Considerations for establishing dimensional stability of both small and large spaceborne visible and ultraviolet optical systems

Whether the application is earth-observing, satellite cross-links or astrophysical observation, optical tolerances typically are tight for high-performance telescopes and instruments operating in space at optical and ultraviolet wavelengths. Simultaneously, both orbital motion and Concepts of Operations (CONOPS) establish changing thermal view factors to the sun, earth and cold sky. Both the optical figure and optical alignment will be affected by these time-varying thermal gradients unless mitigated. While thermal spreaders, finishes, MLI and array heaters may help manage transient effects, the viability, complexity and even cost of these approaches will depend heavily on the materials selected for mirrors and their metering. Although appropriate to all sizes, emphasis is on smaller systems with restrictive budgets. We examine the solution ZERODUR®, a heritage mirror material, can provide telescope and instrument design. ZERODUR® often is a viable material for instrument optical benches as well. Furthermore, we will summarize recent results, enabling the instrument designer to validate dimensional stability under various natural radiation environments.