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Can someone help me with simulating walls of a room with matte paint?

  • 11 November 2020
  • 4 replies
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Hi Team Zemax,


 


I am trying to simulate a sensor inside a room of a defined size. Now I am not sure about it's walls. How should I configure the parameters of the scattering model/function of the wall objects, in order to get an estimate of the received light with accuracy?  Nor do I have a reference for it.


 


Thanks in advance!


Avijit

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Best answer by Mark.Nicholson 17 November 2020, 03:20

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Userlevel 7
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Hi Avijit,


Well, if you have no data, you'll just have to make up something as best you can. First make the walls a MIRROR material, so that light reflects from it, and then use a coating to give it the reflectivity you want. I'd suggest an IDEAL coating with say 98% reflectivity (and hence 2% loss), obviously do better if you can. A TABLE coating is a simple way to add a wavelength-selective response if you have the data.


Then there is the scattering. If the surface has a glossy finish, make say 80% of the light reflect and 20% scatter into a Lambertial distribution. If it's a matte finish I'd go for 50/50 specular/diffuse or maybe 20/80. Again, get as much data as you can and just use my numbers as best-guesses.


The  save the profile as day 'White Surface' so that if you do get better data later on, you only have to update one thing and all surfaces with this finish will automatically update :-)


There's a good KB article here:https://my.zemax.com/en-US/Knowledge-Base/kb-article/?ka=KA-01353 


- Mark

Hi Mark,


Thanks for the insightful response and sharing the article. I follow it completely.


I was using the scattering function without actually putting MIRROR as material. Hoping that splitting the rays might do the job required. I will update the same and try to understand the difference.


Thanks once again.


-Avijit 

Hi Mark,


I have tried simulating by keeping object material as 'mirror' on the walls' surfaces (rectangle object). However, I keep getting an error(1) message of 'not enough intersections'. However, I have tried changing the settings for Maximum intersections per Ray and Maximum ray segments. But, the error just doesn't go. I have attached the file as well. 


I have chosen Lambertian50 profile for the walls object. However, the error(1) disappears if I remove mirror from the first surface. Then there are some gemtery error that surfaces which I ignored and moved further.


Few observations:


1. No. of hits are zero most of the times or under 10 some of the times.


2. There are total 8 objects in the simulations so the max. no of intersections is 2^(8+1) - 1 = 511. I have updated the settings accordingly but the error(1) remain intact.


3. The source of Geometry error is unknown. It appers for different objects each time I remove mirror from the said surface.


 


I have attached the files for your reference. Can you please help me out here.


 


Thanks,


-Avijit

Userlevel 7
Badge +3

Hi Avijit,


Make sure you have 'Use Polarization' checked otherwise the loss of intensity due to the coating will not be accounted for.


- Mark

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