Method for measuring Z height values of a workpiece surface with a machine vision inspection system

A method for measuring Z height values of a workpiece surface with a machine vision inspection system, the method comprising:

• illuminating a workpiece surface with structured light;
• collecting at least two stacks of images of the workpiece with an image detector of the machine vision inspection system, each stack including a different X-Y position between the structured light and the workpiece surface at a corresponding Z height in each of the stacks, where the X-Y position is changed at a slower rate than the Z height in each stack of images, and where the X-Y positions are changed either:
• a) continuously during each of the at least two stacks of images at a slower rate than the Z shift;
• or
• b) fixed to a different value during each of the at least two stacks of images where each stack is collected in a continuous Z shift;
• and
• determining Z values based on sets of intensity values of a pixel of the image detector corresponding to the same workpiece position in the X-Y plane which are at the same Z heights.