On 2017-04-12 10:45 PM (-4), Cousin Ricky wrote:
> I am working on a diamond cut.  A while ago, in comparing ior.inc
> dispersion with Lilysoft's SpectralRender ("Native dispersion v.
> spectral render" in p.b.i), I noticed a discrepancy in the apparent
> index of refraction of BK7 glass between the two renders.  So, just to
> make sure that wasn't a fluke, I tested both methods with a diamond prism.

Besides diamond, there are 8 other materials that ior.inc and 
SpectralRender have in common.  Attached are experiments for all of them 
except sapphire.  I omitted sapphire because it is basically the same 
material as ruby (corundum), and the 380 nm value in SpectralRender's 
sapphire spline looks suspicious to me.  Each material had its own setup 
include file (with its own prism shape, camera, and rod diameter), so 
spectra from different materials should not be compared.

The left spectrum for each material uses the IOR and dispersion values 
from ior.inc.  The middle image uses the IOR from ior.inc with no 
dispersion.  The right spectrum uses SpectralRender.

The values for n are:

               ior.inc   SpectralRender
   Material    (3.7.1)   (wavelength D)
   --------    -------   --------------
   BK7 glass   1.51673   1.5167
   F2 glass    1.61989   1.6199
   Acrylic     1.4905    1.4913
   Amethyst    1.5485    1.5500
   Emerald     1.5800    1.5894
   Ruby        1.7660    1.7600
   Topaz       1.6250    1.6300

For materials where ior.inc and SpectralRender agree on n, the rod 
matches the D wavelength of the SpectralRender panel.

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Attachments:
Download 'thru-pbi-glassbk7.png' (34 KB) Download 'thru-pbi-glassf2.png' (34 KB) Download 'thru-pbi-acrylic.png' (40 KB) Download 'thru-pbi-amethyst.png' (41 KB) Download 'thru-pbi-emerald.png' (28 KB) Download 'thru-pbi-ruby.png' (36 KB) Download 'thru-pbi-topaz.png' (34 KB)

Preview of image 'thru-pbi-glassbk7.png'

Preview of image 'thru-pbi-glassf2.png'

Preview of image 'thru-pbi-acrylic.png'

Preview of image 'thru-pbi-amethyst.png'

Preview of image 'thru-pbi-emerald.png'

Preview of image 'thru-pbi-ruby.png'

Preview of image 'thru-pbi-topaz.png'