By default, the rays released in a model are monochromatic with a ray frequency or free-space wavelength defined in the Ray Properties settings window. However, you can trace polychromatic rays by specifying different frequencies or vacuum wavelengths in each ray release feature.

To allow the rays to be polychromatic, in the settings window for the Geometrical Optics interface locate the Ray Release and Propagation section. By default, Monochromatic is selected from the Wavelength distribution of released rays list. Select Polychromatic, specify vacuum wavelength to release polychromatic rays by entering an expression for the vacuum wavelength or sampling it from a distribution. Alternatively, select Polychromatic, specify frequency to define an expression or distribution for the ray frequency. These expressions are defined in the sections Vacuum Wavelength and Initial Ray Frequency, respectively, in each ray release feature.