User guide

Page 96 Document No: 11294 LBA-USB User Guide
the energy of the laser. An energy measurement must be obtained using an external
measuring device, then enter the energy value here. The value entered must be the
total energy of the beam for the frame currently displayed. For accurate results, the
beam must fit inside of the current ROI.
If a calibrated value of zero is entered, the Total, Peak, Gauss Height(s), and Top Hat
results are displayed as processed digitizer values. Any entry other than zero will
immediately appear as the Total energy results. The Units entry determines the energy
units that appear to the right of various energy displays (i.e., Peak mw/cm², etc.).
When using a Drawn Aperture (without an Auto Aperture), then the Total Energy is the
amount of energy inside the Drawn Aperture.
When using an Auto Aperture (with or without a Drawn Aperture), then the Total Energy
is the amount of energy inside the Auto Aperture. Thus:
An Auto Aperture takes precedence over a Drawn Aperture.
4.7 Percent in Aperture
When a Drawn Aperture is placed onto the beam display, the percentage of the total
energy of the frame that lies inside of the Drawn Aperture is computed.
If an Auto Aperture is present, then the value represents the total energy contained
within the Auto Aperture.
If no aperture is present, then this result displays 100%.
An Auto Aperture takes precedence over a Drawn Aperture.
4.8 Peak and Min
These are the Peak and Minimum energy density values in the displayed frame, or
within the Drawn or Auto Aperture if present. The Minimum value will most often be
negative, and is therefore not meaningful except as an indication of the amount of noise
present in the video signal.
An Auto Aperture takes precedence over a Drawn Aperture.
4.9 Peak Location
This is the first location where the peak intensity value was found. The Peak Location is
found by scanning the pixel data from left to right, and top to bottom. If a Drawn or
Auto Aperture is present, then the scanning is confined to the pixels inside the aperture.
An Auto Aperture takes precedence over a Drawn Aperture.
4.10 Centroid Location
The Centroid location is found by calculating the center of mass of all the pixels that
satisfy the following clip level criteria, based on the chosen Beam Width Method.