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Thread: Surplus Shed Green Dichroic Filter

  1. #1
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    A lab with some dripping water on the floor.

    Default Surplus Shed Green Dichroic Filter

    Surplus Shed is one of my favorite sources for optics.
    The $2.50 green dichroic 2x2 was too good a target to pass
    up, and I have access to a HP CCD spectrometer at work and a pretty good one at home too.

    Call this thing the "poor man's slightly angle sensitive combiner"

    So here goes. Transmission at 0" incidence random polarization
    common laser wavelengths

    457 .627%
    477 1.55%
    488 4.42%
    504 7.87%
    514 21.16%
    532 71.07 %

    peak is at 543 @ 93 %
    A second peak is @ 568 KR yellow, 98%

    I'd say the 3 Db points are 515 and 580 looking at the plot.

    however, tilt this beast about 30' and 532 goes up to 85%

    @ 45', 620-670 nm reflection is greater then 98.5%, and you loose maybe
    8% green

    So if your green beam can come in at ~35' off your red beam and your @ 45, this is a winning combiner @ a mere 2.50 , some 1mm deep spots in the coating at the edges, nothing to complain about in the central 95% of the glass.

    At a 0' green beam and a 45' red beam, your not loosing any red at all.

    if you have more green then you need for color balence and are low on red, this is a Winner.

    If you own a all lines krypton or white light and want to pass only the 568 yellow line and the 530 nm green line, but block the red and blue, this is a WINNER !

    I'm gonna use mine with a mercury lamp to pass the mercury green line for testing optics, but hey, at this price, who cares.

    So its a nice classic angle tunable filter

    For those who ask, the shift in wavelength is a cosine function. All dichros have it to some extent.

    Sadly it has a 80% transmission at 808 nm. What do ya want for 2.50 and shipping.

    Surplus Shed part number is M2147

    Next week, I'll review the zero loss at maxy's red, 1% loss at green 45' dichro from Ealing Electro-Optics currently serving as my yellow projector combiner. Its a Ealing SWP 660 designed for 0', but ran at 45.

    Steve Roberts
    Last edited by mixedgas; 12-19-2007 at 15:18. Reason: I got a D in typing in high school when teacher covered my keys

  2. #2
    Join Date
    Oct 2006
    Cleveland, Ohio


    nice. thanks for the details!

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