User guide

LBA-USB User Guide Document No: 11294 Page 33
Drag and Drop Apertures
Once a Drawn aperture is enabled from either the dialog box or toolbar, move,
resize, and (in the case of an ellipse or rectangle) rotate it.
Move the arrow cursor over the display window and press and hold down the
right mouse button. This reveals the Drag, Drop and Rotate hot spots of the
Drawn aperture.
Move the arrow cursor onto one of these hot spots, release the RIGHT mouse
button and press and hold down the LEFT button. The cursor changes shape
indicating the selected Drag and Drop function.
Now drag the mouse to see what happens to the aperture.
The four cursor styles perform the following operations:
Moves the aperture center.
Sizes the aperture right or left.
Sizes the aperture up or down.
Rotates an elliptical or rectangular aperture.
Using Auto Apertures
To enable the Auto aperture feature, click on the Use Auto Aperture box, or
click on the Auto aperture
button on the Aperture toolbar.
Consider the following when using Auto apertures:
 Auto apertures are drawn in YELLOW, appear as ellipses, and are only visible on
2D displays. Auto apertures will be drawn on the X and Y-axes of the beam if
Elliptical is off, and on the Major and Minor axes of the beam if Elliptical is on.
 Always enable Auto apertures whenever performing second moment D 4-Sigma
beam width measurements.
 If your beam is small, relative to the acquisition window size, either use a Drawn
aperture of 2x to 2.5x the beam width, or enable Auto aperturing to perform this
task for you.
 Auto apertures help improve beam measurement accuracy on almost any beam
shape. However, Auto apertures may not improve accuracy, or operate well, if a
considerable amount of stray energy is present adjacent to the beam profile. In
this case, rely on a well-placed Drawn aperture, and avoid using the D 4-sigma
beam width method.
Display Beam Width
To see the beam widths and diameter graphically overlaid on the laser beam
profile, select the shape that most correctly matches your beam. These choices
are also available from the Aperture toolbar.
The displayed beam widths appear as a BLACK aperture in a 2D beam display
window. This aperture does not appear in 3D displays.