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What is the halo of minuscule dots seen around some LEDs?
David Hess:
Also most lasers, especially laser diodes and gas lasers, have very short coherence lengths making them useless for holography or Interferometry, yet they all produce speckles.
Siwastaja:
--- Quote from: Benta on January 30, 2023, 10:17:32 pm ---What exactly do you mean? Is your question about laser LEDs or plain LEDs?
--- End quote ---
"Laser LED" is a misnomer and as such, so is "plain LED".
Laser diode = LD. OP is clearly asking about LEDs, not laser diodes.
RoGeorge:
Yes, normal LEDs. The one that reminded me to ask was a SMD red LED from an Arduino Nano devboard.
I wonder how much would it be possible to get the projection of a diffraction pattern from such a red LED with visible speckle. From the laser pointers is trivial to project the diffraction pattern of a narrow slit. The LED is not strong enough. I've tried with a closer paper screen but it's hard to say if that's diffraction or just a shadow. ???
SiliconWizard:
https://www.sciencedirect.com/science/article/abs/pii/S0022231309003871
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