Research On Chromatic Confocal Displacement Sensor

Spectral confocal measurement technology is a measurement technology based on wavelength carrying displacement information.It has a good development prospect in the field of precision manufacturing.Among them,spectral signal processing is the core part of measurement system,which has a very important impact on measurement accuracy and resolution.The measuring system uses optical fiber coupling technology to import the LED white light through the collimating lens into the dispersive lens,focusing the different wavelengths on the different positions on the axis,focusing on a monochromatic light reflected from the surface of the measured object and reaching the spectral analysis system.After the spectrum analysis system receives the spectrum,it is due to each wavelength.Corresponding to a distance value,we can calculate the displacement value by determining the wavelength value corresponding to the peak value of the spectral curve.Thecontentsinclude:1、we use the wide spectral fiber light source(LED white light)to import the new focusing lens system by optical fiber.Based on optical color aberration focusing system design.The design is simulated by Zemax software,and the central wavelength is 550 nm.This design is optimized by setting optimized target and operating number(such as focal length,spherical aberration,axial color difference,etc.)to simulate the focus of the lens under different directions of parallel light,and provide an analysis basis for the feasibility of the design.2、the integrated spectral detection system based on high density grating is designed,using reflected grating to divide the light,using one dimension CCD to recognize the spectrum,design the whole hardware signal processing circuit based on FPGA,and improve the signal to noise ratio of the spectral detection signal based on the adaptive wavelet denoising algorithm,so as to realize the high speed of the spectral signal.Precision processing.3、the mathematical model of continuous spectral precision displacement sensor error is established.The error compensation program and the signal demodulation are complicated.A large number of data operations and real-time requirements need to be processed with high MIPS FPGA chip.High speed data processing and data fusion technology are studied,and high speed signal demodulation and error interpolation are developed.The parts are burned in the FPGA chip to meet the real-time and highprecision measurement requirements.4、the system test platform is set up and measured.The whole calibration system is to be placed in the Central Laboratory of constant temperature to reduce the influence of temperature change on the measurement accuracy of the system.The system calibration is divided into system resolution calibration,system accuracy test calibration and system dynamic performance calibration.System resolution calibration is based on highprecision positioning platform,which provides high resolution micro displacement to test the resolution of R & D sensor.The dynamic performance of the system is calibrated,and the dynamic performance is tested based on the vibration platform.The results are compared with the laser interferometer,and the test results are analyzed.