Optical code readers with holographic optical elements
First Claim
Patent Images
1. An optical code reading system comprising:
- a photo sensor employing an array of cells for producing electrical signals responsive to an image directed to said sensor;
an optical system for focusing images corresponding to at least two fields of view which do not completely overlap, the optical system including at least one lens and at least one electrically switchable holographic optical element for switching between said fields of view, at least one of the at least one electrically switchable holographic optical element configured to direct an input light beam to the photo sensor via the at least one lens;
means for electrically controlling said electrically switchable holographic optical element to switch between the fields of view; and
means for decoding data from the electrical signals corresponding to an optical code symbol contained in at least one of the images focused on the photo sensor.
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Abstract
Holographic optical elements are configured and deployed in optical imagers and scanners to produce optical modification of output laser beams and light received and detected by the system. In some preferred embodiments electrically switchable holographic optical elements (ESHOEs) are employed for beam tilting, for varying spot size and shape for modifying system focal distance and field of view, for changing laser aiming patterns and/or for color imaging.
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Citations
28 Claims
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1. An optical code reading system comprising:
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a photo sensor employing an array of cells for producing electrical signals responsive to an image directed to said sensor;
an optical system for focusing images corresponding to at least two fields of view which do not completely overlap, the optical system including at least one lens and at least one electrically switchable holographic optical element for switching between said fields of view, at least one of the at least one electrically switchable holographic optical element configured to direct an input light beam to the photo sensor via the at least one lens;
means for electrically controlling said electrically switchable holographic optical element to switch between the fields of view; and
means for decoding data from the electrical signals corresponding to an optical code symbol contained in at least one of the images focused on the photo sensor. - View Dependent Claims (2, 3, 4)
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5. An imaging system for reading an optical code symbol comprising:
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a photo sensor having a two dimensional array of cells;
an optical system for directing images to the photo sensor, wherein the optical system includes at least one lens and an electrically switchable holographic optical element switchable between two states to vary the optical properties of the images and to direct the images to the photo sensor via the at least one lens; and
means for switching the electrically switchable holographic optical element to select an image of the optical code symbol which is readily decodable. - View Dependent Claims (6, 7)
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8. An imager based optical code reading system with a range finder for determining the distance of an object in a field of view of the system comprising:
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an image sensor having a primary input optical axis;
an electrically switchable holographic optical element for tilting the input optical axis of the image sensor;
means for detecting a shift in position of an image of the object on the image sensor caused by the tilting of the input optical axis; and
means for determining the distance of the object by triangulation from the detected shift in position. - View Dependent Claims (9, 10, 11)
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12. A laser beam source for a laser optical code scanning system comprising:
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a laser diode for producing a laser beam;
an electrically switchable holographic optical element in an output beam path of the laser diode formed with a volume hologram for selectively modifying the laser beam shape in response to a control signal; and
control circuitry for switching the holographic optical element to restore and erase the volume hologram formed in the electrically switchable holographic optical element, wherein a return signal of detected reflections of the laser beam is monitored to determine the appropriate laser beam shape and the electrically switchable holographic optical element is controlled to produce said appropriate laser beam shape in response thereto. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method for changing laser aiming patterns used for aiming an optical code reader comprising the steps of
providing a diffractive optical element; -
directing a coherent light beam at the diffractive optical element;
using the diffractive optical element to transform incident coherent light into at least two different aiming patterns, wherein a first pattern is projected at a relatively higher optical power and a second pattern is projected at a relatively lower optical power; and
varying the power of the coherent light beam directed at the diffractive optical element to vary the appearance of the projected aiming pattern. - View Dependent Claims (20, 21, 22)
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23. An apparatus for producing video signals corresponding to a color image comprising:
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a photo sensor employing an array of cells for producing video signals in response to incident light;
an optical system comprising;
means for focusing an image on the photo sensor; and
filter means for selectively reflecting to the photo sensor different color components of the color image including electrically switchable holographic optical means; and
means for electrically controlling said at least one electrically switchable holographic optical element to selectively reflect the different color components of the color image to the photo sensor. - View Dependent Claims (24, 25, 26, 27)
a first electrically switchable holographic optical element is switchable between a first mode where a first wavelength band is reflected to the photo sensor and a second mode where the incident light is directed toward a second electrically switchable holographic optical element that is switchable between a first mode where a second wavelength band is reflected to the photo sensor and a second mode where the incident light is directed toward a third electrically switchable holographic optical element that is switchable between a first mode where a third wavelength band is reflected to the photo sensor and a second mode where the incident light is directed toward a light stop.
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28. A laser beam source for a laser optical code scanning system comprising:
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a laser diode for producing a laser beam;
an electrically switchable holographic optical element in an output beam path of the laser diode formed with a volume hologram for selectively modifying the laser beam shape in response to a control signal, the volume hologram being configured for producing a message upon illumination; and
control circuitry for switching the holographic optical element to restore and erase the volume hologram formed in the electrically switchable holographic optical element.
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Specification