Rare High-Reflectivity Protected Gold-Coated Premium Convex IR Mirror Witness Sample

This is a rare witness sample for the secondary mirror (M2) in a high-precision telescope system developed at a US Defense Lab for space surveillance, laser communications, and advanced sensors.

• In many telescope designs (e.g., Cassegrain, Ritchey-Chrétien, or some three-mirror anastigmats), the secondary mirror is convex to diverge light toward the focal plane while correcting aberrations and folding the optical path.
• The convex shape helps achieve a wider effective field or compact design.
• Convex coated surface with ~3 mm central sag, estimated radius of curvature ~180–220 mm – ideal for diverging secondary mirror roles in telescope prototypes ;ike wide-field correction or beam expansion in IR systems.

Key Specifications

• Client/Coater: Defense Laboratory / Barr Associates, Inc.
• Description: Protected gold-coated convex mirror witness sample for M2 (convex secondary mirror in telescope assembly)
• Size: ~72 mm total diameter, ~65 mm mirrored area, ~10 mm thickness
• Surface: The likely radius of curvature (R) for the convex mirror is approximately 218 mm – precisely shaped for secondary mirror (M2) in telescope assembly
• Coating: Protected gold (metallic gold layer + thin dielectric overcoat) with gold handling tabs for process conductivity
• Performance: High reflectivity >96–98% average from ~800 nm (NIR) to 20 µm (mid/far-IR) – the gold-standard for IR space/defense applications
• Condition: Pristine surplus – flawless reflective surface, carefully preservedHigh-Value Applications

  This professional-grade convex protected gold mirror is ready for serious use:

  • IR Beam Expansion & Diverging Optics – Perfect convex reflector to widen or diverge beams in CO2, Nd:YAG, or NIR diode or create virtual images.
  • Thermal Imaging & IR Sensor Prototypes – Diverging mirror in DIY FLIR cameras, heat detection setups.
  • Advanced Telescope Building – Test as convex secondary in custom Cassegrain reflectors or educational reflectors.
  • Spectroscopy & Beam Manipulation – Convex element for IR beam spreading in FTIR, Raman, or custom scientific instruments.
  • Artistic & Light Installations – Convex gold reflections create stunning diverging golden patterns for sculptures or immersive displays.