Hi Michael,

Do you have any kind of design in mind? I've read in places that people can achieve some results with a compact disc as the diffraction element, but an optical diffraction grating costs a bit : (

It would be worth investigating astronomy resources, because they are interested in spectrometers too, and some people have constructed them using a grating, mirrors, optical slit and line CCD (lots on ebay) and appropriate circuitry. However, this is in the several hundred-dollars ballpark minimum (and more if experimentation is needed!). Those CCDs (probably intended for fax machines) are good for quite a large portion of spectrum. Specifying the grating, mirrors etc is a hard thing though without either experimentation (which could get expensive!) or maths, but I don't know any optics experts : ( Free optical simulation software is usually limited to a few elements, not enough to simulate the entire thing : (

I have a few optics parts (with part numbers and specifications so it can be replicated) so I will try to see what I can do with them when I get some time, but it really will be guesswork to an extent for me I purchased them in mind to experiment with building a spectrometer a long time ago, but the parts

are with near-certainty sub-optimal since some of it was guesswork based on what I had read at the time, and what I could calculate (which was not much).

There could be more unconventional methods that are cheaper to do, but I've not really investigated those.

shabaz

Do you know why we are currently using diffraction to split wave lengths, could we not have the whole received spectrum hit a conventional optical sensor [multiple wave length sensors with spectrum blocked coatings]  and split it in the software.

Ie have ten sensors, each only allowing a certain frequncy to get to the sensor [like security cameras have uv filters].

I think the difficulty here is finding sharp narrowband optical filters. They may cost as much (or more) than diffraction gratings. If they are not narrow and sharply filtered then there is loss in resolution. Plus, there would be some loss in the optic material even in the pass region. The diffraction grating is likely more efficient.

(This is just a guess though - I really am not knowledgeable in optics at all).

I wish we had some optics experts on this thread! : (

I'm not an optical expert but this may help:

http://store.publiclab.org/products/desktop-spectrometry-kit-3-0

There is a lot of good information here and PublicLab seem to have some optical people on board who know what they are doing.

The price range is good - one of these + RPI + camera ?

MK

Nice simple design : ) I just tried separating a DVD-R, it was quite easy with just a fingernail, the two halves split apart easily, leaving one side that is clear although with a slight-translucent pattern to it depending on how the halves split. However that entire half is usable I think, I could easily see a spectrum through it by holding it at an angle to a lamp.

I suppose their photo emulsion slit could be easy to make with an old camera and b&w film (if that and developer is still available) although probably cheaper just to buy a prepared emulsion slit from that publiclab store.

Anyway, your post reminded me of this childrens' optics kit that costs just $18 from Edmund Optics:

It really is very basic (a few plastic lenses, some filter sheets, a plastic mirror etc) but does come with a thin plastic sheet of diffraction grating (500 lines/mm) mounted in a card frame.

That could be used for a more consistent, repeatable design I guess. It behaves similar to the half DVD, i.e. it is transmission, not a reflective.

It is a shame the kit doesn't have any slit.

Nice simple design : ) I just tried separating a DVD-R, it was quite easy with just a fingernail, the two halves split apart easily, leaving one side that is clear although with a slight-translucent pattern to it depending on how the halves split. However that entire half is usable I think, I could easily see a spectrum through it by holding it at an angle to a lamp.

I suppose their photo emulsion slit could be easy to make with an old camera and b&w film (if that and developer is still available) although probably cheaper just to buy a prepared emulsion slit from that publiclab store.

Anyway, your post reminded me of this childrens' optics kit that costs just $18 from Edmund Optics:

It really is very basic (a few plastic lenses, some filter sheets, a plastic mirror etc) but does come with a thin plastic sheet of diffraction grating (500 lines/mm) mounted in a card frame.

That could be used for a more consistent, repeatable design I guess. It behaves similar to the half DVD, i.e. it is transmission, not a reflective.

It is a shame the kit doesn't have any slit.