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I am looking to be able to heat a sample of material, typically less than 500mg and sitting in a fused silica sample holder about 10mm diameter. Wondering about using (say) a 5W LED with narrow emission angle. The overall sample chamber of the machine is quite small, so ideally I need a small source, possibly with a light pipe. I certainly do not want the thermal mass of something like a halogen bulb. So, the questions...

Does this seem feasible?

What type of LED (in terms of wavelength) is the most efficient?

Does wavelength matter in terms of heating the sample?

Now, I expect you to ask me what sort of temperature I want to get. The answer is "not sure", but probably 80 degC would be adequate. It is to drive off moisture.

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    $\begingroup$ Is it not easier to heat the sample with a bit of resistive wire around your silica holder? What do you mean by "thermal mass" of the halogen bulb? You can get very small halogen bulbs... easily as small as an LED. See for example the Maglite LR00001 $\endgroup$
    – Floris
    Oct 20, 2015 at 14:29
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    $\begingroup$ For an incandescent lamp, the wavelength doesn't matter because so much comes off as infrared and spread over a broad range of wavelengths. For an LED, life is more difficult - very little IR (heat) comes off, and the wavelength is well defined (slightly broader than a laser, but still not broad). So, coupling the energy from the LED to the material will be hard unless your material absorbs that wavelength. $\endgroup$
    – Jon Custer
    Oct 20, 2015 at 14:34
  • $\begingroup$ @Floris We already use that technique and it does not work well. We want as little other stuff to heat up in the chamber as possible. The time it takes to heat and cool the sample chamber is a critical parameter. Ideally only the sample mass should be heated. $\endgroup$
    – user56903
    Oct 20, 2015 at 14:39
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    $\begingroup$ Streamlight 75914 Stinger is also a VERY small (Xenon) light bulb. If you need even less thermal mass, consider focusing the image of a filament from a distance (through a small window). I wonder if you are trying to solve an XY problem here... $\endgroup$
    – Floris
    Oct 20, 2015 at 14:45
  • $\begingroup$ @Floris The problem is heating and cooling just the mass in question in a confined space, reliably. The only cooling we have is to ambient, so heating up as little of the chamber as possible is essential. Think spherical object suspended in a cylindrical space 40mm diameter and about 80mm in height. $\endgroup$
    – user56903
    Oct 20, 2015 at 15:03

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