Cryogenic lens designers of large optics need to know what materials are available and in what size. As of 19-Sept-2019 I’ve identified the following materials:
Up to 200 mm in diameter with good (> 90% in 10 mm samples) throughput up to 2.45 µm in wavelength are:
- Calcium Fluoride (CaF2)
- Infrasil (Heraeus fused silica)
Up to 100 mm in diameter include:
Those interested can grab glass catalogs from my drive. Note, these catalogs do not contain the cryogenic index of refractions. Feel free to contact me with any questions or comments.