LED's classes of radinat intensity and total radiant flux

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Discussion Overview

The discussion revolves around the specifications of LED radiant intensity and total radiant flux, particularly focusing on the SFH 4258 model from Osram. Participants explore the implications of different radiant intensity groups on total radiant flux and related optical characteristics.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that manufacturers specify groups of radiant intensity for LEDs, questioning whether total radiant flux remains constant across these groups.
  • One participant suggests that "Strahlstärke" is a German term for radiant intensity.
  • Another participant proposes that the half angle of emission remains unchanged while total radiant flux may vary according to the group.
  • A participant hypothesizes that radiant intensity groups arise from chip position tolerances during manufacturing, affecting alignment with the lens.
  • Some participants argue that total radiant flux does not change across groups, despite variations in radiant intensity.
  • There is uncertainty about whether misalignment of the chip affects the half angle of emission and the overall radiation cone.

Areas of Agreement / Disagreement

Participants express differing views on whether total radiant flux varies with radiant intensity groups, with some asserting it remains constant while others question this assumption. The discussion reflects multiple competing perspectives on the implications of chip alignment and its effects on optical properties.

Contextual Notes

Participants acknowledge potential limitations in understanding how misalignment affects the half angle and overall radiation characteristics, indicating that these aspects remain unresolved.

vst98
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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.
 
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vst98 said:
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/XPic0/00101891_0.pdf/SFH 4258, 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.

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

My German is a bit rusty.
 
OmCheeto said:
Pardon me for asking, but what is a "Strahlstärke"?

My German is a bit rusty.

I think it is German term for radinat intensity.
 
OmCheeto said:
Pardon me for asking, but what is a "Strahlstärke"?

My German is a bit rusty.
It looks as if the half angle stays the same and the total radiant flux varies according to the group.
 
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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