A single 1" borosilicate glass collimating lens at the exit port is standard on the 201-100 and TH3 lamp housings. This lens not only improves light collection efficiency to f/1.5, but also filters harmful UV rays while allowing visible and IR light to pass through (360-2350nm). This option upgrades the borosilicate glass to CaF such that wavelengths 1-5 μm can pass through as well. Calcium Fluoride has a high transmission from 250nm to 7μm.

Technical Specifications
Material: CaF₂ (standard optical quality)
Design wavelength: 5.0µm
Clear Aperture: 80% central diameter
Diameter Tolerance: +0.00mm / -0.13mm
Thickness Tolerance: ±0.25mm
Surface Irregularity: 1 λ @ 0.63µm
Surface Quality: 40–20
Coating: None