Focusing devices
The non-linear tapered guide for the beamline TOPAZ is the first neutron optics with supermirror coatings m = 5. The highly sophisticated coating technology of Neutron Technologies enabled for an excellent performance with reflectivities between 68 and 72% at the critical edge of the supermirror measured on all substrates. The non-linear tapered guide profile was developed by the customer and realized with the "truly curved" concept (continuous curvature) by Neutron Technologies.

type: non-linear focusing guide optics
path/profile: customized non-linear profile
cross-section: 15.37 × 17.74mm² → 6.06 × 6.06mm²
length: 937mm
coating: Ni/Ti, m = 5
substrate: Borofloat
waviness of truly curved profile < ≈10-4 rad
pronounced beam focusing
reflectivity of supermirror m = 5
Parabolic guide optics – D17, ILL
The D17 reflectometer uses a high resolution in the horizontal plane to probe thin films. However, in the vertical direction the divergence of the neutron beam can be large in order to increase the intensity, in particular for small samples. Therefore a vertical focusing neutron optics was desired utilizing a truly curved parabolic profile with high m = 4 supermirror coating (R ≈ 0.80). At the same instance the device should provide a pre-collimation in the horizontal plane. For this purpose the side walls are straight and equipped with B4C baffles.


After installation, first tests on a standard sample confirm that the neutron flux at the sample is improved by more than a factor of 2. For smaller samples the gain will be even higher compared to the simple geometrical confinement of the probing beam due to sample size and/or beam defining apertures.

type: vertical parabolic focusing guide optics
path/profile: vertical truly curved parabolic / horizontal collimator
height of guide: 150.00mm → 46.19mm
length: 3300mm
coating: Ni/Ti, m = 4
substrate: Borofloat
waviness of truly curved parabolic profile ≈0.6 × 10-4 rad
B4C blades are integrated into the sides to collimate the beam in the horizontal plane
reflectivity data of a standard sample without (left) and with (right) focusing guide
Parabolic multi-channel guide – StressSpec, FRM-II
An optimized multi-channel parabolic guide focuses the neutron beam coming from the monochromator of the instrument StressSpec (FRM-II) to a small spot on the samples. The pictures below show the thin glass plates at the entrance and exit of the device. The narrow nose-pieces of the top/bottom plates at the exit have a width of only 2mm.
Photographs of the entrance (left) and the exit (right) of the multichannel parabolic focusing device.
The picture of the exit (right) shows the device without one side wall.
type: vertical parabolic focusing with sub-division into 5 channels
path/profile: vertical truly curved parabolic / horizontal linear tapering
cross-section outer guide: 30.00 × 30.00mm² → 2.00 × 5.89mm²
cross-section midmost channel: 30.00 × 7.50mm² → 2.00 × 2.36mm²
length: 1000mm
coating: Ni/Ti, m = 3
substrate: Borofloat
waviness of truly curved parabolic profile ≈1 × 10-4 rad
The sides are coated with neutron absorbing material for beam collimation
An optimized multi-channel parabolic guide focuses the neutron beam coming from the monochromator of the instrument StressSpec (FRM-II) to a small spot on the samples. The pictures below show the thin glass plates at the entrance and exit of the device. The narrow nose-pieces of the top/bottom plates at the exit have a width of only 2mm.
Parabolic guide optics - HQR, JRR-3M
The high resolution triple-axis spectrometer (JRR-3M) uses a double focusing parabolic guide optics to enhance the neutron intensity available for experiments. The device is optimized with a focal length of 290mm in the horizontal plane and 92mm in the vertical plane from the exit of the guide. The supermirror coating with m = 3 and high reflectivity (R > 0.85) enables efficient beam focusing.

type: parabolic focusing guide optics
path/profile: truly curved parabolic
cross-section: 21.07 × 54.85mm² → 10 × 16mm²
length: 1000mm
coating: Ni/Ti, m = 3
substrate: Borofloat
waviness of truly curved parabolic profile < ≈10-4 rad
pronounced beam focusing
Multi-channel parabolic optics - JRR-3M
This optics focuses in the vertical and horizontal plane. The vertical focusing is optimized by sub-dividing the guide height into 9 channels with parabolic profiles. The horizontal focusing needs to be only moderate, thus it is sufficient to use a linear tapering.

type: multi-channel parabolic optics – 9 channels
path/profile: truly curved parabolic, linear tapering
cross-section: 20 × 90mm² → 12 × 52mm²
length: 1.8 m
coating: Ni/Ti, m = 3, 3.6
substrate: float glass, Borofloat
pronounced beam focusing

Elliptic neutron guide - PGAA, FRM-II
The Prompt Gamma Activation Analysis station at the FRM-II utilizes an elliptic neutron guide which is attached to the preceding conventional neutron guide. Simulations of the instrument group established that a elliptic neutron guide provides best focusing properties. The last section (≈ 1 m) is mounted on an optional support, which has highly repeatable positioning. Thus a simple change between two different beam sizes is possible.

type: elliptic neutron guide
path/profile: truly curved elliptic
cross-section: 50 × 110mm² → 8.42 × 18.55mm²
length: 7090mm
coating: Ni/Ti m = 3
substrate: float glass
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