A Grism (GRating+prISM) is an optical prism which has a transmission grating fabricated onto one (rarely two) of its plane (rarely curved) functional surfaces. Grisms have a straight view or undeviated wavelength. This property allows them to transform a camera into a spectrograph by inserting the grism in the optical beam path. This can be used in various applications, e.g. astronomy. By selecting the groove density and the apex angle of the prism accordingly, the straight view wavelength and the angular dispersion of the grism can be adapted to the needs of the specific application.

Grism – dispersing optical components

Grisms are suited for applications between wavelength of roughly 115 nm and 30 μm. The transmission grating is usually located on the hypotenuse surface of the prism. Depending on the prism material, the grating is either replicated onto it, so that it is enclosed in an epoxide resin layer, or it is ruled directly into the prism material. The groove profile is usually (in case of direct ruling exclusively) saw tooth-shaped and the blaze angle usually is identical to the prism angle resulting in the straight view wavelength having the maximum diffraction efficiency.

Carl Zeiss can design and produce custom grisms according to required specification. Please send us your drawings and specification and we will be pleased to provide a quotation.