Design of Objective Lens for Infrared and Visible Image Fusion by Optical Passive Thermal Compensation
-
摘要: 图像融合的配准精度是关系到图像融合质量的一个重要性能指标。本文所述的红外与可见光图像融合物镜系统采取平行光路布局、光学被动热补偿的方式提高图像融合的配准精度。本文首先分析对比了机械热补偿方式与光学热补偿方式对提高图像配准精度的贡献;其次根据图像融合物镜系统的性能指标对红外物镜和可见光物镜进行光学被动热补偿的优化设计,并分析了对可见光物镜进行光学被动热补偿设计的必要性;第三从光学布局型式及畸变变化来分析图像融合物镜系统的图像配准精度;最后根据图像融合物镜系统的成像质量和图像配准效果,可得出融合图像质量好、能满足指标要求的结论。Abstract: The registration accuracy of image fusion is an important performance index that is related to the quality of image fusion. The infrared and visible image fusion objective optical system in this study adopts a parallel optical path layout and an optical passive thermal compensation method to improve the registration accuracy of image fusion. First, the contributions of mechanical thermal compensation and optical thermal compensation are analyzed and compared to improve the image registration accuracy. Second, according to the performance index of the image fusion objective system, the optical passive thermal compensation designs of the infrared objective and visible objective are optimized. Moreover, the necessity of optical passive thermal compensation design of the visible objective is analyzed. Finally, according to the imaging quality and image registration effect of the image fusion objective system, it is concluded that the quality of the fused image is high and that the requirements of the index can be achieved.
-
Key words:
- visible lens /
- infrared lens /
- image fusion /
- image registration
-
表 1 图像融合系统光学设计参数
Table 1. Optical design parameters of image fusion system
Infrared lens Focal length
Field
F/#
Wavelength
Detector type38.7 mm
16°×12°
1.1
8 μm-12 μm
UFPA 640×480, 17 μmVisible lens Focal length
Field
F/#
Wavelength
Detector type51.22 mm
16°×12°
1.5
0.6 μm~0.95 μm
CMOS 800×600, 18 μmFusion lens Registration accuracy
Distance temperatureOne pixel(0.017 mm)
45.5 m-∞
-40℃-60℃表 2 随距离变化的图像配准精度
Table 2. Image registration accuracy with distance
L/m △d/mm Pixel Notes 30 0.026 1.5 the size of each pixel is 0.017 mm 40 0.019 1.1 45.5 0.017 1 50 0.015 0.88 60 0.013 0.76 表 3 红外物镜与可见光物镜的畸变
Table 3. Distortion of infrared objective lens and visible objective lens
0.5ω 0.707ω 0.85ω 1ω Infrared lens 20℃ -0.61879% -1.24937% -1.83023% -2.59627% -40℃ -0.61847% -1.24882% -1.82957% -2.59568% 60℃ -0.61883% -1.2494% -1.83017% -2.59595% Visible lens 20℃ -0.61071% -1.25465% -1.83872% -2.588% -40℃ -0.61292% -1.25212% -1.83447% -2.5828% 60℃ -0.60927% -1.25632% -1.84153% -2.59143% 表 4 红外物镜和可见光物镜的图像配准误差
Table 4. Image registration error of infrared objective lens and visible objective lens
Theoretical image height /mm Infrared image height /mm Visibleimageheight /mm Error/mm 0.5ω 3.75 3.72680 3.72710 0.00030 0.707ω 5.3025 5.23626 5.23597 0.00029 0.85ω 6.375 6.25832 6.25778 0.00054 1ω 7.5 7.30528 7.30590 0.00062 表 5 红外物镜零件公差表
Table 5. Tolerance table of infrared objective lens parts
Parameter Tolerance N ±3aperture △N ±0.7aperture Aspheric error ±0.00007 mm Thickness of optical parts ±0.02 mm Focal plane displacement compensation ±0.5 mm Surface tilt ±1' Air distance ±0.02 mm Element tilt 4.5' Element eccentricity 0.052 mm - - 表 6 可见光物镜零件公差表
