Uneven surface image transfer apparatus
First Claim
1. An optical plate for transferring an image from a platen thereon to an external image sensing device, the platen comprising a totally internally reflecting object contact surface for creating evanescent wave image rays, the optical plate comprising:
- an aspheric illuminating lens for illuminating the platen with light from a radiation source, the aspheric illuminating lens having a nominal focus point;
a first reflecting surface positioned on one side of the nominal focus point;
a second reflecting surface positioned on another side of the nominal focus point; and
an imaging lens having a nominal aperture stop, the imaging lens being positioned so that the nominal aperture stop is located at the nominal focus point of the illuminating lens, the imaging lens receiving the evanescent wave image rays from the platen as reflected from the first and second reflecting surfaces and transferring same to a location external to the optical plate.
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Accused Products
Abstract
Enhanced performance of an uneven surface image transfer apparatus is provided by using a well-defined convergent field of illumination that is nominally focussed at the stop of an imaging lens. An integrated optical system exhibiting such enhanced performance includes an aspheric illuminating lens that directs radiant energy onto a presentation platen from which fingerprint or bar code images are transferred to an external image sensing device, such as a charged coupled device chip. An evanescent wave image is totally internally reflected (TIR) off of the platen along an optical path including a plurality of TIR surfaces to achieve a predetermined optical path length. One or more of the TIR surfaces may be curved to reduce or eliminate astigmatism and geometric distortion. An aspheric imaging lens having a split-axis aperture stop transfers the image rays to the image sensing device. The split axis aperture stop has its stop axes on opposite sides of the nominal focal point of the aspheric illuminating lens. The image transfer apparatus has utility with surfaces that are uneven in the sense that there is coded image data in the form of spatial or intensity contrasts, such as bar codes.
119 Citations
31 Claims
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1. An optical plate for transferring an image from a platen thereon to an external image sensing device, the platen comprising a totally internally reflecting object contact surface for creating evanescent wave image rays, the optical plate comprising:
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an aspheric illuminating lens for illuminating the platen with light from a radiation source, the aspheric illuminating lens having a nominal focus point; a first reflecting surface positioned on one side of the nominal focus point; a second reflecting surface positioned on another side of the nominal focus point; and an imaging lens having a nominal aperture stop, the imaging lens being positioned so that the nominal aperture stop is located at the nominal focus point of the illuminating lens, the imaging lens receiving the evanescent wave image rays from the platen as reflected from the first and second reflecting surfaces and transferring same to a location external to the optical plate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An optical plate illuminated by light from a radiation source, comprising:
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a platen having a totally internally reflecting object contact surface for creating evanescent wave image rays; an aspheric illuminating lens for illuminating the platen with light from the radiation source, the aspheric illuminating lens having a nominal focus point; a first planar surface for reflecting the evanescent wave image rays from the platen; a first toroidal surface for reflecting the evanescent wave image rays from the first planar surface; a second planar surface positioned on one side of the nominal focus point for reflecting the evanescent wave image rays from the first toroidal surface; a second toroidal surface positioned on another side of the nominal focus point for reflecting the evanescent wave image rays from the second planar surface; and an imaging lens having a nominal aperture stop, the imaging lens being positioned so that the nominal aperture stop is located at the nominal focus point of the illuminating lens, the imaging lens receiving the evanescent wave image rays reflected from the second toroidal surface and transferring same to a location external to the optical plate. - View Dependent Claims (18, 19, 20, 21)
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22. In combination with a radiation source and an external imaging device, an optical plate for transferring an image from a platen thereon to an external image sensing device, the platen comprising a totally internally reflecting object contact surface for creating evanescent wave image rays, the platen being illuminated by light from the radiation source, the optical plate comprising:
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an aspheric illuminating lens for illuminating the platen with light from the radiation source, the aspheric illuminating lens having a nominal focus point for converging the light from the radiation source; a first reflecting surface positioned on one side of the nominal focus point; a second reflecting surface positioned on another side of the nominal focus point; and an imaging lens having a nominal aperture stop, the imaging lens being positioned so that the nominal aperture stop is located at the nominal focus point of the illuminating lens, the imaging lens receiving the evanescent wave image rays from the platen as reflected from the first and second reflecting surfaces and transferring same to the external image sensing device. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification