Patent ID: 8786694

Claim:
A method for imaging a biologic fluid sample quiescently residing within a chamber, comprising the steps of: positioning the chamber at a Z-axis position relative to an objective lens having a lens axis, wherein the Z-axis is parallel to the lens axis; moving one or both of the chamber and the objective lens relative to one another at a velocity along the Z-axis; and periodically creating one or more images of the biologic fluid sample as one or both of the chamber and the objective lens are moving at a velocity relative to one another within a focus search range along the Z-axis, wherein each image is associated with a known Z-axis position within the focus search range, and wherein each image has a quantifiable focus index, and the quantifiable focus index is contrast; wherein one or both of the chamber and the objective lens move relative to one another at a constant velocity along the Z-axis at the time the images are created; comparing the focus index of the images to determine a relative amount of focus index in each of the images; fitting a polynomial equation to the relative amount of focus index in each image versus the Z-axis position of the respective images for the images taken within the focus search range; identifying a change in sign of the slope of the polynomial equation; and analyzing the sample using the image taken at the Z-axis position associated with the change in slope.