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LED's classes of radinat intensity and total radiant flux

  1. Mar 23, 2015 #1
    I found that for some LED's manufacturers specify groups/classes of radinat intensity in their datasheets.
    For example SFH 4258 from Osram http://www.osram-os.com/Graphics/XP..., Lead (Pb) Free Product - RoHS Compliant.pdf
    has four groups, going from 50 to 250 mW/sr. Does this mean that the total radiant flux (70 mW) also has a spread related to these four groups or remains the same.
  2. jcsd
  3. Mar 28, 2015 #2


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    Pardon me for asking, but what is a "Strahlstärke"?

    My German is a bit rusty.
  4. Mar 29, 2015 #3
    I think it is German term for radinat intensity.
  5. Mar 31, 2015 #4


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    It looks as if the half angle stays the same and the total radiant flux varies according to the group.
  6. Apr 1, 2015 #5
    Here are some of my thoughts, any remarks are welcome.
    I assume that radiant intensity is the radiant intensity which is measured on the optical axis of the lens on the housing.

    What is the cause of radiant intensity groups ?

    Radiant intensity groups are result of the chip position tolerances.
    When the chip is encapsulated in a package, during manufacturing process,
    the chip and the focal point of the lens are not aligned optimally.

    Does the total radiant flux change from group to group ?

    No, it remains the same in all of the radiant intensity groups.
    Misalignment of the chip and the lens will not significantly influence the total output flux.

    But if the radiant intensity can change from 50 to 250 mW/sr can you also expect
    considerable tolerances in the half angle, doesn't this mean that 3D cone in which the radiation is emitted
    has an offset from the optical axis of the lens ?

    Huh, not sure about that. I think that if the chip is misaligned (shifted or inclined to the focal point)
    the cone of the emitted radiation will still lie on the optical axis, the lens will act as a corrector.
    But the collimation by the lens wold be reduced which gives decrease in the radiant intensity.
    Not sure how this affects the half angle.
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