User guide

LBA-USB User Guide Document No: 11294 Page 75
 Capture Resolution Settings – When establishing capture resolutions to
settings other than Full and 1X, it is important to note that the peak location
scatter plot will not have peak locations on any pixel location in the array. A 4X
resolution for example, would have peaks occurring every forth pixel. As a result,
the Peak Scatter plot would look like something like this:
Note how peak locations seem to fall in a grid like pattern. This is to be expected
when capturing every 4th pixel.
 Real World Units – Setting LBA-USB’s Quantitative results to real world units of
length such as µm and mm may be accomplished by returning to the Camera
dialog box from the Option menu.
Make the appropriate real world unit selection in the Pixel Units drop down
box. In many ways, this method of analyzing beam stability is similar to that
discussed above. However, when viewing the scatter plots, the user must
understand that the X and Y-axes will specifically be in the units are selected
above. Also, realize that the grid lines of the scatter plots will not have the same
granularity as the pixel grid on the detector. This method is best used when
scientific units of length or beam centroid displacement are needed. When one
understands the method explained above, this method should be intuitive.
Remember: Reset the scatter plot whenever units are changed in LBA-USB.
 Increment Bins and Reset – The centroid scatter-plot is also a histogram of
the centroid location. The color bar between the Peak and Centroid plots
provides the user insight about centroid location/frequency. Colors in the upper
part of the bar indicate higher frequencies.
When running, notice that blocks of data points have the same color. These
blocks of color represent the binning of the histogram. The program, based on
the range of data being presented, automatically defines the bin size.