Why Crystal IR Windows Just Don’t Work for Industrial Applications

When I think about the use of fluoride based crystal infrared windows, I think about what Albert Einstein purportedly said, “The definition of insanity is doing the same thing over and over again and expecting different results.” Why do we insist on making infrared windows from the same materials that have been failing for years and expect different results?

The IRISS website clearly states that our crystal windows are made of calcium fluoride (CaF2). However, other websites state that their window material is a proprietary material and give it clever names. You cannot determine what material their “crystal window” is actually made of. The reason for this marketing cleverness is that if you know the lens material, then you can begin to investigate the positives and negatives of the crystal material. The two primary crystal materials used in industrial infrared windows are Calcium Fluoride (CaF2) and Barium Fluoride (BaF2). This paper will discuss several commonly made false claims relating to IR windows.

Arc Resistant IR Windows?






First, I would like to address the ridiculous claims out there that crystal IR windows are Arc Resistant.  Crystal IR windows range from 2 to 4 mm in thickness depending on the size and manufacturer.  These windows are then mounted in electrical enclosures that are designed to be Arc Resistant by the Original Equipment Manufacturer (OEM) in line with the standards for such equipment and are then “Arc Containment Tested” by a Nationally Recognized Testing Laboratory (NRTL) such as UL or ETL.  If the OEM electrical equipment in question passes the test, then the equipment is given an “Arc Resistant” certification but this is applicable only to the full assembly.  All of the components fitted to the assembly do not have the right to state that they are separately Arc Resistant.  You do not see an automobile seat manufacturer claiming their seats have the highest crash test ratings as this would be deemed ridiculous.

Claiming an Infrared Window is Arc resistant as a stand-alone component is both misleading and dangerous.  We must concentrate on the facts relating to the mechanical and infrared properties of the infrared transmissive lens materials and infrared window design.  There is no room for marketing spin when it comes to safety.

Non Hygroscopic IR Windows?


Follow IRISS