kecil, dan kejadian yang kejadian. Pada tahun 2014 kita ada di 11 numbara tempat 5. Pada tahun 2014 kita ada di 11 numbara tempat 5. Dan kita membenci peralatan jika jenis 5 milyar dolar USai. Pada tahun 2014 kita ada di 11 numbara tempat 5. Second, Fair Competition. Third, Wealth Creation. And fourth, Archeal Laws Deletion. Sama-sama, kita telah mempunyai area infast sector. We have created a road map of over 100 lakh crore rupees. Kami telah mengenai PPP. Kami memasukkan pppp untuk memutuskan pppp. Dan jika saya mengatakan pppp adalah pppp. It means that the development of the international candidates and powerful progressive push are also an experience sebabnya, jika jika anda beri perhatian menghubungi perusahaan kegeraian ke perusahaan kegeraian, ia mempunyai dengan cepat. Dan sebabnya, syarikat kita mempunyai dengan lebih banyak perusahaan kegeraian ke perusahaan ke perusahaan kegeraian. Untuk mempunyai perusahaan kegeraian, sekarang dalam budget ini, kami berpindah dengan perusahaan dengan perusahaan dengan perusahaan dengan perusahaan yang baru. Dalam perusahaan kegeraian, kami bergerak dengan cepat. Sebelum sebuah perusahaan, syarikatnya membuat perusahaan kegeraian kegeraian. Mereka membuat perusahaan kegeraian. Saya terkejut, bahawa apabila ia membuat lawan, dan membuat perusahaan kegeraian, perusahaan kegeraian tidak menghubungi saya. Saya ingin membaca yang ada di atas itu. Saya melalui bahawa bahasa India Dan ibu-ibu bila itu juga berpindahkapan. Begitu lalu, a 질문 adalah bagaimana kita menerang ke CEO Blackstone? Ibu yang memberitahu itu bahawa ibu-ibu bernama berlainan yang berlambar dan mereka berlainan untuk berlainan. Bagi ibu yang pernah berlainannya. Selama tahun 2019, di negara, harga 48 bilion dolar di luar negara tersebut sebuah kebanyakan berlainan lebih dari 16 persen. Sebenarnya, pada tahun lalu, 19 bilion dolar kebanyakan kebanyakan dan kebanyakan kebanyakan dan kebanyakan kebanyakan. Pada tahun lalu, penyegang-penyegang berlainan lebih darjah 53 persen. Kepotosan negara tersebut juga disini ini sudah berlainan. Lain tahun lalu, penyegang-penyegang berlainan seront berlainan lebih dari 19 bilion. Menurut saya, kebanyakan diindak sebuah harga berlainan, We are now moving towards India. So why? Our government is in constant contact with all stakeholders taking constant feedback and taking big decisions on every level. We are not only focusing on the national level but we are also focusing on the collaboration and creation. You will remember that when the International Yoga Day was presented India was supported by the whole world. And maybe in the history of UN a single revolution has been supported by so many countries in the world for the first time. And the effect of yoga is that for the first time in your summit someone must have done the meditation. They could not do the meditation but they closed their eyes. I have heard of it. Friends, today in India in peacekeeping forces among the most fortunate countries and for the protection of the people of other countries India is the first to move forward today. Not only that but today in the face of the international and Turkish society India is leading a big country. The International Solar Alliance or Coalition for Disaster Resilience InfoSector The world has started to move forward in the face of the international and today the whole world has started to connect with it. But friends those who support status quo those who oppose changes such as the power in our country the power of money even at a global level they are also globalising. They are also creating their own network in the world and they are making their efforts. Friends, in history there was a time period in which everyone was walking on the path of struggle. Then where did it go? Might is right. Then there was a time in which we were thinking that we will be with this group only then will we be able to reach it. No one thought that we will be with the group only then will we be able to reach it. That time also passed. Now there was a time when people tried to be a good person. Then there was a time in which we were thinking that we will be able to mix the relationship with the youth. In this youth of technology today the world is interconnected interrelated and interdependent. This is the change in status quo. This is the change in status quo. But still for a global agenda it is a matter of thinking that despite all these changes for a global agenda for a bright future a very big dream a very big idea how to remove the poverty of the world how to end the terrorists and how to handle issues like climate change even today the world has not come to an end. Even today the whole world is waiting for it. But still it is not happening. Comrades the 21st century is full of many opportunities between these opportunities even today a common global voice is needed the world is feeling it a voice in which even if the world is different but together it is the darkness of a sun. It is the voice of a sun in front of the whole world this is the question that has changed in the situation in the same way adjust or develop a new way a new path Comrades between the changing situation even India has made many changes There was a time when India was difficult but what was the parameter of our difficult we were difficult how our country is so far so far from that country i.e. how far we are from Mandala how many changes even today we are difficult even today India is difficult but not on the basis of distance but on the basis of friendship now how many decisions have we brought even while we were difficult there was a parameter of distance today we have made a parameter of friendship we also make friends with Saudi Arabia and with Iran we make friends with America and Russia still we are difficult and that's why understand the value of these changes even this is the same there was a time when people make things difficult we are difficult by making friends in that time we tried to keep distance today we tried to keep distance we are trying this country today's nationality today's nationality is very big friends Mahatma Gandhi Ji with one thing i would like to finish Gandhi Ji i.e. i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e i.e Untuk itu, saya sangat berterima kasih kepada anda. Saya berterima kasih kepada anda. Saya berterima kasih kepada anda. Kami berterima kasih kepada anda. Saya akan beri kejadian kepada Wani. Terima kasih, Kepunggilan panas. Terima kasih untuk dombo yang menarik saya. Terima kasih, juga, untuk mempunyai penonton yang indah untuk hari ini. Saya akan beritahu anda bahawa pada hari GBS hari kedua-dua ini bermula pada pagi esok pada hari 9.30.


