Method and apparatus for contact image sensing

• US 10,423,813 B2
• Filed: 10/01/2018
• Issued: 09/24/2019
• Est. Priority Date: 07/31/2013
• Status: Active Grant

• Current Assignee: DigiLens Inc
• Original Assignee: DigiLens Inc
• Inventors: Popovich, Milan Momcilo, Waldern, Jonathan David
• Primary Examiner(s): Bayat, Ali
• Application Number:
  US16/148,583
• Publication Number:
  US 20190042827A1
• Time in Patent Office: 358 Days
• Field of Search: 382124
• 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 light sensor incorporating a waveguide device comprising:

a detector;

a first coupler configured to direct light reflected off an object into a waveguide device;

a second coupler configured to direct light propagating within said waveguide device onto the detector;

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

plurality of light absorbing regions on at least one of said surfaces, each light absorbing region bordering at least one non-absorbing region;

wherein each said non-absorbing region of said first surface overlaps with a non-absorbing region of said second surface forming a plurality of waveguiding channels within a waveguiding volume within said substrate such that each waveguiding channel is capable of propagating a light beam without crossing over into an adjacent waveguiding channel.

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 further comprising a portion of the at least one non-absorbing region that is textured on the light reflecting surface to scatter light or coated to provide partial reflection of light.

4. The apparatus of claim 1, further comprising a source of light optically coupled to said waveguide, wherein light from said source is transmitted through said waveguide onto said object.

5. The apparatus of claim 4, wherein said light is collimated before being coupled into said waveguide.

6. The apparatus of claim 4, wherein said source emits infrared or ultraviolet radiation.

7. The apparatus of claim 4, wherein said light is polarized before being coupled into said waveguide.

8. The apparatus of claim 4, further comprising at least one of a polarization selection layer, a polarization rotation layer, a switching grating, a platen for contact image formation, a transparent substrate, a layer of air, a layer of low index material, or a grating layer, which is disposed along a light path from said object to said detector.

9. The apparatus of claim 1, wherein said first coupler includes a grating layer for coupling light reflected from said object into total internal reflection paths within said plurality of channels.

10. The apparatus of claim 9, wherein said grating layer is one of a transmission grating or a reflection grating implemented as 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.

11. The apparatus of claim 9, wherein said grating layer at least partially overlaps said waveguiding volume.

12. The apparatus of claim 9, wherein said grating layer is patterned into a multiplicity of elongate grating elements aligned orthogonal to a light propagation direction of said waveguiding volume.

13. The apparatus of claim 9, 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.

14. The apparatus of claim 9, wherein said grating layer includes a plurality of grating elements switchable between a diffracting state and a non-diffracting state, wherein said grating elements are switched sequentially.

15. The apparatus of claim 9, wherein said optical substrate is divided into a pair of substrates sandwiching said grating.

16. The apparatus of claim 1, wherein said light absorbing regions and said non-absorbing regions form a grid of strips patterned such that multiple parallel waveguiding channels are formed.

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

18. The apparatus of claim 1, wherein said first coupler is one of:

a grating or a prism, and said second coupler is one of;

a grating or a prism.

19. The apparatus of claim 1, wherein said substrate contains waveguiding cores, each said core overlapped by at least one non-absorbing region of said substrate surfaces.

20. The apparatus of claim 1, wherein said detector comprises at least one photoconductive element optically coupled to a waveguiding channel.

21. The apparatus of claim 1, wherein each light absorbing region is formed by a light absorbing coating disposed on the at least one of said surfaces.