相位差异散斑成像技术验证实验

Phase-diverse speckle imaging validity experiments

  • 摘要: 相位差异散斑成像综合了相位差异和散斑成像两种图像处理方法,相位差异同时采集已知相位差的离焦和在焦图像,联合恢复目标图像和解算波前相位,相位差异散斑成像是在相位差异的基础上,利用多帧短曝光图像组来解算出它们所对应的波前畸变序列,同时对图像进行恢复,每帧图像组由在焦和已知离焦量的两幅图像组成。为了实践相位差异散斑成像技术,分别在室内和室外做了相关实验,在室内利用变形镜模拟光学系统像差,利用精密位移台移动相机分时采集焦面和离焦面两幅图像,恢复后的图像分辨率提高12%;室外利用某望远镜光学系统,在其后放置分光棱镜将光束平均分给焦面和离焦面两台相机,外触发同时采集短曝光图像,对20 km外的目标成像,经过单帧和多帧图像的恢复,目标图像分辨率得到显著提高。实验结果证明:相位差异散斑成像技术可广泛应用于靶场光学设备测量和地基大口径望远镜的探测成像。

     

    Abstract: Phase-Diverse Speckle (PDS) method integrates two image restoration methods of Phase Diversity (PD) and speckle imaging. PD method collects focused image and defocused image of known phase diverse at the same time, then target image is restored and wave-front phase is calculated. PDS technique extends PD by calculating the wave-front distortion of a series of short-expose frames to restore the images. Each frame is composed of two images with one in focus and the other defocus. To validate PDS method, experiments indoor and outdoor were carried out in the paper. The deformable mirror was used to simulate optics aberration in lab, and the single CCD collected focused image and defocused image at different time by shifting accurate translation stage. The resolution of restored image increased 12% compared with origin image. Outdoor experiment was also carried out. The cube beam splitter was used to divide the beam into two ways, one for focused CCD and the other for defocused CCD, and cameras were externally triggered to collect short-expose images at the same time. Images of target which was 20 kilometers away were collected, and image resolution was obviously improved by single-frame recovery and multi-frame recovery. Experiments confirm that PDS method can be widely used for optics equipments in shooting range and large aperture ground-based telescopes.

     

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