Well, good afternoon everybody. Thank you very much for coming. This is a, in my view, quite a special occasion really. It's the celebration of 100 years of the Joel chair and in order to do that we've put together a really special programme. I ought to start really by giving you a few little bits of background to the Joel chair and how it became established. And to do that I've put together a few slides and the slides are really in three columns. The column over this side relates to University College London and University College London Hospital. The column in the middle relates to the Middlesex, the Middlesex Hospital and the Medical School associated with that hospital. And the column over this side, apart from these two images, this column relates to a family whose name is Bonato and they are the reason that we have the Joel chair. In other words they provided the money for the Joel chair and I'll give you a little bit of an explanation about the background to that family. But I wanted to start by just putting a few dates up here and the story really begins in 1745 when the Middlesex Hospital or in fact to give it its true name the Middlesex Infirmary was established in Whitfield Street. They took two houses, they had accommodation for eleven beds of which six were put over to women bearing children so midwifery and they had certain rules applied to that. You have to be married before you could enter the building in order to have your baby. And the other law that was laid down is that they could have no female midwives, only male midwives. The hospital expanded somewhat and moved in ten years to the building which I think most of us would have known, Good Street building which is this picture over here and it then expanded in that building and in 1792 the cancer charity as it was called was established and that meant that the hospital became quite concerned about the way in which cancer treatment was being undertaken in those days. And so it decided it would specialise in that area of cancer treatment. And then in 1835 the hospital had a request to form a medical school. Six senior clinicians decided that they ought to have a medical school and I didn't realise quite what the background was to that particular request was until I looked up a few features about UCL. And UCL was established in 1826 and it formed a hospital in 1834 and you'll notice that date is one year prior to that date. The reason being that the students that wanted to train in medicine were being attracted to UCL and the students therefore were leaving what could have been the potential medical school here because there was no official medical school. So the middle sex corrected that by having its own medical school. So there was some slight conflict between the two departments in those early days. But let me talk a little bit more about this guy who begins to play a role in this story. So here are the two lines for UCL and the middle sex and you'll notice they form into the University of London, part of the University of London in 1900. But down here is a description of the Bonato family, at least a very brief description of them. And they are remarkable in 1871. Two of the brothers in this family went to South Africa with the intention of entertaining the miners because they were people that could sing and dance and so they would go along to the miners' rest areas to sing and dance and entertain the miners. They then noticed that they could also get a little sideline in trading in diamonds. This sideline turned out to be a very large business and in 1888 they sold that business for £5.3 million, a large sum in 1988. They then, with this money, went on and did various things. They became gold miners. They spent their money quite sensibly in a sense. But they did include three members of the family who joined at this point, who were much more lively individuals. One of them became a Bentley boy, in other words, raced at Brooklands and one, several of the races there at Brooklands. Another member of the family raced lots of racehorses, had lots of money gained through that racehorsing business. Eventually in 1906 Harry, the guy that had originally started the diamond business, dies and leaves a large sum of money, £250,000, to the Middlesex Hospital. It's not exactly clear why the Middlesex was chosen, but it's believed that somebody in his family required treatment for cancer and therefore this was a sensible place in which to put the money. In that process, the Middlesex and its medical school built up research labs for cancer development and understanding and also established several chairs, one of which was the Joel chair in medical physics. That was awarded in 1920 to the first Joel chair, Sidney Russ. The following members of that elite club, if you like, of the Joel chair professors is Sidney, who started the business 100 years ago. Eric Roberts, he very much worked with Nobel laureate, Joseph Lopblatt, who in developing an MSc course in radiation physics at that time. James Tate, who came along later, a very important individual scientist in his own right, but his wife and he were both made FRSs on the same day. They are the only couple ever to have done that on the same day. The only married couple to have done it otherwise is Vince Albert and Queen Victoria. Oh no, Davey's shaking his head at me, but I stand corrected on that point. It was quite an important aspect, I think, at that time. Then there was John Clifton, who was there for a short period, followed by Roger and myself currently in that position. I think I've told you enough about the Joel chair and how it's become established and I now wanted to pass you on to the second part of the programme. We're going to have two talks by PhD students and I've asked their supervisors if they would introduce those talks in order to give a couple of minutes background. So I think the first one is going to be Savas and so that means Sandro will give us a couple of minutes introduction to the talk and then Savas might want to come and get his slides ready whilst that introduction is taking place. Thank you.


Now, in this module, we are going to learn the basics of Tysaphire laser, what is there inside and how to use it. But before that, this is what we have learnt and this is where we ended the last module. We talked about Carlin's mode locking, Carlin's mode locking means because of the Gaussian distribution of a TemM00 mode, you have greater intensity at the center of the beam and it falls off as it go towards the edge. This brings in an intensity dependent refractive index which sort of act cycle lens, it is called a Kerlin's and since pulse light, so it focuses the intense beams and does not focus beams that are less intense. And since pulse light is intrinsically more intense, what this Kerlin's thing does is that it can select pulse light over CW light. You can do it actively by putting in an aperture in the path of the beam, but that is not even required, the optics usually take care of it, this is what we said and this is how pulses are produced. So, femtosecond pulses are produced by Carlin's mode locking without us having to do much. In subsequent modules, we are going to talk about active mode locking where we have to introduce something and get the mode locking done that is we have to use something called acoustic optic device, but here that is not even required, thermal lensing takes care of it. And of course, why is it that we get femtosecond pulses and not picosecond pulses by thermal lensing? Because in femtosecond pulses, intensity is much more, you are mode locking many more pulse, many more modes are locked, that is why pulse width is so small. So, this is what you can get by Carlin's mode locking. If you want picosecond