Method and apparatus for suppressing the effects of surface light scatter in optical reflective scanning system
First Claim
1. A method of determining the data state of a selected area of a surface independent of the surface light back-scatter effect, comprising the steps of:
- illuminating a selected area of a solid surface with a focused beam which directly projects light only on said selected area;
detecting the intensity of the light appearing to emanate from said selected area and generating a first electrical signal proportional thereto;
detecting the intensity of any light appearing to emanate from an area of said surface adjacent said selected area and upon which said focused beam does not directly project light and generating a second electrical signal proportional thereto; and
subtracting at least a portion of said second electrical signal from said first electrical signal to produce a compensated analog signal representing the actual reflectivity of said selected area.
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Accused Products
Abstract
A method and apparatus for suppressing the effects of surface light scatter in an optical reflective scanning system, wherein the method includes the steps of directly illuminating a small area upon the surface to be scanned, detecting the intensity of the light reflected by that area to produce a first signal proportional thereto, detecting the intensity of the light reflected from a scatter illuminated second area at least partially surrounding the directly illuminated area to produce a second signal proportional thereto, subtracting at least a portion of the second signal from the first signal to develop a compensated signal which represents the reflectivity of the directly illuminated first area as compensated for the light scattered back to the first area from the second area, and either using the compensated signal directly as analog data or converting it to a digital output signal which has a first state when the compensated signal is above a predetermined threshold and which has a second state when the compensated signal is below the predetermined threshold. The apparatus includes a light source and focusing optics for directly illuminating a small area of a surface to be scanned, detector optics for collecting light reflected from the directly illuminating area and directing it upon a first detector, and for collecting light reflected from a scatter illuminated second area at least partially surrounding the first area and directing it upon a second detector, and processing electronics responsive to signals generated by the first and second detectors and operative to produce an analog or digital output signal as described above.
20 Citations
16 Claims
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1. A method of determining the data state of a selected area of a surface independent of the surface light back-scatter effect, comprising the steps of:
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illuminating a selected area of a solid surface with a focused beam which directly projects light only on said selected area; detecting the intensity of the light appearing to emanate from said selected area and generating a first electrical signal proportional thereto; detecting the intensity of any light appearing to emanate from an area of said surface adjacent said selected area and upon which said focused beam does not directly project light and generating a second electrical signal proportional thereto; and subtracting at least a portion of said second electrical signal from said first electrical signal to produce a compensated analog signal representing the actual reflectivity of said selected area. - View Dependent Claims (2, 3)
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4. An optical scanning system having means for suppressing the effects of surface light scatter comprising:
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illumination means for directly projecting a discrete spot of light onto a surface to be scanned, and including means for causing said spot of light to be swept across said surface; first means for detecting light appearing to emanate from the surface area directly illuminated by said spot of light at any point in time and for developing a first electrical signal proportional thereto; second means for detecting light appearing to emanate from an area immediately adjacent the surface area directly illuminated by said spot of light and for developing a second electrical signal proportional thereto; and means for subtracting at least a fraction of each said second signal from the corresponding first signal to produce a series of compensated analog signals which respectively represent the reflectivity of each said selected area. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for suppressing the effecting of surface light scatter in a reflective scanning system comprising:
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a light source; spot forming optics for directing light from said light source onto a first area on a surface to be reflectively scanned; a spot detector having a first photosensitive means responsive to the intensity of light impinging thereupon and operative to produce a first signal proportional thereto; a scatter area detector having a second photosensitive means responsive to the intensity of light impinging thereupon and operative to produce a second signal proportional thereto; detector optics means for gathering and directing only light reflected from said first area onto said first photosensitive means and for gathering and directing light reflected from a second area contiguous with and at least partially surrounding said first area onto said second photosensitive means; and processing electronic means responsive to said first and second signals and operative to produce a digital output signal having a first signal state when the reflectivity of said first area, as compensated for the light scatter detected in said second area, is greater than a given threshold and having a second state when the reflectivity of said first area, as compensated for the light scatter detected in said second area, is less than a given threshold. - View Dependent Claims (14, 15, 16)
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Specification