Development of Visible Multi-Bandpass Filter Based on F-P Structure

In order to reduce the noise interference of smart wearable devices, spectral filtering technology is used to suppress noise. This technology prevents interference signals from entering the detector from the source, thereby achieving high-precision noise reduction processing. According to the system requirements, a multi-bandpass filter with a wavelength range of 400 similar to 1000 nm was designed and prepared on a BK7 substrate. Ta2O5 and SiO2 were selected as the high- and low-refractive-index materials, respectively. By analyzing the -Fabry-Perot narrowband theory, the bandwidth matching coefficient was computed, and the interference order was calculated using the interval of the transmission peak wavelengths. Multiple F-P coating systems were connected through the matching layer to adjust the position of the transmission peak and broaden the bandwidth range. The design was optimized using Macloed film system design software, resulting in the design of a wide half-wave and cutoff multi-bandpass filter. The appropriate preparation process was chosen based on changes in refractive index, surface roughness, and the temperature gradient of the materials. The filter was then produced using Leybold SYRUSpro1110. Sensitivity, filter roughness, and the weak absorption of the film system were tested, and the results met the system requirements.