pulses and nanosecond pulses, you have to do something. We said that this is the advantage of Carlin's mode locking, it produces pulses. Disadvantage of Carlin's mode locking is that it also brings in charge which effectively is going to broaden the pulse. So, before we can think of making a laser, we have to correct for this chart. How do you correct for this chart? The answer is very simple. Once again, you can go back to this analogy of computation, I enter a running race with Tanuja. All of you agreed that Tanuja is going to be enhanced down because she is a faster runner. But I do not want that. I want to reach the end point at the same time as Tanuja, even though I am a slower runner. So, if I am powerful enough, what will I do? I will make her run more and I will run less. I will take a shortcut, I will not let her take a shortcut. So, difference in speed has to be compensated for by altering path length. It is that simple and that is what is done to compensate for charting. What you have to do is whichever path, whichever light is leading has to go through a longer path. The frequencies that are trailing have to go through a shorter path. And this is done quite easily by using a prism pairs. In fact, it is enough to use one prism pair. I am going to show you an arrangement using two prisms. But what is more common and what we have inside the laser we use is two pairs of prism. And the job of this prism is to do compensation for what is called group velocity dispersion. What is the meaning of group velocity dispersion? The separation in time of different frequencies due to different velocities in medium with a finite refractive index that is called group velocity dispersion. We are trying to compensate for it. So, what do you do? Say you have a chart pulse that has gone in. You can see the chart right here the wavelengths are more, here the wavelengths are shorter. Lesser frequency on this side, lesser frequency on this side. So you make it go through a prism. Everybody knows what happens when it goes through a prism it gets dispersed. Then introduce in the path of the light another prism which is facing opposite and the angles have to be same. Then what will happen is look at this path. What is this color on this side? On the top, green, red. What is the color at the bottom? Yellow. So, what we are showing here is that red has travelled less and yellow has travelled more. Then you put this then it will become a collimated beam. And I will show you in a moment what the advantage of using two prism pairs is. And then it goes to another prism pair. Then again they are brought together and it goes out as a beam. So, here the inherent assumption is that the light marked in red is trailing and the light marked in yellow is leading. So, we have given a bigger path length to the yellow beam, yellow I am not saying yellow color the color that I have used to depict the beam here. And I have given a smaller path length to the frequency that I have depicted in red. So, if red was trailing with respect to yellow in this region then that would be compensated for. Have you understood? So, this is how GVD dispersion is done. Are we clear? Now what is the advantage of using two prism pairs instead of one? The advantage is you can have tunability. How do you have tunability? And this is what we have in our tsunami laser when we open it up the next day we are going to show it. In tsunami laser or many other lasers which are tunable what you do is you introduce a slit in this portion that is why you require a collimated beam otherwise it will be very difficult to calibrate. Suppose you have this slit in this region. Then this part of the light is going to go through other part will be blocked so that will be the modal wavelength. If I move the slit I made some animation but I think I have goofed it up but I think you can understand. If I move the slit the way it is drawn here vertically I bring it down then the light that is depicted in yellow will go through to a greater extent. Move it up. That is depicted in red will go through to a greater extent. This is how we get tunability and I am going to show the picture of a laser at least today there we will see how we do it and when you open it up we will see it even better. This is the advantage. If you use only one prism pair then it is difficult to have tunability. Then it is whatever the system gives you the spectral maximum. But advantage of using two prism pairs is in addition to compensating for GVD you can have a tunable output. Now the laser that we use in our laboratory is a titanium sapphire laser. What is the meaning of titanium sapphire laser? Sapphire I think we discussed earlier what is sapphire? What is sapphire to a chemist and what is sapphire to a layman? To a layman a sapphire is a precious stone right. You make a pendant out of it or you wear it on a ring to a chemist what is sapphire? Aluminum oxide with some doping right. So here the doping is titanium. So you can read how it is made it is a titanium oxide, aluminum oxide melted together and so on and so forth with particular level of doping. Aluminum oxide is the matrix. It is a titanium ion that is the actual active ingredient. There can be other depictions of the energy levels but this is one that is there in tsunami manual and this is what describes the system fairly well. Ground state is a doublet T2G, excited state is a doublet EG okay and when you excite you excite use I am going to show you the spectra you excite at say 530 nanometer or so you can excite there. But then post excitation there is an ultrafast relaxation to the zeroth vibrational level and this is where the emission occurs from. And you can see that the equilibrium bond lengths well the minima of the two potential energy surfaces not a good idea to talk about bond lengths right now but minima of the potential energy surfaces are not in the same position right. So when the emission takes place from here this is where you reach. So this energy gap is more or less 800 nanometer equivalent that is why you excite using green light and you get what they have called IR light. See it better in this absorption and emission spectrum right so you can see absorption spectrum is more or less from 400 nanometer to 650 nanometer the maximum is somewhere near 500, 550 that region emission starts at 600 nanometer maximum is at about 800 nanometer and it goes all the way up to 1050 nanometer or so. So this is what you get to play with you can excite anywhere here and you can get emission anywhere here usually one uses 532 nanometer excitation because that is a very robust laser that is already available new medium ELF or new medium YAG laser that is that technology is so robust that it does not make sense to try to pump with anything else in any case it more or less matches the absorption maximum okay. So that is your pump laser pumping is CW in this case you do not we are going to talk later on about cases where pumping is by a pulse laser but not in case of a titanium sapphire oscillator pumping is by CW green laser okay and this is where the emission takes place. Now looking at this diagram the energy level diagram can you tell me what kind of a system is it is it 2 level 3 level or 4 level system 4 level system what kind of output do we expect from 4 level system continuous way right. So intrinsically you expect titanium sapphire laser to give you CW output and it does mode locking takes place because of your car lens effect and so on so forth. Now with that background let me show you one of the earliest successful designs of a titanium sapphire laser this is called the mundane captain design captain and mundane are two professors of I think University of Colorado at Boulder but they have for a