CONTACT IMAGE SENSOR USING SWITCHABLE BRAGG GRATINGS

• US 20150010265A1
• Filed: 01/07/2013
• Published: 01/08/2015
• Est. Priority Date: 01/06/2012
• Status: Abandoned Application

• Current Assignee: DigiLens Inc
• Original Assignee: David Waldern, Jonathan, Momcilo Popovich, Milan
• Inventors: Popovich, Milan Momcilo, Waldern, Jonathan David
• Application Number:
  US14/370,887
• Publication Number:
  US 20150010265A1
• Time in Patent Office: Days
• US Class Current: 385/10
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12138 Sensor
• 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 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area
• CPC Class Codes: G02B 6/12002 Three-dimensional structures
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: H01L 27/14618 Containers
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14678 Contact-type imagers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

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

Claims

1. A contact image sensor comprising the following parallel optical layers configured as a stack:

an illumination means for providing a collimated beam of first polarisation light;

a first SBG array device further comprising first and second transparent substrates sandwiching an array of selectively switchable SBG column, and transparent electrodes applied to opposing faces of said substrates and said SBG substrates together providing a first TIR light guide for transmitting light in a first TIR beam direction;

a transmission grating;

a second SBG array device further comprising third and fourth transparent substrates sandwiching a multiplicity of high index HPDLC regions separated by low index HPDLC regions and patterned transparent electrodes applied to opposing faces of said substrates; and

a platen; and

further comprising;

means for coupling light from said illumination means into said first TIR light guide;

means for coupling light out of said second SBG array device into an output optical path;

and a detector comprising at least one photosensitive element;

wherein said high index regions providing waveguiding cores are disposed parallel to said first beam direction,

wherein said low index HPDLC regions providing waveguide cladding, said substrate layers having a generally lower refractive index than said cores,

wherein said patterned electrodes applied to said third substrate comprise column shaped elements defining a multiplicity of selectively switchable columns of SBG elements orthogonal to said waveguiding cores,

wherein said patterned electrodes applied to said fourth substrate comprise elongate element overlapping said low index HPDLC.

wherein said detector comprises an array of photosensitive elements, each said photosensitive element being optically coupled to at least one said core.

2. The apparatus of claim 1 wherein each said SBG element in said first and second SBG arrays is switchable between a diffracting state and a non-diffracting state, said SBG elements diffracting only said first polarization light,

3. The apparatus of claim 2 wherein said diffracting state exists when an electric field is applied across said SBG element and said non diffracting states exists when no electric field is applied.

4. The apparatus of claim 2 wherein said diffracting state exists when no electric field is applied across said SBG element and said non diffracting states exists when an electric field is applied.

5. The apparatus of claim 2 wherein at any time one element of said first SBG array is in a diffracting state, one element of said second SBG array is in a diffracting state, all other elements of said first and second are in a non-diffracting state.

6. The apparatus of claim 2 wherein an active SBG element of said first SBG array in a diffracting state diffracts incident first TIR light upwards into a first beam direction,

wherein said transmission grating diffracts said first beam direction light upwards into a second beam direction,

wherein when contact is made with an external material at a point on the platen a portion of the second beam direction light incident at the point on the platen contacted by said external material is transmitted out of the platen, wherein light incident on the outer surface of the platen in the absence of said contact with an external material is reflected downwards in a third optical path, said third optical path traversing said cores, wherein an active column of said second SBG array along said third beam direction diffracts said third angle light into a second TIR path down said traversed core to said detector, wherein said first to third optical paths and said first and second TIR paths are in a common plane.

7. The apparatus of claim 2 wherein the output from detector array element is read out in synchronism with the switching of the elements of said first SBG array.

8. The apparatus of claim 1 further comprising an air gap between said first SBG array and said transmission grating.

9. The apparatus of claim 1 further comprising a priming layer between second SBG array device and said platen.

10. The apparatus of claim 1 further comprising at least one of said transparent electrodes and said substrates sandwiches a barrier layer.

11. The apparatus of claim 1 wherein said illumination means comprises a laser and a collimator lens.

12. The apparatus of claim 1 wherein said means for coupling light from said illumination means into said first TIR light guide is a grating.

13. The apparatus of claim 1 wherein said means for coupling light from said illumination means into said first TIR light guide is a prismatic element.

