A digital camera as a spectrophotometer?

Discussion in 'Politics, Religion, Social Issues' started by Cave Man, Jan 6, 2010.

  1. Cave Man macrumors 604

    Cave Man

    Feb 12, 2007
    Neander Valley, Germany; just outside Duesseldorf
    I realize that this thread doesn't seem to belong here based upon its title. However, some of the most thoughtful posts occur in PRSI and I think this is the forum that will most likely generate an answer. Hopefully the mods will agree! This is a 'social' issue, IMO.

    I am working with a group in a developing nation that has very little in terms of modern instrumentation. The infectious agents we are interested in kill tens of thousands of people each year (globally). One device that they really need is a spectrophotometer (visible light) to evaluate density of E. coli cultures for transformation with recombinant plasmids. But they don't have one. So, in the absence of a dedicated spec, does anyone have an idea as to how a digital camera might be used for such a purpose? They have computers (both Macs and PCs) so the use of NIH Image (ImageJ) or some other software can be used. The assay must be quantitative in its assessment of optical density (or absorbance).
  2. Zombie Acorn macrumors 65816

    Zombie Acorn

    Feb 2, 2009
    Toronto, Ontario
    I don't see how you'd be able to get an accurate measurement of how much light gets through with a digital camera. I could be wrong though.
  3. Berlepsch macrumors 6502


    Oct 22, 2007
    You could use a digital camera (without lenses) as a detector for a spectrometer. But the key component for an optical spectrometer is the dispersive element (prism or diffraction grating). Proper design of a spectrometer is not a trivial task and possible approaches depend very much on the present conditions.

    If I understand your problem correctly, what you really need is to measure absorption in a certain wavelength region. In that case, it could be sufficient to use just an optical filter instead of a spectrometer. For a first test, you can take one picture with your samples in the light path, plus a reference picture without sample under the same conditions. When you integrate the pixel intensities over the illuminated areas, it should give you a reasonable measure of the transmitted light. This is of course just a rough idea, since I know no details about your setup.

    Maybe you could ask around in the physics department of one of your local universities - this might be a nice topic tor a bachelor's work in physics or applied sciences.
  4. Leareth macrumors 68000


    Nov 11, 2004
    a digital camera CAN act as a multispectral sensor if have the right filters
    but for what you are talking about you may need a hyperspectral sensor.
    Sure you can modify a camera to have the hyperspec sensor in it but the $ = to buying a decent one
    ADS and Ocean Optics are my fave ones.

    either way , the sensor has to be calibrated before each use to the current light conditions.
  5. glocke12 macrumors 6502a


    Jan 7, 2008
    Im a biologist, not a physicist, but I cant really see how this can be done.

    Why not just get a real spec? Used, they are fairly inexpensive.


    You can even try calling around to pharma companies and see if they have one to donate. I know that at the company I work for we are constantly putting old pieces of equipment into storage and they stay there indefinitely (picture the warehouse at the end of "Raiders of the Lost Ark".

    As a matter of fact, I'll even offer to ask at the place of my employment for you, but you will need to give me some background info (name of your organization, why the instrument is needed, contact person, etc ). Feel free to send me a PM if this interests you.

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