long time now launched a company which is quite successful not so much in India but across the world it is called KM labs and claim to fame of KM labs was this kit that they used to sell at one point of time where you have everything that you require to build an oscillator and you are supposed to put it together and make a titanium sapphire laser yourself that kit is still is available once again on demand this is very simple design but it takes bigger space. So this captain modern laser takes up say 2 feet by 2 feet kind of space on the laser table leaving out the pump laser so square is kind of design. So this is how it works pump laser comes in and then you see one thing that we will say without going into much detail here is that for solid state lasers pumping has to be coaxial for die lasers it is okay if the axis of lasing is this and you pump like this not so for solid state lasers. So pumping has to be more or less along the same line same axis along which lasing takes place so that is achieved always and I am going to show you the ray diagram of our own tricepile laser later it is always used by using one mirror that is your dichroic allows green light to go through does not allow red light to go through so this M3 mirror that is shown here it is a dichroic mirror green light goes straight through in fact even M2 and red light is reflected okay so this is your pump from 530 nanometer typically 4 watt, 5 watt, 3 watt whatever it is CW it is focused on the laser rod the titanium sapphire rod which is shown here as a red trapezoid okay and then emission from this laser rod is captured by these 2 mirrors these are concave mirrors I hope you can see and then they are focused back onto the rod so see we talked about card lens mode locking so this is what sustains mode locked operation even without using a using your an aperture because something the mirrors are aligned in such a way that they are exactly focused where this pulse beam is supposed to get focused so anything that is not focusing will not be in the axis of tracing that is how CW is gotten rid of sometimes there is a little bit of CW contamination you have to play around with the optics and get rid of it okay so now let us go one by one let us take M2 to start with okay M2 catches this focuses it here and then it goes this side goes through a prism pair you see here in this design there is only one prism pair what does it mean you do not have to know ability then it goes and hits M4 which is a plane mirror and it is M4 exactly at right angle so then it is sent back it retraces its path it is focused here from M2 it goes to M1 again M1 is a plane mirror and then it goes to an output coupler which is a partially reflecting mirror through which you get the laser out okay quite a simple design not very difficult to make provided you have all the distances right and that the reason why Captain Martin Kidd became such a hit is that everything was specified so just it was like Lego you have to put things together in the right place and you have your laser and to always titanium sapphire laser starts operation in CW mode because it is 4 level laser right so you have to bring in some kind of disturbance in the cavity that is what kick starts pulse operation so the way in which so well I should say that this figure is from PhD thesis of DS English who is a professor in somewhere in the US right now forgot exactly where and I have used this laser as a poster so what we would do is we would tap a mirror it is an open laser unlike what we now use so go and tap a mirror like this or just disturb the mirror a little bit and then mode locking is done. What we have in our lab looks significantly more complicated in fact if you look at the manual it looks even more complicated because other components are included there I have that is what took a lot of time today I had to erase all those things that we do not have let us see if we can understand the optical layout of the spectrophysics tsunami laser that we use in our lab other lasers from coherent and other places have more or less similar layout but every company has its own design so here we will spend a little time on this because we want to understand exactly why what each component does so you have the pump beam coming in from here on the left there is a Brewster window when we talk about non-linear optics we will discuss Brewster effect goes in so this is the entry point of your tsunami laser go straight P1 means P for pump P1 is a green reflecting mirror so that so P1 as you see is a plane mirror goes to P2 which is a focusing mirror because your pump beam also has to be focused at the crystal for optimal operation P2 a curved mirror concave mirror then see it is going through M3 for the same reason that I discussed when we talked about Captain Martin and design M3 again is a dichroic mirror allows green to go through reflects red and it is see it is more or less coaxial so it goes hits tricepher rod and then it goes straight I am talking to the pump beam now pump beam goes through M2 which is again a dichroic mirror and then there is a beam dump that is where it hits and then it has no further role from this tricepher rod emission takes place once again similar to Captain Martin and design you have 2 mirrors M2 and M3 and here you have the high reflector M1 plane mirror the job of plane mirror is to just send it back send the beam back and make it retrace its path then from there it goes to M3 M4 which is a plane mirror M5 which is a plane mirror and then it goes through what we have discussed already 2 pairs of prism what is the job of 2 pairs of prism GVD GVD compensation and this here is the tuning slate in the portion where the beam is a collinear okay. So basically when you change color using a micrometer screw gauge you move this slit up and down this is actually vertical then M8 M9 well this is the prism pair this M8 M9 are actually increasing the length between P3 and P4 well PRC and PR4 then there is something called acoustic modulator hold on we will come back to it and then it goes to your output coupler and then it goes straight there is something called beam splitter here and first photo derived here we will see what they do but before that suppose you have a tsunami laser here of course we have not had much problem over the last 12 years that we have had it but suppose your laser is not lasing it has happened once or twice how do you get it to lace and this is true not only for a ties of a laser any laser whose cavity you have access to how do you make it lace generally you do not have to do much with the pump beam but you must ensure that the pump beam is horizontal in any good alignment all beams have to be horizontal unless for some design purpose they have to go like this otherwise horizontal it is very very important and here you can see why it has to be horizontal if it is anything but horizontal the entire path gets messed up okay so horizontality of pump beam is an issue then okay now tie sapphire emission is there it is not lacing you put in a card there you will see the fluorescence on the card provided your eyes are not as bad as mine you have to be able to see red nicely okay so you can there are two arms is not it one arm towards m2 one arm towards m3 first thing to do is false on m2 hits m1 and comes back right you have to ensure that m1 is aligned in such a way that the beam retraces its path how do you do that take a white card and punch a hole in it right hold the card in this beam and make sure that the beam goes through while coming from m2 to m1 now when it goes back let us say this is the hole in the card this is how the beam goes from m2 to m1 hits m1 comes back now if it is not going to if it is not retracing its path it