Hi Nadav,

The merit function operand NSDD can be used to target the RMS Angular Radius to zero. And also to target the total flux on the detector to a value which keeps the optimizer from achieving the first goal by sending offending rays off the detector.

The easiest way to do this is to use the merit function wizard like this:

For the design, I use a pickup to force the paraxial lens y focal length to be equal to the x focal length, and make the x focal length variable. Optimization then results in a focal length that collimates the beam. I also attach the resulting file.

Hi David,

Thanks for the quick and detailed answer.

Any advice to make optimization when the rays do not exit from the same point?

like that:

Best regards,

Nadav

Hi Nadav,

A source having a non-zero size and divergence cannot be perfectly collimated. There is a quantified property of a source or any light body called etendue. One number that can be used to represent etendue (though not the most technical) is the product of the radial size and the angular divergence. In transforming a light body, this value can be increased but not decreased. So if you need to produce a collimated beam, you need to start with a source having an etendue as small or smaller than the etendue required of the final output. Another concept that addresses the same issue is the conservation of the Lagrange invariant. There is a lot of material online for each of these concepts. 

Hi Nadav,

seems like you are using an LED from ams OSRAM. In that case you can consult the info file which is part of the rayfile package. In the info file, you’ll find values for “virtual focus”. This is the center of gravity of the emitted ray bundle. In first approximation, you can align the front focal point of your collimating lens to that “virtual focus”.

Best regards,

Peter 

https://www.osram.com/apps/downloadcenter/os/?path=%2Fos-files%2FOptical+Simulation%2F

https://support.zemax.com/hc/en-us/articles/1500005486661-How-to-use-Osram-LED-data-with-OpticStudio

Hi,

Thank you both, David and Peter!

Best regards,

Nadav