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Thread: Polaroid filters

  1. #1
    Join Date
    Oct 2010
    Location
    Stockholm / Sweden
    Posts
    16

    Default Polaroid filters

    I got hold of some pieces of HN-22 polaroid filters that the company that sell them told me would work as damping the rays from a 445nm laser. I got a PDF http://geekjoan.com/hn22.pdf with some data on the filters. The way I read the data this filters block out about 80% of the rays, and if I use two I could get it down alot more. Im I reading the sheet right?

    Have anyone any experiance with this?

  2. #2
    Join Date
    Jan 2007
    Location
    Yorkshire, UK
    Posts
    4,581

    Default

    If you use two polarised filters you can vary the amount of light that passes through them by simply setting one of them at a fixed angle and rotating the other one in front of it. As you rotate the second filter you will observe that all light eventually gets blocked. This is the point where the filters are at right angles to one another. As you continue to rotate you will see light begin to pass through once more.
    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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