will hit here or here so you can see it on the card then you have to play around with controls of m1 so that it goes through this right then this m1 m2 segment is aligned you have to do the same thing here because fluorescence that is captured by m2 has to retrace its path while going back to the crystal and of course you understand the moment you touch m2 not only is the tie sapphire rod to m2 alignment changed m1 and 2 align to also get changed so you might have to do it more than once several times do the same thing on this side and then see the beam goes this way and comes back so once again you have to take your card with the hole somewhere here between m3 and m4 play around with m4 control and make sure that your light going in this direction and this direction travel in the same path when that is done take out the card you will see lazy this is something that unfortunately we do not have to do on a daily basis anymore I am saying unfortunately because once you do it you become an expert in alignment if you do not do it it is a black box and if you ever have to do it somewhere it requires a little bit of practice of course now as we are going to show at the end of this module things have become toys you cannot do anything so maybe that skill is not even required anymore this is what the laser looks like and again we are going to go to the lab and see it we have seen it once already see what you have is this is the side through which the pump beam enters no sorry this is the side through which the pump beam enters from outside you just see some controls in our laser we do not even have this birefringent filter wavelength selector this is a generic diagram we have these two knobs what are these two knobs these are vertical and horizontal controls of the high reflector which one is the high reflector this one right so this blue and green knobs that are there green is for earth horizontal blue is for sky vertical so these are horizontal and vertical controls of the high reflector that is what one usually plays around with in the other end we have similar controls for the output coupler generally we do not touch it because the moment you touch both you are sort of shifting the beam completely and you are not careful it can get misaligned but sometimes we do have to touch output coupler because condition of the lab can change from time to time okay we do not have this gti dispersion thing we do have these two micrometer controls here one for prism dispersion compensation one for wavelength selection what are these two micrometer controls one of them changes the distance between the prisms so when you change the distance between the prism you are essentially changing the path difference among the different modes the other one moves the slit up and down okay so by moving the slit up and down you select the wavelength the modal wavelength and by playing around with the distance between prisms that is how you maximize gvd compensation and ensure that you get a good optimal pulse now there are some problems with this tsunami kind of laser one problem is that the cavity is not sealed so if your lab is not absolutely dust free dust can get in and spoil your optics so regular cleaning might be required fortunately that is not the case in our case and for that is not the case for almost all ultrafast labs in India nobody would invest so much in a laser and keep it in a dirty room but there is another problem of the cavity being not sealed the problem is that no matter how much you try you cannot have a room that is absolutely dry a relative humidity we use demeritifiers and all but at most we can go down to 40% it is important that we go down to 40% but then you can try and use in industrial demeritifier and go down to maybe 15% but that is not good for your health nose bleeds have been reported in labs where too much of dry atmosphere was maintained so some moisture will be there okay even if it is 14% and water absorbs in the region of 950 nanometer onwards so if you are going to tune it then you do not want moisture in the cavity so tuning tunable range is severely affected by the presence of moisture so in a tsunami kind of laser if you want to go up to say 1000 nanometer output then there is no way other than purging the entire cavity with dry nitrogen and we have done it a couple of times and I do not want to do it ever again the one nitrogen cylinder gets over in one day you do one day is experiment the cylinder is always on right and it is an open cavity nitrogen is going out so it is first of all it is cumbersome and secondly it is very highly nitrogen intensive I do not want to do it so because of these problems and also the other issue is technology is moving in a direction where everything has to become a black box user should not worry about how things are of course the purpose of a course is exactly opposite but that is how things work you are a biologist working on two photo microscopy you do not really want to know about modes of lasers and how they are coupled and so on and so forth so this is the state of the art and we have shown this already when we went to the TCSPC lab earlier so everything is sealed in a container advantage of this is that you can have full range of tunability 690 nanometer to 1050 nanometer at the click of a mouse disadvantage is anything goes wrong inside this the laser has to go back to the factory because it is hermetically sealed it cannot be opened anywhere other than the factory where humidity temperature everything well air quality everything is maintained very rigorously. The question that one that should come to one's mind and this is actually a laser in which you have the pump laser on one side and you have the tie sapphire laser on the other side now we should have a question when we see this this year is the laser driver why we had said earlier that you need some kind of a cavity length to have pulsed operation round trip time and so on and so forth. So, in such a small thing how is cavity length maintained and that is the diagram I was looking for and unfortunately did not find this morning we find it I will into it in the presentation and upload. So, what you have there is that you have this tie sapphire crystal and you have two large mirrors and the alignment is such that the light bounces off these mirrors many many times. So, even though the separation between the two mirrors is not much the effective path length is the same as what it is in tsunami that is how compact seal lasers like my tie work okay. So, what we have done today is we have started with principle of mode locking recurrence mode locking and we have given you a little bit of idea about construction of lasers we have not talked about certain things yet one is if you remember that diagram we have not told you what the fast photodiode does we have not told you what the meaning of AOM is. So, in the next module in the next module we are going to go to the lab open up tsunami and show you after that we are going to talk about what acoustic modulators are how they can produce pulse speaker how they can produce pulse operation I told you already that you do not really need the acoustic modulator in this cavity why is it still there is still there because there is this technology called regenerative mode lock and we will discuss that after we have talked about acoustic modulators and we will also talk about electro optic modulators like Pockel cell which can give you not short pulses but large pulses but in this context which are useful in switching the laser pulse outside the cavity once we are done with this discussion we will talk about how amplification of laser is done and then we will talk about optical parametric amplification okay so much for today.


