P512 – PGM ELISA BESSY HZB
Application
Plane grating monochromator (PGM) for soft X-ray synchrotron radiation
Year of delivery
2024
Installation site
ELISA beamline at BESSY II, Helmholtz-Zentrum Berlin, Germany
The relatively long optical elements required a customized design for the internal mechanics to achieve ultimate stability and repeatability. The stadium-shaped footprint of the vacuum chamber, which accommodate the longer optics, allows for reduced mass and higher eigenfrequencies compared to a rectangular chamber.
Design Features
- Plane grating monochromator.
- Spectral range: 40 – 4000 eV.
- Optical elements: one plane mirror and three plane gratings.
- Electrode at mirror surface for carbon contamination prevention.
- Temperature sensors at internal mechanics, mirror and gratings substrates.
-
Active side water cooling of all optical elements.
-
Provisions for RF oxygen plasma cleaning of the optical surfaces.
-
Four motorized, encoded and water cooled OFHC blades at the chamber entrance flange; fluorescence coating of all blades.
- 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
- High positioning resolution.
- 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)
1400 mm
Beam offset
20 mm
Number of plane mirrors
1
Plane mirror dimensions
550 mm x 90 mm x 60 mm
Number of gratings
3
Gratings dimensions
150 mm x 40 mm x 40 mm
Support structure
Adjustment ranges
Vertical translation
30 mm
Horizontal translation
30 mm
Tilt
± 1°
Lateral rotation
± 1°
Plane mirror
Pitch rotation
Range
-0.50° to +14.50°
Resolution (design value)
0.00445 µrad /motor fine step
(1/256, recommended)
0.001463 µrad /encoder count
Resolution (measured value)
0.05 µrad
Repeatability
0.04 µrad (pitch)
0.07 µrad (roll)
Long-term stability (> 1h)
0.015 µrad
Long-term stability (> 1h)
2 l/min water flow rate
0.016 µrad
Scanning speed
700 µrad /s
Translation
Range
-40.50 mm to +40.60 mm
Resolution (design value)
0.0129 µm /motor fine step
(1/64, recommended)
0.05 µm /encoder count
Resolution (measured value)
5 µm
Repeatability
0.06 µrad (pitch)
0.07 µrad (roll)
< 5 µm (translation)
Scanning speed
1 mm /s
Gratings
Pitch rotation
Range
-0.60° to +14.45°
Resolution (design value)
0.00445 µrad /motor fine step
(1/256, recommended)
0.001463 µrad /encoder count
Resolution (measured value)
0.05 µrad
Repeatability
0.08 µrad (pitch)
0.11 µrad (roll)
Long-term stability (> 1h)
0.013 µrad
Long-term stability (> 1h)
2 l/min water flow rate
0.014 µrad
Scanning speed
700 µrad /s
Translation
Range
-80.20 mm to +80.70 mm
Resolution (design value)
0.0129 µm /motor fine step
(1/64, recommended)
0.05 µm /encoder count
Resolution (measured value)
5 µm
Repeatability
0.07 µrad (pitch)
0.08 µrad (roll)
< 5 µm (translation)
Scanning speed
1 mm /s
Aperture unit
Blades
Material
OFHC
Translation range / blade
-27 mm to +1.30 mm
Resolution (design value)
0.00157 µm /motor fine step
(1/64, recommended)
0.05 µm /encoder count
Resolution (measured value)
0.50 µm
Repeatability
< 1 µm
Performance Test Results
Pitch deviation after pitch change (mirror)
Roll deviation after pitch change (mirror)
Pitch deviation after pitch change (grating)
Roll deviation after 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 step width
Grating pitch positioning resolution
Grating pitch step width
Mirror translation positioning resolution
Grating translation positioning resolution
Mirror pitch long-term stability
Grating pitch long-term stability
Mirror pitch long-term stability
(2 l/min water flow rate)
Grating pitch long-term stability
(2 l/min water flow rate)
Blade position deviation after blade translation
Blade translation positioning resolution
Residual gas analysis
