Cameras and imaging
Crystran Newsletter March 2017
August 13, 2018
A guide to selecting CaF2 grades
Calcium Fluoride (CaF2) is one of the most useful optical crystals and is available in different grades which can be specially selected for your application. It is often used for IR spectroscopic windows, lenses and prisms. Especially pure grades of CaF2 find useful applications in the UV and as Excimer laser windows. CaF2 is available in several quality grades according to transmission range. All material transmits without absorption bands in the infra-red, but for other applications selection can be balanced against cost.
Below is a useful breakdown of the different grades available:
IR Grade – 0.4μm to 10μm
Calcium Fluoride crystal was historically manufactured by fusing naturally mined CaF2. More commonly now, medium quality reagent grade material is used where the most inexpensive material is required. The principal impurities are generally purged further by the crystal growth process but often result in a broad absorption at 0.3μm due primarily to iron, and reduction of transmission at wavelengths shorter than 0.25μm. All Crystran CaF2 is guaranteed free of absorption bands within the Visible and IR spectrum.
UV Grade – 0.19μm to 10μm
Using a higher grade of synthetically produced raw material, Crystran UV grade guarantees transmission through the UV-Visible spectrum as well as the IR. Further absorptions at 0.19μm and 0.25μm in the IR grade are avoided.
VUV Grade – 0.13μm to 10μm
Using analytical grade synthetically produced raw material, Crystran VUV grade guarantees transmission into the vacuum UV part of the spectrum extending to the theoretical limit for the material.
Eximer Grade – 157nm, 193nm, 248nm selected
Crystran Eximer grade is supplied from pure crystal ingots manufactured from highest purity raw material to ensure the lowest possible absorption for high power laser use. The internal absorption of the crystal is tested by transmission through long path lengths at particular Eximer wavelengths.
Raman Grade – for Raman spectroscopy applications
Crystran Raman grade material is supplied from specially selected ingots not exhibiting any fluorescence emission bands which might interfere with Raman spectroscopy applications.
Please do get in touch if you have any questions or would like to request a quotation.