Design Of Light Screen Target For Measuring Speed Of Ultra High Speed Targets

Space debris is a deadly killer of space satellites.In order to develop satellite protective materials,it is necessary to launch high-speed flying fragments of 3-5 km/s on the ground,while accurately measuring the speed.The current conventional speed measurement light screen target has a low speed measurement range and cannot meet the requirements of space debris ground simulation systems for high-speed fragment velocity measurement.This paper studies and designs a super high-speed light screen target capable of measuring high-speed flying fragments.The main research contents are as follows:(1)The overall scheme of ultra high speed light screen target is designed.The theoretical model and frequency characteristics of the screen passing signal are analyzed to obtain the signal bandwidth.The method of layering the light curtain and increasing the thickness of the light curtain is used to reduce the response frequency bandwidth requirements of the signal processing circuit.The quasi parallel light source for detecting the light curtain is studied,and the overall structure of the light curtain,the overall scheme of the signal processing circuit,and relevant technical indicators are designed.(2)A quasi parallel light source based on a semiconductor laser and a Fresnel lens was designed.The light curtain formed with a receiving device has a thickness of 5 mm.The irradiation range and uniformity of the light source were experimentally verified.(3)The signal processing circuit of ultrahigh speed light screen target is designed,including power supply circuit,photoelectric conversion circuit,pre amplifier circuit,post amplifier circuit,Nixie tube display circuit and drive circuit.The light curtain is divided into three layers along the height direction,and each layer of light curtain uses an independent front-end amplifier circuit.A Sallen-key bandpass filter circuit is designed.After the three front-end amplification circuits are superimposed,they are amplified by a programmable gain amplification circuit.The gain of the programmable chip VCA810 is controlled by a single chip computer STM32F103RCT6.The gain of the circuit can be adjusted according to different test requirements,thereby achieving sensitivity adjustment.The final signal is driven by the drive circuit and output.ADC alignment display circuit is designed to display the alignment status of the light curtain through AD acquisition of the alignment voltage and digital display.(4)The performance test of the signal processing circuit for developing a light screen target was conducted,including the debugging of the amplification circuit,the display of positive voltage,and the adjustment of sensitivity.The simulated high-speed signal was used to test the light screen target.The test results verified the correctness and effectiveness of the design,and the technical indicators met the predetermined requirements.The design of this paper and the conclusions obtained lay the foundation for the development of high-speed optical screen target speed testing requirements for satellite fragments.