Megan Birch, Georgia Tech Research Institute and Georgia State University; Leticia Garcia Verela, Georgia State University and Instituto de Astrofisica de Canarias; Fabien Baron, Georgia State University Dept. of Physics & Astronomy
Keywords: Adaptive Optics (AO), Atmospheric turbulence, Benchtop simulation, Earth-orbiting objects, Fourier optics, Hybrid Optical Telescope (HOT), Object generator module, Optical simulation, Point Spread Function (PSF), Space surveillance systems, Spatial Light Modulators (SLMs), Spaceborne targets, Wavefront distortion corrections, Closely Spaced Objects (CSOs)
Abstract:
To increase the resolution and visibility of both celestial and Earth-orbiting objects, the astronomical community has traditionally moved towards constructing larger aperture telescopes, such as the Keck, Gran Telescopio de Canarias, and the Extremely Large Telescope. While larger diameters facilitate greater photon capture and better angular resolution, they introduce formidable challenges regarding overall construction and optimal performance. Addressing these challenges, modern telescopes have adopted segmented mirrors combined with adaptive optics (AO) to create lighter, cost-efficient systems capable of high-precision wavefront distortion corrections. This innovation underpins the development of the Hybrid Optical Telescope (HOT), a Fizeau imaging sparse aperture telescope, which leverages segmented mirrors and AO to not only mitigate atmospheric turbulence but also to enhance resolution affordably by using lightweight mirrors and a tensegrity support structure. Furthermore, the HOT’s ability to engineer a “dark hole” in the Point Spread Function (PSF) enables the detection of faint sources adjacent to bright objects.
Building upon the HOT framework, our study introduces an object generation module designed to accurately simulate a diverse array of celestial and man-made objects. This module uses the principles of Fourier optics and spatial light modulators (SLMs) to simulate stellar and spaceborne targets under various atmospheric and observational scenarios. The HOT system and this module are both employed within a benchtop simulation designed to replicate atmospheric conditions. By utilizing three SLMs and AO together, these systems form the basis of our benchtop technique for modeling and correcting atmospheric turbulence and the effects on propagating wavefronts.
Our experimental setup employs two SLMs to mimic atmospheric conditions affecting the wavefront pre-aperture, and a dual-pass configured third SLM to apply precise phase and amplitude corrections, optimizing the PSF for observation of low-intensity objects. We explore polarization rotation and a secondary phase modulation technique for amplitude modulation. This capability to simulate space objects, including satellites and debris, with high fidelity is crucial for space agencies and defense organizations. It allows validation of algorithms or simulations for sensors within space surveillance systems, improving our capacity to monitor and mitigate orbit-based threats and collisions.
This research represents a scalable hardware-based optical simulation tool, with broad implications for scientific research, industrial applications, and the protection of space assets. By integrating the HOT system with a novel object generation module, we have developed a comprehensive approach to simulating and analyzing a wide range of celestial and man-made objects under various atmospheric conditions. This integrated system allows for the precise modeling of atmospheric turbulence effects on image quality. The practical applications of this research are wide-ranging. For the scientific community, it could be the means for the observation and study of distant celestial objects, potentially revealing previously undetectable phenomena. In industrial contexts, the ability to simulate and correct for atmospheric disturbances in real-time can significantly enhance the accuracy and reliability of satellite imaging systems, improving data quality for applications ranging from weather forecasting to Earth observations. Moreover, the enhanced simulation capabilities provided by the HOT system and object generation module are of critical importance for space surveillance and defense. By accurately modeling the behavior of satellites, space debris, and other objects in orbit, this research supports the development of more effective monitoring and tracking systems. These systems are essential for preventing collisions and ensuring the safety and longevity of space assets, contributing to the sustainability of space activities.
In summary, this research demonstrates achievable capabilities in optical simulation and contributes to the ongoing efforts to explore, utilize, and protect our extraterrestrial environment. Through the detailed examination of the HOT system’s integration with the object generation module, we demonstrate a forward leap in our ability to simulate complex optical phenomena and enhance telescope-based observation capabilities.
Date of Conference: September 17-20, 2024
Track: SDA Systems & Instrumentation