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摘要:
为了克服近地面湍流对几十到几百米中长成像距离下光学系统成像质量的不利影响,设计了基于长焦距望远物镜和一体化自适应模块的光学成像系统。在系统中心高度1.9 m及50~200 m的成像距离下,开展了分辨率板的室外成像实验。实验结果表明,在近地面的50~200 m中长距离下湍流对成像质量的影响明显,所搭建的实验系统能够在不同距离下有效克服湍流影响,提高图像的分辨率和清晰度的一致性,但随着成像距离的增加,湍流影响的增大,系统的校正能力降低,成像质量下降。系统在100 m成像距离下的成像分辨率能够达到0.5 mm。在200 m的距离对混凝土模型表面裂缝进行了观测及校正实验,实验结果表明,系统能够抑制湍流影响,提高裂缝图像的清晰度,验证了系统的实际应用能力。
Abstract:In order to overcome the adverse effects of near-ground turbulence on the imaging quality of the optical systems at imaging distances of tens to hundreds of meters, an optical imaging system based on a long focal length telescopic objective lens and an integrated adaptive module is designed. With a system center height of 1.9 m and the imaging distance of 50−200 m, the outdoor imaging experiment of a resolution plate is carried out. The experimental results show that the influence of turbulence on imaging quality is obvious at medium and long distances of 50−200 m near the ground. The experimental system can effectively overcome the influence of turbulence at different distances and improve the consistency of image resolution and clarity. As the imaging distance increases, the influence of turbulence increases, and the system’s correction ability and the imaging quality decrease. The imaging resolution of the system can reach 0.5 mm at an imaging distance of 100 m. Cracks on the surface of a concrete model are observed and corrected at a distance of 200 m. The experimental results show that the system can suppress the influence of turbulence and improve the clarity of the image, which verifies the practical application ability of the system.
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Key words:
- adaptive optics /
- near-ground turbulence /
- wavefront sensing /
- wavefront correction
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图 5 不同距离处校正前后的分辨率板图像,从左到右分别为第1、6、11、16和21帧图像。(a)50 m校正前;(b)50 m校正后;(c)100 m校正前;(d)100 m校正后;(e)150 m校正前;(f)150 m校正后;(g)200 m校正前;(h)200 m校正后
Figure 5. The resolution plate images before and after correction at different distances. From left to right are the 1st, 6th, 11th, 16th and 21st frame images. (a) Before and (b) after correction with 50 m imaging range; (c) before and (d) after correction with 100 m imaging range; (e) before and (f) after correction with 150 m imaging range; (g) before and (h) after correction with 200 m imaging range
表 1 关键器件参数
Table 1. Parameters of key devices
Device Parameter Value Telescope objective Aperture/mm 356 Focal length/mm 3556 DM Aperture/mm 13.5 Number of drives 97 Drive interval/mm 1.5 S-H WFS Aperture/mm 5.85 Number of sub-apertures 1280 Frame rate/fps 100 Wavelength range/nm 400~1100 Microlens focal length/mm 3.5 CCD Horizontal and vertical pixels 2560×2048 Frame rate/fps 62 Pixel size/µm 5 表 2 透镜及棱镜的主要参数
Table 2. Main parameters of the lens and prism
Optical element Focal length/mm Aperture/mm Material L1 90 30 H-K9、H-ZF2 L2 50 30 H-K9、H-ZF2 L3 100 25.4 H-K9、H-ZF2 L4 60 20 H-K9、H-ZF2 BS — 25.4 K9 表 3 不同成像距离的分辨率板在校正前后的PV及RMS均值
Table 3. PV and RMS mean values of the resolution plate at different distances before and after correction
Distance/m PV /μm RMS /μm Before After Pct/% Before After Pct/% 50 4.703 1.745 62.89 1.218 0.384 68.47 100 6.077 2.579 57.56 1.519 0.643 57.67 150 8.822 3.863 56.21 1.927 0.936 51.43 200 31.36 16.58 47.15 7.826 4.105 47.55 表 4 不同距离的分辨率板在校正前后的BRISQUE及PIQE均值
Table 4. BRISQUE and PIQE mean values of the resolution plate at different distances before and after correction
Distance/m BRISQUE PIQE Before After Pct/% Before After Pct/% 50 16.79 11.61 30.83 13.03 9.38 28.01 100 23.37 17.63 24.56 22.05 16.99 22.92 150 32.31 20.53 36.46 27.17 19.9 26.78 200 45.63 36.2 20.66 40.42 35.1 13.16 表 5 200 m处的混凝土模型在校正前后的PV及RMS均值
Table 5. PV and RMS mean values of the concrete model at 200 m before and after correction
Distance/m PV /μm RMS /μm Before After Pct/% Before After Pct/% 200 17.598 4.556 74.11 4.411 0.916 79.23 表 6 200 m处的混凝土模型在校正前后的BRISQUE及PIQE均值
Table 6. BRISQUE and PIQE mean values of the concrete model at 200 m before and after correction
Distance/m BRISQUE PIQE Before After Pct/% Before After Pct/% 200 38.65 21.34 44.79 39.95 24.72 38.12 -
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