两种提高扩展信标波前探测信噪比的方法

Methods for Increasing the Wavefront Detection SNR Based on Extended-Beacon

为了空对地观测相机在工作时达到接近衍射极限的高分辨率成像,采用扩展信标和相应的H-S波前传感器探测成像系统入瞳面上的波前畸变,以实现动态补偿.基于这种波前探测、重构的模式下,推导和分析了波前探测系统焦面上子孔径图像信噪比的估算公式.根据模拟实际的一组参数值,表明该图像信噪比过低,不能满足探测精度的要求,继而提出减小探测系统的垂轴放大率和增加测量次数提高图像信噪比的方法,实例计算验证了其可行性.

In order to achieve and maintain high resolution imaging performance in space-based earthobserving system, extended-beacon （extended-scene） and H-S wavefront sensors are employed to estimate the pupil wavefront for compensating the aberrations. Taking this model into consideration, sufficient illuminance of the extended-beacon is required, thus directly constrains the application of extended-beacon to the space-based earth-observing system. By the derivation and analysis of the signal to noise ratio （SNR） formula of the sub-aperture image on the detector array, two methods are proposed to raise the SNR： decreasing the lateral magnification of the wavefront sensing system and increasing the number of measurement. The feasibility of these two methods is shown by a practical example