Measuring and setting techniques for relative component (50 and 55) orientations and separations is accomplished by projecting a coherent light beam into one end of a gap (60) formed between facing surfaces (52,57) of adjacent components. This light beam projection causes a corresponding light ray pattern to be projected out of an opposite end of the gap. The arrangement of light rays in the resulting pattern (30) is indicative of the relative positions of, and distance between, the facing surfaces. Such a projected pattern is used for determining the relative positions between adjacent components, alone, or as feedback for adjusting such component positions to achieve a desired orientation and/or separation distance between the components.
The light ray pattern (30) projected on the detector (10) is produced by one or a combination of (1) reflection of the light beam (25) from the respective surfaces (52) and (57), (2) portions of the light beam (25) that travel trough the gap unhindered, i.e., not reflected by the facing surfaces (52 and 57), and (3) light diffraction. Typically, the projected pattern (30) includes at least one primary region of light intensity caused by reflection and/or unhindered portions of the light beam (25) superimposed over secondary regions of varying light intensities caused by diffraction of the light beam (25).