Sigma LBA-712, LBA-710 manual Percent in Aperture, Peak and Min, Peak Location, Centroid Location

energy results. The Units entry will determine the energy units that will appear behind the various energy displays, i.e., Peak mw/cm², etc.

If you are using a Drawn Aperture (without an Auto Aperture), then the Total Energy is the amount of energy inside the Drawn Aperture.

If you are 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 precedent over a Drawn Aperture.

6.7 Percent in Aperture

If you place a Drawn Aperture onto the beam display, the percentage of the total energy of the frame that lies inside of the Drawn Aperture will be computed.

If an Auto Aperture is present, then the value will represent the total energy contained within the Auto Aperture.

If no aperture is present, then this result will show 100%.

Auto Aperture takes precedent over a Drawn Aperture.

6.8 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.

Auto Aperture takes precedent over a Drawn Aperture.

6.9 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.

Auto Aperture takes precedent over a Drawn Aperture.

6.10 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 upon the chosen Beam Width Method.

•In the case of Percent of Peak, the included pixels are those that are greater than the Clip% level.

•With Percent of Energy, the included pixels are those that are greater than or equal to the Clip% level.

•If the 4 Sigma or one of the Knife Edge methods are chosen and the Top Hat calculations are not checked, the clip level is set to 86.5% of energy. If the Top Hat calculations are checked, then an 80% of Peak clip level is set.

Operator’s Manual	131	LBA-PC
Doc. No. 10654-001, Rev 4.10