测量空间相机像移量的联合变换相关器的改进

Improvement of joint transform correlator for measurement of space camera image motion

针对基于光学手段实现的传统光学联合变换相关器不适应空间环境等问题,对传统相关器进行了改进和试验验证。首先,采用完全电子学手段替代采用光学器件实现的方法解决了联合变换相关器适应空间环境的问题。然后,在联合变换过程中加入自相关运算,消除了零级衍射峰的影响,并引入过采样离散傅里叶变换方法提升相关器的测量精度。最后,采用精密直线导轨开展静态测试试验,验证了改进后的联合变换相关器的性能。静态测试试验表明:对于亚像元级的微小位移量,改进后的联合变换相关器测量误差均方根(RMS)值为0.22pixel。改进后的联合变换相关器显示了良好的空间环境适应性和较好的可实现性,其精度基本满足空间相机像移补偿的要求。

As traditional joint transform correlators based on space light modulators can not adapt to the radioactive environment in space, a new correlator implemented by an electronic processor was introduced and testified. First, the traditional optical device was replaced by a digital processor to allow the new correlator to adapt to the radioactive environment. Then, a self-correlation calculation was added to the joint transform processing to eliminate the influence of zero-level diffraction, and the over-sampled discrete Fourier transform method was introduced to increase the measurement precision. Finally, the static measurement with a linear platform was performed to testify the improved joint transform correlator. Experimental results indicate that the measuring precision of the system on subpixel displacement is within 0.22 pixel（Root Mean Square, RMS）. The improved joint transform correlator is good at both space environment adaptability and realization, its measurement precision can satisfy the system requirements of satellite cameras for the image motion compensation, and has agood application prospecl.