Changes between Version 11 and Version 12 of DemoIntegrateTilted


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Timestamp:
Jul 28, 2011 4:00:39 PM (12 years ago)
Author:
toby
Comment:

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  • DemoIntegrateTilted

    v11 v12  
    1515In the simplest case, all that is needed is to click on the "Do full integration?" checkbox and likely adjust the inner and outer 2-theta values with the two "Inner/Outer 2-theta" controls. For the La_hex_+45deg-00015.tif image loaded before, good values are 0.5 and 7 degrees.
    1616
    17 It is helpful to see the two-theta limits on the plot visually, while adjusting the two-theta range. This is done by clicking on the "Show integration limits?" checkbox. Note that inner limit is shown as a green ellipse and the outer is shown as a red ellipse. ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d2w1.jpg view]).
     17It is helpful to see the two-theta limits on the plot visually, while adjusting the two-theta range. This is done by clicking on the "Show integration limits?" checkbox. Note that inner limit is shown as a green ellipse and the outer is shown as a red ellipse ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d2w1.jpg view]).
    1818Note that changes are displayed only after pressing return, when numbers are placed in the boxes.
    1919
    … …  
    2323 Start/End azimuth: The integration is started at the Start azimuth angle in the left box, and when the "Do full integration?" checkbox is not checked, then the integration will be run only to the maximum value specified. When the range is less than 360 degrees, the integration range will be shown (if selected) with the high and low limits plotted and only segments of the max and min ellipses drawn.
    2424
    25  Number 2-theta bins: The resulting 1-D powder pattern after integration will consist of this many points. This number should be on the order of the number of pixels in one direction (since resolution cannot be much better than this) or less, if instrumental resolution does not require that many points.
     25 Number of 2-theta bins: The resulting 1-D powder pattern after integration will consist of this many points. This number should be on the order of the number of pixels in one direction (since resolution cannot be much better than this) or less, if instrumental resolution does not require that many points.
    2626
    27  Number azimuth bins: In cases where the diffraction experiment shows changes as a function of azimuthal angle, it
     27 Number of azimuth bins: In cases where the diffraction experiment shows changes as a function of azimuthal angle, the integration can be performed as a function of angle. This number specifies the number of bins to use by azimuthal angle. The process of breaking up the integration in this way is sometimes called "caking" since the integration region grows with distance from the beam-center, with a shape like a slice of cake or pie. When more than one azimuthal bin is used, the regions are shown in the plot with dashed lines, when the Show integration limits?" checkbox is checked.
    2828
    29 When only a section of the
     29=== Step 3: Perform integration ===
    3030
     31 Use the Image Operations/Integrate image data menu item to start the integration. This will take at least a few seconds and
    3132
    32 === Step 3: read in the data file ===
    33 
    34  Use the Data/Read image data menu item to read the data file into the current GSAS-II project.
    35  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1m1.png view]).
    36  Select the La_hex_+45deg-00015.tif data file and press Open.
    37 
    38  At this point the data tree window will have several entries
    39  ; the plot window
    40  shows a faint image
    41  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w2.png view]) and a new window
    42  is opened to edit the image controls
    43  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w3.png view]). 
    44 
    45 === Step 4: Edit image parameters ===
    46 
    47  Note that, alas, very few image formats allow for storage of important metadata about the image, so this information needs to be added manually. In this case set the '''wavelength to 0.10798'''. It is also helpful to change the display of the image so that it is easier to see the diffraction rings. Lowering the maximum intensity to 10,000 to 20,000 counts will help (note that this can be done by moving the slider, or by typing a value in the box and then clicking on another control). You may also wish to select another color scheme using the color bar selector.
    48 
    49  Alternately, the view of the image can be enhanced by displaying it on a logarithmic scale. Click on the window and press the upper or lowercase "L" key to toggle logarithmic plotting, or use the keypress selector button at the lower left of this window.
    50 
    51 === Step 5: Calibrate ===
    52 
    53  First:
    54    Set the material used as a sample in the box labeled Calibrant
    55 
    56  Second:
    57    Use the Image Operations/Calibrate menu item (note this menu is on the Image Controls window or for the Mac, the Image
    58    Controls window must be active to place this into the system menu bar). At this point the status line on the bottom of the
    59    Image Controls window changes with a prompt to select points for calibration.
    60    ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w4.png view]).
    61 
    62  Third:
    63   Use the left mouse button to click on at least four locations on the innermost ring. As each point is defined a red "+" is added to the plot
    64   ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w5.jpg view]). 
    65 
    66   To remove a point added in error click on that point with the right mouse button [on the Mac, if you have a single-button mouse, hold the Command (⌘) key down and click].
    67 
    68  Fourth:
    69   When done, press the right mouse button well away from any points that have been added [on the Mac, if you have a single-button mouse, hold the Control key down and click].
    70 
    71  The calibration is then performed. First the rings are located and an ellipse is optimized for each ring. The indexed rings are shown in blue and center of each ellipse is noted with a blue "+"
    72  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w6.jpg view]).
    73  The derived calibration results are shown in the Image Controls window.
    74  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w7.jpg view]).
    75 
    76  To see the actual points selected by the program, click on the "show ring picks?" check button
    77  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w8.jpg view]).
    78  When this is done, it becomes clear that the points selected for the outermost ring are scattered between that and the next ring. This can be repaired by using the Image Operations/Clear Calibration menu item, lowering the area the program uses for searching for points by changing the "pixel search range" to 10 and then repeating the calibration steps (selecting points again on the first ring and then using the right mouse button)
    79  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w10.jpg view]).
    80  This produces very slightly better calibration constants
    81  ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d1w9.jpg view]).
    82 
    83  Assuming that these calibration results will be applied to other images in the same GSAS-II project, click on "Use as default for all images." To save the project, including the now-derived calibration information, use the File/Save Project menu item associated with the data tree window.
    84 
    85 == Next step: [DemoCalibrateTilted Integrate the Data] ==
     33 At this point the data tree window will have a new entries for each azimuthal "slice" added to the data tree
     34 ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d2w2.jpg view]). Also,
     35 two plots are added to the plot window: One (with tab 2D Integration) shows the diffraction intensity as a function of
     36 both 2-theta and (when there is more than one azimuthal integration region) azimuthal angle
     37 ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d2w3.png view]); The other shows a
     38 conventional 1-D powder pattern(s) for each "slice"
     39 ([https://subversion.xor.aps.anl.gov/trac/pyGSAS/attachment/wiki/DemoIntegrateTilted/d2w4.png view]).