Transparent material for thermal imaging

Hope i came to the right forum, I’m looking for materials that thermal imaging can see through.

My application is actually paintball, with FLIR coming out with the new Flir One camera for Iphone 5,

i’m designing a protective aluminum housing for the phone, my background is CAD/CAM and CNC machining so i can do all the things needed to manufacturing the housing, but i have little experience with lens and thermal imaging.

The problem is, this camera will inevitably take a paintball to the lens(paintball’s at 300fps produce around 18ftlbs or 24joules of energy) and since I can’t just stick a piece of plexiglass or acrylic in front of it, i have a potential $350 broke piece of equipment.

Now I’ve read up on the popular materials for the specific wavelength 8-14um which is mostly germanium and I’ve been contacting a few suppliers for quotes on some flat, disk windows but none of them are below a price feasible for something that will inevitably need replaces with prolong use.

With long hours of research I was about to stop looking until i ran across a random youtube video;

Now i can design the housing to mechanically absorb most of the impact and hopefully the plastic can hold up to the remaining energy and keep the lens clean. What i don’t know is the specific plastic used(i read somewhere polystyrene?) Since the actual lens of the IR camera will only be around .2", i think a mildly thick plastic would work but I was hoping some of you that have a lot more experience and knowledge than i, could give some advice or possibly know any other materials feasible for this application.

Do you know of any materials that thermal imaging can see through?


Plastic bag.

Good for rain or if they were just tossing the paintballs to each other. :slight_smile:

Cameron, you have to get the he-man plastic garbage bags…faster than a speeding bullet and all that, you know? :stuck_out_tongue:

Who Knew? Sapphire glass.
From Jeff’s link above:

Sapphire Viewport

Sapphire viewports are selected for their superior optical transmission properties in the IR spectrum. Windows are silver-brazed to Kovar® sleeves. They are mounted in stainless steel tube-weld adapters and CF type flanges for use below 1x10-11, or ISO type Kwik-Flange® or Large Flange® for intermediate vacuum ranges.

Sapphire window surfaces which are extremely hard and scratch resistant offer a minimum of distortion and provide maximum light transmission suitable for most applications. UV grade viewports have a 90° crystal orientation normal to the optical axis.


Germanium is a versatile infrared material commonly used in imaging systems and instruments in the 2 to 12 microns spectral region. It is used as a substrate for lenses, windows, and output couplers for low-power CW as well as pulsed TEA, CO2 lasers.

Very good cut-and-paste there John.

Would you have any personal experience or vendors point of view on this subject?

I’m sure a paintball enthusiast is going to go hunt down germanium…

Fluke are using silicon in their new Ti200,300 and 400 series.
Flir use Germanium in their T420/440 series. I do not know if they use Germanium throughout their product line.