Abstract: A probe system for probing a device under test (DUT) includes a DUT support chuck for holding the DUT. A plurality of flexible probe needles are positioned along a "Z" axis that extends orthogonally from the surface of the DUT. Each probe needle is movable with respect to the DUT support chuck. A motor provides for relative movement, at least along the Z axis, between the probe needles and the DUT support chuck. A variable focus imaging system is positioned along the Z axis and provides image signals to a control processor. The control processor causes the variable focus imaging system to image the surface of the DUT and at least one probe needle. The control processor is responsive to a determined distance between focal planes containing the DUT surface and probe needle to cause the motor to move the probe needle and the DUT surface into physical engagement.

Abstract: A method of, and apparatus for, automatically focussing a microscope objective (18). The apparatus includes an image detector (26) for obtaining an image, through the microscope objective, of a surface having at least one visual feature. The apparatus further includes a processor (28) for determining, from the image, a plurality of overlapping curves, each of which represents a quality of focus for different areas of the feature. The apparatus also includes an actuator (32), controlled by the processor, for positioning the microscope objective at an optimum focus position, relative to the surface, based upon the shape, specifically the sign of the slope, of the overlapping curves.