LED Light - Beam Charactoristic?

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SUMMARY

The discussion centers on the phenomenon of high-powered LED lights exhibiting bright and dimmer sections along their beam when projected through air, a characteristic not observed in HID beams. Participants speculate that this could be due to variations in the reflector's curvature, leading to multiple focal lengths, or possibly due to environmental factors such as water vapor or dust in the air. The consensus suggests that the quality of the LED reflector plays a significant role in beam consistency, with poorly finished reflectors causing noticeable variations in brightness. The phenomenon appears to be a common occurrence across different geographical locations, indicating a potential environmental influence.

PREREQUISITES
  • Understanding of LED technology and beam characteristics
  • Knowledge of optical principles related to light propagation
  • Familiarity with HID lighting systems
  • Basic concepts of environmental factors affecting light visibility
NEXT STEPS
  • Research the impact of reflector design on LED beam quality
  • Investigate the effects of atmospheric conditions on light propagation
  • Explore the differences between LED and HID lighting technologies
  • Conduct experiments comparing LED and HID beams under various environmental conditions
USEFUL FOR

Lighting engineers, optical scientists, and anyone involved in the design or application of LED lighting systems will benefit from this discussion.

Tea Jay
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For some of the high powered LED lights, the beam seems to have bright and dimmer sections along its length when projected through air.

They seem to be regularly spaced rather than random. Some people have described it as looking as though the beam would get thinner and wider along its length.

It was not observed (noticed) for HID beams for example...just for high powered LED.


What would be an explanation for that?

Off hand, I wondered if it were some sort of resonance/harmonic between the emitter frequencies and the media or wavelength of the light?
 
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It's probably just the lenses or reflectors in the flashlight making a beam that is convergent rather than divergent.
 
How would that make the beam cross over more than once though?

IE: If it had one bright spot in the middle somewhere...I could se that...but what would be happening for the beam to have a spot like that every so many meters, etc?
 
Variations in fog density?
 
Delta Kilo said:
Variations in fog density?
Yeah, that would be a media issue...but its not visually foggy at least...albeit I'm sure there is plenty of vapor in the air nonetheless.

It would need to be a regularly spaced interval of vapor to explain people in Australia and NJ and TX describing the same thing...but no one measured it specifically...so it could be a common, habitat phenomenon.

Why would this affect an LED, but not an HID beam though?
 
If the reflector of the LED is not well finished (varying curvature across its diameter) then you can expect a number of focal lengths to be involved. It looks that different bits of your beam are focussed at different points. I think you probably get what you pay for.
 
Tea Jay said:
Yeah, that would be a media issue...but its not visually foggy at least...albeit I'm sure there is plenty of vapor in the air nonetheless.

It would need to be a regularly spaced interval of vapor to explain people in Australia and NJ and TX describing the same thing...but no one measured it specifically...so it could be a common, habitat phenomenon.


well it may not be fog, but there is something there else you wouldn't be seeing the beam being reflected back to you as it is. so its water vapor, dust ... something ??
and variations in that media is going to cause variations in the brightness of the beam along its length as its reflected back to you


Why would this affect an LED, but not an HID beam though?

dont know, set up your experiment again so we can see both beams going out side by side


Dave
 

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