P478 – SGM ATHOS Swiss FEL PSI
Application
Spherical grating monochromator (SGM) for soft X-ray synchrotron radiation
Year of delivery
2020
Installation site
ATHOS beamline at SwissFEL, Paul Scherrer Institut, Switzerland
Design Features
- High-resolution grazing incidence variable line spacing spherical grating monochromator (SGM).
-
Negative beam offset design (downward deflecting mirror) for high stability when using long optical elements.
- Spectral range: 200 – 2000 eV.
- Optical elements: one plane mirror and three spherical gratings.
- Temperature sensors at internal mechanics, mirror and gratings holders.
-
Passive water cooling of all optical elements.
- Mechanically decoupled internal mechanics from the vacuum chamber.
- Internal mechanics directly connected to the adjustable support structure underneath.
- Adjustable support structure.
- Permanently installed bakeout provisions.
Performance Features
- Extremly high positionig resolution (minimum incremental motion).
- Very high pitch rotation stability and repeatability.
- Minimized mounting induced deformations.
Outer Dimensions
Technical specifications and performance values
General
Vacuum chamber
Chamber type
stadium shaped footprint
Main flanges
at the top
Material
1.4404 (C < 0.02%)
Base pressure
10-10 mbar range
Optical design parameters
Beam height (entrance)
1200 mm
Beam offset
-9 mm
Number of plane mirrors
1
Plane mirror dimensions
600 mm x 80 mm x 80 mm
Number of gratings
3
Gratings dimensions
300 mm x 50 mm x 60 mm
150 mm x 50 mm x 60 mm
Support structure
Adjustment ranges
Vertical translation
± 5 mm
Lateral translation
± 10 mm
Longitudinal translation
± 10 mm
Pitch
± 1°
Roll
± 1°
Yaw
± 1°
Plane mirror
Pitch rotation
Range
-0.6° to +3.3°
Resolution (design value)
0.00165 µrad /motor fine step
(1/64, recommended)
0.005 µrad /encoder count
Resolution (measured value)
0.025 µrad
Repeatability
0.07 µrad (pitch)
0.05 µrad (pitch bilateral)
Long-term stability (> 1h)
0.012 µrad
Translation
Range
-39.3 mm to +39.3 mm
Resolution (design value)
0.078 µm /motor fine step
(1/64, recommended)
0.005 µm /encoder count
Repeatability
0.08 µrad (pitch)
0.09 µrad (pitch bilateral)
0.15 µrad (roll)
Gratings
Pitch rotation
Range
-0.5° to +3.2°
Resolution (design value)
0.0033 µrad /motor fine step
(1/64, recommended)
0.005 µrad /encoder count
Resolution (measured value)
0.025 µrad
Repeatability
0.07 µrad (pitch)
0.08 µrad (pitch bilateral)
Long-term stability (> 1h)
0.010 µrad
Translation
Range
-80.5 mm to +80.5 mm
Resolution (design value)
0.078 µm /motor fine step
(1/64, recommended)
0.005 µm /encoder count
Repeatability
0.08 µrad (pitch)
0.56 µrad (pitch bilateral)
0.22 µrad (roll)
Performance Test Results
Pitch deviation after pitch change (mirror)
Pitch deviation after bilateral pitch change (mirror)
Pitch deviation after pitch change (grating)
Pitch deviation after bilateral pitch change (grating)
Pitch deviation after mirror translation
Roll deviation after mirror translation
Pitch deviation after grating translation
Roll deviation after grating translation
Mirror pitch positioning resolution
Mirror pitch long-term stability
Grating pitch positioning resolution
Grating pitch long-term stability
Residual gas analysis
