Z-axis measurement fixture and method of determining the planarity of objects using the fixture

A method of measuring the degree of Z-axis variability or surface topography irregularities in a chemical reagent test slide, the chemical reagent test slide having an upper surface and a lower surface situated opposite the upper surface, the method comprising the steps of:

• placing a Z-axis measurement fixture on a surface of a gauge block of an optical measurement instrument, the Z-axis measurement fixture having a main body and a plurality of test slide supporting members, the main body having a top wall and a bottom wall disposed opposite the top wall, the main body defining a plurality of member receiving openings extending between the top wall and the bottom wall, each test slide supporting member of the plurality of test slide supporting members having a known and calibrated dimension in at least one coordinate direction, each test slide supporting member of the plurality of test slide supporting members being received by a respective member receiving opening of the plurality of member receiving openings extending in the main body, each test slide supporting member of the plurality of test slide supporting members having a first portion which projects outwardly from the top wall of the main body and a second portion which projects outwardly from or is at least level with the bottom wall of the main body, each test slide supporting member of the plurality of the test slide supporting members being arranged within the respective member receiving opening of the plurality of member receiving openings such that the first portion thereof projecting outwardly from the top wall of the main body and the second portion thereof projecting outwardly from or being level with the bottom wall of the main body are in alignment with the known and calibrated dimension of the test slide supporting member in the at least one coordinate direction, wherein the second portion of each test slide supporting member of the plurality of test slide supporting members engages the surface of the gauge block of the optical measurement instrument, the optical measurement instrument further having a camera;
• mounting the chemical reagent test slide on the Z-axis measurement fixture such that the chemical reagent test slide rests on and is supported by the first portion of each test slide supporting member of the plurality of test slide supporting members;
• and
• positioning the chemical reagent test slide mounted on the Z-axis measurement fixture in optical communication with the camera of the optical measurement instrument.

A method of measuring the degree of Z-axis variability or surface topography irregularities in an object to be tested, the object to be tested having an upper surface and a lower surface situated opposite the upper surface, the method comprising the steps of:

• placing a Z-axis measurement fixture on a surface of a gauge block of an optical measurement instrument, the Z-axis measurement fixture having a main body and a plurality of object supporting members, the main body having a top wall and a bottom wall disposed opposite the top wall, the main body defining a plurality of member receiving openings extending between the top wall and the bottom wall, each object supporting member of the plurality of object supporting members having a known and calibrated dimension in at least one coordinate direction, each object supporting member of the plurality of object supporting members being received by a respective member receiving opening of the plurality of member receiving openings extending in the main body, each object supporting member of the plurality of object supporting members having a first portion which projects outwardly from the top wall of the main body and a second portion which projects outwardly from or is at least level with the bottom wall of the main body, each object supporting member of the plurality of object supporting members being arranged within the respective member receiving opening of the plurality of member receiving openings such that the first portion thereof projecting outwardly from the top wall of the main body and the second portion thereof projecting outwardly from or being level with the bottom wall of the main body are in alignment with the known and calibrated dimension of the object supporting member in the at least one coordinate direction, wherein the second portion of each object supporting member of the plurality of the object supporting members engages the surface of the gauge block of the optical measurement instrument, the optical measurement instrument further having a camera;
• mounting the object to be tested on the Z-axis measurement fixture such that the object to be tested rests on and is supported by the first portion of each object supporting member of the plurality of object supporting members;
• positioning the object to be tested mounted on the Z-axis measurement fixture in optical communication with the camera of the optical measurement instrument;
• imaging the object to be tested using the camera of the optical measurement instrument having a predetermined field of view at a first focal point or first focal area on an imaged surface of the object to be tested to provide a first optical image of the object in which the first focal point or first focal area on the imaged surface of the object is in focus in the first optical image, the first optical image being in a first X-Y plane in which the first focal point or first focal area, in focus in the first optical image, resides, the first X-Y plane establishing a zero reference plane for measuring the degree of Z-axis variability or surface topography irregularities in the object;
• successively imaging the object to be tested using the camera of the optical measurement instrument at successive spaced apart focal points or focal areas on the imaged surface of the object to provide successive optical images of the object in which the successive focal points or focal areas are respectively in focus, the successive optical images being in optical X-Y planes in which the respective focal points or focal areas reside and are in focus.