Development Of High Precision Transmittance Testing System For Japanese Blind Filter

As core component of solar blind UV detection system, solar blind filter can effectively filter the light of its response waveband expect solar blind ultraviolet, which can reduce the impact of UV radiation expect solar blind ultraviolet. Transmittance is an important performance parameter of solar blind filter. However, apart from solar blind ultraviolet, the transmittance of solar blind filter is extremely low. It is about 10-10, which brings difficulties for filter transmittance testing. In this paper, after in-depth study of filter transmittance testing technology, the filter transmittance testing system based on photomultiplier tube and the filter transmittance testing system based on ICCD photon counting have been developed respectively.Firstly, this paper introduces the concept of solar blind UV detection and the status of UV detection development at home and abroad, and summarizes the development situation of solar blind filter transmittance testing. Then, according to the high-precision requirement of the filter transmittance testing system, a filter transmittance testing method based on photomultiplier tube has been proposed. In this method, using the optical modulator and the lock-in amplifier can inhibit dark noise and spurious signal effectively. Selecting the laser pump source can not only achieve the wide spectrum test, but also make up for the lack of single-beam transmittance test method. According to the proposed method, the corresponding hardware platform has been set up and the debugging between software and hardware has been completed. Next, according to the photon counting technology and the working principle of ICCD, a filter transmittance testing system based on ICCD photon counting has been developed. After the multi-frame accumulation processing and threshold binarization processing for the ICCD output video signal, a connected area labeling algorithm is used to counter the photons for the processed image. Eventually, the solar blind filters have been tested. The test result proves that the detectable limit filter transmittance is 10-12, which meets the high-precision requirement of test.