How do I choose the material for an retroreflector?
Demand	Recommended material
Visible light, low cost, general environment	BK7
UV/IR, high power laser	Fused Silica
Space, nuclear environment, extreme temperatures	Fused Silica
High precision interferometry	Fused Silica (low thermal expansion)
Traffic reflective, general target	BK7

What are the applications of BK7 retroreflectors?
Visible laser ranging (industrial laser rangefinders).
Optics lab instruction (low cost, easy access).
General laser interferometry (Michelson interferometer).
Robot navigation (AGV) (indoor environments).

Comparison of the environmental suitability of BK7 Glass Retroreflectors and Fused Silica Retroreflectors
Application Environment	BK7 Glass Retroreflectors	Fused Silica Retroreflectors
High/Low Temperature	Higher thermal expansion may affect accuracy	Excellent thermal stability for extreme temperatures
Space/Vacuum	May deteriorate due to radiation or temperature changes	Radiation resistant, low outgassing, suitable for satellites, deep space exploration
High Humidity/Corrosion	General corrosion resistance	Resistant to acid, alkali and salt spray, suitable for marine or chemical environments
Vibration/Shock	Higher mechanical strength, but not as good as fused silica	Better shock resistance