14. The apparatus of claim 1 wherein said means for coupling said second TIR light into said waveguide is a grating.

15. The apparatus of claim 1 wherein said means for coupling light out of said waveguide is a grating.

16. The apparatus of claim 1 wherein said transparent substrates are fabricated from plastic.

17. The apparatus of claim 1 wherein said transparent substrates are fabricated from a polycarbonate.

18. The apparatus of claim 1 wherein said waveguide cores are fabricated from an electrically conductive material.

19. The apparatus of claim 1 wherein said waveguide cores are fabricated from PDOT.

20. The apparatus of claim 1 wherein said waveguide cores are fabricated from CNT.

21. The apparatus of claim 1 wherein said detector is a linear array.

22. The apparatus of claim 1 wherein said detector is a two dimensional array.

23. The apparatus of claim 1 wherein said transparent electrodes are fabricated from ITO.

24. The apparatus of claim 1 wherein said transparent electrodes are fabricated from CNT.

25. The apparatus of claim 1 wherein said transparent electrodes are fabricated from PDOT.

26. The apparatus of claim 1 wherein said waveguides are fabricated from PDOT.

27. The apparatus of claim 1 wherein said SBG arrays are fabricated using a reverse mode HPDLC.

28. The apparatus of claim 1 further comprising a half wave plate array disposed above said first SBG array.

29. A method of making a contact image measurement comprising the steps of:

a) Providing an apparatus comprising the following parallel optical layers configured as a stack;

an illumination means for providing a collimated beam of first polarisation light;

a first SBG array device further comprising first and second transparent substrates sandwiching an array of selectively switchable SBG column elements, and transparent electrodes applied to opposing faces of said substrates and said SBG substrates together providing a first TIR light guide for transmitting light in a first beam direction;

a transmission grating;

a transparent substrate;

a second SBG array device further comprising third and fourth substrates sandwiching a multiplicity of high index HPDLC regions separated by low index HPDLC regions and patterned transparent electrodes applied to opposing faces of said substrates; and

a platen; and

further comprising;

means for coupling light from said illumination means into said first TIR light guide;

means for coupling light out of said second SBG array device into an output optical path; and

a detector comprising at least one photosensitive element;

said high index regions providing waveguiding cores disposed parallel to said first beam direction and said low index HPDLC regions providing waveguide cladding;

said substrates layer having a generally lower refractive index than said cores, said patterned electrodes applied to said third substrate defining a multiplicity of selectively switchable columns orthogonal to said waveguiding cores and pattered electrodes applied to said fourth substrate overlapping said low index HPDLC regions;

a platen; and

a detector;

b) an external material contacting a point on the external surface of said platen;

c) sequentially switching elements of said first SBG array into a diffracting state, all other elements being in their non-diffracting states;

d) sequentially switching columns of said second SBG array device into a diffracting state, all other columns being in their non-diffracting states;

e) each diffracting SBG element of said first SBG array diffracting incident first TIR light upwards into a first optical path,

f) said transmission grating diffracting said first optical path light upwards into a second optical path,

g) a portion of said second optical path light incident at said point on said platen contacted by said external material being transmitted out of said platen, portions of said second optical path light not incident at said point being reflected downwards in a third optical path, said third optical path traversing one said core,

h) an active SBG column element of said second SBG array along said third optical path diffracting said third angle light in a second TIR path down said traversed core and proceeding along a TIR path along said core to said detector,

wherein said first to third optical paths and said first and second TIR paths are in a common plane.

30. The method of claim 29 wherein said illumination means comprises a laser, a collimator lens.

31. The method of claim 29 wherein said means for coupling light from said illumination means into said first TIR light guide is a grating.

32. The method of claim 29 wherein said means for coupling light from said illumination means into said first TIR light guide is a prismatic element.

33. The method of claim 29 wherein said second SBG array device is optically coupled to said detector by means of a grating.

34. The apparatus of claim 29 wherein said columns of said second SBG array are switched in cyclic fashion with only one said column element being in a diffracting state at any time.

35. The apparatus of claim 29 wherein said column elements of said first SBG array are switched in cyclic fashion with only one said column element being in a diffracting state at any time.

36. A contact image sensor comprising:

an illumination means for providing a collimated beam of first polarisation light;

an SBG array device further comprising first and second transparent substrates sandwiching an array of selectively switchable SBG columns, and transparent electrodes applied to opposing faces of said substrates and said SBG substrates together providing a first TIR light guide for transmitting light in a first TIR beam direction;

a first transmission grating layer overlaying the lower substrate of said SBG array device;

a second transmission grating layer overlaying the upper substrates of said SBG array device;

a quarter wavelength retarder layer overlaying said second transmission grating layer;

a platen overlaying said quarter wavelength retarder layer;

a polarization rotating reflecting layer overlaying said first transmission grating layer;

means for coupling light from said illumination means into said SBG array device;

means for coupling light out of said second SBG array device into an output optical path; and

a detector comprising at least one photosensitive element;