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Author Topic: Green laser pointers  (Read 180 times)

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Offline tony.673

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Green laser pointers
« on: 12:06:52, 23 July, 2018 »
OK guys,

Here's a quick one for our scientifically minded members.

Why is a green laser pointer beam visible at night but not a red beam?

Tony
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Offline chris.bailey

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Re: Green laser pointers
« Reply #1 on: 14:55:24, 23 July, 2018 »
Off the top of my head, red light penetrates water vapour, dust, pollution better than green light, which is why it is best to do your R filter imaging when the object is low in the sky and do the B filer either side of the meridian when it is highest. The green is more likely to be scattered by this and it is the scattering you see. On a foggy night you can see the beam from a red light LED.
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Offline tony.673

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Re: Green laser pointers
« Reply #2 on: 15:17:07, 23 July, 2018 »
Thanks Chris,
I did Google this and tried Wiki but the text got a little to complex for my brain to understand but your answer makes so much more sense.

Tony
102mm f6 refractor, HEQ5, AA Gpcam130c, Neximage, SPC900, Celestron 15x70 binos, Canon 550D 70-300mm, 18-250mm, 400mm f6.3 & nifty fifty.

Offline tomhow

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Re: Green laser pointers
« Reply #3 on: 15:38:11, 23 July, 2018 »
I think the human eye has something to do with it - we are far more sensitive to green than the long wavelength reds typical in lasers
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