Blacklight with OSL?

I like to make a shader who can react with blacklights (wavelength 440nm)* . In that case, a emitter with a high saturation and value. But it should also react diffuse with normal white light.

How can I analyse incoming rays, about there saturation and value with osl? is that possible?

i guess there is not a solution with OSL.
so for my test i used the composer.

thats the result. left the white light, right the blacklight.
the composer subtracts from the whitelight the blacklight and use that as factor for the diffuse and the ambient occlusion material.
Thats the material for suzanne. that get mixed with the final scene where suzanne has a holdout material.

Cycles doesn’t include wavelength values in the ray, just RGB. Even in renderers that do have spectral sampling, it’s normally cutoff below 380-400nm for performance reasons. Blacklights, or good ones anyway, peak around 360nm. 440nm is bluish-purple light, not UV, btw.