Research On Precision Optical Thin Film Filter For Intelligent Sensing And Machine Vision

With the rapid development of intelligent sensing and machine vision recognition technology,higher technical requirements are also putting forward the development of optical filters to meet the system application.Two most representative devices are selected from the application direction,,you will find the analyzation of the system light source,detection target,photoelectric sensor,signal interference and other information.A new kind of optical filter with better pertinence and adaptation has been designed to achieve better signal light extraction.For intelligent sensing applications,a comb-shaped asymmetric film system is proposed.The high refractive index silicon hydride and low refractive index material silicon dioxide are prepared by sputtering process.The low angle effect band-pass filter device with central wavelength of 940 nm is simulated and designed.While the AOI is alter from 0° to 30°,the central wavelength offset is less than 12 nm.For machine vision applications,according to the system and application environment,the spectral parameters are formulated as follows : central wavelength is 850 nm,full width at half maximum is 40 nm,average transmittance of passband > 80 %,blocking > OD4,blocking range is 300 – 1200 nm.The 850 nm filter is designed with F-P multi-cavity structured film,long pass film and short pass film.850 nm band-pass filter was manufactured by adjusting the deposition process using the thermal evaporation ion assisted coating method.The factors affecting the test transmittance and cut-off background were analyzed,and the parameters such as slit width and integration time of Cary7000 spectrophotometer were set to ensure the test accuracy.The spectral technical parameters such as transmittance and cut-off depth of the plated products were tested.According to the national standard of filter,the environmental tolerance test was carried out.The test results show that the filter meets the design requirements.After the completion of the test,the gap between the design parameters is compared,and the results are systematically analyzed.