Date of Completion

Spring 5-8-2011

Thesis Advisor(s)

John Enderle

Honors Major

Biomedical Engineering


Bioimaging and Biomedical Optics | Biomedical Engineering and Bioengineering


This senior project is to design and fabricate a near infrared imaging system using laser diodes for imaging biological tissues. The device will have three major sections comprising the signal source, detection and data analysis sections.

In the source signal section, a circuit would be designed and built which will contain two laser diodes with different wavelengths (780nm and 830nm). Each of the two laser diodes will modulated at different frequencies to enable a spatial coding system. The detection section of the device will have an optical detector channel which will be designed to detect signals from all the laser diodes and reveal their spatial locations. The device will have the photodetectors(avalanche diodes) placed next to each laser diode to detect the back-scattering off of biological tissue, and ultimately convert that analog (optical) signal into an electrical signal. In the data analysis component of the device, an amplifier will be incorporated into the design to strengthen the signal from the photodetectors for proper processing through a data acquisition device, which will be connected to a computer and monitored with LABVIEW® software. This software will programmatically detect the states of each diode and filter any noise using a bandpass filter. The filter will be designed to sort out the specified frequencies and separate multiple frequencies that might be detected by the photodetectors, placing each separate signal on a graph that is displayed on an interactive user interface.