COMSOL Optics Tutorial: Spot Diagrams and Ray Tracing

[@aleksandarhaber]

If you need help with your professional engineering problem, or you need to develop new skills in the fields of control, signal processing, embedded systems, programming, optimization, machine learning, robotics, etc., we are here to help. We provide professional engineering services as well as tutoring and skill development services. We have more than 15 years of industry, research, and university-level teaching experience. Describe your problem and we will send you a quote for our services. The contact information is [e-mail] It takes a significant amount of time and energy to create these free video tutorials. You can support my efforts in this way: - Buy me a Coffee: www.buymeacoffee.com/AleksandarHaber - PayPal: www.paypal.me/AleksandarHaber - Patreon: www.patreon.com/user?u=32080176&fan_landing=true - You Can also press the Thanks KZbin Dollar button

[@tilkesh]

Thanks

[@aleksandarhaber]

Welcome

[@vitorhugoRH]

Hey, fantastic video! Thanks for the upload.

[@aleksandarhaber]

Thank you.

[@Muradsahar]

Very good video, I want to simulate rays as they pass through 3 slabs of different materials with refractive indices of n_1, n_2 and n_3. I was wondering if there is a good book that you can recommend on the optical simulations in COMSOL..

[@aleksandarhaber]

I learned this toolbox by following online tutorials and by reading the user manual. The problem you are trying to simulate is not complex and it can be done easily. Unfortunately, I cannot do it at this point simply because my COMSOL license expired. Thank you, A. Haber

[@Muradsahar]

@@aleksandarhaber I am geting closer, I am facing the following challange now, I need to define a slab with a rough surface, where light can do both, transmit and scatter randomly, and I need to define the material property of allowing light to pass through, (a semi conductor material let us say), I do not want my material to be a slab of glass or any simple material that just allows light to go through. But the most impartant challange now is how to define a rough surface, I do not see it in the available shapes in the Geometry section.

[@aleksandarhaber]

@@Muradsahar Hello Murat, I cannot help more at this point. Sorry about that.

[@hunballom]

Thank you for the good video. Is it possible to simulate how light is transmitted in the lower part after covering the path of light with a patterned mask?

[@hunballom]

Like photolithography.

[@aleksandarhaber]

We do not provide free help

[@priyankarai2381]

Hey these videos are very helpful. Will you please demonstrate solar radiation ray release feature considering the building. Thank you.

[@aleksandarhaber]

Hi Priyanka, Thank you for the comment. These days I am super busy. When I have a chance I will look into the solar radiation related to buildings.

[@李彦锐-b6s]

Sir, when I was practicing the thermally induced focal shift case in the comsol case library, I found that the calculation result: temperature and deposite ray power will increase correspondingly with the increase of the grid density, and it seems that there is no trend towards stability. Why does this happen? Waiting for your answer, most thanks!

[@aleksandarhaber]

I do not know why this happens, it should converge. Did you increase the mesh density significantly? Also, did you scale the number of rays propagating in the system with the mesh density? How about optical and thermo-mechanical boundary condition?

[@李彦锐-b6s]

@@aleksandarhaber yeah, I only change the mesh density like 2 or 10 order of original and without change other things, and the calculating results (especially the deposite ray power) also increased maybe 2 or 10 order of original. By the way, this case you can find easy in comsol case library which named thermally_induced_focal_shift.

[@aleksandarhaber]

@@李彦锐-b6s Thank you!

[@shubhamgupta9029]

Hello Sir, I was trying to do the same as your video but instead of lens I tried to make my own geometry using a block and a refractive index of 1.92, but now for some reason my rays are not entering the block. Please help.

[@aleksandarhaber]

I do not know what is the reason. Sorry, but I cannot help more at this point.

[@medoabotalb5409]

can you tell me how i can simulate a ray tracing for a reflector dish and a solar cell

[@aleksandarhaber]

www.comsol.com/blogs/how-to-model-solar-concentrators-with-the-ray-optics-module/

[@vitorhugoRH]

If we simulate in 2D (for example, planar lenses) is there a way for Comsol to calculate the focal point? And what type of post processing could we made to see results, since in 2D we can't see spot diagrams i think. Thanks again!

[@aleksandarhaber]

I think that you can simulate everything in 3D, and then you can easily obtain a 2D view. You can perform ray tracing. I did something similar over here: kzbin.info/www/bejne/b4HYlZqhmb12m80 On the other hand, you can automatically compute the focal point in COMSOL mutliphysics, following the methods I presented. You need a reference hemisphere that can be automatically computed. You can also manually compute the reference hemisphere. Under Results, there is an option Dataset, and there you can specify "Intersection Point 3D". There you can enter the center of the hemisphere.

[@vitorhugoRH]

Thanks, COMSOL can't correctly guess the focal point. In reality, the "focal point" for a planar lenses is going to be a very thin elipse, and maybe that's why COMSOL can't correctly guess it. I did not understand what you mean by reference hemisphere but i'll try looking into it a bit more. Here is an image of what I'm talking about. i.imgur.com/NVDmLCf.png Wish there was a way to know what optical path corresponds a certain time.

[@aleksandarhaber]

@@vitorhugoRH I saw the figure you uploaded. It looks to me that you are dealing with an afocal system - that is the rays are not being focused. The reference sphere is used to define wave-front aberrations, and usually, it is placed at the center of an approximate focal plane.

[@aleksandarhaber]

@@vitorhugoRH COMSOL can determine an approximate focal plane. I doubled checked this, see for example this video: kzbin.info/www/bejne/b4HYlZqhmb12m80 I used a thin lens equation to analytically compute the location of the focal plane, and then I verified the location in COMSOL. The results match each other.

[@vitorhugoRH]

@@aleksandarhaber Thanks so much for the replies. I'm trying to simulate planar lenses to "focus" light on a small area in a microchannel for detection. I will check your suggestion!