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looking towards source = more noticeable beam?

I

ixfd64

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A few days ago, I was trying to measure the divergence of a generic laser pointer (it was really bad, like 6 mrad or something) when I noticed a very faint beam. This only happens when I look in the direction of the source of the laser. Under normal circumstances, I could never get a visible beam from a <5 mW red laser pointer except maybe in a steamy bathroom. Is there an explanation for this?

The beam was much dimmer than that of my Core, but it was just beautiful. I tried to get some beam shots, but the beam didn't show in the pictures as my camera doesn't handle low-light settings very well.
 





Raiden Gekkou

Raiden Gekkou

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Maybe you're picking up faint IR? I used to stare into the red laser pointers that you get from the dollar store sometimes, and would notice a bit of a beam when shining it to the side of my eye. I could also see little "shapes" moving through the beam while doing this.
 
Dr_Evil

Dr_Evil

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Raiden Gekkou said:
Maybe you're picking up faint IR? I used to stare into the red laser pointers that you get from the dollar store sometimes, and would notice a bit of a beam when shining it to the side of my eye. I could also see little "shapes" moving through the beam while doing this.
Click to expand...

Unless it is DPSS red, there won't be any IR. Not only that, he said he saw a faint beam.

ixfd64 said:
A few days ago, I was trying to measure the divergence of a generic laser pointer (it was really bad, like 6 mrad or something) when I noticed a very faint beam. This only happens when I look in the direction of the source of the laser. Under normal circumstances, I could never get a visible beam from a <5 mW red laser pointer except maybe in a steamy bathroom. Is there an explanation for this?

The beam was much dimmer than that of my Core, but it was just beautiful. I tried to get some beam shots, but the beam didn't show in the pictures as my camera doesn't handle low-light settings very well.
Click to expand...

That will happen with almost any pointer. The beam will be brighter if you looks torwards the source. You won't notice a beam with most low power pointers unless you look torwards them. You'd need a really low power green to not really see a beam during the night until to looks towards it.
 
Cyparagon

Cyparagon

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This is a well known phenomenon called Mie scattering.

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