Using Type IV aberration-corrected monochromator Gratings, a single concave grating disperses, collimates and refocuses the light from the entrance slit onto the exit slit. Wavelength scanning is obtained through a simple rotation of the grating.

The groove spacing of these gratings is computer-optimized to produce high quality images with a minimum of astigmatism and coma, even at large numerical aperture.

Compared with Czerny-Turner monochromators (equipped with one plane grating, one collimating mirror and one focusing mirror) Type IV aberration corrected monochromator gratings provide much better light collection efficiency and signal-to-noise ratio.

Example monochromator model H10-61
Optical aperture: F/3
Focal length: 100 mm
ACH grating: aberration corrected
holographic grating

Monochromator concave grating
L_A: distance between the grating and the entrance slit
L_B: distance between the grating and the exit slit
D: deviation angle
F/#: optical aperture

Custom, Aberration Corrected, Concave Gratings

In addition to the standard lists of Type IV flat field and monochromator gratings, HORIBA Jobin Yvon currently produces specific aberration-corrected concave gratings to maximize performance for a given application.

In that case, using proprietary ray-tracing software, we optimize performance: resolution, throughput and signal to noise ratio. We need following data from our customers:

• spectral range
• configuration of use: monochromator or spectrograph
• numeral aperture (F number) or size of grating
• maximum overall dimension or maximum focal length
• desired dispersion
• desired resolution
• entrance slit width and height or source geometry
• minimum deviation: in general deviation has to be minimum to improve correction of astigmatism, so indicate possible minimum deviation when overall dimensions of source, sample chamber and detector are taken into consideration.
• at exit: if monochromator, exit slit width and height, and if flat field, length of detector, height and width of pixel.