The purpose of this project is to develop a technique that can measure very small changes in optical property of a medium for sensing applications.
Yong Zhang (ECE)
Change in concentration of molecules in a solvent or density of molecules on a surface of a medium can lead to changes in optical properties of the system. This project will develop a lock-in amplifier based technique that can provide much higher sensitivity than conventional CW measurements. In the lock-in based technique, the signal is modulated at certain frequency with a defined phase, thus the noise and interference signals can be more efficiently suppressed. This technique can find a wide range of applications, such as bio- and chemical sensing.
REU Students’ Role
The student will implement the technique by setting up a data acquisition system including a lock-in amplifier, optical chopper, laser or white light source, photo-detector, and computer, as shown schematically in the figure above. The lock-in amplifier will be interfaced with the computer using something like Labview. The student will evaluate the sensitivity improvement between a CW and lock-in based technique.