P441 – SGM I21-IXS DLS
Application
Spherical grating monochromator (SGM) for soft X-ray synchrotron radiation
Year of delivery
2016
Installation site
Beamline I21-IXS at Diamond Light Source, Didcot, United Kingdom
This grating unit was developed and built to be integrated into the high energy resolution RIXS system at I21-IXS at DLS. The challenge was to accomodate all components for standard functionality and for compensation of spectrometer related spurious movements into a very limited space, without perfomance lost.
Design Features
- Grating unit for high resolution soft X-ray spectrometer.
- Spectral range: 250 – 3000 eV.
-
Very compact design for integration into the RIXS system.
- Optical elements: three spherical gratings.
- Temperature sensors at internal mechanics.
- Motorized and encoded vertical translation of the internal mechanics for compensation of spurios height and roll variation upon scattering angle change.
- Permanently installed bakeout provisions.
- Adjustable support structure.
Performance Features
- High pitch rotation stability and repeatability.
- Minimized mounting induced deformations.
Outer Dimensions
Technical specifications and performance values
General
Vacuum chamber
Chamber type
rectangular footprint
Main flanges
at the top
Material
1.4404 (C < 0.02%)
Base pressure
10-10 mbar range
Optical design parameters
Beam height
1415 mm
Number of gratings
3
Grating dimensions
200 mm x 40 mm x 50 mm
Grating mechanics
Pitch rotation
Range
-10.70° to +1.4°
Resolution
0.004 µrad /motor fine step
(1/64, recommended)
0.0047961 µrad /encoder count
Repeatability
0.08 µrad (pitch)
0.20 µrad (roll)
Stability
0.012 µrad
Translation (grating exchange)
Range
-115.3 mm to +76.3 mm
Resolution (design value)
0.40 µm /motor fine step
(1/128, recommended)
0.05 µm /encoder count
Repeatability
0.20 µrad (pitch)
0.17 µrad (roll)
Translation (grating height)
Range
-1.18 mm to +1.13 mm
(wedge leveler 1)
-1.15 mm to +1.48 mm
(wedge leveler 2)
Resolution (design value)
0.40 µm /motor step (at actuator)
0.02 µm /motor step
(at wedge leveler)
0.005 µm /encoder count
Performance Test Results
Pitch deviation after pitch change
Roll deviation after pitch change
Pitch deviation after grating translation
Roll deviation after grating translation
Grating pitch stability
Residual gas analysis
