Dmitriy,

How do you define the light collection efficiency of a lens?

Best regards,

David

I want light collection efficiency calculations.

light collection efficiency η (%) = Amount of radiation reaching the detector / Total amount of radiation.


 


Source data: radiation wavelength, radiation power, distance from the source to the lens.


Lens data: refractive indices, lens materials, focal length.

through which function can I calculate this using Zemax Opticstudio?

Hi Dmitriy,

For me, collection efficiency is still very dependent on context. In the attached file I constructed a simple example based on a particular situation: That of the suns rays being focused by a singlet onto a rectangular detector.

1. The sun subtends an angle of 0.5 degrees, so a Source Two Angle with a 0.25 degree half angle is used to simulate the suns rays. It has an elliptical shape in position and angle space and is slightly larger than the collection lens.



2. A singlet is used to focus the rays onto the detector. Both the front and back radii are variable in optimization.



3. A Detector Surface is used to measure the power hitting the lens. Its diameter and radius are forced to match the lens by pick ups. It is placed just in front of the lens. It is set to Front Only so it does not detect back reflection from the lens.



4. A Detector Rectangle is placed at a fixed distance from the lens to represent a physical detector. For other shapes an aperture could be placed in front of it, or a Detector Surface could be used for a disc.

The Merit Function Wizard was used to create a merit function that seeks to minimize the spot size on detector 4 while also seeking to maximize the power. To this was added operands to obtain the power on the lens detector 3 and then divide the total power on detector 4 by that on detector 3.

Optimization was done by Orthoganal Descent. This determined the radii of the front and back of the lens, and a collection efficiency of 0.915.  For this case, the major loss is certainly the Fresnel reflections of the two faces of the lens. (For real detectors, it might be best to fill the detector more uniformly and not produce a hot spot.)

I hope this helps,

Kind regards,

David 

Hello, David.

I have a lens objective consisting of 3 lenses. I am sending you a sequential and non-sequential build file. The purpose of this lens objective is to collect light from a point light source. The source can be in different locations from 0 to 12 °. I modeled my system in sequential mode. Please help me calculate the efficiency of collecting light in my conditions, for each source.


David, thank you in advance.

Hi Dmitry

I think that the method that David shows works with your file. Here is what you can do for example:

When the source is 1W, it is quite easy because the flux gives directly the efficiency / collection. We have this article that explains the optimization wizard in non-sequential: https://support.zemax.com/hc/en-us/articles/1500005575582-Using-the-OpticStudio-Non-Sequential-Optimization-Wizards

In sequential mode, it can be done using the Geometric Image Analysis. This article is about fibers but that also can be applied to light collection: https://support.zemax.com/hc/en-us/articles/1500005486601-How-to-model-multi-mode-fiber-coupling