[feynman]

EVONIK has improved its Plexiglas product for LED applications. It is, for what it's worth, perfectly transparent, but when light is introduced on an edge, it is radiated at 90° to the surface, which is nothing short of amazing. Is it possible with Maxwell's material system to design a MXM with this property? See the diagram below. Thanks for some suggestions!

[Q2]

Tricky!

Am looking for a solution for similar problem I am having....

[feynman]

After searching for days, I came to the conclusion that the current material system of any renderer does not allow for such specific molecular level issues. Lights with these materials will have to be faked.

[seghier]

interresting
can you give real photos of plexiglas ?

[feynman]

EVONIK's Plexiglas LED looks like regular Plexiglass, but emits the light the "wrong way". I can't show you the prototype luminaires we are doing, but the diagram I had in the original post describes exactly what happens: When switched on, the piece becomes bright white, as if backlit - but it isn't, which is the idea behind it.

[seghier]

thanks ; i read in their website : "Le secret des éléments PLEXIGLAS EndLighten® réside dans ses particules de diffusion"
"The secret of PLEXIGLAS EndLighten® elements is its scattering particles"
i tried with volumetric and sss material :
glass with volumetric :

glass with sss :

glass with lights :

glass with light and volumetric :

glass with sss material ; 1 layer (2 bsdfs)

glass with sss material ; 1 layers (2 bsdfs) / 1 layer (1 bsdf)

[feynman]

It's not "Plexiglas Endlighten" though. It's "Plexiglas LED" - very different stuff...

[eric nixon]

Theres no need to fake it, maxwell can render this effect. Although I havent seen plexiglass LED, any pics?

[feynman]

Unfortunately, that's not what it looks like. It is transparent when no light is fed in and glaring white when light is fed in from an edge. It is not the effect we know from low-illuminance signage. When we put a correctly dimensioned IES/EULUMDAT based emitter, the material should light up at a 90° angle without faking it - the great thing with Maxwell is that you can design luminaires with it, seeing how the illuminance will react to a given design.

I see if I can make a photo of the real thing without violating confidentiality.

[feynman]

Here's crude mock-up: You can see that the light is emitted at 90° to the input direction (high-power LED and heat-management element in the cardboard box)… If the top is painted matt opaque white, the bit of light which escapes in a linear fashion is fed back and 360° sideways illumination increases further. There is no IES/EULUMDAT data available for such illuminant, since we don't own an Ulbricht Sphere to measure illumination.

[tom]

Isn't it glass (or sss) bsdf + emitter layer?
From above description it looks nothing else than an SSS plexi though... (unless these particles are flourescent)

[feynman]

The molecules in this special kind of plexiglass are extruded in such a way that microscopic particles acting as prisms are fairly ordered so that the light is primarily emitted at 90°. All plexiglass materials I have tried conduct the light in the traditional fashion - from input source through to the opposite surface, 180° so to speak.

[tom]

If the particles are arranged to reflect light 90 degrees it would have serious problems with the viewing angle. Interesting...

[feynman]

Evonik won't reveal formulation and production process, so it's probably a material one can't figure out to get physically correct in MR when lit with an IES/ELUMDAT emitter.