P489 – RIXS Monochromator SSRF
Application
Spherical grating monochromator (SGM) for soft X-ray synchrotron radiation
Year of delivery
2022
Installation site
Dreamline beamline at synchrotron radiation source SSRF, China
Design Features
- Grating unit for high resolution soft X-ray spectrometer.
- Spectral range: 250 – 1700 eV.
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Very compact design for integration into the RIXS system.
- Very short vertical distance between bottom interface plate and grating axis.
- Optical elements: three spherical gratings.
- Temperature sensors at internal mechanics and gratings’ chin guards.
- Motorized and encoded vertical translation of the internal mechanics for compensation of spurious height and roll variation upon scattering angle change.
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Motion control system with EPICS interface, EtherCAT, fast encoder readout suitable for on-the-fly measurements.
- Mechanically decoupled internal mechanics from the vacuum chamber.
- Internal mechanics directly connected to the adjustable support structure underneath.
- Permanently installed bakeout provisions.
Performance Features
- High positioning resolution (minimum incremental motion).
- 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 (entrance)
1320 mm
Number of gratings
3
Gratings dimensions
180 mm x 50 mm x 50 mm
Grating mechanics
Pitch rotation
Range
-8.30° to +1.06°
Resolution (design value)
0.0048 µrad /motor fine step
(1/128, recommended)
0.00146 µrad /encoder count
Resolution (measured value)
0.05 µrad
Abolute accuracy
0.50 µrad
Repeatability
0.20 µrad (pitch)
0.17 µrad (roll)
Long-term stability (> 1h)
0.037 µrad
Translation (grating exchange)
Range
-90.05 mm to +90.04 mm
Resolution (design value)
0.078 µm /motor fine step
(1/128, recommended)
0.05 µm /encoder count
Resolution (measured value)
5 µm
Repeatability
0.14 µrad (pitch)
0.12 µrad (roll)
Translation (grating height)
Range
-3.37 mm to +3.39 mm
(wedge leveler 1)
-3.35 mm to +3.36 mm
(wedge leveler 2)
Resolution (design value)
0.20 µm /motor step (at actuator)
0.02 µm /motor step
(at wedge leveler)
0.05 µm /encoder count
Resolution (measured value)
0.20 µm
Long-term stability (ca. 1h)
0.01 µm
Performance Test Results
Pitch deviation after pitch change
Roll deviation after pitch change
Pitch deviation after grating lateral translation
Roll deviation after grating lateral translation
Grating pitch long-term stability
Grating pitch positioning resolution
Grating pitch absolute accuracy
Grating lateral translation positioning resolution
Grating vertical translation positioning resolution
Residual gas analysis
Grating vertical position long-term stability
