Learning Forum

[jeonhj]

I'm trying to ray trace using a cicular sector fresnel lens.
I've seen people modify cicular lenses to rectangular form, but can not find any information about cutting it into circular sectors.

Is there a way to achieve this using the created lens in Zemax?

The shapes I want to achieve are attached in the picture below.

[Flurin Herren]

Hi Jeonhj,

Thanks for posting here in the Forum!

The main question would be in which mode you are working. In non-sequential this would be quite straight forward: Use either the Fresnel 1 or 2 as you main object.

• (Fresnel 1:This object is a general radially symmetric or cylindrical solid Fresnel lens constructed by modeling the detailed faces of the Fresnel surface; Fresnel 2: This object is an idealized Fresnel lens. Unlike the Fresnel 1, this Fresnel lens uses the approximation that the Fresnel faces are infinitesimally small, and may be ignored for purposes of computing the ray-object intersection point.)  

And then utilise Boolean operations to shape or cut your Fresnel lens into any shape you want. How to use the Boolean CAD, Boolean Native and Compound Lens objects, and the Combine Objects tool – Knowledgebase

 

In sequential this is might be a bit more work, but I am fairly certain you'd be able to get all of these shapes in one way or another. As you have already mentioned, in the Surface properties of any sequential surface, you can change the aperture of this specific surface. Some of these shapes might be possible to achieve with some of the native aperture types, i.e. Spider aperture with 3 arms. Additionally, you can also look into User Defined Apertures and Obscurations.  For that you can create your own UDA file. The UDA files are text files that may be created and edited using any text editor.

 

Further approaches would also be to simply place a "Blocker" surface in front of the front side of the Fresnel lens. As shown in the picture below:

You can always hide (Do not draw) the blocker surface.

 

Let me know if you have any follow up questions,

Best,

 

[abhilash.sukumari]

Hi Jeon, what software and tools did you use to make your sketches? It looks great! Best - Asuku

[jeonhj]

Thanks for the compliment! Those are just sketches I drew using the Goodnote on my ipad. Nothing too fancy.