The innovation of this paper is combining the micro-nano optical technology and the vacuum photoelectric imaging devices manufacturing. The multialkali photocathode deposition substrate is designed with a meta-surface structure by using the Finite-difference time-domain. According to the nanoimprinting and the atomic layer deposition, the structure of meta-surface can be obtained. Metasurface have the ability of simultaneously controlling the phase of the light by tailoring the geometry of microstructures. The negative loss in the direction of light wave propagation is suppressed, the reflection at the interface between the cathode and the deposited substrate is reduced, and the absorption coefficient of the cathode material to the incoming light is improved. And the absorption rate of the incident light can be increased by 20.5%. The atomic layer deposition is used to prepare the nanolaminate on the surface of the micro-structure. Based on the imaging tube with the meta-surface, the experiment results show that the average value of the quantum efficiency increased by 21.2% in the visible light range and increased by 10.3% in near infrared band respectively, which reaching the international advanced level. A new method is provided to improve the performance parameters of the vacuum photoelectric imaging devices and point the direction for the improvement of the imaging tube. As shown in this paper, the performance parameters of the vacuum photoelectric imaging devices still have great development potential by optimizing the structure of the meta-surface.
The image intensifier is the core component of all kinds of low-light-level night vision devices, which are widely used in security, medicine, biology, and other fields of detection and imaging devices. Multialkali photocathode is one of the important parts of the image intensifier photoelectric conversion. Its optical constant and thickness will affect the sensitivity of the image intensifier. The photocathode material is a chemically active alkali metal (Na2KSb (Cs)). When the photocathode is removed from the high-vacuum alkali source environment of the image enhancement tube, its properties will change. Therefore, it has been impossible to directly measure the optical constant and thickness of the photocathode. In this paper, we established the photocathode optical model with the help of the Snellmeier dispersion model. The optical constants and thickness of the photocathode in the visible band 380nm-780nm are obtained for the first time by the full-spectrum fitting method. The deviation between the fitted value and the measured value is 0.03%, which is in good agreement. The optical constants and thickness of the photocathode obtained in this paper can provide more accurate guidance for the optical system design of image intensifiers. In addition, the method can be extended to the analysis of optical properties of other easily oxidized thin film materials by changing the dispersion formula, which has practical significance in the fields of vacuum optoelectronics and optical thin films.
The microchannel plates are electron multiplier which mainly used in image intensifier tubes for imaging and intensification of the photoelectron image. In this paper, the research models of the funnel microchannel plate are established by the CST Studio Suite software. The whole research model includes the particle emission source, the funnel microchannel plate model with input reinforcement film and the detector module. Under the same parameter settings of the particle emission source, the influence of the input electrode depth of the funnel microchannel plate on the incident particles is studied. The detector module is placed in a fixed position and the electrode depth vary from 0 μm to 7 μm with an appropriate step. Under different electrode depth, the electron distributions on the input surface and at the 7 μm depth of the funnel microchannel plate are obtained. After processing the data, the influence of the input electrode depth on the incident electron distribution is obtained, which lays a foundation for the further theoretical and structural research of the funnel microchannel plate. Meanwhile, the related experiments are carried out for the funnel microchannel plate with different input electrode depth, and the experimental results are compared with the simulation results.
Image intensifiers have been wildly used for military, law enforcement and commercial applications. Its small size, weight and power (SWaP) make it ideal for integration into different systems. Normally, the performance of image intensifiers is measured at room temperature, but it is expected to operate in vary temperature environments. Therefore, it is very important to know the variation of the image intensifiers performance with temperature. Here, we characterize the variation of intensifier photocathode, microchannel plates (MCPs) and phosphor screen over a large range of temperatures. The “bare” tube is connected to high voltage power supplies via cables. The power supplies and all measuring instruments are outside the chamber in order to avoid the influence of temperature. The result could be used to optimize and control the luminance gain of image intensifiers.
Micro-nano structure applied to photoelectric fields were made on high borosilicate glass by the MEMS process. This paper discussed the transmittance characteristics of micro-nanostructures by analyzing the transmittance of high borosilicate glass with different surface states and combining them with the theoretical analysis results. The transmittance of high borosilicate glass with different surface states was tested by an ultraviolet-visible spectrophotometer in the range of 400–850 nm. Through testing and comparison, it is found that the micro-nano structure makes the transmittance of high borosilicate glass obviously different in the test band. The average transmittance has been down 68%, and micro-nano structure can achieve anti-reflection in the specific band. Therefore, through matching the micro-nano structure with the photoelectric materials, the incident light could occur total reflection at the interface between the photoelectric materials and vacuum. Micro-nano structure can improve the utilization rate of light energy.
In this paper, the influence of the microchannel plates (MCP) opening area ratio (OAR) and secondary electron emission (SEE) coefficient of SEE layer on the noise factor of image intensifier tube have been studied. According to the experiment, the influence percentage of MCP OAR and SEE coefficient of MCP SEE layer on noise factor reduction has been obtained. A MgO SEE layer with SEE coefficient of 4.5 was coated on the MCP input side with an OAR of 68%. After being assembled as an image intensifier, the noise factor of MCP decreases from 1.638 to 1.096, and drop 33.0%, which laid a good foundation for improving the signal-to-noise ratio of image intensifier.
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