Hi everyone,i am trying to design a refractive beam shaper to generate a collimated top hat beam of emitting beam from a laser diode.Approach: To simplify the design, i defined the beam source circular and not elliptical. After parameter-design for fast axis i will scale the lens and use the scaled parameter for slow axis. All as compound element. With the flint lens i try to achieve top hat distribution before clown lens and collimate it with the clown lens. Distance between lenses is not variable (about 2mm) for my merit function i took Spot Radius(Target 4mm) + Spatial uniformity(Target 0) → NSC Variables: radius, conic, coeffr4, coeffr8 The result of optimization due to uniformity is nit satisfying. Is there any additional merit function or any other method to achieve a good uniformity?

Question

Top Hat collimated beam from Laserdiode

2 years ago
6 October 2021
3 replies
697 views

amarandi
13 replies

Hi everyone,

i am trying to design a refractive beam shaper to generate a collimated top hat beam of emitting beam from a laser diode.

Approach: To simplify the design, i defined the beam source circular and not elliptical. After parameter-design for fast axis i will scale the lens and use the scaled parameter for slow axis. All as compound element.
With the flint lens i try to achieve top hat distribution before clown lens and collimate it with the clown lens. Distance between lenses is not variable (about 2mm)
for my merit function i took Spot Radius(Target 4mm) + Spatial uniformity(Target 0) → NSC
- Variables: radius, conic, coeffr4, coeffr8

The result of optimization due to uniformity is nit satisfying. Is there any additional merit function or any other method to achieve a good uniformity?

3 replies

Userlevel 7

Hi Amarandi,

Have you had a look at this article? It might help you solve some of your issues.

It makes use of the sequential mode to design the beam shaper, which is much faster than the non-sequential mode.

I hope this helps.

Take care,

David

Hey David,

tanks a lot for your reply. I am familiar with the article. In fact i used it first, but got geometry as answer, which are far away from target. Optimization speed is not my first problem. I dont get, why it is not possible to achieve a collimated top hat beam shape with three even aspheric surfaces and the standard merit function?

Ata

Userlevel 6

Hi Ata

Feel free to open a ticket by email support@zemax.com. We can have a look at how your merit function is built.

When you target for uniformity, sometimes non-sequential can be a good 2nd step to finish the optimization. The wizard contains settings to target for a uniform output.

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