| Due to the extensive and special use of the ultra-smooth optical element,it has been very important to study the detection technology of the ultra-smooth optical element.In this paper,a detection device is designed to detect the scattering signal caused by defects on the surface of super-smooth components.After deeply studying the bidirectional reflection distribution function and the angular resolution scattering model and combining with the weak optical signal detection technology,a detection system for the spatial weak scattering signal is designed to extract the spatial scattering signal from the background of strong noise.The measurement system uses He-Ne laser as the incident light source and PMT photomultiplier tube to collect the scattering signal,and designs the processing module of the subsequent electrical signal,including the circuit modules of current-voltage signal conversion,voltage signal amplification and filtering,phase sensitive detection and digital signal circuit processing,which can detect and process weak scattering signals in space.In the software part,the cumulative average algorithm is used to calculate the average value of the signal repeatedly,filter out the noise,improves the signal-to-noise ratio of the signal,realizes the data transmission between the measured results and the host computer.Finally,the hardware and software of the whole test system were debugged and tested,and the test system was built.The detection experiment of the scattered signal and the analysis of the experimental results were carried out.The detection device designed in this paper can realize high-precision and high-signal-to-noise ratio measurement of nA-level weak scattering signals at low frequency.The test results show that the standard deviation of repeated test at multiple angles is up to 0.0801 V,and the fluctuation range of signal amplitude is small.The measuring system has a good detection effect. |
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