Spherical Grating Monochromator High Resolution Grazing Incidence Monochromator for Synchrotron Beam Line Applications This triple or quad grating Spherical Grating Monochromator (SGM) provides soft x-rays with high resolution and exceeds the range of 1.2 to 15-nm (1000 to 80-eV). Theoretical resolution with a 200g/mm grating is less than 0.1eV at 113-eV and less than 0.3eV at 310-eV. The synchrotron beam is focused on the water cooled entrance slit. It then passes through the diagnostic cross and into the monochromator chamber. The selected water cooled grating disperses the energy downward, deflecting it 5 degrees. After the monochromator chamber, zero order energy is trapped by an adjustable two jaw aperture, with a water cooled upper jaw. The unit shown currently operates as beamline 8 at the UC Berkeley synchrotron Advanced Light Source.

The energy then passes through a second diagnostic cross and through the exit slit into the second chamber. The entrance slit and exit slit travel on air bearings in coordination with grating rotation. For each grating the coordination of focus is satisfied with one slit fixed in position while the other slit is scanned.

Spherical Grating Monochromator Salient Features

1. Entrance Slit

Water cooled assembly features: bilaterally adjustable molybdenum slit jaws (from 5 to 250 microns), ±150mm translation along the optical axis with one micron accuracy, with stepper motor and encoder control. Slit assemblies are Roll, Pitch and Yaw adjustable.

2. Diagnostic Cross

A six way cross is employed which holds four adjustable aperture blades and provides pumping access and possible future insertion of a beam position indicator photodiode.

3. Insertion Section

For use with a laser during beam line installation and alignment, and for photodiode beam position indicator.

4. Grating Chamber

This assembly provides the housing for three ion etched holographic water cooled metal gratings. Each grating is kinematically mounted and has Roll, Pitch and Yaw adjustments. The grating adjustments are independent of each other and of the grating's primary rotation. The grating rotates through and angle of 5°- individual step size when scanning is less than .02 arc seconds. In-vacuo selection of gratings is standard. Additionally, the grating chamber is equipped with a water cooled zero order baffle.

5. Exit Slit

Not cooled, horizontally and vertically adjustable, translates over ±350mm.