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Thread: Dichros PBS cubes etc?

  1. #1
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    Default Dichros PBS cubes etc?

    hi ppl.

    ok cant wait soon to start building my projector but still need that blue one. ive found some nice sellers and prices.

    Im the type who wants everything in my hand untill i start installing etc etc.

    Anyway, im litle confused about the dichros and PBS cubes as i thought i would only need dichros.?

    my projector will conisist of:

    1 x green 532
    2 x red 650 (or perahps one 650 and one 635)
    1 x blue 405
    1 x blue 473

    Couldent i just do like this ?
    Attached Thumbnails Attached Thumbnails theworldscoolestsorryhotestlighter.jpg  


  2. #2
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    I realise this doesn't answer any of your questions, but I have to ask why you want a blue 405nm in there, that's almost in ultra-violet territory?, this will barely be visible and it will be difficult to focus on. I could understand a 457nm to give deep blue but 405, surely that's just going way toooo deep or is it ???

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  3. #3
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    yea i know. i just bought a 150mW 405nm on ebay. and as i only have one blue i might aswell put it in there also. its very darkly blue/violet but its a really nice colour.

    As far right now thats the only thing i can afford.

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    Quote Originally Posted by rfourt View Post
    yea i know. i just bought a 150mW 405nm on ebay. and as i only have one blue i might aswell put it in there also. its very darkly blue/violet but its a really nice colour.

    As far right now thats the only thing i can afford.
    Hey, i'm not knocking it as i've never tried it

    BUT>>> We need some pictures AND a full description of what it looks like when its built

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

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    Some of those dichros will be hard to find. I know there has been talk about a custom dichro to combine 635 with 650 nm on the forums, but I don't know if they actually got around to ordering any. If you go with 650 nm you will need a PBS cube to combine them as dichros can only be used to combine beams of different wavelengths. A PBS cube can combine two lasers with different polarization (but preferably the same wavelength). Dichros are basically mirrors that only reflect certain wavelengths. For example, in your drawing the beam from the upper red laser would simply be reflected into the blue laser.

    As for the 405 nm diode it is my opinion that they do not have a place in laser projectors, unless you're using them for graphics and have a fluorescent target. Keep in mind you'll need 30 times the power with 405 nm to achieve the same perceived brightness as 473 nm. I suspect it will also be hard to find the dichros for it. Nevertheless, it is a wonderful color that is impossible to reproduce with pretty much any other display device.

    Then you will have a final problem; with 5 different wavelengths controlled individually you have a 5-dimensional color space. How do you control that? I can't even begin to imagine what any object beyond 4 dimensions would look like.

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    yeah you dont need dichros you need cubed beamsplitters
    Eat Sleep Lase Repeat

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    As far as I know there are dichros that will do what you want. buffo did some really good research on exactly what you are talking about doing.

    http://www.photonlexicon.com/forums/...5&postcount=91

    Also, I think you are spot on in wanting to include 405nm, but you should modulate it separate from the 473nm blue. You will be able to do this with a LaserBoy setup. Since it's software, and it gets added to as needed, it can go anywhere and do anything. If you build the LaserBoy DAC, as it appears on this forum, you will already have 4 channels for color!

    The reality is that, you will absolutely expand your total color gamut. Violet is NOT the same as dim magenta!

    PS I like your drawing!

    James.

  8. #8
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    You guys know that prisms work in reverse if your not trying to be too compact, there is a prism designed for color combining with low or no loss, a pellin-broca , litrows work for that too. waveplates work wonders too. I have a few waveplates that are broadband, to combine two argon beams. You can pull 633 nm waveplates out of older video disk players, and while it is not efficiant, you can get quarterwave sheet from Edmunds et al for about 10$. This lets you combine two beams with polarizaton,using a cube instead of a expensive dichro. However if somebody like did a bulk order group buy with semrock or omega optical, I'm in. The guy from omega is on ebay, is el presidente of the company, and buffo's talks with him ended open ended, with concern about a small percentage of polarziation loss, but hes very friendly and will try to find a piece of overstock glass to help you. hes bjomejag on ebay. many of the commercial waveplate shops would sell you what they woudl call a "second" or "overstock" if you asked.

    and btw, lumalaser sold a commecial club projector with 660 nm and lots of 410 nm in one package. they sold quite a few of them. I used a mobolaser retrofitted with 405 and 658 at a rave last year for static beams. It was a wierd glowing sort of UV light violet color in static beams off haze, but dissapeared when you scaned a effect. its like a fuschia 50: http://www.lumalaser.com/chart_beamburst-models.htm

    Steve
    Last edited by mixedgas; 07-24-2008 at 14:28.

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    Quote Originally Posted by James Lehman View Post
    The reality is that, you will absolutely expand your total color gamut. Violet is NOT the same as dim magenta!
    Going a bit off topic here, but isn't it interesting that violet actually looks like there's a touch of red in it. This is naturally exploited by anyone trying to make violet using only RGB colors. I was very puzzled as to why this trick works, but after a while I came up with a theory.

    The theory was that the absorbance of the L (red) cones in your retina are not only to red wavelenghts, but there's another peak in the UV region. I recently discovered an article that seems to confirm this theory. However, the M (green) cones also have another peak in the UV area, which would work against my theory.

    Anyway, here's the article. A very interesting read in my opinion.
    http://www.pubmedcentral.nih.gov/art...?artid=1279132

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    I think the answer to the mystery is hidden somewhere in the fact that color, in reality, is linear in the electromagnetic spectrum, but human perception of those wavelengths seems to be circular. That is to say, it seems to make sense that the rainbow has no ends. Violet blends right back into red. If you look at the chromaticity chart, there is a thing called "The Purple Line". This is the straight line that joins violet back to red to close the shape. What? Huh?

    James.
    Last edited by James Lehman; 07-24-2008 at 15:49.

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