Abstract:Because of good anti-interference , quick reaction, high sensitivity , high accuracy and wide range of photoelectric measurements , it can be used to high-speed shaft rotational velocity for more accurate measurements. Laser can convert the rotational velocity parameter of the shaft into periodic optical signals , high-speed silicon photodiode receives the optical signals and converted them into current signals , as current signals pass through analog circuitry , there output the digital voltage pulse signal , then FPGA-based high-precision digital phase-shifting measurement method is put to measure pulse-width of the digital voltage pulse signals , finally , accurate results are displayed on lcd . The results showed the high accuracy and good stability of measurement, and it is applicable to general high-speed measurement occasions.