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Infrared penetration of meterials

Hello, I’m working on a project where I need to see hot air moving through a resin tube. Wich materials will let IR rays though? dose clear, tough 2000, or draft v2 work?

If I was you I would contact Formlabs support for this information.

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I would start with Clear. Tough 2K and Draft are opaque. If Clear doesn’t transmit IR, Tough and Draft will only be worse because of their pigments. But I suspect Clear will transmit IR with minimal attenuation. It’s the UV end of the spectrum that the resin is designed to absorb…

I would still contact Formlabs. Although they probably do not know the answer. Just because something is clear does not mean it will allow IR wavelengths to go through the material.

True. But if it’s opaque you can be sure there’s a much lower probability that it’ll pass IR.

I’m not sure if Formlabs would know.

The way to check would be to buy as close to a full-spectrum IR sensor as you can find, and check. Or whatever part of the IR spectrum you need. I have a near-visible IR sensor, but not full spectrum. Depending on what part of the IR spectrum you need, you can maybe get by with body heat to generate the IR light. There’s cheap IR flashlights that generate near-visible IR light, available in hunting shops.

You can build an IR sensor from a digital camera, by removing the internal filters and then putting in filters that take out visible light. This is the hard way to do it. Full-spectrum IR sensors are relatively expensive if you want high resolution. There are fairly affordable ones available for Arduinos. But I think they’re 8x8 resolution.

Interesting suggestion. If you have a IPCam with its own IR LEDs for night vision, you could try that. These cameras have shutters that move the IR filter out of the way of the lens when the IR LEDs are active. If something is translucent to IR, it will pass rather than reflect the illumination from the LEDs and it’ll appear “ghostly” in image from the camera.

But I’m betting Clear is translucent to IR. The resin is tuned to strongly absorb UV and not frequencies below that level. Having “band gap” properties where it’s opaque to UV at one end of the spectrum, translucent to all the visible light frequencies below that, and then opaque again for IR doesn’t make a lot of sense from a physics perspective.

Unless you’re going to continually have to measure the wavelengths of resins I wouldn’t spend any money buying a sensor. I would send it off to a lab and have them do testing on the resin(s) to determine what wavelengths are absorbed, transmitted, reflected, etc. Or, if it is something that is going to be done over and over again, and you have then $ to spend, then I would recommend contacting Thor Labs. My company uses them a lot for light sensors. Product Catalog - Thorlabs

I guess it comes down to if you are working on some for home use or for industrial use and how much you want to spend.