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How to read Radiance/Luminance with a Non-sequential Merit function

  • 17 November 2023
  • 2 replies
  • 137 views

I have a detector rectangle in my system. In the detector view for this detector, I can select show data to be either “Radiance/Luminous (area space)” or “Radiance/Luminous (angle space)” depending on my source units. Then below the image/plot in the lower left box there a number labeled either “Peak Radiance/Luminance” in W/cm^2/Steradian or lm/cm^2/Steradians. How do I get this number to appear in a Merit function?

I can easily get the other number, “Total Power”, in the plot to appear in the Merit function using NSDD with Pix#=0 and Data=0. I thought setting the Detector Rectangle Data Type = 5 and setting NSDD Pix#=-1 and Data=2 would work but instead that seems to give me the peak Luminous Intensity in Lm/Sr. 

Is there really no way to read out the Radiance/Luminous in a Merit function?

2 replies

David.Nguyen
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Userlevel 7
Badge +2

Hi @Andrew_Davies,

 

The Help File for Detector Viewer says for Radiance (Position Space):

Since it is not possible to display the variation in angle space and position space at the same time, this plot is effectively identical to the Incoherent Irradiance display, with the data values divided by two pi.

 

So you could use CONS to define the value 2 x PI and DIVI to take the division:

Hope this helps.

Take care,


David

Andrew_Davies
Userlevel 1

David that is a good option for the Radiance (Position Space) :).

Is there a way to do it for Radiance (Angle Space)? Since angle space seems closer to what we typically mean by Radiance. I have pasted the relevant text from the help file on Detector Viewer below.

“Radiance (Angle Space): The power per area per solid angle in steradians as a function of incident angle upon the detector. Since it is not possible to display the variation in angle space and position space at the same time, this plot is similar to the Radiant Intensity display, with the data values divided by the product of the area of the detector and the cosine of the angle at the center of the pixel. This option becomes Luminance when using photometric rather than radiometric units.”

I would guess that the “area of the detector” would be the pixel size in lens units of the pixel with the peak Luminous Intensity (Lm/Sr). Dividing by this area then gives you units of Lm/cm^2*Sr. I would guess that the “cosine of the angle at the center of the pixel” has already been done in the Luminous Intensity calculation given by the peak pixel in Lm/Sr.

Hopefully it is already calculated by Zemax because it’s less clear to me how“cosine of the angle at the center of the pixel”is calculated. Since there are many rays that hit the pixel and thus many angles. I would guess that the angle is defined similar to the help file “Detector Rectangle Object” in the “Comments on Detector Rectangle angular binning” section for each ray and then an average is taken? 

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