P413 – Mirror Unit RGBL BESSY
Application
Mirror unit (M4a) for soft X-ray synchrotron radiation
Year of delivery
2016
Installation site
Russian-German beamline at BESSY, Helmholtz-Zentrum Berlin, Germany
The constant-strut-length hexapod design used in this switching mirror unit is adapted from that of the EMIL beamlines hexapods (see projects P405 to P412).
Design Features
-
Constant-strut-length hexapod mechanism.
- Six degrees of freedom and selectable rotation center.
- Spectral range: 10 – 1300 eV.
- Optical elements: two focusing mirrors.
- Electrode at mirrors surfaces for carbon contamination prevention.
-
Provisions for RF oxygen plasma cleaning of the optical surface.
- Provisions from measuring the photocurrent at each mirror.
- Permanently installed bakeout provisions.
- Adjustable support structure.
Performance Features
- High positioning resolution (minimum incremental motion).
- High stability and repeatability for all degrees of freedom.
- Minimized mounting induced deformations.
Outer Dimensions
Technical specifications and performance values
General
Vacuum chamber
Chamber type
cylindrical, vertical axis
Main flanges
at the top
Material
1.4404 (C < 0.02%)
Base pressure
10-10 mbar range
Optical design parameters
Beam height
1420 mm
Number of mirrors
2
Surface shape
toroidal
Dimensions
200 x 40 x 40 mm3
(T-Profile)
Actuator drives for hexapod axes
Resolution (design value)
0.004 µm /motor fine step
(1/128, recommended)
0.005 µm /encoder count
Mirror mechanics
Pitch rotation
Range
± 8 mrad
Resolution (measured value)
0.05 µrad
Repeatability
0.09 µrad (pitch)
0.13 µrad (roll)
Long-term stability (3h)
0.048 µrad
Roll rotation
Range
± 10 mrad
Resolution
0.05 µrad
Repeatability
0.08 µrad (pitch)
0.13 µrad (roll)
Yaw rotation
Range
± 8 mrad
Resolution
0.05 µrad
Vertical translation (switch)
Range
± 30 mm
Performance Test Results
Pitch deviation after pitch change
Roll deviation after pitch change
Pitch deviation after roll change
Roll deviation after roll change
Mirror pitch positioning resolution
Mirror pitch long-term stability
Residual gas analysis
