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US 9,864,339 B2Granted
Surface relief volume reflective diffractive structure
AssigneeAztec Systems, Inc.
InventorJames J. Cowan
Life of this patent
Estimating the term…
Abstract
A surface relief structure includes a recording medium configured to be structurally modified when exposed to interfering and non-interfering portions of radiation beams, the structurally modified recording medium including, when viewed in a two-dimensional cross-section along one of the axes of the recording medium a plurality of equally spaced steps of fine-sized periodicity superimposed upon a plurality of deep depressions of substantially coarse-sized periodicity. The structurally modified recording medium is configured to produce in reflection single and multiple colors in a broad spectral range when illuminated by a source of light.
Claims15
A surface relief structure comprising:
- a recording medium structurally modified by exposure to interfering and non-interfering portions of radiation beams, the recording medium including:
- a top surface which lies substantially in an x-y plane;
- a plurality of deep depressions with coarse-sized periodicity, the plurality of deep depressions extending from the top surface inwards along a z-axis perpendicular to the x-y plane into the recording medium and arranged as a cross-grating with a contiguous array of openings of the plurality of deep depressions, the array of contiguous openings including an x-axis periodicity and y-axis periodicity such that each opening of the array has dimensions equal to one x-axis period and one y-axis period;
- and
- a plurality of pyramidal structures with substantially equal height steps of fine-sized periodicity, each of the plurality of pyramidal structures being asymmetrically superimposed upon a respective one of the plurality of deep depressions such that a top of the each of the plurality of pyramidal structures is located at an off-center position of the opening of a respective one of the plurality of deep depressions, and a base of the each of the plurality of pyramidal structures is located at a bottom of the respective one of the plurality of deep depressions, with the base of the each of the plurality of pyramidal structures having a larger surface area than the top of the each of the plurality of pyramidal structures;
- wherein each of the plurality of substantially equal height steps of each of the plurality of pyramidal structures is stepped in both an x-direction perpendicular to the z-axis and in a y-direction perpendicular to the z-axis and to the x-direction, such that x- and y-dimensions of each step of a particular one of the plurality of pyramidal structures increase relative to a preceding step of the particular one of the plurality of pyramidal structures at increasing depths of a corresponding one of the plurality of deep depressions,
- wherein the structurally modified recording medium with the plurality of deep depressions arranged as the cross-grating is configured to produce in reflection a small diffraction efficiency at adjacent orders with respect to that of direct reflected light when illuminated by a source of light.
4 more elements
A method for recording a holographic image of an object, the method comprising:
- placing the object proximate one of two principal surfaces of a recording medium configured to record a holographic image;
- and
- directing radiation beams at the other surface of the two principal surfaces of the recording medium at an angle with respect to a normal to the other of the two principal surfaces of the recording medium such that a resultant radiation beam reflected from the object interferes with a resultant first reference beam progressing in a direction that is at least partly similar to the progression direction of the radiation beam reflected from the object, both beams being separated by a small angle such that a first interference fringe structure is formed in the recording medium that is skewed with respect to the two principal surfaces of the recording medium, and such that a resultant second reference beam progresses in a general direction that is at least partly opposite to the direction of the radiation beams reflected from the object such that a fine-sized set of interference fringes is formed in the recording medium, the second set of interference fringe being skewed with respect to the two principal surfaces of the recording medium;
- wherein the first and second set of interference fringes include a plurality of pyramidal structures with substantially equal height steps of a fine-sized periodicity, each of the plurality of pyramidal structures being superimposed upon a plurality of deep depressions of substantially coarse-sized periodicity, with the plurality of deep depressions extending from one of the principal surfaces of the recording medium inwards along a z-axis perpendicular to the one of the principal surfaces, and with the plurality of deep depressions arranged as a cross-grating configuration with a contiguous array of openings of the plurality of deep depressions, the array of contiguous openings including an x-axis periodicity and y-axis periodicity such that each opening of the array has dimensions equal to one x-axis period and one y-axis period;
- wherein the each of the plurality of pyramidal structures being asymmetrically superimposed upon a respective one of the plurality of deep depressions such that a top of the each of the plurality of pyramidal structures is located at an off-center position of a respective one of the openings of the plurality of deep depressions, and a base of the each of the plurality of pyramidal structures is located at a bottom of the respective one of the plurality of deep depressions, with the base of the each of the plurality of pyramidal structures having a larger surface area than the top of the each of the plurality of pyramidal structures;
- wherein each of the plurality of substantially equal height steps of each of the plurality of pyramidal structures is stepped in both an x-direction perpendicular to the z-axis and in a y-direction perpendicular to the x-axis and the z-axis direction, such that x- and y-dimensions of each step of a particular one of the plurality of pyramidal structures increase relative to a preceding step of the particular one of the plurality of pyramidal structures at increasing depths of a corresponding one of the plurality of deep depressions;
- wherein the structurally modified recording medium with the plurality of deep depressions arranged as the cross-grating is configured to produce in reflection a small diffraction efficiency at adjacent orders with respect to that of direct reflected light when illuminated by a source of light.
