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DIY Thermoluminescence project

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jcday

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Well, if you're going to try the impossible, might as well make it something fun and impossible.

A bit of background, cos it's needed. Thermoluminescence is a property of certain crystal structures and ceramics, where background radiation is absorbed at a fixed rate and causes the electrons to be pushed into higher orbits. On heating, the electrons drop back to the normal state and light is emitted. For pottery, the heat you need to apply is around 300'C. This technique is used in archaeology and geology, but can probably be used in other areas too. Technical reports on the subject show blue light is common with pottery, but that other frequencies appear with other materials.

What is needed: This is not much more than the DIY spectrometer, in terms of basic elements. However, it isn't exactly the same. The amount of light involved in basic spectrometry isn't a problem, but here the light levels may be considerably greater and the amount of light that is important will likely be considerably smaller. I am guessing that how fast I can drain the CCD buckets and how many useful samples I can take over time will be the decider over whether I can do this.

Webcams don't have massively high refresh rates (they don't need them) and it's going to be hard for me to calculate how much energy was released if the response curve for the CCD is a mess. So, question 1 is - should I go for a recycled webcam or get a low-cost CCD with better characteristics?

Noise is also going to be a serious problem. With very high temperatures involved, there will be a lot of serious problems. That's going to require some serious cooling, OR a greater distance between the oven and the electronics. Extra big tends to mean more fragile, more expensive, less portable - all the properties a DIY kit absolutely has to have if it is to be a disaster, but not ones you want if you want it to work. Question 2, then, is - what would other DIYers do in this situation? Other than take two aspirin and see the doctor in the morning.
 

pinout

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Great project!

Many years ago I worked on an early CCD spectrometer for Laser Raman and CCDs had really just become available, We used one designed for long exposures for space exploration, the key to it's low noise was cooling, it used liquid nitrogen via a heat exchanger - great fun.
A Peltier cooled one using a stack of 3 peltiers or increasing power away from the CCD also gave good results and is practical even if you start off with one peltier.
Going the long way round! I'm saying you need to keep your detector cold!
Our refresh rate by the way was 6 seconds and that provided excellent signal to noise for our application.

I did see some open source spectrometer projects on the web a while back, some even using a blank CD as the grating!

I'll follow these discussions with interest.
 

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