American Hoechst Corporation

Excellon Industries, Inc.

Other

Eocom Corporation

Don B Neumann

Eric V Olson

Lyle K Norton

Richard P Eddy

The image formed by a laser flying spot scanner on a photosensitive medium is subject to error in size and/or position because of deviation of the photosensitive surface from a nominal position. The deviation will occur if the substrate carrying the photosensitive surface does not have a uniform thickness. In a scanning system having a code mask that produces reference signals for controlling timing of writing beam modulation, compensation for the error is provided by maintaining a fixed distance between the code mask and the surface of the medium. The code mask floats freely upon the medium surface to move up and down with height variations of the surface as the medium passes under the code member and under the writing beam. Alternatively, the platen that supports the photosensitive medium is allowed to float and is continuously urged upwardly against spacing or position sensing devices to maintain the medium surface at a fixed distance from the mask.

Surface deviation compensation for a beam scanning system

The laser beam of a flying spot scanner is turned on and off to write data under control of a reference clock that generates clock signals determined by the position of the writing beam. To detect position of the writing beam a reference beam is scanned in synchronism with the writing beam along and through a coding mask to a strip of retroreflective material fixed adjacent the mask. The reference beam is retroreflected through the mask back through the scanning optics to a fixed detector that produces an output determined by the scanning coded reference beam. Unwanted reflections from the mask surface are separated by tilting the mask. Reading of a document having a pattern of opaque and transparent areas is accomplished by retroreflecting a scanning laser reading beam from a body of retroreflective material adjacent to but spaced from one surface of the document. The scanning beam passes through transparent areas of the document and is retroreflected back through the document and through the scanning optics for collection by a fixed detector.

Scanning beam reference and read system

To compare the change in surface contour of a test object subjected to a stress with the changes that occur in a similar master object, subjected to the same stress, first and second holograms are formed of the surface of the master object before and after stressing employing convergent reference waves. A third double-exposure hologram is then formed wherein the first exposure is made of the test object illuminated using the first hologram reconstructed using a wave conjugate to the reference wave employed in its formation. Similarly, the second exposure is made of the test object stressed in the same manner as the master and illuminated using the second hologram reconstructed with a conjugate wave. The image of the test object as reconstructed from the third hologram will include fringes representative of the difference in strain between the model and test objects as a result of the stressing. Alternatively, the difference between surface contours of the model and test object may be analyzed by successively forming first and second holograms of the model while it is illuminated with light of first and second different wavelengths, respectively, and then using the two holograms successively, as sources of object illuminating waves during the formation of a double exposure hologram of the test object while illuminated using the two different wavelengths, successively. The image of the second object reconstructed from the double exposure hologram will contain fringes arrayed as a function of the difference in shape of the master and test objects.

Differential holographic interferometry

The laser beam of a flying spot scanner is turned on and off to write data under control of a reference clock that generates clock signals determined by the position of the writing beam. To detect position of the writing beam a reference beam is scanned in synchronism with the writing beam along and through a coding mask to a strip of retroreflective material fixed adjacent the mask. The reference beam is retroreflected through the mask back through the scanning optics to a fixed detector that produces an output determined by the scanning coded reference beam. Unwanted reflections from the mask surface are separated by tilting the mask.

Scanning beam reference employing a retroreflective code means

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.

System and method for producing artwork for printed circuit boards

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.

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.

Imaging system and method for printed circuit artwork and the like

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.

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Laguna Beach, CA, United States of America

Don B Neumann