极紫外波段空间相机的辐射定标

考虑极紫外波段空间相机尚无合适的辐射定标方法和装置,本文提出了适用于该波段的小目标成像辐射定标方法并基于该方法在实验室建立了辐射定标装置。提出的标定方法首先使用标准传递探测器标定小目标的辐射亮度;然后,用待定标相机中心视场对该小目标成像,获得中心视场部分的辐射强度响应度;最后,通过调整转动结构使不同视场对该小目标成像,得到不同区域的辐射强度响应度。构建的辐射定标装置由光源系统、标准传递探测器、真空罐及四维运动转台等组成。光源系统包括空心阴极光源、极紫外掠入射单色仪、准直反射镜,能够出射工作波段的准直光束;标准传递探测器标定出光束照度并计算得到小目标的辐射强度;运动平台使相机能够以不同视场角对小目标成像,测得不同视场的辐射强度响应度。利用该装置对一台极紫外相机进行了辐射定标实验,并进行了误差源分析。实验结果表明该装置的定标精度优于15%,能够实现整机状态下的辐射定标。

Radiation calibration of EUV space cameras

There are no proper radiation calibration methods and devices for EUV space cameras, so this paper proposes a small target imaging radiation calibration method suitable for the EUV band and establishes a radiation calibration device based on the method in a lab. This method uses a standard transfer detector to calibrate the radiance of the small target. Then, a EUV space camera is used to take the small target's image in its center Field of View(FOV) and to get its radiance responsivity. Finally, by adjusting the motion platform, the small target's images in different FOVs are taken by the EUV camera, and the radiance responsivity in different FOVs are obtained. The developed radiation calibration device consists of a light source system, standard transfer detectors, a vacuum tank and a four-dimensional motion platform fixed in the camera. The light source system consists of a hollow cathode light source, an extreme ultraviolet grazing incidence monochromator, and a collimating mirror generating a parallel monochromatic beam. The standard transfer detectors are used to calibrate the beam's photon flux and small target's radiance and the motion platform enables the camera to take the small target's images in different FOVs and to get camera's responsivity in different FOVs. A EUV camera has been calibrated by this device, and the error sources are analyzed. The calibration results indicate that its accuracy is better than 15% and implements the radiation calibration for whole bands.