Concave diffraction gratings are compounds for modern, compact spectrometers and miniaturized spectrometer modules. They combine dispersive and imaging properties in a single element. This reduces stray light, increases light intensity, and is ideal for imaging the spectrum on a diode array or a CCD sensor. The basic form of all imaging gratings is the Rowland circle grating.

At ZEISS, all concave gratings are produced holographically; this optimize the focal plane and minimize aberrations such as astigmatism, spherical aberration and coma over a wide spectral range with a range of groove profiles.