Machine Vision Inspection System and Method for Obtaining an Image With an Extended Depth of Field

A method for operating an imaging system of a machine vision inspection system to provide at least one image that has a larger depth of field than the imaging system in a single focal position, the method comprising:

• (a) placing a workpiece in a field of view of the machine vision inspection system;
• (b) periodically modulating a focus position of the imaging system without macroscopically adjusting the spacing between elements in the imaging system, wherein the focus position is periodically modulated over a plurality of focus positions along a focus axis direction in a focus range including a surface height of the workpiece at a frequency of at least 300 Hz;
• (c) exposing a first preliminary image during an image integration time while modulating the focus position in the focus range;
• and
• (d) processing the first preliminary image to remove blurred image contributions occurring in the focus range during the image integration time to provide an extended depth of field (EDOF) image that is substantially focused throughout a larger depth of field than the imaging system provides at a single focal position.