This is William Taylor, Taylor, former U.S. ambassador to Ukraine and senior military analyst and retired Army four-star General Wesley Clark, former NATO Supreme Allied commander. General Clark, I want to start with these 8,500 U.S. troops. What is the purpose of a possible deployment like that? I mean, is it really just to send a message to Russia or are there actual tactical reasons for it? Well, there might be tactical reasons, but the first purpose is to send a message to Russia. It's a message of NATO resolve. The 8,500 U.S. troops that are on alert would be matched by at least 8,500 troops from our allied nations. And there's nothing that signals resolve better than deploying troops. Now, if you want to make a difference, you've got to put airplanes in. We need a NATO composite air expeditionary force into Romania. That way we could actually backstop our allies, and we could prevent any spillover of Russian actions in Ukraine. But I suspect that will come. I'm sure it's being planned. Master Taylor, I mean, thus far do you think Russia is engaged in diplomacy in good faith? Is it a stall for time? Is they apparently are moving more troops into position? As you know, I don't think you can say it's they're operating in good faith. What they have been doing is they've been willing to sit down and talk with first Deputy Secretary Wendy Sherman and President Biden has been involved, of course. Secretary Blinken has been there to see the foreign minister. So they've been going through the motions. They've got demands, as your report just indicated, that are untenable, that are not serious, that will violate principles that NATO and the United States and European Americans have lived by, which is a principle of sovereignty. We're talking about Ukraine as a sovereign nation. It gets to Jews. And this proposal, these proposals from President Putin, would deny that clearly. General Clark, I mean, part, you know, one of Russia's huge concerns is Ukraine joining, ultimately joining NATO. And there is a path forward for that, for Ukraine. How likely do you, I mean, do you think this, what's happened, makes it more likely that down the road Ukraine would be allowed to join NATO or less likely? Oh, I think it makes it more likely. I think what Putin has done is energized all of the alliance to recognize that we need strength and resolve to cope with Russia. You know, when we started NATO enlargement back in the 1990s, we actually invited Russia to join. Now, Russia wasn't quite there as a democracy, but we were prepared to work with it. But the Russians insisted no, they wanted to view NATO as an adversary. I went to Russia. I talked to generals over there. They told me we want our countries back in Eastern Europe, so they're not your countries. And this is the fundamental problem. So is Russia negotiating in group faith? Well, they certainly want anything we'll give them. But this is about the structure of the world, whether nations have the right to choose, whether a nation's borders are sacrosanct, whether other nations have the courage to assist in that nation and self-defense if necessary. Putin's raising all those issues. He's headed to get an answer he won't like. But he does have the military power to cause a lot of damage and kill a lot of people. I hope he doesn't do it. Yeah, Ambassador Taylor, from your knowledge of Ukrainian forces and their capabilities, and obviously it's been bolstered over the last several weeks with different kind of weaponry, what would an invasion end up looking like? I mean, we've talked to some people who say this could be another Afghanistan for Russia. There's such antipathy toward Russia among parts of Western Ukraine and elsewhere. What do you think are the capabilities of the Ukrainian people and the Ukrainian forces? As in the Ukrainian military is much stronger, much stronger today than it was when Russia invaded the first time in 2014. It's better led, it's better equipped, it's better trained, morale is high among the military. And you asked about the civilians, the morale is also very high among civilians. Since 2014, when Mr. Putin invaded the first time, the Ukrainian people have come together exactly as General Clark said. He has generated the opposite of what he was interested in. General Clark is exactly right that Mr. Putin has done the opposite of what he's interested in doing, which is he has united Ukrainians, certainly the military, and united the civilians on East and West, no matter what language they speak, he's united them against him. So they will resist. General Clark is, of course, right. The military is an imbalance. The Russian military is very strong. They will have a battle on their hands, but they could prevail if they decide to go, if he decides to go. Mr. Putin has the decision. We hope he's deterred. We hope that he will cost up, he'll take a look at the cost and benefits and decide it's just not worth it better to sit down and have that conversation that President Biden and Secretary Blinken were talking about. But if he does go, if he is not deterred, then he will have a fight on his hands. First with the Ukrainian military, as we just said, but also the Ukrainian people will resist, will fight guerrilla warfare. They will fight in the villages, on the streets, in the towns. It will be very difficult. It will be a former defense minister that General Clark and I both know said that the Ukrainian military will make it hard, but the Ukrainian people will make it hell for an occupier. General Clark, do you agree with that? Absolutely. But you know, Anderson, we've got to make one other point here, and I know Ambassador Taylor will agree with me on this. What Putin's doing is illegal. It's against international law.  And you know, we need to go to the United Nations and call him out for it. He will become an international pariah. Russia will be treated as a rogue state. It's the end for Russia if he does this. We need to make sure he understands that, and then we need to be able to follow through. General Clark, Ambassador Taylor, I appreciate your expertise, both of you. Thank you so much. Coming up next now, now that we've learned.


Everybody for a steer upping 2023 boom and chrome. I'm not bum a chrome. Sorry. I didn't change the title here select hobby prism draft choice mixer here So force prism draft choice in 2324 and to select hobby from 2223 Six bucks mixer random teams. Let's random and then we'll rip. Good luck everybody eight times on our random four and four one two three four five six seven and eight Fill K down to Ezekiel and then eight times on the teams One two three four five six seven and eight Clippers down to pistons. You'd use a another mix in her at the end touchdown here.  I'm a mixer. Here's a link for the results About 21 total spots left for tonight guys. All right, let's do the prism draft choice first four of these Nebula come on Nebula that's right. That's right. You got a silver Tatum Silver rookie Colby Jones with a KJ Williams autograph rookie green choice one of eight Nice start. Well, thanks for sure about prism draft a lot of low numbers in this stuff KJ Williams is a he's part of the Thunder organization, right? I know he's G League right now Yep, nice hit for the Thunder Louie yellow green Jacoby Walter Jason Tatum Colby Jones Red very nice scoot Henderson numbered 42 of 88 Blazers hell of a box Congrats Portland. Love it Scoot to 88 They rated prospect Donovan Klingon green four of eight That is gonna be part of a random at the end I would say tiger tiger is my favorite choice parallel outside of Nebula. There we go. There we go at the end reception There we go Update that speaking of tiger. We got one We got that Silver's of KD she could be Walter Demption is Kobe buff can I believe Hawks choice signatures red Kobe buffkin. Yes Hawks Blue yellow green Russell Westbrook Matas Bazellus Kevin Durant Red Derrick Whitehead rookie for Brooklyn there Go Brooklyn out of 88 And for Brooklyn rookie Tiger striped to wreak Whitehead Pat's gone and NT NT is it seven to go seven to go on NT Let's go Choice