SNR Grazing Incidence Soft X-Ray Monochromator

Model SNR-SXR-0.6 is a high aperture (φx = 12.5 mrad), single-element soft x-ray monochromator. The grating has a 100 mm circular aperture with grooves extending to the edge. The distance from (slitless) source to exit slit is 628 mm. The fixed angular deviation of 4.5 degrees and gold coated grating provide efficient reflection to wavelengths as short as λmin = 10 Angstroms in first order and to approximately 6 Angstroms in second order. The spectral resolution is determined by the sagittal apertureφy which may be set by knife-edges at the entrance port or exit slit, over the range of approximately 0 to 30 mrad. A typical setting ofφy = 3 mrad (illuminating 2 mm at the exit slit) provides a fractional spectral resolution of 1/160 at 23Å, 1/68 at 50Å,and 1/33 at 100Å. However, the long wavelength performance is improved considerably by employing an exit slit mask containing 6 slits (100μm wide) at different angles, to match the image tilt over different regions in scanned wavelength. Using the appropriate slit, the spectral resolution is approximately 1/100 over 10~50Å using a 6 mrad sagittal aperture. 

An externally mounted micro-stepping motor with Compumotor indexer provides rotational control of the grating scan under vacuum by means of a shaft feedthrough. The exit slits are also selectable under vacuum using a micrometer shaft feedthrough. Both the grating chamber and the slit chamber are electroless-nickel plated aluminum and are machined square relative to the grating surface and slit mask, enabling alignment by mechanical indication of the chamber exteriors. 

The photograph shows a custom system including model SNR-SXR-0.6 and associated optional equipment (not included with base instrument) such as a Manson model 2 soft x-ray source and compact chamber, pumps, gages, mounting brackets, CCD, filter assembly, vacuum-selectable aperture and microscope visible alignment system, for calibrating x-ray transmission gratings in the 5-114 Å region. 

Hettrick SNR monochromators have been used to calibrate astronomical satellite-borne telescopes, transmission grating spectrographs, reflection grating spectrographs, x-ray microcalorimeter detectors, CCDs, filters and other optical elements.  

----------------------------------- SNR-SXR-0.6 SPECIFICATIONS ---------------------------------------

Scan Geometry ............................................          Hettrick, U.S. Patent 5,274,435; Spherical Grating

Angular Deviation ......................................            4.5^o (Fixed). Nominal graze angle of 2.25^o

Grating Format ...........................................           Gold Surface; Active Aperture 100 mm Circular

Grating Groove Density .............................           750 g/mm

Wavelength Range ......................................            10~100 Angstroms (m=1); approx. 6~50 Angstroms (m=2), depending on source intensity.

Fractional Dispersive Resolution (Δλ/λ) ....           0.167/mm (at Source and Exit Slit)

Optical Aberration (image tilt) ...................            Δλ/λ < 0.010 at 6 mrad Sagittal Aperture, 10~50 Angstroms (m=1)

Meridional Aperture / Focusing .................            12.5 mrad (φ_x), on Rowland Circle.

Sagittal Aperture .........................................           0-30 mrad (φ_y), astigmatic.

Exit Slit Width (Vacuum selectable) ..........             200 μm at 0.2^o                                     100 μm at 0.2^o (10-13Å)         100 μm at 0.7^o (13-20Å)

                                                                100 μm at 1.2^o (20-28Å)         100 μm at 1.7^o (28-37Å)         100 μm at 2.2^o ( > 37Å)

Exit Slit Length ..........................................            20 mm

External Drive ............................................            Single Micro-Stepped Motor with Compumotor ZETA 6104-57-51 Indexer/Drive w/RS232C Interface

Vacuum Chamber .......................................            Weld-Free 6061 Aluminum, Electroless Nickel Plated; TEFLAT™ Sealed Knife-edge Ports

Entrance and Exit Ports ..............................           4.5” Knife-edge Flange (ICF114)

User Ports ...................................................           Three Ports Accept 2.75” Knife-edge Flange (ICF63)

Length .........................................................           0.63 meters (Source-Slit)

Aperture Center ..........................................           Stationary