In order to measure spectral transmittance of solar-blind filter ranging from ultraviolet to visible light accurately, a high-precision filter transmittance measuring system based on the ultraviolet photomultiplier is developed. The calibration method is mainly used to measure transmittance in this system, which mainly consists of an ultraviolet photomultiplier as core of the system and a lock-in amplifier combined with an optical modulator as the aided measurement for the system. The ultraviolet photomultiplier can amplify the current signal through the filter and have the characteristics of low dark current and high luminance gain. The optical modulator and the lock-in amplifier can obtain the signal from the photomultiplier and inhibit dark noise and spurious signal effectively. Through these two parts, the low light passing through the filters can be detected and we can calculate the transmittance by the optical power detected. Based on the proposed system, the limit detection of the transmittance can reach 10-12, while the result of the conventional approach is merely 10-6. Therefore, the system can make an effective assessment of solar blind ultraviolet filters.
Microchannel Plates(MCP) have been widely used in X-ray detection, night vision and other fields. X-ray detection used
in the field of space usually requires a lot of large area of MCPs. A set of multi-station electron scrubbing and
performance testing device for large area MCP is developed in this paper. Four sets of large area electron source are
designed for electron scrubbing. Aiming at single MCP and dual-MCP structure, the high voltage power system, signal
processing module and mechanical control structure are designed to achieve scrubbing and testing of 4 groups of large
area MCP at the same time. By using this device, the scrubbing and testing of large area MCPs of 106mm in diameter are
achieved. The test results are given and analyzed.
The UV image intensifier is one kind of electric vacuum imaging device based on principle of photoelectronic imaging.
To achieve solar-blind detection, its spectral response characteristic is extremely desirable. A broad spectrum response
measurement system is developed. This instrument uses EQ-99 laser-driven light source to get broad spectrum in the
range of 200 nm to 1700 nm. A special preamplifier as well as a test software is work out. The spectral response of the
image intensifier can be tested in the range of 200~1700 nm. Using this spectrum response measuring instrument, the
UV image intensifiers are tested. The spectral response at the spectral range of 200 nm to 600 nm are obtained. Because
of the quantum efficiency of Te-Cs photocathode used in image intens ifier above 280nm wavelength still exists,
especially at 280 nm to 320nm.Therefore, high-performance UV filters is required for solar blind UV detection. Based on
two sets of UV filters, the influence of solar radiation on solar blind detection is calculated and analyzed.
During the laser cutting of brittle material using controlled fracture technique, thermal stress is used to
induce the crack and the material is separated along the moving direction of the laser beam. In order to
investigated the process of pulsed Nd:YAG laser thermal stress cutting brittle silicon wafer, a
three-dimensional mathematical thermoelastic calculational model which contains a pre-existing crack
was established. The temperature field and thermal stress field in the silicon wafer were obtained by
using the finite element method. During the pulse duration, the changes of stress intensity factor around
crack tip were analyzed. Meanwhile the mechanism of crack propagation was investigated by
analyzing the development of the thermal stress field during the cleaving process, and the calculational
results in this paper are in agreement with the reported experiment results.