X-ray Optics

Flat and curved multilayer X-ray optics can be used as monochromators, collimators or focussing optics in X-ray diffraction, X-ray reflectometry, X-ray fluorescence analysis and for synchrotron applications. Several types of multilayer X-ray optics can be designed depending on the customers application.

Parallel Beam X-ray Optics

Parallel beam X-ray optics are optical components with a graded multilayer deposited on a substrate having a parabolic shape in beam direction. These optical devices convert (in one dimension) a divergent incoming beam into a parallel one, or vice-versa an incoming parallel beam into a focusing one.

In order to obtain high efficiency, the d-spacing of the multilayer has to be varied from the front end to the rear end of the optics in correspondence to the aspheric curvature. Either the X-ray source or the detector (or detector slit) may be placed at the optics focal distance, for primary or secondary side applications, respectively.

High precision 60 mm parallel beam optics on prefigured substrate (right) and on flat substrate, which are glued and bended after deposition (left)

Generation of a monochromatic parallel beam in one dimension

Spectral lines

Cr, Co, Cu, Ga, Mo, Ag
(others on request)

Mean Reflectivity

R > 70%

Monochromacy

1+Kα2 or Kβ

Divergence

Δφ < 0.03°
(40 μm source width)

Mirror length

L = 40...100 mm
(on customers' request)

X-ray source geometry

line focus

Parallel beam width b

dependent on mirror length, geometry and X-ray wavelength

Typical b values

1.5 mm (Cu-K, L = 60 mm)
1.0 mm (Mo-K, L = 100 mm)

Geometry

typical focal length
(source - mirror center)
L = 60 mm, xm = 100 mm

 

Focusing X-ray Optics

Focusing X-ray optics are artificial optical components with a 1-dimensional lattice deposited on a substrate.

These optical devices convert a divergent incoming beam into a focusing one. To obtain high efficiency, the d-spacing of the lattice has to be changed from the front end to the rear end of the optics.

The device needs to have an elliptical figure of curvature to produce a focusing beam. The focus of the X-ray source is located in one of the two focal points of the ellipse.

Parallel beam and focusing X-ray optics with various geometries

Generation of a monochromatic focusing beam in one dimension

Beam path and main parameters of focusing X-ray optics

Spectral lines

Cr, Co, Cu, Ga, Mo, Ag
(others on request)

Mean Reflectivity

R > 70%

Mirror length

typical values
L = 40 mm ... 80 mm
(on customers' request)

X-ray source geometry

line focus

Focal line width b

dependent on spectral
line, geometry and
mirror length

Geometry

customized

 

ASTIX-c 2-dim. collimating

Collimating 2-dimensional X-ray optics in a modified Montel geometry (1) for the generation of 2-dimensional high intensity parallel X-ray beams

  • Typical length 60 mm - 150 mm

  • Application with all typical types of X-ray
    sources (rotating and fixed anodes, liquid
    metal jet and micro focus X-ray tubes)

  • Typical parallel beam width:
    1 mm² ≤ b² ≤ 5 mm²

  • Wavelengths: Cr, Co, Cu, Ga, Mo, Ag...

  • High precision vacuum mirror housing

Working principle of ASTIX-c collimating geometry

Parallel beam profile for Mo Kα radiation, I>107 cps (low power µ-source), b² ≈ 1 mm²

Photo of different ASTIX mirrors.

High precision vacuum mirror housings for ASTIX optics

ASTIX-f 2-dim. focusing

High Flux Optics

  • high flux (HF) at sample position
  • high integrated pixel intensity

High Resolution Optics

  • small spot size at sample position
  • high resolution (HR) in the detector plane

Focusing 2-dim. X-ray optics in a modified Montel geometry (1) for the generation of 2-dimensional high intensity focused X-ray beams

  • Typical length 60 mm - 150 mm
  • Application with all typical types of X-ray sources (rotating and fixed anodes, liquid metal jet and micro focus X-ray tubes)
  • Typical spot diameter: <30 µm ... 500 µm
  • Convergence: customized
  • Wavelengths: Cr, Co, Cu, Ga, Mo, Ag...
  • High precision vacuum mirror housing

(1) M. Montel - "The X-Ray Microscope with Catamegonic Roof-Shaped Objective" in: X-ray Microscopy and Microradiography, Vol.5, 1957,pp 177 - 185

ASTIX-f: focusing geometry

Profile of the diffracted beam between optics and focal point (f2 = 310 mm)

Flat Graded X-ray Optics

Flat graded multilayers are artificial optical components with a 1-dimensional lattice deposited on a substrate.

These optical devices monochromize the incoming beam while leaving the divergence unchanged, i. e. they generate a divergent monochromatic beam. To obtain high efficiency, the d-spacing of the lattice has to be changed from the front end to the rear end of the multilayer. A plane figure is required for this type of mirror. The device has a single focal point. Either the X-ray source or the detector (or detector slit) may be placed at the optics focal distance, for primary or secondary side applications, respectively.

Generation of a monochromatic 1-dimensional divergent beam

Beam path and main parameters of a flat graded multilayer

Spectral lines

Cr, Co, Cu, Ga, Mo, Ag
(can be used for different wavelengths)

Mean Reflectivity

R > 70%

Monochromacy

1+Kα2

Mirror length

L = 20 mm ... 80 mm
(on customers' request)

X-ray source geometry

line focus preferred

Capture angle

φ=0.20° (L = 20 mm) ...
φ=0.50° (L = 80 mm)
for Cu Kα

Application

monochromator
(primary or secondary)
in Bragg-Brentano geometry

 

Monochromators and synchrotron mirrors

Monochromators are optical devices with a 1-dimensional multilayer deposited on a substrate. To obtain high efficiency, the d-spacing of the multilayer is constant from the front end to the rear end of the monochromator. A plane figure is required for the monochromator.

Depending on the application either high resolution or high flux multi-layer monochromators can be fabricated.

Download: Synchrotron optics prospectus (pdf)
Download: Tender X-ray optics prospectus (pdf)

Spectral range

<50 eV - 100 keV

Material systems

optimized on wavelength
or on customer's request

Typical sizes

500 mm length
or 8 inches diameter

Resolution

0.25% < ΔE/E < 2%
(periodic multilayers)
ΔE/E > 5% on request
(aperiodic multilayers)

Thickness
homogeneity

Δd/d < 0.02%

Applications

monochromators for laboratory X-ray sources and for synchrotrons, optimized for high reflectivity or tailored resolution polarizers in the soft X-ray range (O-K, Fe-L, Ni-L)

 

Broadband Mirrors

Tailored depth-graded multilayers

  • Multilayer with large number of different bilayer thicknesses to fulfill Bragg’s law for many photon energies / wavelengths
  • Broadband or bandpass reflectors possible
  • Energy bandwidths of 20% and more feasible
  • Can be optimized for photon energies from EUV up to hard X-rays (80 keV and more)
  • Selected bandwidth is maintained even if energy and corresponding incidence angle are changed
  • Adaptation of the energy band to the source spectrum possible
  • Large photon flux due to the collection of a large portion of the source spectrum e.g. at bending magnets

Reflected wavelength spectrum for a 17% bandwidth mirror around 4.13 nm (300 eV) at 45° incidence angle for polarization measurements with a laser plasma source (red: measurement, black: simulation)

Reflectivity vs. grazing angle for a 22% bandwidth multilayer mirror at 22.2 keV (red: measurement, black: simulation)

Reflectivity vs. grazing angle for a 21% bandwidth synchrotron mirror around 40 keV (red: measurement, black: simulation)