What's the exact opacity and translucency of transparent bricks? As answered in this question, transparent bricks are made of PC (polycarbonate) and as listed in this answer and on Brickipedia there are fourteen transparent colors:

40  Transparent (clear) 
41  Transparent Red 
42  Transparent Light Blue  
43  Transparent Blue    
44  Transparent Yellow  
47  Transparent Fluorescent Reddish-Orange (Transparent Dark Orange)    
48  Transparent Green   
49  Transparent Fluorescent Green (Transparent Neon Green)  
111 Transparent Brown (Smoke)   
113 Transparent Medium Reddish-Violet   
126 Transparent Bright Bluish-Violet    
143 Transparent Fluorescent Blue    
182 Transparent Bright Orange   
311 Transparent Bright Green


I am interested in the exact optical properties Transparency and translucency of this colors. How much percentage of light is absorbed? Has anyone measured with a prism which wavelength gets filtered out for each color?

P.S.: Why do I want to know? I want to put different kinds of LEDs in transparent bricks and like to know how the light is influenced. There are LEDs in different colours (light temperature) and one can calculate the luminosity at specific voltage and current. I'd like to calculate the luminosity as modified by the polycarbonate which the LEDs are put into.
I have a couple friends in the LEGO company, so I asked one of the guys behind piece creation about this. It turns out that TLC itself doesn't have this information.

The problem is,  lab-testing the exact opacity and light absorption depends on certain ideal conditions. These conditions, like for any test, require the material to be identical in every way to the other materials except for the tested variable.

But there is no piece that comes in every color! And even worse, each batch varies slightly from the others. TLC's QA department is good, but not that good. 

So while this is certainly a worthy concept to test, you will likely find that your own results will be the most thorough ones you can get. I recommend that you personally do whatever you need to find your answer, and maybe tell us in a comment or on chat what you found!