Instructables
Picture of Spectrum light source
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Need monochromatic light sources?  Noticing the fact that many LEDs have very narrow spectra, I wanted to make a multi-narrow-spectra light source for various scientific purposes such as for botanical specimens under the microscope.  This project was a test run to see how well it works, and it seems to work very well.  With the exception of the LEDs themselves, it's made entirely from scrap and offcuts.  On top, the dial chooses the colour by its central wavelength, in nanometres.

The first part is choosing the LEDs: use a reputable source so you can get the datasheets to find out the spectra.  Choose as many and as varied as you like -- these are all quite narrow beams (15 degree), quite bright, and go from ultraviolet to infrared.  The graph shows the spectra from the datasheets, except the 400 nm LED which is an estimation.

Make it any way you like: on breadboard, on a circuit board, just-soldered-together.  This instructable shows the housing I made with a CNC mill, which gives a nice turnable control, and keeps the light output in one place for easily fixing fibre optics.  You could easily make one with laser cut materials, 3-D print one, or just solder it together on a piece of breadboard.
 
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foobear11 months ago
Its interesting. I wish I understood the purpose of it more, but I like it - so beautifully made
jonathanjo (author)  foobear11 months ago
Thanks for the compliment; I'm glad you like it.

It's for photographing flowers and moss under a microscope. Insects and birds can see different bands of colours to humans, and some flowers are intricately patterned in ultravioltet (http://en.wikipedia.org/wiki/Nectar_guide); many plants have interesting patterns in infrared too. By making a light which illuminates with a fairly pure (ie, narrow band) of colour, we can take photographs to see these patterns. I wanted to find out more about it, so I made this.

Hope that explains the purpose a bit better. If I get a good photo from it I'll put it up here.
foobear jonathanjo11 months ago
That is very interesting. You might consider adding a paragraph like that to your intro
foobear11 months ago
Its interesting. I wish I understood the purpose of it more, but I like it - so beautifully made