P402 – PGM_soft EMIL BESSY
Application
Plane grating monochromator (PGM) for soft X-ray synchrotron radiation
Year of delivery
2015
Installation site
EMIL soft X-ray beamline at BESSY, Helmholtz-Zentrum Berlin, Germany
This soft X-ray monochromator is part of the combined hard and soft X-ray EMIL beamlines at BESSY. The vacuum chamber accomodates not only the actual beam but also the passing hard X-ray and pink beams of the neighbouring branch. In all EMIL systems we integrated for the first time electrodes for carbon contamination prevention of the optical surfaces. In this monocromater we additionally installed provisions for RF oxygen plasma cleaning.
Design Features
-
High-resolution grazing incidence plane grating monochromator (PGM).
- Spectral range: 80 – 2000 eV.
- Optical elements: one plane mirror and two plane gratings.
- Temperature sensors at mirror and gratings chin guards.
- Electrodes at mirror and gratings surfaces for carbon contamination prevention.
- Provisions for RF oxygen plasma cleaning of the optical surfaces.
-
Active water cooling of all optical elements.
- Four water cooled, motorized OFHC aperture blades at the entrance flange.
- Permanently installed bakeout provisions.
- Adjustable support structure.
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
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 (entrance)
1400 mm
Beam offset
20 mm
Number of plane mirrors
1
Plane mirror dimensions
500 mm x 30 mm x 60 mm
Number of gratings
2
Gratings dimensions
100 mm x 20 mm x 40 mm
Support structure
Adjustment ranges
Vertical translation
± 10 mm
Lateral translation
± 10 mm
Longitudinal translation
± 10 mm
Pitch
± 1°
Roll
± 1°
Yaw
± 1°
Mirror mechanics
Pitch rotation
Range
-15.3° to +1.32°
Resolution (design value)
0.004 µrad /motor fine step
(1/64, recommended)
0.00146 µrad /encoder count
Resolution (measured value)
0.10 µrad
Repeatability
0.05 µrad (pitch)
0.06 µrad (roll)
Stability
0.05 µrad
Translation
Range
76 mm
Resolution (design value)
0.05 µm /motor fine step
(1/64, recommended)
0.005 µm /encoder count
Repeatability
0.08 µrad (pitch)
0.07 µrad (roll)
Grating mechanics
Pitch rotation
Range
-18.66° to +2.5°
Resolution (design value)
0.004 µrad /motor fine step
(1/64, recommended)
0.00146 µrad /encoder count
Resolution (measured value)
0.10 µrad
Repeatability
0.14 µrad (pitch)
0.07 µrad (roll)
Stability
0.06 µrad
Translation
Range
190.3 mm
Resolution (design value)
0.05 µm /motor fine step
(1/64, recommended)
0.005 µm /encoder count
Repeatability
0.18 µrad (pitch)
0.05 µrad (roll)
Aperture unit
Blades
Material
OFHC (water cooled)
Stroke
50 mm
Resolution (design value)
15 µm /motor step
(full step at actuator)
4.125 µm /motor step
(full step at blade)
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
Grating pitch positioning resolution
