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Spherical Grating Monochromator - Chamber & Mechanism
This SGM is equipped with three spherical gratings in order to cover the energy range from 200 to 1400 eV. The gratings in the grating holder is mounted in a slide which enables transversal movement of the gratings and thus a choice of a particular grating. The slide is coupled via linear bearings to the frame which rotates in precision bearings and exerts the rotational movement to the gratings.
The grating holder allows the following movements to be set:
movement | coarse | fine | ||
range | accuracy | range | accuracy | |
height | ±1.5 mm | 0.05 mm | N/A | N/A |
pitch | N/A | N/A | ±7 mrad / ±0.4° | 0.13 mrad / 27 arcsec |
roll | ±36 mrad / ±2.1° | 1 mrad / 0.06° | ±7 mrad / ±0.4° | 0.063 mrad / 13.1 arcsec |
yaw | ±14 mrad / ±0.8° | 1 mrad / 0.06° | ±2 mrad / ±0.1° | 0.036 mrad / 7.4 arcsec |
The Entrance Slit
The entrance slit and the exit slit are designed similarly. The main difference is that the entrance slit is cooled and the exit slit is arranged in a double configuration to enable the build up of a rectangular slit and the entrance slit chamber is arranged on a table which enables a movement of 400 mm in longitudinal direction.
The construction of the slit consists on the slit wedges, which are sliding on a polished quartz surface. The wedges are made of glidcop and are cooled by a copper tube.
The guiding of the slit wedges is realized with the help of two levers for each plate to provide the movement, which is very sensitive for small openings of the slit and becomes more crude for the bigger openings of the slit blades.
The spherical grating monochromator was designed and manufactured for the beamline BL5 of the SPEAR 2/3 storage ring in the Stanford Synchrotron Radiation Laboratory, Stanford, California.
Stanford Synchrotron Radiation Laboratory
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