Li Jin, Tian Shou-Fu
Department of precision instrument, Tsinghua University, Beijing, 100084, China.
School of Mathematics and Institute of Mathematical Physics, China University of Mining and Technology, Xuzhou, 221116, China.
Sci Rep. 2017 Sep 29;7(1):12479. doi: 10.1038/s41598-017-12752-2.
In this work, we report an expedient auto-collimating method for self-measuring the internal parameters (IPs) of optical cameras. Several key optical components, including the thin optical fibre (TOF), reflecting prism, and receiver, are introduced into optical cameras. The TOF outgoing end and area-array image receiver are integrated onto the focal-plane assembly of optical cameras. Different wavelengths of light, which are emitted by external sources, are transmitted to the focal plane through optical fibres. Because one optical fibre can transmit different wavelengths of light, the same position on the focal plane can obtain point light sources (PLSs) with different wavelengths. Then, the optical system of the cameras spontaneously transforms the PLSs into auto-collimating lights. The auto-collimating lights are reflected by a two-plane prism, return to the camera optical system, reach the focal plane and are received by the area-array sensor. Finally, the IPs are calculated based on a mathematical model of the imaging relation between fibre light sources and images. The experiment confirms that this method is efficient and has a level of precision of dozens of micrometres for an optical camera with a short focal length and small field of view. Our method is suitable for on-orbit IP measurements for cameras without spatial or temporal limitations.
在这项工作中，我们报告了一种用于自行测量光学相机内部参数（IP）的便捷自准直方法。将包括细光纤（TOF）、反射棱镜和接收器在内的几个关键光学元件引入光学相机。TOF输出端和面阵图像接收器集成到光学相机的焦平面组件上。由外部光源发出的不同波长的光通过光纤传输到焦平面。由于一根光纤可以传输不同波长的光，焦平面上的同一位置可以获得不同波长的点光源（PLS）。然后，相机的光学系统自动将PLS转换为自准直光。自准直光由双平面棱镜反射，返回相机光学系统，到达焦平面并被面阵传感器接收。最后，根据光纤光源与图像之间成像关系的数学模型计算IP。实验证实，该方法对于短焦距和小视场的光学相机是有效的，精度可达几十微米。我们的方法适用于对相机进行无空间或时间限制的在轨IP测量。
