一种日夜两用光学低通滤波器的研制

利用石英晶体的双折射效应和特殊红外截止滤光片设计并实现了一种日夜两用光学低通滤波器.该滤波器置于CCD摄像机传感器前可以有效地降低或消除离散光电探测器对不同空间频率目标成像所产生的拍频效应或条纹混叠现象,并能消除红外光对彩色还原的影响,从而提高了CCD摄像机成像的视觉效果.在分析光学低通滤波器原理和红外截止滤光片作用的基础上,设计了一种特殊的红外截止膜系,可使CCD摄像机白天成彩色像,夜晚成黑白像.采用双离子束溅射技术在石英晶体薄片上淀积了该膜系,经测试,光谱特性满足设计要求,成像效果理想.

Design and manufacture of a day and night optical low pass filter

An optical low pass filter(OLPF) used in front of the sensor of a CCD camera was designed,according to the birefringent effect of quartz crystal and infrared cut-off optical filter.When a object is imaged on the discrete photoelectric detector at different spatial frequencies,OLPF can reduce the frequency-mixing phenomenon effectively and eliminate the effect of infrared light on color rendition to improve image quality of the CCD camera.Especially,when the objects such as fringes or grates are imaged on the sensor of the CCD camera,it can enhance the image distinction and eliminate the effects of the disturbing fringes of false color.Based on analyzing the operational principle of OLPF and function of IR-CUT optical filter,a special IR-CUT coating is designed to make the CCD camera obtain colored image in daytime and black-white image at night.The coating is deposited on thin quartz crystal sheet with double ion beam sputter technique,the measuring results show that the spectral character and image quality are perfect.