This is a Dall-Kirkham optical design with coatings that are optimized to transmit in infrared wavelengths. There are no refractive lens, only reflective components to the design. For IR application, reflective coatings are a protected gold which give better than 98% reflectivity from .65 micron (650nm) to 5 micron (5000nm). This design is ideal for infrared astronomy or LIDAR applications. UV optimized coatings can be provided as well, so please reach out to our technical sales team to discuss UV optimization.
 
IRDK20 is a 20 inch infrared optimized optical tube with fused silica mirrors
Focal length of 3,454 mm (f/6.8)
Dall-Kirkham optical design with coatings that are optimized to transmit in infrared wavelengths (ultra violet optimization available)
Ready for Delta-T dew prevention