Acquiring Elemental Survey Images
Elemental survey images are new to AugerMap 2. They enable you to acquire
data over a spectrum (survey) of energy, as opposed to specifying the peak and
background. This can give you a more accurate and flexible account of the data
for the region, at the expense of acquisition time. It also gives you the
ability to acquire large amounts of survey data over an area (similar to acquiring
multiple-points).
Elemental survey images are created using the maximum – minumum of the data acquired over the energy range specified.
Before acquiring, you’ll want to ensure that you are acquiring clean Auger data using AugerScan. See
your AugerScan documentation for more information.
To acquire an elemental surveyt image(s), click Elemental Survey in the Acquisition menu. This will bring up the Setup Elemental Survey Acquisition dialog. From
this dialog, you can acquire (or re-acquire) multiple images. If you have not
already acquired an elemental survey image, you may also setup your images
without acquiring by clicking the Apply button. You may also acquire more than one of each elemental region (for
example, if you want to acquire two Si images at different resolutions)
Elemental Survey Acquisition Dialog
Element List
The Element List is a list of all the elemental region images for this map. To add an element
image, simply click the Add button. To remove an element, select the element from the list and click the Remove button. To remove all the elements, click the Remove All button.
When you click the Add button to add an element, you’ll be presented with the Select Element dialog. From here, you can click one
or more elements to add. Note that you can also edit the element table from
this dialog. Click here for more information on editing the element table.
The following all refer to the selected element:
Energy
These parameters determine what kinetic energies will be used to acquired data
for the selected element. Each element using data from points defined by the Lower Limit to the Upper Limit. The step size is defined by the eV/Step. Note that smaller step sizes will greatly increase your acquisition time.
The default values for the lower and upper limits and eV/Step are provided by
the element table. However, it is recommended you modify these values, especially with an eye
towards narrowing the range (becuase of the long acquisition time). The best
way to obtain these values is to use AugerScan to do a quick survey of the area.
Resolution
Use this drop-down box to select the resolution (XxY pixels) of the image.
The choices available are 16x16, 32x32, 48x48, 64x64, 96x96, 112x112, and
128x128. Since elemental survey images take so long to acquire, it is worth the extra
time to take a small (16x16) image to ensure good results before acquiring a
larger one. Even though there will be few pixels available, the overall
contrast and depth can be determined.
Time Per Step
This value determines the amount of time (in milliseconds) spent acquiring
data at each energy, for each pixel of the image. For example, if you were
acquiring from 100 to 120 eV using 1 eV/step, and 10ms t/s, your time to acquire each
point would be 210ms.
A good default value here is 10ms. Longer times may result in better signal
to noise ratios (and resulting images), but at great cost to acquisition time.
Comment
Type a comment in this field (optional) for the selected image. The comment
will also appear in the Project Window, and on the printout, so it can be a useful reference.
Acquire All
Click this box if you wish to automatically acquire all the elemental region
images in the list. If unchecked, only the selected acquisition will be
acquired at this time. You can always acquire the other acquisitions later.
Acquire
Click this button to acquire the selected image, or all the images if you have
that option selected (see above).
Apply
Click this button to apply the current settings for all images, without
actually acquiring. You can then save the file, and use it later as a template.
Note that, if you have acquired any elemental images, this button is inactive.
Acquisition Control
Evaluating Data During Acquisition
AugerMap displays the image as it is being acquired, so you can often easily
tell if there are problems with the image quality. As new data is acquired, the
image gray-scale range is automatically adjusted to take into account the min
and max of the new data. Therefore, you may see the contrast of the image
fluctuate as it adjusts to accommodate. The status bar at the bottom of the main
AugerMap window will update with the current line being acquired, counts, and
estimated time remaining. The counts may vary anywhere from the hundreds to
thousands, depending on the type of image being acquired and the current settings.
The overall range is usually not important, but if you are only see a
fluctuation of less than a hundred, you will probably notice a lack of image depth and
quality, and need to make some adjustments to your image setup to compensate.
To cancel the rest of an image acquisition (and any other images queued up
afterwards), click Stop Now from the Acquisition menu. The acquisition will stop immediately. Note that this removes any
previously collected data (for that image), since it is incomplete. To cancel any
queued-up acquisitions after this one is complete, click Stop from the Acquisition menu.
After Acquisition
After acquisition, there are a number of actions you can take. You can annotate the image, or add a microm marker. You can also process, enhance, colorize, and invert the image. All of these commands are available from the image menu. You can
also use the Project Window to delete the image.
Often, an image will need some adjustments to brightness and contrast before
the quality is acceptable. This may be the case if there is any noise in the
image. If there are a few pixels with very high counts in an image, this will
lower the overall contrast. Brightness and contrast are adjusted using the Threshold and Gamma controls available from the Processing command in the Image menu. Click here for more information on image processing.
Keep in mind that, for elemental images, the resulting image should be
representative of the underlying data. Adjusting the processing or enhancing an
elemental image will obviously changed the way the grey-scale image maps to the
underlying data, and may no longer reflect an accurate representation.
Elemental images can be most useful as part of a composite (especially if overlayed on an SED or ABS image). Before using an elemental image as top layer in a composite, you
must colorize the data.
Lastly, saving, exporting and printing commands are covered in the File Management topic.