Abstract: A servo control system for maintaining an information detection device, such as a light beam, at the optimum focused position above an information track for retrieving the maximum amount of reflected radiation from an information track, such as a spiral recording track on a videodisc. The system of the invention includes an optical system, a piezoelectric dither element, a dither oscillator, circuitry for deriving an intermediate signal indicative of the effect of the dither on the detected signal derived from the information track, phase comparison circuitry for deriving an error signal from a comparison of the dither signal applied to the piezoelectric dither element and the actual dither modulation of the light beam retrieved from the information track, and a movable lens assembly responsive to the error signal for accurately focusing the light beam upon an information track.

Abstract: System and method utilizing a laser beam to produce artwork for printed circuit boards. The laser beam is modulated in accordance with the artwork and scanned across an output medium to form an image of the artwork. Compensation is provided for chromatic aberration and non-linearities which would otherwise detract from the quality and accuracy of the image.

Abstract: Laser imaging system for imaging printed circuit artwork on an output medium such as a photosensitive film, a glass plate or a printed circuit board. The laser beam scans the output medium and is modulated in accordance with the image to be formed. A correction signal is applied to the modulator to maintain substantially uniform exposure across the output medium notwithstanding variations in the velocity of the beam.

Abstract: Imaging system and method suitable for producing artwork masters for use in the manufacture of printed circuit boards. A beam of coherent radiation is modulated in accordance with data from a source defining the image to be produced, and the modulated beam is scanned across an output medium to form the desired image. A reference signal is generated in accordance with the position of the beam on the output medium, and this signal is shifted forward in phase to compensate for any delay between the generation of the reference signal and the arrival of the modulated beam at the output medium.

Abstract: System and method utilizing a laser beam to produce artwork for printed circuit boards. The laser beam is modulated in accordance with the artwork and scanned across an output medium to form an image of the artwork. Compensation is provided for chromatic aberration and non-linearities which would otherwise detract from the quality and accuracy of the image.

Abstract: Laser engraving system suitable for use in the production of artwork for printed circuit boards. The system includes a massive base table to reduce vibration and thermally induced variations, and modulation of the writing beam is controlled by a reference signal generated by a non-linear reticle scanned concurrently with the writing beam to compensate for spherical aberration in the optical system. Modulation of the writing beam is further synchronized in accordance with the position of the carriage which holds the output medium on which an image is formed by the writing beam.

Abstract: A servo control system for maintaining an information detection device, such as a light beam, centered on a moving information track, such as a spiral recording track on a video disc. The system of the invention includes an optical system, a piezoelectric dither element coated with a resistive material, a dither oscillator, circuitry for deriving an intermediate signal indicative of the effect of dither on the detected signal derived from the information track, phase comparison circuitry for deriving a known error signal from a comparison of the dither signal applied to the piezoelectric element and the actual dither modulation of the light beam retrieved from the information track.