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Infra-Red optical filters: What are made of ?

  1. Apr 13, 2014 #1
    Dear friends,

    I wish know what is/are the chemical elements commonly used for build filter lens applied on moderns night vision cameras.

    Thanks in advance.

  2. jcsd
  3. Apr 13, 2014 #2


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    Staff: Mentor

    Welcome to the PF.

    What has your reading told you so far? What research have you done on this? Can you post links to some of the reading that you have been doing, and ask specific questions on things that you are not understanding in that reading?
  4. Apr 18, 2014 #3
    Dear berkeman,

    Thanks a lot for the prompt reply, however I do not understand what properly I need provide beyond the problem stated on previous description itself, but I´ll try answer each one of your questions, as follows

    I just heard from a friend who worked on projects of professional cameras designed for Industrial applications ( more specifically, temperature measurement based on IR 'light' spectrum ), that there exists a lot of industrial optical filters designed for specific frequencies on 'light' spectrum. Each one of these lens are manufactured by a process on what the glass is doped with specific chemical elements.

    Concerning to research, I googled a lot, but could not find any reference about manufacturing process and chemical elements employed.

    I came here to this board because unfortunately could not get those information at other websites and expected could be the suitable place for that, but thanks anyway.

  5. Apr 18, 2014 #4


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    Staff: Mentor

    In your OP you asked about night vision systems. But in your 2nd post you mention IR temperature sensing. The two systems are pretty different. Which are you interested in? Do you know already what the main differences are?
  6. Apr 18, 2014 #5
    Both vision systems essentially operate on the same working principle, based on reading the radiated energy emitted from a 'black body', which is a function of its own temperature.

    For some reason that does not matter for this subject, frequencies near the infrared range are the most suitable for obtaining this information on current sensor technologies.

    However, once the frequency range of cameras CCD and CMOS is quite large, becomes necessary filtering frequencies of all the other 'light' spectrum ( mostly visible ), which could saturate measurement if occurring during the day, or under artificial lighting.

    This filtering "bandpass" is performed by special lenses, made with the inclusion of primary chemical elements in their substrate, so that for each desired spectrum of light energy is applied a different 'ingredient' in its glass formula.

    My curiosity just lies on know what chemical element is used in the case of IR lenses.

  7. Apr 18, 2014 #6


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    Staff: Mentor

  8. Apr 19, 2014 #7
    Dear berkeman,

    The last link you gave brings exactly what I need.
    In fact, I was not applying proper keywords on Google search.

    Thanks a lot for assistance.

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