Photonic Science
Professional Imaging

X-ray Laue Method for Crystal Orientation

 

Backscattered real-time Crystal Orientation down 0.1 degrees accuracy misalignment measurements down 0.05 degrees using PSEL orientation software

The Laue backscatter mode records X-rays scattered a broad spectrum source. This is useful if the sample is too thick or bulky for X-rays to transmit through it.

The diffracting planes in the crystal are determined by knowing that the normal to the diffracting plane bisects the angle between the incident beam and the diffracted beam. Crystal orientation is determined from the position of the spots.

Each spot can be indexed, i.e. attributed to a particular plane, using special charts.

The Laue technique can also be used to assess crystal perfection from the size and shape of the spots. If the crystal has been bent or twisted in anyway, the spots become distorted and smeared out.

With modern synchrotron and laboratory optics able to deliver micrometer beam size, it is possible to highlight the grain orientation and strain distribution of individual grains in a polycrystalline alloy before and after tensile loading.

This solution is also ideal for replacing film-based Laue systems for industrial applications; for example monitoring for imperfections in high performance turbine blades made from single crystal advanced alloys.” To avoid poor creep resistance and failure of blades at high temperature.

The Laue method can be used to determine the orientation of large single crystals. White radiation is reflected from, or transmitted through, a fixed crystal.

The diffracted beams form arrays of spots, that lie on curves on the film. The Bragg angle is fixed for every set of planes in the crystal. Each set of planes picks out and diffracts the particular wavelength from the white radiation that satisfies the Bragg law for the values of d and q involved.

Each curve therefore corresponds to a different wavelength. The spots lying on any one curve are reflections from planes belonging to one zone Laue reflections from planes of the same zone all lie on the surface of an imaginary cone whose axis is the zone axis. Below are examples of LAUE diffraction patterns; sapphire C-axis aligned, SiC hexagon aligned and diamond edge substrate 011 aligned. The PSEL Laue Single Crystal Orientation Tool provides reliable crystal orientation down to 0.05° accuracy .

Features of Laue Single Crystal Orientation Tool

  • Acquire multiple region of interest on wafers at high resolution.

  • Automatically detects diffraction spots and calculates spot position against reference.

  • Calculates mis-orientation against goniometer & crystallographic axis automatically (no manual fit of distorted patterns).

  • Saves angular measurements in CSV format for further quality assurance and traceability.

  • Compact bench-top design.

  • Automatic scanning of Si wafer, grain segmentation, orientation, map analysis.



    Automatic scanning of Si wafer, grain segmentation, orientation, map analysis.

    Custom Laue systems for wafer scanning include optical cameras and dynamic structured lighting to identify and target individual crystal grains within the wafer.

    Measuring the crystal orientation just once for each grain reduces the time to scan the whole wafer from 32 days to 3 hours.

LAUE X-ray Camera system

LAUE X-ray Camera system