Hi all,
let's assume a have a list of refractive indices according to wavelength.
Is it possible to calculate from this list to a valid cauchy value?
Example Diamond:
nominal refractive index given 2,4488
lambda [nm] n (lambda)
364,659375 2,473323675
387,450586 2,464986815
413,280625 2,455051934
442,800669 2,441251728
476,862259 2,431478974
516,600781 2,427076431
563,564488 2,420857286
619,920937 2,411429037
688,801041 2,406543164
774,901171 2,406202402
885,601339 2,400035416
Thanks or your suport and ideas.
BR
Calculating Cauchy from list of refractive indices
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Calculating Cauchy from list of refractive indices
OS - Windows 7 X64
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease
Re: Calculating Cauchy from list of refractive indices
Cauchy's equation is well defined curve so it can not approximate an arbitrary set of values however I assume you are using real world data so there should be a value approximating them.lighting_freak wrote: ↑Sat Oct 06, 2018 2:40 pm let's assume a have a list of refractive indices according to wavelength.
Is it possible to calculate from this list to a valid cauchy value?
Example Diamond:
nominal refractive index given 2,4488
lambda [nm] n (lambda)
364,659375 2,473323675
387,450586 2,464986815
413,280625 2,455051934
442,800669 2,441251728
476,862259 2,431478974
516,600781 2,427076431
563,564488 2,420857286
619,920937 2,411429037
688,801041 2,406543164
774,901171 2,406202402
885,601339 2,400035416
Thanks or your suport and ideas.
A simple brute force/one-time solution would be to use Excel, Mathematica or a similar tool, to draw your tabulated data and various Cauchy's curves (https://en.wikipedia.org/wiki/Cauchy%27s_equation) and pick the one better matching your values.
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Re: Calculating Cauchy from list of refractive indices
Hi,
so you mean doing something like this to find B & D as refractive index and coefficient combination:
B 2,38 D 0,01
lambda [µm] lambda [nm] n lambda) real world n(lambda) from formula
0,36 364,66 2,47 2,47
0,39 387,45 2,46 2,46
0,41 413,28 2,46 2,45
0,44 442,80 2,44 2,44
0,48 476,86 2,43 2,43
0,52 516,60 2,43 2,42
0,56 563,56 2,42 2,42
0,62 619,92 2,41 2,41
0,69 688,80 2,41 2,41
0,77 774,90 2,41 2,40
0,89 885,60 2,40 2,40
This values B for IOR and D for dispersion cauchy coefficient are right one to enter them into luxcorerender?
Thanks for your help. This seems to work for diamond. Let's see whether it works for PMMA and PC plastics as well.
BR
so you mean doing something like this to find B & D as refractive index and coefficient combination:
B 2,38 D 0,01
lambda [µm] lambda [nm] n lambda) real world n(lambda) from formula
0,36 364,66 2,47 2,47
0,39 387,45 2,46 2,46
0,41 413,28 2,46 2,45
0,44 442,80 2,44 2,44
0,48 476,86 2,43 2,43
0,52 516,60 2,43 2,42
0,56 563,56 2,42 2,42
0,62 619,92 2,41 2,41
0,69 688,80 2,41 2,41
0,77 774,90 2,41 2,40
0,89 885,60 2,40 2,40
This values B for IOR and D for dispersion cauchy coefficient are right one to enter them into luxcorerender?
Thanks for your help. This seems to work for diamond. Let's see whether it works for PMMA and PC plastics as well.
BR
OS - Windows 7 X64
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease
-
- Posts: 234
- Joined: Thu Jan 18, 2018 6:02 pm
Re: Calculating Cauchy from list of refractive indices
Those are values on wikipedia:
I`m still not sure whether the interpretation of those values is right.
The dispersion curves while using this value pairs is very well.
Please let me know what you're thinking about that.
Code: Select all
Material B (IOR)C (Cauchy)
Fused silica 1,458 0,00354
Borosilicate glass BK7 1,5046 0,0042
Hard crown glass K5 1,522 0,00459
Barium crown glass BaK4 1,569 0,00531
Barium flint glass BaF10 1,67 0,00743
Dense flint glass SF10 1,728 0,01342
The dispersion curves while using this value pairs is very well.
Please let me know what you're thinking about that.
Code: Select all
This values i got from my excel experiments:
Material B (IOR)C (Cauchy)
Diamond 2,385 0,0117
PMMA 1,4780 0,0044
PC 1,5530 0,012
OS - Windows 7 X64
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease
CPU - Intel CORE i7
GPU1 - Variants of notebook card from nVidia
GPU2 - Variants of notebook onboard card from Intel
Lux - Latest possible relaease