As the LEO satellite industry rapidly expands, the demand for remote sensing and telecommunications in marine and suburban areas is increasing. Developing higher bandwidth communication interfaces has b ecome a crucial focus in the space industry. Free space optical (FSO) communication offers bandwidths hundreds of times greater than traditional microwave links, enabling the efficient transmission of large volumes of data. However, current commercial sate llite tracking systems lack the high precision needed for space-ground laser communication. For high-speed data transmission, the laser beams between the ground station and the satellite must be precisely aligned. In this Taiwan Space Agency’s (TASA) project, we were originally designed optical ground station to communicate with HICALI (High -speed Advanced Optical Communication Equipment) onboard the Engineering Test Satellite No. 9. This project is changed to specifically communicate with future High-Precision LEO Remote Sensing and Laser Communications Satellites including 6U CubeSat(s) built by National Yang Ming Chiao Tung University (NYCU). The system consists of a medium-sized telescope, a mount, and a newly developed high-precision controller, which meets the accuracy requirements for FSO communication. By analyzing optical images of targets, we achieve the necessary tracking accuracy for satellite -ground FSO communication. This system not only enhances the transmission efficiency in space -ground laser communications but also improves the remote sensing and data transmission capabilities of LEO satellites. This paper provides an overview of the current optical ground station, the system performance and lessons learned.
Surface quality of optical lenses is an important parameter to achieve optimal imaging quality. Surface imperfections such as scratches, pits, or digs which may be caused during manufacturing or handling induce light scattering and degrade the overall performance of the imaging system. For a lightweight lens, the pockets behind the lens will affect the defect judgment due to excellent optical transmittance. This article discusses the measurement flow of automatic optical inspection for large lenses, defect detection algorithm, and the practicality of application of this technique for inspection of large lenses. Surface defect detection module comprises of high dynamic range camera combined with telecentric imaging lens creating an imaging system with resolution of 2.7μm. Inspection of the whole surface before and after coating is carried out through concentric scanning and different illustrating angles. The images are captured with a 20% overlap between two consecutive images to ensure complete coverage of the whole surface. Image processing algorithms are applied to detect and classify any surface defects on the surface. Detection results consists of exact size, type, and location of the defects are analyzed by the system and summarized into an inspection report. Compared to classical manual inspection this system provides reproducible and objective detection results and allows users to perform revalidation after measurement is finished.
A transmission and receiving optical antenna is built-in-house by TASA and Taiwan domestic optical company CALIN. A Cassegrain type telescope is designed and manufactured with primary aperture 80 mm. It could provide the transmitted and received gain about 104 dB, and the obscuration loss about -3.8 dB in the link channel for free space optical laser communication. It could also be integrated in the CubeSat or in the optical communication terminal for small satellite missions. The root-mean-square wave front error for the optical antenna is less than 100 nm. The optical aberrations introduced on-axis WFE loss is estimated about -0.72 dB in the link budget. An eyepiece is designed to locate near the focus of telescope to collimate the output beam with beam size about 3.3~4.7 mm for propagating 50 cm distance in the follow-up communication module system. With the strong supporting domestic electro-optical industry, it is expected to help a lot on the development of the Taiwan space technology.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.