Old 03-01-2012, 07:40 AM #1
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Question beam focus offset? HELP?

ok does anyone know the reason for this? i have just bought this laser off deal extreme as i need it for a photography assignment at school when i bought it i received this stuffed up laser... the beam doesn't go very far, is it out of focus? heres photos of close up and far away. (not the best)

laser pointer is about 1.5-2m away from the wall


laser pointer is close up to the wall


im not sure if you can tell my the images but the laser dot is not a dot from far away, it is more of a dot with a feathery bit sticking out the side.

thanks.


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Old 03-01-2012, 07:45 AM #2
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Default Re: beam focus offset? HELP?

What exactly is the issue you're having with it; is the spot/beam too large/wide at a distance for your application or is it the "feathery bit sticking out" that is the problem?

If it is the latter, it could be quite a few things; dirty aperture, dirty IR filter, dirty lens, internal reflection, mode hopping, or even a misaligned lens. Always go with Ockham's Razor until tests/evidence suggest otherwise though. =)

Out of curiosity, what is your assignment?
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Old 03-01-2012, 08:00 AM #3
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Default Re: beam focus offset? HELP?

um its the fact that the beam is too large at a distance, resulting in short range, but its for my topic which is "drawing with light" and i chose to use lasers as a part of it thanks anyway
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Old 03-01-2012, 08:10 AM #4
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Default Re: beam focus offset? HELP?

Ahh, the beam is too divergent then. Unfortunately this is not easily (inexpensively) fixed. The laser's divergence is a fixed factor based on the diameter of the beam at the aperture. In order to lower the divergence (make the beam smaller at a distance) you have to increase the diameter of the beam at the aperture. This can only be accomplished by what is called a "beam expander". Beam expanders can easily be made if you have access to lenses and a suitable housing, but they are expensive to buy. They also don't work very well with pointers since it greatly increases the form factor and weight.
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Old 03-01-2012, 08:19 AM #5
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Default Re: beam focus offset? HELP?

hmm interesting, if thats the case i might just buy another one :L and hope for the best, thanks for your help man!
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