In active laser light curtain speed measurement system

sky background light is transformed to form sky screen by optical system. Sky screen seriously interferes output of system signal and affect system sensitivity.Through mathematical modeling and analysis of received light energy of system

an improved method is proposed

and adjustable slit diaphragm is designed. The influence of position and width of different slit diaphragm on light energy received by the system is analyzed under different sky background brightness. By adjusting the relative position and width of the diaphragm

the influence of the sky screen on the system is effectively suppressed

and corresponding experiments are carried out. The results show that when the thickness of the laser light curtain is2 mm

the slit diaphragm is located on the focal plane

and the slit width is 0. 15 mm

the signal-to-noise ratio is increased by 1. 8 times after improvement

the system sensitivity is the highest

and the skyscreen suppression effect is the best.