Research on Laser Triangulation Measurement System Based on PSD
|School||Huazhong University of Science and Technology|
|Course||Measuring Technology and Instruments|
|Keywords||position sensitive detector (PSD) laser triangulation measurement nonlinearity compensation faint electric current preamplification wide range signal inputting|
Laser triangulation measurement is one of the main methods of noncontact measurement. Many questions, have been studied in the measuring system, regarded Position Sensitive Detector (PSD) as the photoelectric sensor. Achieved a circuit for measuring the position of PSD. Base on the characteristic of PSD, combine the principle of the laser triangulation, a signal processing system has been design. Realize the measurement in physical quantities, such as displacement, libration, etc. Nonlinearity compensation. There is nonlinearity between the distance of the object and the distance of its image in the laser triangulation. A new analog signal processing circuit, which is based on the character of PSD, is presented to compensate this nonlinearity. The experiment proves , this problem has got very good settlement. Faint electric current’s preamplification. Because the laser triangulation realizes measurement according to diffuse reflection, the output of the PSD is a a faint electric current. How to amplify it, many elements should be taken into account, such as preamplifier’s chosen, design of PCB, and so on. Wide range signal inputting. light intensity is diverse for different reflection ability, the output of PSD is divers. Control the time of integral to guarantee the output of preamplifier on a rational range. Measurement speed. PSD is quick in response speed, high precision, however, if you want to realize fast and high-accuracy measurement, these are not still enough。The speed of the circuit system is the key to measuring speed, choose the parameter of the circuit rationally, guarantee the bandwidth is required. Systematic error source . some factors, which influence the system precision, have been discussed and analysed. Have made an attempt to improve the systematic precision.