# How to calculate the ( rtn gtn btn ) values of the material type glass ?

Hello all,

i don´t know haw can you get the values rtn, gtn and btn of the material
description "glass":

void glass id
0
0
3 rtn gtn btn

from some glass samples.

I have measured their transmittance values with a Spectrometer ( Varian -
Cary 5000) in the field 350 - 780 nm wavelenght and have calculate the
Transmittace.
Should I then calculate the transmissivity from the transmittance by
computing

tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn ?

and, in this case, how can I get the values rtn, gtn and btn?

Thanks a lot,

Marina

Good question. Apply the formula you cite at each of three wavelengths:

Red: 700 nm
Green: 546 nm
Blue: 436 nm

-Greg

···

From: marina aviles <[email protected]>
Date: March 11, 2009 4:12:27 AM PDT

Hello all,

i don´t know haw can you get the values rtn, gtn and btn of the material description "glass":

void glass id
0
3 rtn gtn btn

from some glass samples.

I have measured their transmittance values with a Spectrometer ( Varian - Cary 5000) in the field 350 - 780 nm wavelenght and have calculate the Transmittace.
Should I then calculate the transmissivity from the transmittance by computing
tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn ?

and, in this case, how can I get the values rtn, gtn and btn?

Thanks a lot,

Marina