The Design And Research Of Laser Triangulation Thickness Measuring Instrument

Laser triangulation measurement technology has the features of high accuracy,fastspeed,wide application and simpe structure,can meet the requirements of measurementtechnology of high precision,non-contact real-time online measurement in theproducing and processing sites of modern industry.The development of laser triangulation measurement technology field started earlyin foreign countries,in which there are some main representatives as Europe,USA andJapan.In recent years,the market has emerged many products of laser triangulationdistance(thickness) sensor made in Europe,USA and Japan,these products have shownsome superior performances of high precision,strong anti-interference ability and issuitable for the special field of application,but they are very expensive.The developmentof laser triangulation measurement technology started late at home,until today is still inthe experimental and application stage,many famous universities and researchinstitutions made thorough research about laser triangulation distance(thickness) sensorsand achived some certain results,but currently the laser triangulation distance(thickness)sensor made in our country with superior performances on the market is rare,these fewproducts generally have the defect of complex structure,difficult installation and can notmeet the requirements of stable measurement under harsh environment.Currently,in the field of domestic laser triangulation measurement technology,it isthe urgent and difficult problem to design a laser triangulation distance(thickness)sensor with high accuracy,good stability,simple structure,easy installation and can beapplied under harsh environment.This paper designs a direct online laser triangulationthickness measuring instrument of double optical path of PSD,which is based onFPGA(Field programming Gate Array) and has the features of high accuracy,fastresponse speed,compact structure,good stability and so on,the main work is as follows:1. To research the theoretical basis of laser triangulation thickness measurement.The working principle of PSD,the principle of laser triangulation distancemeasurement(direct,oblique and comparision),the principle of laser triangulationthickness measurement.2. To make the thickness measurement plan of system,to devide the underlayinghardware modules.To apply the laser triangulation distance measuring system of double optical path,to use the method of calibration measurement,the system’s hardware includes:theoptical system,stepping motor and its driving circuit,PSD op amp circuit,swichingcircuit and the data acquisition circuit of PSD signal.3. To design the hardware of system.The driving and operational amplifier circuit of PSD,mainly to achieve the I/Vconversion of weak current signal and the post amplification of PSD;the swichingcircuit,to complete the PSD op amp signal transfer;the data acquisition circuit of PSDsignal,mainly to complete the AD conversion,storage,processing of PSD op amp signaland the real time display of thickness values.4. To design the software of system.To complete the Verilog HDL programming and debugging of system’s four majormodule in Quartus-II development environment,respectively,for the initial valuemeasurement module,real time calibration module,real measurement module andthickness’s real time display module.5. To finish the thickness’s real-time online measurement on the platform ofsystem’s software and hardware.To complete the thickness’s measurement by singlepoint single sampling and simple point multi smpling average methods,and to make theanalization and comparision of measurement results of two methods.6. To research the error sources and improvement measures of system’s thicknessmeasurement.To analize the error sources from optical system,properties of measuredsurface,linearity of PSD,PSD op amp circuit,AD converter,environment factor and soon,and to put forward the corresponding improvement measures.