Method and Apparatus for Contact Image Sensing

• US 20190042827A1
• Filed: 10/01/2018
• Published: 02/07/2019
• Est. Priority Date: 07/31/2013
• Status: Active Grant

• Current Assignee: DigiLens Inc
• Original Assignee: DigiLens Inc
• Inventors: Popovich, Milan Momcilo, Waldern, Jonathan David
• Granted Patent: US 10,423,813 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 27/4277 being separated by an air space
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955
• CPC Class Codes: G02B 6/0026 Wavelength selective element, sheet or layer, e.g. filter or grating
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02B 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: H01L 27/14678 Contact-type imagers

Abstract

A contact image sensor having an illumination source; a first SBG array device; a transmission grating; a second SBG array device; a waveguiding layer including a multiplicity of waveguide cores separated by cladding material; an upper clad layer; and a platen. The sensor further includes: an input element for coupling light from the illumination source into the first SBG array; a coupling element for coupling light out of the cores into output optical paths coupled to a detector having at least one photosensitive element.

Claims

1. A waveguide device comprising:

an optical substrate with first and second light reflecting surfaces; and

a light absorbing coating applied to at least one of said surfaces with portions of the coating removed to provide at least one non-absorbing region disposed between light absorbing regions,

each said non-absorbing region of said first surface overlapping a non-absorbing region of said second surface to form a waveguiding volume within said substrate.

2. The apparatus of claim 1, wherein said non-absorbing regions are portions of said substrate surface at which total internal refection can take place.

3. The apparatus of claim 1, wherein said non-absorbing regions are portions of said light reflecting surface textured to scatter light or coated to provide partial reflection of light.

4. The apparatus of claim 1, wherein said waveguide volume provides a rectangular waveguiding core.

5. The apparatus of claim 1, further comprising a source of light optically coupled to said waveguide.

6. The apparatus of claim 5, wherein said light is collimated before being coupled into said waveguide.

7. The apparatus of claim 5, wherein said light is infrared or ultraviolet.

8. The apparatus of claim 5, wherein said light is polarized before being coupled into said waveguide.

9. The apparatus of claim 5, further comprising at least one of a polarization selection layer, a polarization rotation layer, a platen for contact image formation, a transparent substrate, a layer of air, a layer of low index material, or a grating layer disposed between said source and said waveguide.

10. The apparatus of claim 1, further comprising at least one grating for coupling light into said waveguiding volume.

11. The apparatus of claim 10, wherein said grating is one of a forward mode switchable Bragg grating, a reverse mode switchable Bragg grating, a stack of thin switchable gratings or a surface relief grating.

12. The apparatus of claim 10, wherein said grating at least partially overlaps said waveguiding volume.

13. The apparatus of claim 10, wherein said grating is patterned into a multiplicity of elongate grating elements aligned orthogonal to a light propagation direction of said waveguiding volume.

14. The apparatus of claim 10, wherein said optical substrate is divided into a pair of substrates sandwiching said grating, and transparent electrodes are applied to a surface of each substrate.

15. The apparatus of claim 10, wherein said grating comprises a plurality of grating elements switchable between a diffracting state and a non-diffracting state, wherein said grating elements are switched sequentially.

16. The apparatus of claim 10, wherein said grating is a reflection grating.

17. The apparatus of claim 1, further comprising a detector optically coupled to said waveguide.

18. The apparatus of claim 1, wherein said light absorbing regions and said non-absorbing regions form a grid pattern.

19. The apparatus of claim 1, wherein external faces of said waveguide abut air or a low refractive index material layer.

20. The apparatus of claim 1 wherein said waveguide provides a detector waveguide in a contact image sensor comprising:

an illumination source providing a collimated beam of light;

an illuminator waveguide configured for propagating said light in a first total internal reflection path and containing a first array of grating columns;

a detector comprising at least one photosensitive element;

a platen;

said detector waveguide configured for propagating light in a second total internal reflection path and containing a second array of grating columns;

at least one beam steering grating disposed between said platen and said waveguide;

a first waveguide coupler for coupling light from said illumination source into said illuminator waveguide; and

,

a second waveguide coupler for coupling light out of said detector waveguide into an output optical path,

wherein said grating elements of said first array are orthogonal to said first total internal reflection path and said grating elements of said second array are orthogonal to said second total internal reflection path,

wherein said columns in said first and second grating arrays are switched in cyclic fashion with only one said column element in each array being in a diffracting state at any time.