4 more elements
A system to record a holographic image, the system comprising:
- a recording medium having two principal surfaces and configured to record a holographic image of an object placed proximate one of the two principal surfaces of the recording medium;
- and
- a radiation source to direct radiation beams at the other surface of the two principal surface of the recording medium at an angle with respect to a normal to the other of the two principal surfaces of the recording medium such that a resultant radiation beam reflected from the object interferes with a resultant first reference beam progressing in a direction that is at least partly similar to the progression direction of the radiation beam reflected from the object, both beams being separated by a small angle such that a first interference fringe structure is formed in the recording medium that is inclined at an angle with respect to the two principal surfaces of the recording medium, and such that a resultant second reference beam progresses in a general direction that is at least partly opposite to the direction of the radiation beams reflected from the object such that a fine-sized set of interference fringes is formed in the recording medium, the set of interference fringes being inclined with respect to the two principal surfaces of the recording medium;
- wherein the recording medium is structurally modified by exposure to the interfering and non-interfering portions of one or more of the radiation beams or the resultant radiation beam, the recording medium including:
- a top surface, corresponding to one of the two principal surfaces, which lies substantially in an x-y plane;
- a plurality of deep depressions with coarse-sized periodicity, the plurality of deep depressions extending from the top surface inwards along a z-axis perpendicular to the x-y plane into the recording medium and arranged as a cross-grating with a contiguous array of openings of the plurality of deep depressions, the array of contiguous openings including an x-axis periodicity and y-axis periodicity such that each opening of the array has dimensions equal to one x-axis period and one y-axis period;
- and
- a plurality of pyramidal structures with substantially equal height steps of fine-sized periodicity, each of the plurality of pyramidal structures being asymmetrically superimposed upon a respective one of the plurality of deep depressions such that a top of the each of the plurality of pyramidal structures is located at an off-center position of the openings of a respective one of the plurality of deep depressions, and a base of the each of the plurality of pyramidal structures is located at a bottom of the respective one of the plurality of deep depressions, with the base of the each of the plurality of pyramidal structures having a larger surface area than the top of the each of the plurality of pyramidal structures;
- wherein each of the plurality of substantially equal height steps of each of the plurality of pyramidal structures is stepped in both an x-direction perpendicular to the z-axis and in a y-direction perpendicular to the z-axis and to the x-direction, such that x- and y-dimensions of each step of a particular one of the pyramidal structures increase relative to a preceding step of the particular one of the plurality of pyramidal structures at increasing depths of a corresponding one of the plurality of deep depressions,
- wherein the structurally modified recording medium with the plurality of deep depressions arranged as the cross-grating is configured to produce in reflection a small diffraction efficiency at adjacent orders with respect to that of the direct reflected light when illuminated by a source of light.
7 more elements
Dependencies are inferred from the claim text.