P487 – DCM-PGM MIFO PTB
Application
Combined double crystal monochromator (DCM) and multilayer plane grating monochromator (MLM) to bridge the gap between soft and hard X-ray synchrotron radiation
Year of delivery
2022
Installation site
MIFO beamline of National Metrology Institute of Germany (PTB) at BESSY HZB, Germany
This monochromator was developed as a combination of a DCM and a multilayer PGM in order to cover the whole available tender X-ray energy range of 1.5-10 keV at the MIFO beamline of the PTB at BESSY using one monochromator system only. Change of operation mode between PGM and DCM is automated and does not require venting of the system.
Design Features
- Variable included angle multilayer monochromator (MLM).
- Double crystal manipulator (DCM) mounted on the MLM grating cradle.
- Piezo controlled pitch and roll correction of the second crystal upon crystal gap variation.
-
Transversal translation stages to switch between DCM and MLM operation modes.
- Spectral range: 1.5 – 10 keV
- Optical elements for MLM: one ML plane mirror and one ML plane grating.
- Optical elements for DCM: one Silicon crystal pair.
- Temperature sensors at internal mechanics, mirror and grating substrates and crystals.
-
Active water cooling of mirror, grating and first crystal.
- Passive cooling of second crystal.
- Water cooled zero-order stop.
-
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.
- Adjustable support structure.
- Permanently installed bakeout provisions.
Performance Features
- High positioning resolution (minimum incremental motion).
- High pitch rotation stability and repeatability.
- High scanning speed of pitch rotations.
- 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
-22 mm
Number of plane mirrors
1
Plane mirror dimensions
420 mm x 50 mm x 50 mm
Number of gratings
1
Gratings dimensions
130 mm x 40 mm x 40 mm
Crystal 1 dimensions
85 mm x 20 mm x 15 mm
Crystal 2 dimensions
32 mm x 20 mm x 10 mm
Support structure
Adjustment ranges
Vertical translation
± 5 mm
Lateral translation
± 5 mm
Longitudinal translation
± 5 mm
Pitch
± 1°
Roll
± 1°
Yaw
± 1°
Plane mirror
Pitch rotation
Range
-0.92° to +52°
Resolution (design value)
0.0218 µrad /motor fine step
(1/256, recommended)
0.00146 µrad /encoder count
Resolution (measured value)
0.05 µrad
Repeatability
0.47 µrad (pitch)
0.38 µrad (roll)
Long-term stability (> 2h)
0.04 µrad
Scanning speed
> 1° /s
Lateral translation
Range
+1.22 mm to -139.66 mm
Resolution (design value)
0.0065 µm /motor fine step
(1/128, recommended)
0.05 µm /encoder count
Repeatability
0.24 µrad (pitch)
0.23 µrad (roll)
< 100 µm (translation)
Long-term stability (> 2h)
0.02 µrad
Scanning speed
1 mm /s
Grating / crystals
Pitch rotation
Range
-1.03° to +56°
Resolution (design value)
0.0218 µrad /motor fine step
(1/256, recommended)
0.00146 µrad /encoder count
Resolution (measured value)
0.05 µrad
Repeatability
0.09 µrad (pitch)
0.11 µrad (roll)
Long-term stability (> 2h)
0.06 µrad
Scanning speed
> 1° /s
Lateral translation
Range
1.68 mm to -139.48 mm
Resolution (design value)
0.0065 µrad /motor fine step
(1/128, recommended)
0.05 µm /count
Repeatability
0.28 µrad (pitch)
0.15 µrad (roll)
< 100 µm (translation)
Long-term stability (> 2h)
0.03 µrad
Scanning speed
1 mm /s
Crystals
Distance between crystals
Range
10 mm
Resolution (design value)
3.64 µm /step (full step)
0.001 µm /encoder count
Upper crystal rotation
Range
-0.1° to +0.1°
Piezo travel range
105 µm
Resolution
~28.3 µrad /V (pitch)
~21.5 µrad /V (roll)
0.001 µm /encoder count
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
Pitch deviation after grating translation
Mirror pitch positioning resolution
Mirror pitch positioning resolution
Mirror pitch long-term stability
Mirror lateral position long-term stability
Grating pitch positioning resolution
Grating pitch positioning resolution
Grating pitch long-term stability
Grating lateral position long-term stability
Scanning speed of mirror pitch
Scanning speed of grating pitch
Scanning speed of mirror translation
Scanning speed of grating translation
Residual gas analysis
