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Simulation of LED-Array in Sequential mode

  • 26 January 2022
  • 5 replies
  • 584 views
M

Hi everyone,

 

I’m currently trying to simulate an LED-Array in sequential mode and I’m running into a bit of trouble. For first approximation, I simulate the LED-Array using a 5 fields. I’m planning to use a merit function for optimization using the GENF (Enclosed Energy) which only works for one field at a time. But as my aim is to describe the entire enclosed energy of all 5 fields at the image, I can’t properly tell Zemax the optimization target.

 

My options are:
Find a better operand for the merit function
Describe the entire system in the NSC → Is there something similar to the enclosed energy operand?
Describe the LED-Array as one field for first approximation. But as far as I know, there is no way to define a beam profile in SC which could be built corresponding to the different angular intensity of the LED-Array.

 

Does anyone have an idea about this? Thanks in advance.

 

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Best answer by David 26 January 2022, 21:16

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David
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I recommend non-sequential mode for this. The LED array can be described using Source Diode, or as an array of Source Radial or other source objects, including vendor supplied models. There are  good articles on this here and here.  Non rectangular arrays can be constructed of individually placed sources  

Enclosed energy can be measured on a Detector Rectangle or other detector, by making the detector the size and shape of the desired measurement region -- possibly masking it for shape -- and optimizing for total power and perhaps uniformity. You can also measure and target the RMS spot radius. These can be measured and targeted in the merit function using the NSDD operand.

Kind regards, David
M

Very good, thanks for the advice. Using the NSDD operand helps a lot, exactly what I was looking for.

M

I have a follow up question about this. As far as I know, the computing power required for the NSC optimization is significantly higher than when using SC. As I’m trying to simulate an array consisting of about 15 LEDs and at least two odd aspheres, I’m wondering if this will result in very long optimization times. Is there any way of reducing the optimization time?

David
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Userlevel 6
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I don’t know of a better way to do this. The only thing I would suggest is to use only as many analysis rays as are needed to drive the optimization. You can later increase the rays for a final optimization. 

Kind regards, David
Mark.Nicholson
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Userlevel 7
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I agree with everything @David says, but lets think of this in the sequential mode.

To model an LED array you’d want to use Telecentric Object mode (there’s a switch on the Aperture tab of the System Explorer) so that each field point is radiating out to an entrance pupil at infinity. You’ll then have some optical system that images the field points onto the image plane.

I don’t see any problem in using normal Optimization Wizard targets like RMS Spot or RMS wavefront. Assuming each LED is images to some kind of finite point, the encircled energy will be high because the rays all land on the target.

Also, I think you should use IMAE rather than GENC. GENC is as you say computed for an individual field point, whereas IMAE considers the whole field. It’s the optimization equivalent of the Image Analysis feature.

Hope that helps,

  • Mark 

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