Multiple emerging small satellite constellations aim to provide worldwide connectivity through high-speed free-space optical communication across many thousands of kilometers. The scale of these constellations requires a new approach to the design, build, and verification of high-performance space optics, one that will focus on mass-producibility, low-cost design, and limited touch-time. Honeywell and our partners have developed an optical intersatellite terminal that builds on our combined decades of experience in reliable space optics, electronics, and mass production of space hardware. The critical technical drivers of optical systems for space are their susceptibility to the thermal and radiation environments. The system is designed around Honeywell's Optical Pointing and Tracking Relay Assembly for Communications (OPTRAC), a low-cost subsystem which is designed to drive all of Honeywell's optical link products by providing a common interface between swappable front-end telescopes and back-end optical transceivers. The lowest-cost traditional approach to performing pointing and tracking is to apply quadrant photodiode sensors. These large-area devices have limited sensitivity and must maintain tight alignment tolerances over temperature. This chapter discusses the advantages and impacts of tracking with a pixelated sensor and presents results of laboratory testing and environmental qualification of a pixelated prototype subsystem.

Chapter Contents:

• 21.1 Introduction
• 21.2 Pixelated versus quad cell trades
• 21.2.1 Angular resolution versus range
• 21.2.2 Environmental factors
• 21.2.3 Trade summary
• 21.3 Test results
• 21.3.1 Closed loop testing
• 21.3.2 Radiation testing
• 21.4 Conclusions
• Acknowledgments
• References

Inspec keywords: optical links; free-space optical communication; photodiodes; satellite links

Other keywords: back-end optical transceivers; reliable space optics; optical intersatellite links; Honeywell Optical Pointing and Tracking Relay Assembly for Communications; optical intersatellite terminal; pixelated sensor; satellite constellations; high-performance space optics; low-cost subsystem; mass production; mass-producibility; Honeywell's optical link products; pixelated prototype subsystem; optical systems; high-speed pixelated acquisition; critical technical drivers; worldwide connectivity; limited touch-time; free-space optical communication; low-cost design; thermal radiation environments; space hardware

Subjects: Image sensors; Photoelectric devices; Free-space optical links