Optical Remote Sensing Satellite-borne Integrated Miniaturized Design and Verification

This study tackles the key challenges in designing integrated， lightweight， and high-resolution remote sensing satellites， with a focus on miniaturization， structural stability， and thermal control. Its primary objective is to propose and validate a novel satellite-borne integrated scheme that incorporates an optical camera， a laser communication terminal， and star trackers onto a unified platform. The design aims to achieve sub-meter resolution imaging and high-speed laser data transmission while maintaining high optical axis stability and thermal performance under complex on-orbit conditions.A holistic， multi-disciplinary design and optimization approach was adopted. The imaging payload centers on an improved Cassegrain system. A key innovation is the square primary mirror （190 mm× 190 mm）， providing an equivalent circular aperture of 215 mm. This design increases the photon collection area by approximately 27% within the same envelope compared to a conventional circular mirror， directly enhancing the signal-to-noise ratio. Coupled with a 3.2 µm pixel pitch detector and a 1 300 mm focal length， the system is designed to deliver better than 1-meter ground sampling distance from a 400 km orbit. For the laser communication terminal， a reflective off-axis afocal beam expander was developed. This system features multiplexed optical paths， allowing the transmit， receive， fine tracking， and self-calibration subsystems to share key components such as the fast steering mirror and beam expander optics. This integration drastically reduces the terminal's volume， resulting in a compact assembly with a 60 mm effective aperture capable of supporting a 4× beam expansion ratio for high-rate data transmission. Structurally， the integration cornerstone is a Z-shaped precision base made of aluminum-based silicon carbide （SiC/Al）. This material was selected for its superior specific stiffness and high thermal conductivity， which are critical for maintaining dimensional stability under thermal and mechanical loads. All core payloads such as the optical camera， laser terminal telescope， and star sensor are mounted on this unified reference structure， which not only ensures inherent alignment stability among the payloads but also simplifies the system architecture. To counteract the detrimental effects of temperature fluctuations on optical alignment and image quality， a sophisticated “active compensation + passive isolation” thermal management strategy was implemented. The active system employs a network of five distributed heaters on the Z-base， governed by a discrete Proportional-Integral （PI） control algorithm with finely tuned parameters （proportional gain=0.8， integral gain=0.05）， maintaining the base temperature within 20±0.5 ℃. Passive measures include applying high-conductivity graphene films to critical structures like the camera truss to homogenize temperature gradients and using L-shaped thermal isolation brackets to decouple sensitive optical paths from external thermal disturbances. We established a rigorous analytical framework to guide and validate the design. This involved developing linear mathematical models for multi-payload line-of-sight stability and system wavefront aberration， which directly link mechanical and thermal deformations to optical performance metrics. These models feed into a coupled optical-mechanical-thermal multi-disciplinary analysis and optimization workflow. This integrated simulation platform enables the iterative assessment and refinement of system performance under a comprehensive set of environments， including ground gravity-thermal coupling and extreme on-orbit thermal cases spanning the satellite's full orbital beta angle range. The final design underwent extensive verification through thermal balance testing in a space environment simulator and thermal-optical MTF testing， culminating in on-orbit performance evaluation after launch.The proposed integrated design demonstrates significant improvements in compactness， stability， and performance. The optical system has a total length of 330 mm with an equivalent aperture of 215 mm， enabling sub-meter resolution. The laser terminal beam expander has a 60 mm effective aperture， supporting 4× beam expansion/reduction for data transmission up to 10 Gbps. The Z-shaped SiC/Al base ensures high structural rigidity. Under a coupled gravity and 4 ℃ thermal load， the maximum optical axis deviation between payloads is ≤3.24″， and mirror displacements are ≤5 µm with tilts ≤5″. The system wavefront error remains ≤0.06λ （RMS， λ=632.8 nm）. In extreme on-orbit thermal cases， the peak-to-peak optical axis variation is ≤6.77″. The thermal control system maintains the camera and base within 19.5~20.5 ℃， with gradients 0.1 under controlled conditions. On-orbit validation shows that the satellite maintains a dynamic MTF >0.08 at the Nyquist frequency （156 lp/mm） after one year in orbit， with no significant degradation. High-resolution panchromatic images have been successfully downlinked via the laser terminal， confirming stable imaging and data transmission performance.In conclusion， this work successfully develops and validates a highly integrated， miniaturized satellite design that effectively combines high-resolution optical imaging and high-speed laser communication within a compact 42 kg platform. The innovative use of a common Z-shaped precision base， advanced thermal management， and multi-disciplinary optimization results in a system with superior structural stability， thermal precision， and optical performance compared to existing designs. The integration scheme not only reduces volume and mass but also enhances payload synergy， as demonstrated by using the optical camera for coarse tracking in the laser communication link. The proposed approach provides a feasible and efficient technical pathway for future lightweight， high-performance multi-payload remote sensing satellites， balancing rigorous performance requirements with stringent size and mass constraints.