Interferometric method of measuring plotter distortion.
نویسندگان
چکیده
The authors are with the Itek Corporation, Lexington, Massachusetts 02173. Received 25 September 1973. In this letter an interferometric method of measuring plotter distortion is described. A common method of measuring plotter distortion is to draw a known pattern, such as straight lines, and scan this pattern with a microdensitometer. This is a precise method of measuring distortion; however, it is a time consuming process; and it gives distortion only along the microdensitometer scan lines. The technique described below gives a contour map for the whole plot showing lines of constant distortion in a particular direction. By combining two contour maps for distortion in two orthogonal directions, the distortion in any arbitrary direction can be found. If the plotter distortion is repeatable and the plotter is computer controlled, once the distortion is known it can be eliminated as described by Fercher et al. As will now be shown, if a plotter draws straight lines the plot can be thought of as a hologram produced by interfering two plane wavefronts. The plotter distortion produces the same effect on the plot as aberration in one of the plane wavefronts would produce on the hologram. If a plotter were to draw perfectly straight lines perpendicular to the x direction, the equation of. the straight lines would be (x / ∆ x) = M, where ∆ x is the line spacing and M is an integer, 0, 1, 2, and so forth. Because of plotter distortion, the lines are never perfectly straight. Let the distortion in the x direction be δ x (x, y). Thus a point that should have the x coordinate x will have the x coordinate x + δ x (x, y). Therefore, the equation of the lines drawn by the plotter will be
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ورودعنوان ژورنال:
- Applied optics
دوره 13 7 شماره
صفحات -
تاریخ انتشار 1974