> What wavelengths of light specifically affect the type of film used in
> the first movie containing an variable-density optical audio track? I
> am specifically interested in the chemical composition of the optical
> audio track.

> From what I know, most of the more modern films are unaffected by red
> light.

> I'm thinking of a theoretical device using analog audio recording on
> VD optical tracks containing the oldest film chemical composition. The
> source of light are multiple laser beams consisting of wavelengths
> that could record the audio onto the film. Each beam has a different
> wavelength. The beams are then mixed together to get a single beam of
> all the necessary wavelengths. The beam then shines onto the film to
> record the audio.

> I don't have much of an application here. I'm just in it for the
> science.

> Thanks