Barr Associates Protected Silver Secondary Mirror Witness Sample

An authentic optical witness sample from Barr Associates, Inc. (now part of Materion Precision Optics), coated in the exact same vacuum chamber run as the secondary mirror for the Wide Field of View (WFOV) Telescope Assembly – better known as the Space Surveillance Telescope (SST).

This groundbreaking telescope developed by a US Defense Lab is one of the most advanced ground-based systems for deep-space object detection, tracking satellites, debris, and asteroids. —- demanding ultra-high-performance, durable coatings.

Key Details from Original Label:

• Coating: high-reflectivity protected silver with dielectric overcoat for broadband visible/NIR performance and superior environmental durability – defense/aerospace grade

• Optics Fabricator Reference: Brashear, now L3Harris, who polished and figured the SST mirrors

• Substrate: 1.5″ (38.1 mm) diameter × 1.5 mm thick fused silica (SiO₂) witness

This witness piece was used for non-destructive quality verification of reflectivity, uniformity, adhesion, and spectral performance – ensuring the actual large secondary mirror met stringent military specifications. It exhibits a brilliant mirror finish with subtle color shifts typical of multi-layer dielectric-enhanced silver coatings.

Condition: Excellent – stored in original protective case (included). No scratches, defects, or degradation visible. A true piece of astronomical and national security engineering history from a landmark program.

Perfect for collectors of space/optics artifacts, educators, museums, or as a high-quality demo mirror for optics labs