Checkerboard Constellation High-Resolution Imaging Method for Earth Observation Based on Optical Pupil Plane Interferometry and Phase Retrieval Algorithms

High-resolution Earth observation, particularly from geostationary orbits (GEOs), requires the deployment of optical telescopes with apertures exceeding 10 m or more; however, a universally accepted solution to achieve this goal has yet to be formulated. This article proposes a high-resolution imaging method of checkerboard constellation based on optical pupil plane interferometry (PPI) and phase retrieval algorithms. An innovative solution is provided to address the issue of inadequate spatial frequency sampling in conventional sparse optical PPI: incorporating several checkerboard imagers and a monolithic telescope to create a checkerboard constellation that achieves an ultra-Nyquist sampling rate. Based on this sampling approach, the challenge of phase measurement can be resolved with phase recovery algorithms, which make it possible to generate high-resolution images comparable to that of a super-large-aperture traditional monolithic telescope based on modulus-only measurements. A checkerboard constellation is designed comprising four checkerboard imagers with a maximum baseline of 18 m and one conventional monolithic telescope with an aperture of 3.5 m, which achieves a twice Nyquist sampling rate and provides a ground resolution of 0.5 m at visible wavelengths in GEO. Simulations demonstrate that this setup can produce relatively optimal imaging quality when the signal-to-noise ratio (SNR) is higher than 40. An experiment conducted in the lab confirms the feasibility of this approach. The results show that: 1) high-resolution images can be produced by fusing the high-frequency data from the long-baseline checkerboard imagers with low-resolution data from the monolithic telescope and 2) using optical fibers as core components allows the equivalent aperture of telescopes to be extended to 10 m or even greater, demonstrating the potential scalability of this approach.