Sigma LBA-700, LBA-710, LBA-300 Elliptical beam, Percent of Energy Method, Percent of Peak Method

equivalent second moment width for TEM00 beams, and are a good approximation for many beams of mixed modes.

The second Knife Edge selection will allow you to program your own Clip% and Multiplier values. This option will allow you to set up for beams requiring special settings, which could get you into all kinds of trouble, since you can set these values to just about anything you like.

When the LBA’s Elliptical results are disabled, the computed beam widths will be aligned with a pair of simulated knife-edges cutting one in each of the X and Y directions. Hence, the displayed beam widths will be indicated in the results window as X and Y. If your laser beam is not radially symmetric but does contain two axes of symmetry, you should rotate the beam such that the beam's axes align with the X and Y axes of the display.

When the LBA's Elliptical results are enabled, the computed beam widths will be aligned with a pair of simulated knife-edges cutting one in each of the Major and Minor axial directions. Hence, the displayed beam widths will be indicated in the results window as Major and Minor. The implication is that the displayed values represent the major and minor widths of an elliptically shaped laser beam.

6.11.3Percent of Energy Method

The LBA measures the lengths of two orthogonal lines that pass through the beam centroid. The beam widths are determined by separately looking out along each line and count all the pixels that are greater than the set clip level. The reported beam widths are the number of pixels greater than the clip level multiplied by the pixel pitch.

When the LBA's Elliptical results are disabled, the computed beam widths are the measure of the pixels in the row and column that pass through the centroid. The beam widths in the results window are labeled X and Y.

When the LBA's Elliptical results are enabled, the computed beam widths are the measure of the pixels along the Major and Minor axes that pass through the centroid. The beam widths in the results window are labeled Major and Minor.

6.11.4Percent of Peak Method

The LBA measures the lengths of two orthogonal lines that pass through the beam centroid. The beam widths are determined by separately looking out along each line and counting all the pixels that are greater than the set clip level. The reported beam widths are the number of pixels greater than the clip level multiplied by the pixel pitch.

When the LBA's Elliptical results are disabled, the computed beam widths are the measure of the pixels in the row and column that pass through the centroid. The beam widths in the results window are labeled X and Y.

When the LBA's Elliptical results are enabled, the computed beam widths are the measure of the pixels along the Major and Minor axes that pass through the centroid. The beam widths in the results window are labeled Major and Minor.

6.12 Elliptical beam

The LBA-PC can compute and display the Orientation of an Elliptical or rectangular beam and a coefficient of Roundness. The criteria for computing the Elliptical beam's Major and Minor beam widths are described in the Beam Widths and Diameters section.

Operator’s Manual 134 LBA-PC