The POWDER DIFFRACTION (2-D) Interface

The POWDER DIFFRACTION (2-D) interface allows Debye-Scherrer rings which have been recorded of a 2-D detector to be integrated to the equivalent of a 2-theta scan with a zero-dimensional detector [10]. An example of an input image and the main menu are shown in Figure 32, Page . To aid with this the MASK sub-menu allows interactive definition of masked areas i.e. pixels which will be ignored during further operations. The TILT button allows the beam centre and any non-orthogonality of the detector to the main beam to be refined, and this tilt is used by the INTEGRATE command. Other types of output are also available. The CAKE sub-menu allows different regions of the image to be defined with graphical coordinate input for the starting azimuth, end azimuth and inner and outer radii of the integrated region. The number of output bins in both the azimuthal and the 2-theta or radial direction are user specified. This allows a variety of different output possibilities e.g. A number of different 2-theta scans, for different azimuth ranges; a 1-D profile of intensity of a ring as a function of azimuth (e.g. for texture studies); or a polar transform of the data. The output formats include one of the GSAS formats [15], one of the Cerius formats⁹, and a general purpose ASCII two column format, which may easily be edited.

Figure 32: The POWDER DIFFRACTION (2-D) Main Menu

The POWDER DIFFRACTION (2-D) Main Menu contains the following commands:

EXIT: Exit POWDER DIFFRACTION (2-D) menu and return to main interfaces menu

BEAM CENTRE: Determine beam centre by a choice of methods

FULL: View image of full data

OUTPUT: Save data in an output file

?: List of available commands with short explanations

CAKE: Versatile multiple 2-theta scans integration

INPUT: Input data from a file on disk

TILT: Fit tilt and beam centre to powder rings

HELP: Help text on this graphical menu

CORRECTION: Spatial distortion correction

INTEGRATE: 2-D to 1-D 2-theta integration

Z-SCALING: Automatic or user control of intensity display range (see Section 5.3, Page )

PRINT: Output current graphics to PostScript file

EXCHANGE: Swap current data with the "memory"

MASK: Defined masked-off regions of the image

ZOOM IN: Define smaller graphical display region

CALIBRANT: Refine wavelength, distance, tilt, etc from powder pattern with known D-spacings.

DISPLAY: Further graphical display possibilities (see Section 5.4, Page )

OPTIONS: Graphics display control menu

UN-ZOOM: Zoom out to see more of the data