Research On Optical Interference Thin Film Filter For Biomedicine And Life Science

With the rapid development of biomedicine and life sciences,people have higher and higher requirements for in vitro diagnostic and testing equipment.As the core optical component of the system,optical thin film filter plays an important role in light splitting and filtering.Its spectral characteristics directly affect the detection accuracy of the system.Aiming at biochemical analysis and fluorescence analysis,this paper completes the design of filter for real-time fluorescence quantitative PCR（q PCR）and the development of filter for biochemical analyzer.Through the study of the physical and chemical properties of various optical film materials,H-Ta2O5 and L-Si O₂ were selected as the all dielectric materials.The research shows that the common light source of biochemical analyzer is halogen lamp,the detector is silicon photocell,and the detected substances include glutamic oxaloacetic transaminase,glucose,cholesterol and hemoglobin.For the detection of oxygen and hemoglobin,the spectral performance index of biochemical filter is determined and designed.The common light source of q PCR is led and the detector is CCD.According to its detection principle,the common fluorescent reagents include hex,Rox,Cy5 and SYBR Green I.According to the excitation spectrum and emission spectrum of hex reagent,the spectral performance index of fluorescent filter is determined and designed.The biochemical narrow-band filter is prepared by plasma assisted electron gun evaporation deposition process.According to the average molecular free path theory and molecular collision theory,the vacuum degree of the coating equipment is at least 7.4×10^-4Pa。Through the study of process parameters and many experiments,the effects of various process parameters on the film properties are analyzed,and the absorption loss of Ta2O5 and Si O2 films at different deposition rates is studied.It is determined that the deposition rate of Ta2O5 and Si O₂ should be 0.4nm/s and 0.8nm/s;By adjusting the substrate temperature,the physical structure of the film growth is changed to achieve a uniform and compact film,and the substrate temperature is determined to be 200℃.The ability of the film thickness monitoring system of the equipment is evaluated,and it is determined that the plating of the theoretical film system design can be completed.The spectra of 60 biochemical filters are tested.The central wavelength is 546nm,the transmittance is greater than 84.11%,the half width of passband is 7.9nm-8.6nm,and the average background cut-off depth is greater than OD4 at 400nm-1200nm.The spectral characteristics meet the design index.Through the environmental resistance test of the test piece,it is found that the film falls off,indicating that the adhesion between the substrate and the film has not reached the expected results.The plating process parameters are further adjusted and a protective film is added.Finally,all the data meet the design indexes.