Measurement method and apparatus of an external digital camera imager assembly

A method for determining a position of an imager plane relative to an image sensor camera-mounting plane in an imager assembly, comprising the steps of:

• a) temporarily mounting the imager assembly onto an imager mounting apparatus having an imager mounting reference surface such that the imager sensor camera-mounting reference plane and the imager mounting reference surface are in intimate contact;
• wherein the imager mounting apparatus includes an optical probe with a pellicle reference surface in a predetermined orientation with respect to the imager mounting reference surface such that the pellicle reference surface is disposed at a first depth relative to the imager mounting reference surface;
• b) utilizing low-coherence light interferometry to determine (i) a second depth from the pellicle reference surface to a front surface of the optically transparent plate, (ii) an optical thickness of the imager cover glass, and (iii) a third depth from a back surface of the imager cover glass to the imager plane;
• and
• c) calculating the optical position of the imager plane relative to the imager sensor camera-mounting reference plane.