Table 6. Tolerance table of visible objective lens parts
Parameter Tolerance N ±4aperture △N ±0.6aperture Thickness of optical part ±0.03 mm Air distance ±0.05 mm Focal plane displacement compensation ±0.5 mm Surface tilt ±6' Element tilt ±6' Element eccentricity ±0.052 mm nd ±0.001 vd ±1% 表 7 红外物镜公差分析结果
Table 7. Tolerance analysis results of infrared objective lens
Lens percentage /% MTF minimum(Nyquist frequency) 90 0.135 80 0.158 50 0.196 20 0.248 10 0.275 表 8 可见光物镜公差分析结果
Table 8. Tolerance analysis results of infrared lens visible objective lens
Lens percentage /% MTF minimum(Nyquist frequency) 90 0.301 80 0.351 50 0.455 20 0.531 10 0.597 -
[1] 安福, 杨风暴, 李伟伟, 等.基于DWT的红外偏振与光强图像的融合[J].光电技术应用, 2013, 28(2): 18-23. http://www.cnki.com.cn/Article/CJFDTotal-GDYG201302008.htmAN Fu, YANG Fengbao, LI Weiwei, et al. Fusion of Infrared Polarization and Intensity Images Based on DWT[J]. Electro-optic Technology Application, 2013, 28(2): 18-23. http://www.cnki.com.cn/Article/CJFDTotal-GDYG201302008.htm [2] 曾朝阳, 程相正, 陈杭, 等.基于改进SURF算子的高低分辨率图像配准方法[J].激光与红外, 2014, 44(2): 207-212. http://d.wanfangdata.com.cn/Periodical/jgyhw201402022ZENG Zhaoyang, CHENG Xiaozheng, CHEN Hang, et al. Registrantion method of high-low resolution images based on improved SURF[J]. Laser & Infrared, 2014, 44(2): 207-212. http://d.wanfangdata.com.cn/Periodical/jgyhw201402022 [3] 郭李华.基于金字塔和HIS变换的图像融合研究[J].微计算机应用, 2010, 31(11): 67-72. http://d.wanfangdata.com.cn/Periodical/wjsjyy201011011GUO Lihua. Research of Image Fusion Based on Laplacian-Pyramid and HIS-Transform[J]. Microcomputer Applications, 2010, 31(11): 67-72. http://d.wanfangdata.com.cn/Periodical/wjsjyy201011011 [4] 韩泽, 蔺素珍, 赵竞超, 等.基于直觉模糊集的多波段图像融合[J].红外技术, 2018, 40(3): 253-258. http://hwjs.nvir.cn/oa/DArticle.aspx?type=view&id=201711015HAN Ze, LIN Suzhen, ZHAO Jingchao, et al. Multi-band Image Fusion Based on Intuitionistic Fuzzy Set Theory[J]. Infrared Technology, 2018, 40(3): 253-258. http://hwjs.nvir.cn/oa/DArticle.aspx?type=view&id=201711015 [5] 李博博, 马泳, 张晓晔, 等.基于BMA滤波器和边缘的红外与可见光图像融合[J].红外技术, 2018, 40(2): 139-145. http://hwjs.nvir.cn/oa/DArticle.aspx?type=view&id=201706011LI Bobo, MA Yong, ZHANG Xiaoye, et al. Infrared and Visible Image Fusion Based on BMA Filter and Edge[J]. Infrared Technology, 2018, 40(2): 139-145. http://hwjs.nvir.cn/oa/DArticle.aspx?type=view&id=201706011 [6] 张俊举, 常本康, 张宝辉, 等.远距离红外与微光/可见光融合成像系统[J].红外与激光工程, 2012, 41(1): 20-24. http://d.wanfangdata.com.cn/Periodical/hwyjggc201201005ZHANG Junju, CHANG Benkang, ZHANG Baohui, et al. Long-distance image fusion system for infrared and LLL/visible bands[J]. Infrared and Laser Engineering, 2012, 41(1): 20-24. http://d.wanfangdata.com.cn/Periodical/hwyjggc201201005 [7] 孙爱平, 龚杨云, 朱尤攀, 等.微光与红外图像融合手持观察镜光学系统设计[J].红外技术, 2013, 35(11): 712-717. http://hwjs.nvir.cn/oa/DArticle.aspx?type=view&id=201307017SUN Aiping, GONG Yangyun, ZHU Youpan, et al. Optical System Design of Low-light-level and Infrared Image Fusion Hand-held Viewer[J]. Infrared Technology, 2013, 35(11): 712-717. http://hwjs.nvir.cn/oa/DArticle.aspx?type=view&id=201307017