Grism

A grid prism is an optical member which combines a prism and a diffraction grating. As English coinage, the term exists " grism " ( grating prism ). Grating prisms are mainly used in spectrographs use.

The prism is used to select the wavelength that is continued as a zero order on the optical axis of the system. The grid has a significantly higher dispersion than the glass, it serves to further splitting of wavelengths around the zero order around.

• Prism