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Abstract

An optical input beam is split into first and second beams lying in first and second non-parallel planes. A polygon mirror scanner receives the first and second beams on a single facet and generates first and second angularly displaced, non-parallel synchronized scans. Redirecting means is positioned in the optical path between the scanner and a scanned plane for redirecting a portion of the first and second synchronized scans onto a timing plane to generate third and fourth non-coincident, synchronized scans. A beam position signal consisting of equally spaced, sequential pulses is generated in response to the travel of either the third or fourth synchronized scan along a second scanned line lying within a timing plane. The beam position signal is representative of the position of both the first and second synchronized scans along the first scanned line. The second section of the laser inspection apparatus reads information from a surface having an area illuminated by the dual beams of the optical scanner. The first and second synchronized scans from the optical scanner cause the illuminated area to emit radiation in the form of first and second modulated scans. Segmented radiation detection means includes first, second and sandwiched radiation detection means which each generated an electrical output signal representative of the detected radiation emitted by the first and second modulated scans. Signal processing means receives and selectively combines the electrical output signals from each of the three sections of the segmented radiation detection means in response to the beam position signal and generates first and second modulated output signals. The first modulated output signal is representative of the information residing within the area scanned by the first scan, while the second modulated signal is representative of the information residing within the area scanned by the second scan.

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