Method and apparatus for determining crystallographic orientation on crystalline surfaces

A method of determining 3D crystallographic orientation of a grain on a crystalline surface of a sample, the method comprising:

• directing a beam of collimated light to strike a spot on the crystalline surface at a predetermined angle of incidence, wherein reflections from the crystalline surface at said spot are projected onto a detector screen positioned in a path of reflected light, thereby displaying a reflectance pattern on the detector screen;
• capturing an image of the reflectance pattern on the detector screen;
• obtaining a directional reflectance profile from the captured image of the reflectance pattern by pixelising the reflectance pattern, according to a polar coordinate system, into a pixelated-image with a center coinciding with an intersection of a specularly reflected light beam and the detector screen, wherein the pixelated-image is radially divided into equal radial-pixels-segments about the center and each radial-pixels-segment is divided into pixels in respective radial direction to form a row of pixels extending along the respective radial direction;
• and
• processing the directional reflectance profile based on analyzing reflection intensity data in the pixels of the pixelated-image of the directional reflectance profile to determine the 3D crystallographic orientation of the grain on the crystalline surface at said spot of the crystalline surface.

An apparatus configured to perform a method of determining 3D crystallographic orientation of the grain on a crystalline surface of a sample, the apparatus comprising:

• a collimated light source configured to be disposed above the crystalline surface and to direct a beam of collimated light at a predetermined angle of incidence to strike a spot on the crystalline surface;
• a detector screen disposed in a path of reflected light so as to display a reflectance pattern on the detector screen;
• a camera disposed relative to the detector screen in a manner so as to capture an image of the reflectance pattern on the detector screen;
• and
• a processor in communication with the camera to receive the image of the reflectance pattern captured by the camera,
• wherein the processor is configured to obtain a directional reflectance profile from the image of the reflectance pattern by extracting an annular portion of the reflectance pattern and pixelising the annular portion of the reflectance pattern, according to a polar coordinate system, into a pixelated-image with a center coinciding with an intersection of a specularly reflected light beam and the detector screen, wherein the pixelated-image is divided into equal radial-pixels-segments about the center and each radial-pixels-segment is divided into pixels in respective radial direction to form a row of pixels extending along the respective radial direction, and
• wherein the processor is configured to process the directional reflectance profile based on analyzing reflection intensity data in the pixels of the pixelated-image of the directional reflectance profile to determine the 3D crystallographic orientation of the grain on the crystalline surface at the spot which the beam of collimated light is directed.