Method and apparatus for contact image sensing
AssigneeDigiLens Inc.
InventorsMilan Momcilo Popovich, Jonathan David Waldern, Alastair John Grant
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Abstract
A contact image sensor having a waveguiding structure for propagating light in a first direction including, in series, a first clad medium, a first core, a switchable grating clad, a second core, and a second clad medium sandwiched by transparent substrates, patterned parallel electrode elements orthogonally traversing the waveguides, a light source, a platen and a detector. Switchable grating regions overlapped by a first voltage-addressed electrode element diffract TIR light from the first core towards the platen. Switchable grating region overlapped by a second voltage-addressed electrode element diffract TIR light reflected from the platen into a TIR path within the second core.
Claims20
A contact image sensor comprising:
- a waveguiding structure for propagating light in a first direction comprising, in series disposed in a layer sandwiched by transparent substrates:
- a first clad medium, a first core;
- a switchable grating clad having a plurality of switchable grating regions;
- a second core;
- and a second clad medium;
- electrodes applied to opposing surfaces of said transparent substrates, wherein at least one of the electrodes is patterned into a set of parallel elements orthogonally traversing said first and second cores;
- a light source optically coupled to said first and second cores;
- a platen in optical contact with said waveguiding structure;
- and
- a detector optically coupled to said first and second cores;
- wherein switchable grating regions overlapped by a first voltage-addressed electrode element are operative, in their diffracting state, to diffract TIR light from said first core into a path to an outer surface of said platen;
- and
- wherein switchable grating regions overlapped by a second voltage-addressed electrode element are operative, in their diffracting state, to diffract TIR light reflected from said platen into a TIR path to said detector along said second core.
A method of making a contact image measurement comprising the steps of:
- providing:
- a waveguiding structure for propagating light in a first direction comprising, in series disposed in a layer sandwiched by transparent substrates:
- a first clad medium;
- a first core;
- a switchable grating clad having a plurality of switchable grating regions;
- a second core;
- and a second clad medium;
- electrodes applied to opposing surfaces of said transparent substrates, wherein at least one of the electrodes is patterned into a set of parallel elements orthogonally traversing said first and second cores;
- a light source optically coupled to said first and second cores;
- a platen in optical contact with said waveguiding structure;
- and
- a detector optically coupled to said first and second cores;
- coupling said light into a TIR path in said waveguiding structure;
- contacting a region on the external surface of said platen using an external material;
- setting first and second electrode elements to a first voltage state and all other voltage-addressed electrodes set to a second voltage state;
- diffracting TIR light from said first core into a path to the platen outer surface using switchable grating regions overlapped by said first electrode element;
- diffracting light reflected from one of said region or said platen external surface into a TIR path in said second core using switchable grating regions overlapped by said second electrode element;
- transmitting said reflected light to said detector.
Dependencies are inferred from the claim text.