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Quick question on Laser diode specifications regarding fast/slow axis beam divergence angles:

LazyBeam

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When looking at a specification sheet for a laser diode (like this one, for example: https://www.laserlands.net/datasheet/11091055.pdf) is the angle listed the FULL angle of the beam exiting the diode or the HALF angle, as measured from the beam center-line?

I'm wanting to make a homemade infrared illuminator with a full angle divergence of about 10-16 degrees (not collimated), and the above example diode (https://www.laserlands.net/datasheet/11091055.pdf) appears to produce 12 degrees of divergence on the slow axis ... exactly what I'm already looking for, assuming of course that the specification sheet is indicating full angle divergence. So to use that diode, all I might need is either a plano-convex cylindrical lens or pair of anamorphic prism to slow the fast axis. According to the specification sheet on the diode, the divergence ratio is about 3:1 so perhaps something like this prism pair would work: https://www.thorlabs.com/thorproduct.cfm?partnumber=PS879-B
 
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diachi

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When looking at a specification sheet for a laser diode (like this one, for example: https://www.laserlands.net/datasheet/11091055.pdf) is the angle listed the FULL angle of the beam exiting the diode or the HALF angle, as measured from the beam center-line?

I'm wanting to make a homemade infrared illuminator with a full angle divergence of about 10-16 degrees (not collimated), and the above example diode (https://www.laserlands.net/datasheet/11091055.pdf) appears to produce 12 degrees of divergence on the slow axis ... exactly what I'm already looking for, assuming of course that the specification sheet is indicating full angle divergence. So to use that diode, all I might need is either a plano-convex cylindrical lens or pair of anamorphic prism to slow the fast axis. According to the specification sheet on the diode, the divergence ratio is about 3:1 so perhaps something like this prism pair would work: https://www.thorlabs.com/thorproduct.cfm?partnumber=PS879-B

It's the FWHM (Full Width Half Maximum) divergence.

This article does a good job of explaining the measurement. https://www.rp-photonics.com/beam_divergence.html
 

LazyBeam

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so "full width" being the full angle of divergence... "half-maximum" being as measured roughly where the beam radius is half-the-max brightness.
 







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