P387 – VLS-PGM I21-IXS DLS
Application
Plane grating monochromator (PGM) for soft X-ray synchrotron radiation
Year of delivery
2015
Installation site
Beamline I21-IXS at Diamond Light Source, Didcot, United Kingdom
Design Features
- High-resolution grazing incidence variable line spacing plane grating monochromator (PGM).
- Spectral range: 250 – 3000 eV.
- Optical elements: one plane mirror and four plane gratings.
- Temperature sensors at internal mechanics, mirror and gratings.
- Electrode at mirror surface for carbon contamination prevention.
- Active water cooling of all optical elements.
-
Combined drives with piezo actuator and stepper motor for ultra-high mirror / grating pitch positioning resolution over the entire motion range.
-
Water cooled zero-order stop with mask.
- 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 step resolution.
- Very 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
15 mm
Number of plane mirrors
1
Plane mirror dimensions
450 mm x 70 mm x 50 mm
Number of gratings
4
Gratings dimensions
170 mm x 40 mm x 50 mm
Support structure
Adjustment ranges
Vertical translation
± 15 mm
Transversal translation
± 15 mm
Longitudinal translation
± 15 mm
Pitch
± 1°
Roll
± 1°
Yaw
± 1°
Plane mirror
Pitch rotation
Range
0.60° to -9.80°
Resolution (design value)
0.00375 µrad /motor fine step
(1/64, recommended)
0.0047961 µrad /encoder count
Resolution (measured value)
0.05 µrad
Repeatability
0.11 µrad (pitch)
0.07 µrad (roll)
Long-term stability (> 1.5 h)
0.021 µrad
Long-term stability (> 1.5 h)
2.4 l/min water flow rate
0.028 µrad
Recommended scanning speed
2 °/min
Translation
Range
-13.27 mm to +68.64 mm
Resolution (design value)
0.078 µm /motor fine step
(1/64, recommended)
0.05 µm /encoder count
Repeatability
0.07 µrad (pitch)
0.12 µrad (roll)
Recommended scanning speed
20 mm /min
Gratings
Pitch rotation
Range
0.70° to -9.40°
Resolution (design value)
0.00375 µrad /motor fine step
(1/64, recommended)
0.0047961 µrad /encoder count
Resolution (measured value)
0.01 µrad
Repeatability
0.08 µrad (pitch)
Long-term stability (> 1.5 h)
0.009 µrad
Long-term stability (> 1.5 h)
1.8 l/min water flow rate
0.021 µrad
Recommended scanning speed
2 °/min
Translation
Range
-20.30 mm to +181.50 mm
Resolution (design value)
0.078 µm /motor fine step
(1/64, recommended)
0.05 µm /encoder count
Repeatability
0.17 µrad (pitch)
0.44 µrad (roll)
Recommended scanning speed
20 mm /min
Performance Test Results
Pitch deviation after pitch change (mirror)
Pitch 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 position resolution
(2.4 l/min water flow rate)
Grating pitch positioning resolution
Grating pitch positioning resolution
(1.8 l/min water flow rate)
Mirror pitch positioning resolution
Grating pitch positioning resolution
Mirror pitch long-term stability
Mirror pitch long-term stability
(2.4 l/min water flow rate)
Grating pitch long-term stability
Grating pitch long-term stability
1.8 l/min water flow rate)
Grating pitch positioning resolution (piezo actuator)
Residual gas analysis
