Signal Detection And Process Of High-speed Laser Distance Sensor Based On PSD

The development of modern industry put an increased demand on distance measurement. Be different from traditional measurement, high-speed laser distance sensors could take high-speed, high-precision measurement of the distance of high-speed moving target in non-contact way. It will have great significance and broad application in military and civilian applications.This paper presents the design process of high-speed laser distance sensors. The design is based on laser triangulation measurement. We analyse the theoretical model and method of distance calculation of laser triangulation measurement first. Then compare Charge Coupled Device (CCD) with Position Sensitive Device (PSD), choose PSD as the position sensor. If the spot on photosensitive surface of PSD moves, the PSD'S output current will change. Based on this characteristic, we discuss the detail design of signal process circuit of high-speed laser distance sensor after.Traditional signal process circuit of PSD uses plenty of analog devices, which makes it complex and low in accuracy. Design in this paper is processed in digital way. Signal process circuit consists of four departments: power supply, preamplifier, data acquisition circuit and MCU interface. Since the signal from PSD is very weak, choose a linear power module as power supply. Then achieve I/V conversion and per-amplify using resistance and integrated operational amplifier. How to convert analog signal to digital signal is the crux of the matter. In subject, sensor should measure distance of the target which is 1~1.5 meters away with accuracy of 20 centimeters. So choose a 12 bit high-speed A/D chip to acquire data. Micro Controller Unit (MCU) takes charge of control of the sensor, including selecting working state, A/D control, calculation and alarm. Design external circuit using button and LED. Improving traditional average algorithm, propose a new algorithm to control A/D chip, calculation and alarm. At last of design, use optocoupler device, ferrite beads and bypass capacitor to reduce system noise.Finally, different experiments are done to test sensor's performance, including different targets and different illuminations. Experiments prove that prototype could measure the designed distance of the target which is 1~1.5 meters away, performance is improving with increasing of target's reflectivity, illumination have no influence on result. According to regulation of judgement value and cumulative number, the most high-precision could reach to 2.5 centimeters, which meet the request of the project.