I'm going to be using infrared light of wavelength somewhere around $700-800 \space \text{nm}$ and I need cheap materials that can be easily found/bought which are transparent to infrared light.

It has to have a solid structure so I can make different shapes which would help in my testing. If I missed some information, please let me know.

  • $\begingroup$ What exactly do you mean by transparent to? $\endgroup$ – Alaz Cig Jul 17 '19 at 13:30
  • $\begingroup$ Common salt, NaCl, is often used in IR work. $\endgroup$ – PM 2Ring Jul 17 '19 at 13:40
  • $\begingroup$ Look into polymethylmethacrylate (acrylic plastic, perspex or lucite). It's pretty transparent in the near infrared, and possibly easier to cut and shape than rock salt. $\endgroup$ – Philip Wood Jul 17 '19 at 13:49
  • $\begingroup$ @TNTCookie, it has to be transparent to infrared light of wavelength 700 - 800 nm $\endgroup$ – Danush Jul 17 '19 at 14:12
  • $\begingroup$ @PM2Ring, it has to be something rigid, like say cardboard or wood, etc $\endgroup$ – Danush Jul 17 '19 at 14:15

The region 700-800 nm is in the near infrared. Glass and transparent plastics (clear plastics) are fine there. You can test with the remote control of your TV.

  • $\begingroup$ Cool, I'll give glass a shot. Any constraint on thickness? By transparent plastic, you mean any plastic? Like there are certain kinds of plastics with thickness and composition right? $\endgroup$ – Danush Jul 17 '19 at 14:18
  • $\begingroup$ @Danush Many plastics are opaque in the visible. If they are not transparent in the red they are not likely to be transparent in the near-IR. Just test ordinary packaging, kitchenware, etc with the remote (typically 940 nm). For glass (window-pane quality), anything under 10 cm should work fine (thicker glass is often greenish). $\endgroup$ – Pieter Jul 17 '19 at 14:23
  • $\begingroup$ cool thanks :) Just one last question; would toughened glass under 10cm also work? $\endgroup$ – Danush Jul 17 '19 at 14:55
  • $\begingroup$ @Danush I just checked my remote with the heaviest piece of glass that I have right here (about 5 cm), and that worked. As I had expected; there is no reason why it should not. $\endgroup$ – Pieter Jul 17 '19 at 15:17

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