been good so far they said screw this we're stopping the run Silver pat Ewing try young Is it Christian a later auto out of 40? He would go to the wolves Hawks. Where would leitner go it's wolves, isn't it? It is Wolves over Washington they played force he played four seasons of the piece but Games tiebreaker goes to Minnesota 276 to 206 games played Tricolor case and Wallace rookie Evan Mobley Shaq Red Victor Wembanyama San Antonio Rookie card 11 of 88. Oh My Whoo, Barry Barry grab five. I think the last five or something like that. I can't remember Actually, I think it was last time either way. Congrats, Barry It's what we like to see right there Red Scoot red Wemby red 88 is Steph Curry as well for the Warriors Blue yellow green Rainer Rainer prospect KJ Evans. Man choice bring in the heat There's a jump baller down inside the five now Punch it with ETN. Let's go But our guy Travis out there get Travis out there. Let him run it in Sonogo and Mitchell Turquivion Smith green choice auto number to eight It's a query on Smith Or is that not a cash Where it's one terrible terrible terrible Sixer to query on Smith blue yellow green bird Steph That woman red Keegan Murray Kings 88 and a rookie Marquise Noel on the tiger Marquise Noel is for the Raptors There's like a we'll send a boxrapper with the 76ers for the Sixers It's like a weird scuff like Marquise not like a roller line because the roller line would go this way We'll send a boxrapper strap to get that one in place if you wanted to two slight hobbies now Jags blew it. Oh, they needed to feel the wind right should get a mix and touchdown instead That's what he do. He's always open He's always open All right, two slight hobbies come on Scope concourse Jalen Green for the Rockets Purple rookie premiere level is gonna be Brandon for the Spurs Out of 99 Murray Silver concourse Jamal Murray for the Nuggets Jalen sucks a 199 go magic Jersey autograph here game-warrant Jersey out of second year scope premiere level Kyrie Well, not about the boss Yeah, silver premiere level Jalen Brown Tricolor concourse rookie Laravia for the Grizzlies Spencer to anybody to 99 Jersey autograph for the Nets go Nets Some peeling right there. I'll send a boxrapper out to the net spot case you want to get that one replaced Purple or orange premier level be able to 65 for the Wizards Tricolor concourse debunk for the Suns Browning's going off the night premier level Tricolor Middleton for the Bucks silver concourse rookie Brandon Spurs Jersey car Jalen Brown Celtics concourse light blue Middleton 2.99 for the Bucks Silver premier level rookie chat Holmgren for the Thunder silver chat that's one Slug off football to fill up everybody still have football to fill up Another spot for iMac just came in Viking sold in NT. We're down to 12 and 6 to go now 12 and 6 to go 18 total spots for the night dude. We have Washington and Pittsburgh discounted heavily It's that Monday night mixer madness right there Sam Cassell gold autograph for the Wolves out of 10 nice Cassell white concourse debuck Over to 149 Suns Tricolor concourse Halliburton Pacers Premier level Tricolor Devin Booker for the Suns Silver concourse rookie Jabaris with junior for the Rockets Dyson Daniels Jersey card for the Pelicans Rookie there premier level blue Clay Thompson for the Dubs How was it to 49? No green between his heel Silver premier level Halliburton Pacers Yeah, and then he felt he's like they're like two yards short As he dove after he stepped out Silver premier level rookie Yobich for the heat Being around would be so easy Be so easy Scope from your level Anthony Davis Lakers like just watch the game Give me a give me a give me one game trial Palo Bancaro concourse tricolor rookie Caleb Houston for Orlando Sohan rookie neon To 75 hair color match dude. I love that hair color match look at that That's fire your spurs is 75 Silver concourse out of a metro for the cabs. That's got to be worth more money has to be Dubbed there out of 99 is gonna be metta world peace auto for the Lakers Scope concourse rookie Keegan Murray Kings. I was a pretty good overall mixer there We're gonna random every single non MBA card is gonna go to one spot on this break This is the big one here Klingon. There's a few others Klingon eight is the big one Okay, so John grabs Seattle and he appreciates you John sketchy again Four to go on NT now Four to go Packers gone. Thanks to Charlie So we're coming down to like the big it's really weird that we have falcons Steelers in Washington left the Falcons are at 399 the Steelers at 799 Washington at 699 Holy crap all nine and be a card seven times between everybody here Yeah, the full sellout promo is that will rip the break when it sells out That's the promo and we hold chairman's packages horses will give us extra hundred bucks seven times here one two three four five six and seven Bulls up top always getting all nine of the eight cards do a quick recap here Oh, it's third down up there. Yeah, why were they review here for so long? If it was only second down on the play that took a long time to get us here Jesus All right, break free get 70 yards in touchdown The neon color match for the hair there Jeremy so on to 75 Jersey of Dyson Daniels Clay Thompson Jalen Brown Milton Murray Steph a skewed red Malachi Branham red to wreak whitehead Bradley Beal to wreak whitehead Noel autos of a metal world peace Jalen Suggs Spencer Dinwiddy Christian Latiner sir Quavion Smith KJ Williams Hawks Kobe Buffett redemption Red Auto Gold Cassel for the wolves and a red Wembanyama Awesome Wembanyama that does it for the break. Thanks again everybody moving on now to some football


Now, I want to introduce the CDB group. A very good morning to one and all present here. I am Smriti. This is Anushree. This is Raki. And we are from the CDB group. Our project is interoperability between video conferencing and web conferencing. Now, first question that comes into mind is that what is web conferencing? Web conferencing is when we want to talk to a person, like we are using the browser and we are conferencing with a person. It includes, it is application-based and desktop sharing and texting is also included in web conferencing. In video conferencing, what happens is you have to have some requirements, some hardware equipment, a definite video camera, a definite room so that we can share. And both of their clients should have it. Now, we want to interoperate both of them. They both use different protocols. The web conferencing uses RTMP and the video conferencing uses SIP, that is the session initiation protocol. Now what is SIP? SIP is designed to provide signaling and session management. And it performs basically five tasks. It is user location, availability, capability, setup and management. The basic five functions have been described, like first of all the user client will have to register on the SIP client. Then an invite will be called. After the invite, it would be acknowledged by the server. Then if he wants to cancel the call before it has been fixed, we can cancel it. Options are also provided and by means that the session will be declined. RTMP. RTMP, as I said, it is a proprietary protocol and it has been used in web conferencing. Proprietary protocol because it has been owned by Adobe and it is a TCP-based protocol. It can also work in virtual channels and it is active simultaneously, like we can use different channels. The basic commands of RTMP are net connection and net stream. So net connection, we have to connect it. Like sockets have to be connected, connect, call, close and create stream. And when you want to play, play, delete stream, close stream, receive audio, receive video. So I will pass on the mic to Raki to explain more. Thank you, Smriti. Good morning. One and all present here. So I am here to describe how the SIP and RTMP server actually work and how the translation and transcoding is done by the SIP RTMP server. There is a RTMP that is the web client, there is a SIP client and first of all RTMP client has to register into the RTMP server, SIP client has to register into the