[Radiance-general] Accurately characterized translucent materials?

[Lars O. Grobe]

Hi Randolph,

some data is available. First, Peter has some translucent samples in his BME database:

http://www.pab.eu/gonio-photometer/demodata/bme/

There used to be an opal glass manufactured by Schott called Opalika. Unfortunately, when I tried to get some, I found that it was hardly available any more, so I would not plan an installation with it before getting a supplier. Still, it is interesting as there is quite detailed information even about the scatter characteristics available:

http://www.reichmann-feinoptik.de/assets/applets/opalika_phys.pdf

So this would be an example for an opal glass which is quite close to a perfect diffuser in the visible range. The peak overlaid on the plot is obviously measured in the NIR (the directional transmission increases beyond 800nm as mentioned in the text).

Of course you could also get a sample of the product of your choice and have it measured, now that there are all those goniophotometers around :)

Cheers, Lars.

> It appears that Bayer’s Makrolon polycarbonate material has been sufficiently characterized; Bayer has done scattering studies, which can be found in this report:
>  http://www.plastics.bayer.com/~/media/Product%20Center/PCS/Images/5_Library/Broschueren/Optical%20properties%20of%20Makrolon%20and%20Apec%20for%20nonimaging%20optics.ashx?la=en
>  
> Is anyone aware of a Radiance material type for Makrolon? I will also be contacting a rep, and find out if perhaps Bayer already has files I can use. If all else fails, can someone offer me advice on converting that data in that file to a BRTDF description?
>  
> Randolph M. Fritz
> Luma
> 206.596.8625 d
>  
> From: Randolph Fritz [mailto:randolphf at lumald.com] 
> Sent: Monday, December 29, 2014 9:12 AM
> To: Radiance general discussion
> Subject: [Radiance-general] Accurately characterized translucent materials?
>  
> Anyone know a vendor that makes one of these? I have a sort-of-light-shelf application that I would like to simulate, and so far I haven’t found a material that does the job.
>  
> Randolph M. Fritz
> Lighting Designer
>  
> Luma
> 206.596.8625 d
> Portland | San Francisco | Seattle
> lumald.com
>  
> inspire  interpret  integrate
>  
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