Design And Implementation Of Laser Doppler Velocimeter

The Laser Doppler Velocimeter(LDV) is a kind of precise instrument, which is used to measure velocity of liquid and the moving objects. It is based on Doppler principle of light. It uses particles of the objects to scatter the laser incident on it, then detects the change of the frequency of the scattered light by photoelectric detector. Finally gets the velocity of moving object according the velocity info contained in the scattered light based on the frequency achieved is proportional to the velocity. The LDV has many merits, such as a rapid dynamic response, good space differentiating ability, wide measure range, high precision, its non-contact and real-time operation.In this paper, a new design scheme of the LDV based on double digital signal processors is introduced. TMS320F2812 is used as the main controller in the LDV system and the signal processor. We have designed the circle of preamplifier and filter, the A/D sample circle and D/A output circle. And the communication with PC and the display module are also showed. The algorithm of FFT based on 2 is the main method for signal processing, that combined the C and assembly program, and carried out by DSP. The calibration system is designed based on a finer division technique driven by MSP430F149. This system provides a standard velocity for LDV and it can also be used to calibrate the parameters of optical parts.The preliminary experiment is implemented in the lab, and the results meet the theoretical model well.