SIP server. Then there is a gateway between this, that is the SIP RTMP server, where the translation from RTMP to RTMP is proceed and the transcoding from the RTMP protocols format that is RTMP and SIP protocol that is RTMP is done here. Like there is a transcoding between RTMP to RTMP, RTMP to RTMP, FLV to RTMP, H264 for audio and video like this thing. Then this is the simple flow diagram through which I can tell you this whole story that how the transcoding is and translation is done. Like first of all Alice is a RTMP client and Bob is a SIP client. So first of all he has to register into that SIP RTMP server to on connect command there is a registration of Alice in the gateway. Then after registration there is a OK command from the both the server that you are registered on the both the server. Then after that if RTMP client want to call the SIP client then there is a command that is call invite. So after that inviting the call there is a method invite is going from the gateway to the SIP server and from SIP server it is passes to the SIP client. Then when it reply with the OK then after that the call is accepted by him by the SIP client and then there is a publishing play of that particular packet then the session is created for the streaming of audio and video. Then after that if the SIP client want to disconnect it then there is a command buy from the SIP client and it will be accepted by the RTMP client. So the same process will be done if the SIP client want to invite RTMP client in this next flow. Then this is all about the translation and transcoding through the RTMP SIP server. Then the third party libraries in codec we have used is further explained by my friend Anushree. Good morning all of you. No project is complete without using third party libraries especially when it involves execution of code. So first of all we require audio and video communication. So for audio communication we have used the speaks module. This module we have used because it is more reliable and it can be used by both RTMP and SIP. Speaks is an audio compression format and we have used both narrow band and wide band. The next library that we have used is the RFC 3261. This is request for command. For SIP communication we require the SIP messages to be interpreted and this is done by a library that was developed for the SIP header that involves the decoding of the SIP header and accordingly the messages will be communicated. Then we have restricted ourselves for video communication we have restricted ourselves to the H264 format that is the only codec we are using for video compression. It has a lower bit rate than MPEG 2, MPEG 4 and H263 and it involves also HD communication HD video can be transmitted and it is RTMP is more comfortable with H264 codec. Then we have now we will show the demo that will involve SIP communication to web and web to SIP. We are showing the first from the SIP client. So SIP client is basically a soft phone that we are using that is the Ekiga. So first we have developed the connection. This is the video of the web client that we can see that is Smithies and this my video is I am the SIP client currently. So first we have established the call and this is the audio communication can also be heard. I think video does not allow audio communication but there is audio communication. Now we will show the web client. Web client again uses SWF format we have embedded in this HTML page. What is happening? We will register as RTMP server over there, RTMP and SIP server over there that is an IP that we are using. Then we will call the SIP client like for example her name is Smithies. She is registered in the domain. For example the particular domain is <IP_ADDRESS>. So she will register her address unique address will be Smithie at the rate domain's name. So that is how we will be calling and this is the communication happening. We need a Flash Play plugin for video communication again. So this is her video that is the SIP client now and I am the web client. And now we will have the log like we will explain the log what is happening. So first we will start with the SIP server and then we will start with the SIP RTMP server. SIP server is basically to register the SIP client. So this is showing the registration. Smithie has registered so it will show her name. Smithie has registered the domain name and everything. Then this is how this is the registration going on. Then we start with the SIP RTMP server. This is the SIP RTMP server that is starting. This in turn starts the RTMP server that is the Flash server because we are using Flash Player and this is the socket connection that is established and then the communication will go on. We will see the streaming of audio and video messages once the communication is established. So this is the now again the web client has registered over there. Her name is Anushree. Now we will establish the call. So we started with the call and we will see the streaming. So the streaming has begun. So these are compressed audio and video that is being streamed to the SIP client and to the web client vice versa. So now we come while doing a project we face certain challenges. First of all browser restrictions. We've used Flash Player has restriction like certain browsers do not allow you to access your hardware because we require microphone to be used and video phones to be used of our system. So only STTB through STTB we can do that so therefore that's the reason plugin restriction is like we have used the S264 plugin. So RTMP does not support all the plugins. That's why these are the restrictions that we are facing. Then we have the server restrictions. Again different servers does not allow, they are codec specific, they are hardware specific and then we have the codec restrictions. We have restrict ourselves to certain codecs like speaks, PCMU, PCMA and for video we've used S264. So these are the certain restrictions. What we have learned while doing since it is more of an analysis and implementation project so we have learned about the basic protocols that is the SIP protocol and the RTMP protocols. These are the most known protocols for video and web conferencing. Then we have come across different open source libraries. As we mentioned the Pi Audio for this audio communication, then a request for command that is for SIP communication. Then we have learned about the softwares. We have tried to establish calls using different SIP softwares like Ekiga, Xlite, then Asterisk server over that Zuiper. Analysis like we have analyzed different codes so that we can implement the communication. We can establish the communication both ways like web to SIP, SIP to web and again debugging. There's every project that inverse debugging like if a certain part of the program is not working. So like we debug. So that's all we have learned in the project. Thank you. Ma'am like in business organization, for example like we have a meeting and one of the person is not available, he's outside or she's outside. So like if video conferencing is going on, for video conferencing it's infrastructure based. Like if I have to have a video conference with you, I have to have the same infrastructure as the person. So that imposes the problem. So if it was web conferencing I would have done it from anywhere because it's browser related and it does not require much of hardware. So through the center of probability what we can do, a person sitting remotely can join in the conference and important business matters can be discussed. So that is how it can be used like organization based. First of all this system is a peer to peer based system. We have not implemented this multi-party. Secondly we have restricted ourselves to certain codecs. For example video only H264 communication is there seeing that it is more comfortable with the RTMP side. Then again order codecs are also restricted like we have speaks PCMA PCMU. So these are the restrictions and we like to go ahead with more of the codecs like H263 because they are used by other browsers and other web servers. So we can do that. Thank you.