In 1960, Theodore Maiman used a ruby crystal in one of these devices not long after Charles Townes created a precursor to one of these objects that produced microwaves.
The rate at which one process occurs in these devices is proportional to Einstein's B-coefficient, and mode-locking can make them active for shorter periods of time. These devices typically require the gain medium to reach a state of population inversion, where there are more molecules in an (*) excited state than not. In 1960, Theodore Maiman used a ruby crystal in one of these devices not long after Charles Townes created a precursor to one of these objects that produced microwaves. For ten points, identify these devices that emit a very focused beam of light.
The rate at which one process occurs in these devices is proportional to Einstein's B-coefficient, and mode-locking can make them active for shorter periods of time.
lasers (prompt on masers, accept light amplification by stimulated emission of radiation) &lt;MS&gt;