On-Orbit Self-Focusing Using Conjugated Optical Fiber Waveguides for Space Optical Cameras

High-precision focusing of space optical cameras is the prerequisite for capturing high-quality images in earth observation applications. On-orbit focusing methods are basically based on image-processing algorithms. However, these focusing methods have several limitations, such as calculation complexity, low reliability, and high susceptibility to noises. We propose a real-time self-focusing method using conjugated optical fiber waveguides, which can measure the focal length of on-orbit cameras in real time. We use two conjugated optical fiber waveguides. At one end of each waveguide, there is a light source located external to the camera. The light is guided into the focal plane of the camera and it acts as an infinite point target. Contrary to image processing algorithm, our method is based on the optical components for focusing.