Beam
This routine plots the contour, the X-cross section, the Y-cross section and a mesh plot. The results are displayed in individual windows, and in the PostScript files: xsec.ps, ysec.ps, contour.ps, mesh.ps.

Beam will prompt you for a data file name. You should not include the extension of the file, which should be .dat. The routine will then search for a text file of the same name with extension .txt which should include a description of the measurement set-up and some beam parameters. The first four lines of the text file contain the frequency, Gaussian beam waist size, distance from the waist to the measurement plane, and the reference centre position in the beam map.

Here is an example of what the text file should look like:

nu=568.5
W0=1.85
dz=0.0
183.0 512.0

Any number of comments can follow the above four lines.

Syntax:
Beam
No arguments to the command. You will be prompted to enter a data file name. Don't include the extension. The routine will then search for a text file of the same name with extension .txt which should include a description of the measurement set-up and some beam parameters as described above.

Example:
Beam,fitlvl=10,noise=-50

Options:
fitlvl=X
By default, the routine will try to fit a Gaussian to the beam cross sections, and will use the 3dB level as the fit constraint. ie. a Gaussian will exactly fit at that level. It is possible to force the fit at a different level by specifying X to be something else. Note that X is a positive number.

noise=X
If you would like to make a correction for the noise floor of the power meter, include this option. Give the noise floor level in dBm, which should be a negative value. Positive numbers here will result in no correction for the noise floor.