Learning Forum

[arezoo.tahmasebi]

Dear colleagues,

I am relatively new to Zemax and hope you will forgive me for asking a lengthy question.

My objective is to design a lens that incorporates specific features. The aim is to create a lens that can convert a laser beam with a Gaussian intensity profile and circular beam shape into a beam with an almost uniform intensity profile and rectangular beam shape.

I am considering designing a lens in the Zemax sequential user interface using a biconic surface, as this allows me to define two radii of curvature in two transverse directions. To achieve a rectangular output beam, I believe that two radii of curvature in the transverse direction will be required to stretch and shape the beam into the desired rectangular shape. However, I would like to seek advice on the following questions:

1. Please confirm whether biconic surfaces will assist me in achieving this.

2. Is there an option in ZEMAX that allows me to optimise the curvature of the biconic surface by defining a specific merit function, thereby achieving the desired rectangular beam shape on the detector?
Following a review of the relevant literature, I became aware of the terms like ray mapping, ray mapping least square calculation,  and the Monge-Ampère equation, which are used for mapping light from a source (e.g. an LED) into a target irradiance distribution. I also learned about the SQM approach (Supporting Quadric Method), which is used to design a lens that transforms a Gaussian circular beam into a rectangular beam. This approach is iterative and computational, and it is used to define the lens shape. To design my desired lens, do I need to do some computation and probably some proramming to solve some nonlinear partial differential equation to find the exact shape of the lens?

Should you require further clarification on this topic, please do not hesitate to contact me.

I would be extremely grateful for any assistance you could provide.
I have also attached a link showing an example of beam shaping that is closely related to my goal.

Regards,
Arezoo

https://www.polymer-optics.co.uk/wp-content/uploads/2023/03/FreeForm-Solutions.pdf

[Niki Papachristou]

Hi Arezoo, 

I think you are right here. A biconic surface can be used for this type of beam shaping. Its Radius is the radius along Y, and its first parameter is X Radius. Therefore, you can independently change each radii. They can also be both made variable, and used during optimization.

I would also suggest to have a look in this article in case you can find it helpful: How to design a Gaussian to Top Hat beam shaper

I hope that was helpful, let me know if I can be of further assistance.

Kind Regards,

Niki