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3 Double Crystal Monochromatoren

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Technical Description


3 pieces of water cooled Double–Crystal–Monochromator with 2 crystal pairs.

The function of the Double Crystal Monochromator (DCM) is to select and transmit X–ray radiation of the desired photon energy from an incident white synchrotron radiation beam.
The DCM will be incorporated into a beamline with a horizontal incident beam. It will use two parallel crystal pairs in (+, –) configuration to produce a monochromatic exit beam which is running parallel to the incident white X–ray beam.

When Si (111) crystals are used the energy of the monochromatic beam will be continuously selectable from 3 keV to 20 keV.

The energy will be selected by rotating both crystals (varying the Bragg angle) whilst keeping the crystals parallel to each another.
The beam offset, i.e. the distance between the optical axes of the incident beam and the exit beam, does not change during the energy scan. This is realised by a common rotation of both crystals and two perpendicular motions of the second crystal.

The DCM is designed for a beam offset between 40mm and 46 mm. Different beam offsets are available on request.
The Bragg angle can be set between –3° and 50°. In the 0° position (horizontal crystal orientation) the first crystal can be moved out of the Bragg rotation axis to let the beam go through.

All positioning elements are in vacuum drives. These are:
• Bragg angle goniometer (stepper driven)
• 1 Linear slide (stepper driven) for crystal 1 positioning
• 2 Linear slides (stepper driven) for crystal 2 positioning
• 2 Linear slides (stepper driven) for crystal change
• 4 angular drives (manual/picomotor driven) fine positioning of the crystals in roll and pitch
• 1 angular drive piezo driven for fast feedback control of crystal 2 pitch

The DCM is high–vacuum compatible.
The first crystal is indirectly water–cooled in order to dissipate the absorbed photon energy.
The DCM control system is mounted in a single 19”–24U control rack. It includes a control PC running on Microsoft Windows XP.
The control software based on AgilentVEE provides a graphical user interface.

Technical Datas


Bragg angle range: -3° .. 50°

Bragg angle resolution: 0.1 arcsec

Crystal 1 size:
(length x width x thickness)

(100 x 60 x 10)mm³

Optical surface crystal 1:
(length x width)
(100 x 50)mm³

Crystal 2 size:
(length x width x thickness)

(116 x 60 x 10)mm³

Optical surface crystal 2:
(length x width)
(116 x 50)mm³

Size (flange to flange):
(length x width x height)
(1150 x ca. 1400 x 2075)mm³

Weight: approx. 2000 kg


Customer & Period


Customer:

RRCAT Indore, India ; BARC Mumbai, India

Period of Implementation:

Februar 2007 bis September 2008



 

REIXS Monochromator

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Technical Description


Plane Grating Monochromator for Resonant Elastic and Inelastic X–ray Scattering Beamline

Technical Datas


Energy range: 80 - 2000 eV

Resolution: ≤0,02 arcsec

Pitch angle of the gratings:

-1⁰ - 11⁰

Max. number of gratings:

3
Max. grating size:
(length x width)

130x30, 170 x 30
grating cooling: Indirect Water side cooling

Max. grating size:
(length x width)

410x100

Mirror cooling: Intrinsic Water Cooling

Grating and mirror pitch drive &
Grating and mirror change drive

Stepper motors with gears in air
Angular encoder:
Heidenhain RON 905 UHV type

Linear encoder:
Renishaw UHV type

Base pressure:
< 5 x 10e-10 mbar

Customer & Period


Customer:

Canadian Light Source – CLS

Period of Implementation:

November 2006 to August 2007


 

Plane Grating (PGM) | VUV Monochromator

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Technical Description


It is the task of the monochromator to realize the necessary pitch movement of the gratings and of the mirror as well as to guarantee the exchange of the gratings and of the mirror.
The gratings and the mirrors are arranged separately in highly precise and stable supports which are equipped with fine adjustment facilities.
A normal incidence mirror and a normal incidence grating are used for the lower energies. The gratings are oriented towards the bottom, while the mirror surface shows upwards.
The gratings can execute a pitch rotation up to 55°, the mirror has an angle range of 35°. The exact positioning of the grating surfaces in the rotational axis is important. High–precision hybrid ball bearings will be used as bearing mechanisms.
For the exchange the gratings and the mirror travel in separate linear slides. The exchanging positions are read via linear encoders, which can be operated in the vacuum. The pitch positions are determined using high–precision angular encoders, which are mounted directly on the axes in the vacuum.
The entire mirror and grating mechanism is based on a very stable base plate which is screwed to feet which come from the outer main frame and are led through the chamber wall. Thus the mechanism is not connected with the chamber and is isolated from thermal and mechanic deformations of the chamber. The monochromator frame consists of solid pipes or a monolithic block and allows an adjustment in all six degrees of freedom. A sputtering ion pump is used as a vacuum pump.
The vacuum chamber has a diameter of approx. 800 mm and is completely metal–sealed. All optical elements are fitted with lateral cooling plates. Cooling is performed using water.

