ZEISS concave gratings are always holographic gratings. The benefits of holographically produced gratings are their high diffraction efficiency, even with high groove frequencies, and their very low straylight. Holographic procedures also allow the generation of asymmetric and symmetric groove profiles. The radii can be selected within a wide range, making it possible to achieve aperture ratios of up to 1:1.
The use of concave gratings makes it possible to have systems with a relatively small number of components. This not only reduces scattered light but also increases light intensity.
Holographic correction during production of concave gratings can both optimize the focal plane and minimize aberrations, such as astigmatism, spherical aberration and coma, over a wide spectral range. Unlike Rowland circle gratings, these aberration-corrected gratings feature grooves with a variable spacing and variable curvatures. This holographic design allows optimum adaptation of a grating's imaging properties to the specific requirements of the spectral unit in which the grating will be used.
This ensures that gratings are obtained whose imaging properties effectively concentrate the available light energy on the detector over a wide spectral range. Holographically corrected gratings are ideal for imaging the spectrum and a diode array or a CCD sensor. lt is therefore possible to produce modern, compact high-resolution spectrometers and spectrometer modules at a justifiable cost.