PROJECT TITLE :

Heterodyne System for Measuring Frequency Response of Photodetectors in Ultrasonic Applications

ABSTRACT:

The heterodyne interferometer using acousto-optic modulation is presented to live the frequency response of photodetectors (PDs) used in ultrasonic applications by optical ways. The heterodyne signal is served as the excitation source. The measurement frequency additional than 150 MHz can be achieved by 2 serial or parallel connected acousto-optic frequency shifters (AOFSs) within the interferometer. The frequency shift of AOFSs will be adjusted continuously, so that the frequency resolution of the measurement better than five hundred kHz is straightforward to appreciate. The experimental results for 2 PDs with bandwidth one hundred fifty and fifty MHz are mentioned. The presented theme can conjointly be used to characterize the PDs in the frequency range of megahertz for alternative optical measurement applications.