Setting Laser Beam Pointing

The Pointing tab is used to specify the pointing of the laser beam.

To point a laser beam, the position of a Reference Point must be specified. The direction vector of the beam is defined using a line from the port position of the beam (at the target chamber surface) to the Reference Point.

The focus point offset is the distance between the focus point and the Reference Point, along the direction vector of the beam. A positive value for the focus point offset moves the focus in the direction of beam propagation.

The beam's Reference Point position can be specified using one of the following methods:

• Target Chamber Center (TCC)
• Distance toward a diagnostic port
• Position in the target chamber coordinate system, or the coordinate system of any target component

When specifying the pointing position using the coordinate system of one of the target components or the target chamber, the relative position can be specified using Cartesian, cylindrical, or spherical coordinates. Also in this case, it is often useful to display the axes of the reference coordinate system.

When specifying the beam pointing using the Reference Coordinate System button, it is possible to have the Position parameters automatically re-computed when the Reference Coordinate System is changed. To do this, check the box in the lower part of the Position of Reference Point for Pointing Beam group box prior to changing the Reference Coordinate System. The new values are then automatically entered in the position boxes when the coordinate system is changed.

When changing the Coordinate System in the Position of Reference Point box (e.g., from Cartesian to Spherical), the position values are automatically updated such that the position vector is maintained even if the "Automatically Update Position" option is not checked. This feature can be turned off in the User Interface tab of the Preferences dialog.

Position values are typically entered in units of cm (or degrees in the case of angles). To change the default units used to specify position, go to the User Interface tab of the Preferences dialog.

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