Technical Datas


Energy range: 3eV … 1500eV

Mx. Resolution E/ÄE: Up to 100000

Modes:

Normal incidence and grazing incidence

Pitch angle of the gratings:

-2° … 55°

Max. number of gratings:

4

Max. grating size:
(length x width)
120 x 40 mm2

grating cooling: Water

Mirror size:
(length x width)
300 x 50 mm2

Mirror cooling:
Water

Grating and mirror pitch drive:
In vacuum piezo motors or Stepper motors with gears on air

Grating and mirror change drive:
In vacuum piezo motors or Stepper motors with gears on air

Angular encoder:
Heidenhain UHV type

Linear encoder:
Renishaw UHV type

Base pressure:
< 5 x 10-10 mbar

Customer & Period:


Customer:

BESSY, Berlin, Germany

Period of Implementation:

2004 bis Dezember 2005


 

Double Crystal Monochromator

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Technical Description


Double Crystal Monochromator (DCM)

The function of the Double Crystal Monochromator (DCM) is to select and transmit X–ray radiation of the desired photon energy from an incident white synchrotron radiation beam.
The DCM uses two parallel crystals in (+, –) configuration to produce a monochromatic exit beam which is running parallel to the incident white X–ray beam. Depending on the type of crystal by use of several crystals the energy of the monochromatic beam will be continuously selectable from 3 keV to 25 keV.
The energy will be selected by rotating both the crystals and varying the Bragg angle whilst keeping the crystals parallel to one another. The beam offset, i.e. the distance between the optical axes of the incident beam and the exit beam, does not change during the energy scan. This is realised by a common rotation of both crystals and two translational motions of the second crystal, a parallel and a perpendicular motion with respect to the surface of the first crystal.
The DCM will be high–vacuum compatible with first crystal indirectly water–cooled in order to dissipate the photon energy that is absorbed. As option LN2 cooling is possible. To achieve sagittal focusing, the second crystal can be dynamically bent by in–situ mechanical bending (ESRF licence). FMB delivers crystal holders for up to three crystals.
The DCM is designed for a beam offset in the range of 25 to 35 mm and in order to reach the specified energy range. the Bragg angular range must be from 0 to more than 50 degrees. The Bragg angle can, however, be set up to –5° for alignment purposes. In the 0° position the first crystal can be removed out of the rotation axis to let the direct light beam go through.

Technical Datas


Energy range: 3 keV … 25 keV (using Si 311 or Si111 crystals)

Angular resolution of the mechanic: 0.1 arcsec

Bragg angle range:

-3° … 55°

Max. number of crystal pairs:

1 (Standard and if using bender) up to 3 (option)

Max. crystal size:
(length x width)

80 x 100 mm2

Crystal 1 cooling: Water, LN2 (option)

Crystal 2 bending: ESRF licence (option)

Feedback control crystal 2: Piezo translator
Stroke: 80 µm


Crystal drives: In vacuum stepper motors

Crystal adjustment drives: In vacuum piezo motors (Pico motors ®)

Angular encoder: Heidenhain UHV type (RON 905)
Encoder resolution: 0.01 arcsec

Linear encoder: Renishaw UHV type (RGH 25)
Encoder resolution: 10 nm

Base pressure: < 2 x 10-7 mbar

Customer & Period


Customer:

Centre for Advanced Technilogies (CAT), Indore, India

Period of Implementation:

February 2004 to December 2004


 

Spherical Grating Monochromator

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Technical Description


It is the task of the monochromator to realise the pitch movement of four gratings and to guarantee the exchange of the gratings.
The gratings are arranged separately in highly precise and stable supports which are equipped with fine adjustment systems under vacuum.
The silicon gratings are downwardly oriented and can perform a pitch rotation of approx. 20°. The exact positioning of the grating surface in the pitch axis is important.
High–precision hybrid ball bearings will be used as bearing mechanism.
For the exchange of the gratings the gratings will travel in a linear slide. An optional pressure mechanism forces the respective active grating against a reference plate, so that a high repeatability of the grating position is achieved.
The pitching movement of the grating system is performed via a translatory movement which is transfered from the outside into the vacuum chamber via a membrane bellow.
The motorization is outside the vacuum, the stepping motors can be combined with harmonic drive gears which will allow very high transmission ratios and thus the necessary angular resolution for the pitching movement.
The exchange of the gratings will be performed via a translatory motion from the outside.
The pitch and exchanging positions of the gratings are read via linear and angular encoders, which can be operated in vacuum.
The entire grating mechanism is arranged on a very stable base plate which come from the outer main frame.
The monochromator frame consists of solid tubes which are welded to the floor base plate.
A sputtering ion pump (500 l/s) is used as a vacuum pump. The vacuum chamber has a diameter of approx. 800 mm and is completely metal–sealed. All four gratings are fitted with lateral cooling plates. Cooling is performed using water.

Technical Datas


Gratings

Number : 4

Bulk material :

Silicon
Bulk dimension :

180 x 38 x 35

Shape :

Spherical / Plane

Grating fine adjustment : Pitch, Roll, Yaw, Height possible under vacuum

Grating cooling : Water




Grating pitch drive


Stepper motor : 500 steps

Gear : Harmonic Drive

Gear ratio : 100 : 1

Vertical range : + 25 … -45 mm relative to the horizontal position

Vertical movement : 0.00001 mm per full step

Encoder : incremental

Encoder resolution : 50 nm

End switch number: 2 x 2 (active and redundant)

Grating change drive


Stepper motor : 500 steps

Gear : Planetary Gear

Gear ratio : 6 : 1

Horizontal range : 0 … 225 mm

Horizontal movement : 0.00033 mm per full step

Encoder : incremental

Encoder resolution : 1µm

End switch number: 2 x 2 (active and redundant)

Customer & Period


Customer:

Singapore Synchrotron Light Source (SSLS)

Period of Implementation:

September 2001 to May 2002