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Q & A: shaping beam

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Most recent answer: 10/15/2009
Q:
I have a led laser and would like to know if it is possible to make the beam into a small dot instead of a dash shape with the use of focus lenses? Will I need to make a aperture in the shape of a small dot in order to create the beam shape I need?
- Vic Meek
Casa Grande Az.
A:
An aperture doesn't sound like a great idea, since it throws away some of the beam. Also, the sharp edges of an aperture  lead to beam spreading. A better bet is to combine a cylindrical lens and a spherical lens or two.

Mike W.

This is the answer I sent on Oct. 8.  Perhaps you didn't read it:
Welcome back Vic,
Many lasers have dash shaped beams.  This is due to astigmatism of the lenses in the laser.   It is possible to have an external astigmatic lens to correct this.  You have to measure the beam width,  beam length and beam divergence and then do a little calculating in order to specify the correct lens prescription.  You can buy a cylindrical lens that will focus light in only one dimension from the Edmond company.  They run about $110 each.  See:
http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2053
A cheap possibility is to orient the laser so that the wide part of the dash is aligned parallel to the direction of the cut.

LeeH
p.s. I'm glad you bought protective glasses

(published on 10/15/2009)

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