Method and apparatus for producing and measuring dynamically focussed, steered, and shaped oblique laser illumination for spinning wafer inspection system

A high frequency fast auto focus mechanism;

• said high frequency fast auto focus mechanism suitable for being used on a spinning wafer inspection system;
• wherein said wafer inspection system inspects a wafer having a wafer surface using a laser beam incident on said wafer surface at an intercept point;
• said high frequency fast auto focus mechanism dynamically adjusts tilt of a rotatable mirror to bring and maintain a laser beam focal spot onto said wafer surface;
• wherein there are no focusing optics in said laser beam's optical path between said rotatable mirror and said wafer surface;
• and;
• wherein said high frequency fast auto focus mechanism comprises a control system configured to utilize feedback from position-sensitive detectors to dynamically calculate actual beam position, actual position of said wafer surface, and intercept point between the beam and said wafer surface at any sampling time.