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  • black light

    From RichD@21:1/5 to All on Mon Feb 11 14:51:34 2019
    I saw a pocket flashlight in a hardware store yesterday,
    it shines UV. Such a package is new to me.

    What is it good for? What's inside?

    And whence the origin of the term 'black light'?
    I recall days gone by, the wall posters were popular, is
    that still in fashion?

    --
    Rich

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  • From Phil Hobbs@21:1/5 to RichD on Tue Feb 12 10:29:44 2019
    On 2/11/19 5:51 PM, RichD wrote:

    I saw a pocket flashlight in a hardware store yesterday,
    it shines UV. Such a package is new to me.

    What is it good for? What's inside?

    Probably a 385 nm LED, and used for checking money or something. Folks
    also use fluorescent dye for finding leaks, I think. (If they don't,
    they should.) ;)


    And whence the origin of the term 'black light'?

    Marketing. It's light, but you basically can't see it. The original
    ones are just fluorescent tubes with a short-pass filter to pass the
    365-nm I-line of mercury. (The more dangerous 254-nm

    I recall days gone by, the wall posters were popular, is
    that still in fashion?

    I haven't seen one in years, but that doesn't prove anything since I'm
    not in fashion anymore either. ;)

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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