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  1. #51

    Join Date
    Oct 2006
    Medium Format
    Quote Originally Posted by Kirk Keyes View Post
    Blu-Rays use LASER diodes at 405 nm - funny thing is that is considered a "violet" wavelength!
    It is. Moreover, in contrast to what the eye sensitivity curve suggests, these lasers are highly (painfully) visible!

    Quote Originally Posted by Kirk Keyes View Post
    I see Sony unvieled a Blu-Ray prototype in Oct. 2000 - I'm not sure when the diodes were invented, but it's certainly a few years before they showed the Blu-Ray.
    Meanwhile these lasers have become pretty cheap and are available with powers >1W. I assume they might be interesting for photographic applications involving the use of dichromates or ferric salts etc.

  2. #52
    holmburgers's Avatar
    Join Date
    Aug 2009
    Rochester NY (native KS)
    Multi Format
    Thanks for the answers to my questions Kirk.

    So if we imagine a simple "shoe-box" spectrosensitometer, it might look like this.

    Light source (let's imagine a simple tungsten flash-light bulb for now) -> far enough away or with collimating lens -> diffraction grating -> focusing lens -> film plane.

    The light needs to hit the grating dead on, and then we need to focus that image sharply onto the focal plane. Any idea what kind of lenses we'd need, and approximate focal lengths? There are some acrylic lens sets that you can get, or we might be able to order some more appropriate lenses, both from Edmund.

    It seems one of the lens kits would be great for this; they have all the different types of lenses for abotu $15.
    If you are the big tree, we are the small axe

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