Sigma LBA-500PC, LBA-710, LBA-714PC, LBA-300, LBA-712, LBA-708, LBA-700, LBA-400 manual Beam Width Method

Models: LBA-500PC LBA-708 LBA-710 LBA-700 LBA-712 LBA-714PC LBA-400 LBA-300

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For a detailed discussion of the above items see Chapter 4, Results Display, and Chapter 6, Computations.

3.2.6.4Beam Width Method

The Beam Width Method edit selection will determine the technique used to compute the beam width results. The first two methods (4 Sigma and 90/10 Knife Edge) are computed based upon industry standard definitions. The remaining three choices are user definable, so use care in setting up and restoring their related options. See Beam Widths and Diameters in Chapter 6 for a technical discussion of the methods described here.

Notice: Beam Width measurements should never be made without Ultracal! processing. Failure to perform an Ultracal! operation will most certainly lead to inaccurate beam width results.

Note: The Diameter results are always computed as the mean of the two Beam Width results.

The five Beam Width Methods are:

4 Sigma

90/10 Knife Edge

Knife Edge (user definable)

Percent of Energy (user definable)

Percent of Peak (user definable)

Figure 24

3.2.6.4.1D4 Sigma

The 4 Sigma, or second moment method, will directly compute second moment beam widths in the X and Y beam axial directions, or along the computed orthogonal Major and Minor axes of the beam if the Elliptical calculations are enabled. The 4 Sigma method should always be used in conjunction with the LBA’s Auto Aperture feature. The 4 Sigma method is most sensitive to noise. If your camera or beam noise content is high you might want to employ Frame Averaging or Statistical analysis to home in on more accurate results. A big advantage of this method is that it is not influenced by mode content.

Operator’s Manual

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LBA-PC

Doc. No. 10654-001, Rev 4.10

 

 

Page 69
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Sigma LBA-500PC, LBA-710, LBA-714PC, LBA-300, LBA-712, LBA-708, LBA-700, LBA-400 manual Beam Width Method