KEYWORDS: Control systems design, Satellites, Telecommunications, Free space optical communications, Acquisition tracking and pointing, Optical tracking, Design and modelling, Wavefronts, Beam steering, Optical simulations
This paper discusses a testbed that implements a beam acquisition and tracking system essential for inter-satellite optical communication. It summarizes the results of optical and control system design. Recent research on free-space optical communication has been thriving due to the increasing demand for data transmission in clustered operations of small satellites. However, since the distances between satellites are often hundreds of kilometers, a beam acquisition and tracking system is necessary to establish communication by accurately detecting and tracking the position of the target satellite. The optical system of the testbed, developed by Telepix, shows the attenuated output and flatness of wavefront propagated over long distances. The control system applies an adaptive control method to manage disturbances, resulting in the successful reduction of beam pointing errors to the desired level, as demonstrated by simulation results. In the future, this technology holds potential for various applications, including clustered operations of small satellites using free-space optical communication, as well as communication between ground stations and deep-space optical communication.
Taean is a small peninsular along the west coast of the mainland of Korean peninsula. It faces with the yellow sea to the west, while it is bordered with the mainland Korea to the east. The area is well known to have 1) heavy mid and high altitude air traffic, 2) busy traffic routes of ocean liners between Korea and neighboring countries and 3) complex and rapid changes in its atmospheric characteristics that tends to reduce the accuracy of regional weather forecast and therefore influencing the local industry including ocean liners. In this conference, we report a progress on customization of atmospheric transmission model suitable for direct solar irradiance measurement in the region. A large volume of direct solar irradiance and atmospheric variable data were collected over the period of 12 months in 2018. The data were obtained not only from the ground stations for low altitude, but also from the radiosonde measurement for high altitude. Initial analysis using MODTRAN showed some portions of the direct solar irradiance data that disagree with the predictions from the MODTRAN standard atmospheric models. Further in-depth study including sensitivity analysis were carried out and resulted in construction of a customized MODTRAN atmospheric model offering more accurate prediction to the measured direct solar irradiance data of the local area.
Taeangun is a small peninsular district located on the west coast of the main Korean peninsula. To the west, it faces with the yellow sea while its east side is bordered with the main land Korea. This area is well known to have 1) busy mid and high altitude air traffic routes between Korea and neighboring countries and 2) complex and rapid changes in its atmospheric characteristics that tends to reduce the performances of mid infrared (IR) surveillance equipment looking at the aerial targets. In this conference, we report a progress of our study on atmospheric radiative transfer characterization of a coastal interface area, as a precursor to the main study for Taeangun, by using a black body and a mid IR camera. Mid-wave IR camera used are the model X8500 and SC7600 with a lens assembly of 200mm focal length from FLIR® Systems. A blackbody of 7 inch in aperture with the uniformity of ±0.010 and emissivity ℃ of 0.97±0.02.is used as the target to be measured. The camera and the target blackbody are stationed at the distance of 0.73km to each other. The target was observed across the mid IR wavelength range. In this report, we summarize the current progress of the simulation of atmospheric transmission characterization and of the analysis result of experiment data.
The Software Configurable Optical Testing System (SCOTS) is one of the newest testing methods for large mirror surfaces. The Integrated Ray Tracing (IRT) technique can be applicable to the SCOTS simulation by performing non-sequential ray tracing from the screen to the camera detector in the real scale. Therefore, the radiometry of distorted pattern images are numerically estimated by the IRT simulation module. In this study, we construct an IRT SCOTS simulation model for the Fast Steering Mirror Prototype (FSMP) surface of the Giant Magellan Telescope (GMT). GMT FSMP is an off-axis ellipsoidal concave mirror that is 1064 mm in diameter and has PV 3.1 mm in aspheric departure. The surface error requirement is less than 20 nm rms. The screen is modeled as an array of 1366 by 768 screen pixels of 0.227 mm in pitch size. The screen is considered as a Lambertian scattering surface. The screen and the camera are positioned around 4390 mm away from the mirror and separated by around 132 mm from each other. The light source are scanning lines and sinusoidal patterns generated by 616,050 rays per one screen pixel. Of the initially generated rays, 0.22 % are received by the camera’s detector and contribute to form distorted pattern images. These images are converted to the slope and height maps of the mirror surface. The final result for the height difference between input surface and reconstructed surface was 14.14 nm rms. Additionally, the simulated mirror pattern image was compared with the real SCOTS test for the GMT FSMP. This study shows applicability of using the IRT model to SCOTS simulation with nanometer level numerical accuracy.
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.