[a_e_k]

Look into spectral rendering.

For a very simple form, you can sample a specific wavelength with each ray, trace it using wavelength-dependent refraction indices (e.g., from the Sellmeier equation) whenever you compute refraction or internal reflection. Then tint the ray by the color and visible intensity of the wavelength when averaging it into the image pixel.

For a lot more detail, see e.g., "Efficient Spectral Rendering on the GPU for Predictive Rendering" (https://hal.inria.fr/hal-03331619/document).