Doppler velocimetry for photodetector frequency response measurement

A new method for photodetector frequency response characterization based on laser Doppler velocimetry techniques is reported. The vibration of a commercial loudspeaker in a Michelson-type interferometer is used as a Doppler signal source. Frequencies in the range 0 to 240 kHz are produced but they may be easily extended to the MHz range. The whole measurement is performed in a short time compared to those from usual noise sources. A pin-photodiode is studied to illustrate the method.