Method and apparatus for checking automated optical system performance repeatability

An automated method for checking stage performance repeatability in an automated optical system having an automated microscope positioned to view an object on a stage along an optical path, where the optical path includes an optical axis therethrough, and where the stage is initially positioned at an origin, the automated method comprising the steps of:

• a) selecting a lens having a first magnification characteristic;
• b) inserting a calibration plate into the optical path, where the calibration plate includes a fiducial and the fiducial is located and centered in a field of view;
• c) moving the stage along a Z axis, the Z axis being parallel to the optical axis of the lens, in a negative direction away from the lens a first distance;
• d) returning the stage to the origin;
• e) analyzing an actual Z position of an image;
• f) moving the stage is in a negative direction for a second distance and then returning to the origin;
• g) analyzing the actual Z position of the image;
• h) repeating steps b through g again in except reversing a direction of movement of the stage so that the stage is moved toward the lens;
• i) storing each Z coordinate in a data array;
• and
• j) processing the data array to determine a difference between a minimum and maximum Z coordinate where an absolute value of the difference is taken as a repeatability of the stage.

An automated method for testing objective centration and parfocality in an automated microscope system having multiple objective lenses, wherein each objective has its own optical axis, the automated method comprising the steps of:

• a) selecting a lens having a first magnification characteristic;
• b) inserting a calibration plate into a first optical path, where the calibration plate includes a fiducial and the fiducial is located and centered in a field of view, and obtaining a first set of X,Y and Z coordinates;
• c) selecting a lens having a second magnification characteristic;
• d) inserting the calibration plate into a second optical path, where the calibration plate includes a fiducial and the fiducial is located and centered in a field of view, and obtaining a second set of X,Y and Z coordinates;
• and
• e) subtracting the first set of X,Y and Z coordinates from the second set of X,Y and Z coordinates, where an X and Y difference comprises a centration characteristic of the objectives and a Z difference comprises a parfocality factor.

An automated apparatus for checking stage performance repeatability in an automated optical system having an automated microscope positioned to view an object on a stage along an optical path, where the optical path includes an optical axis therethrough, the automated apparatus comprising:

• a) a lens having a first magnification characteristic;
• b) a calibration plate inserted into the optical path, where the calibration plate includes a fiducial having a fiducial center, wherein the fiducial is located and centered in a field of view;
• c) means, coupled to the stage, for grossly positioning the stage in a vicinity of the fiducial;
• d) means, coupled to the automated microscope, for performing a focus pan;
• e) means, coupled to the stage, for determining a location of a center of the fiducial with respect to an optical axis;
• f) means, coupled to the stage, for translating the stage in an X, Y plane so as to center the fiducial in the field of view, where the X, Y plane is defined by a top surface of the stage;
• g) means, coupled to the stage, for recording the location of the fiducial center;
• and
• h) means, coupled to the stage, for incrementally moving the stage in a star pattern so as to repeatedly move the fiducial out of the optical axis and then back into line with the optical axis for a predetermined number of repetitions, where each time the stage returns the fiducial to an original position, an image of the fiducial is captured and processed so as to determine a lateral position of a fiducial center in the X,Y plane with respect to the optical axis.

An automated apparatus for checking stage performance repeatability in an automated optical system having an automated microscope positioned to view an object on a stage along an optical path, where the optical path includes an optical axis therethrough, and where the stage is initially positioned at an origin, the automated apparatus comprising:

• a) a lens having a first magnification characteristic;
• b) a calibration plate inserted into the optical path, where the calibration plate includes a fiducial and the fiducial is located and centered in a field of view;
• c) means, coupled to the stage, for moving the stage along a Z axis, the Z axis being parallel to the optical axis of the lens, in a negative direction away from the lens a first distance;
• d) means, coupled to the stage, for returning the stage to the origin;
• e) means, coupled to the stage, for analyzing an actual Z position of an image;
• f) means, coupled to the stage, for moving the stage in a negative direction for a second distance and then returning to the origin;
• g) means, coupled to the stage, for analyzing the actual Z position of the image;
• h) means, coupled to the stage, for reversing a direction of movement of the stage so that the stage is moved toward the lens;
• i) means for storing each Z coordinate in a data array;
• and
• j) means, coupled to the storing means, for processing the data array to determine a difference between a minimum and maximum Z coordinate where an absolute value of the difference is taken as a repeatability of the stage.