Quasi-optical transmission/reflection switch and millimeter-wave imaging system using the same
First Claim
1. A quasi-optical switch comprising:
- a first substrate;
a pattern of first conductive elements disposed on a first surface of the first substrate; and
means for connecting adjacent first conductive elements in a first direction, said connecting means having a first impedance in a first state when not conducting and a second impedance in a second state when conducting, the conductive elements having an impedance which in response to incident radiation that is polarized in said first direction substantially cancels said first impedance such that the incident radiation is substantially reflected, and which impedance of the conductive elements in combination with said second impedance yields a non-zero, finite value such that the incident radiation is substantially transmitted.
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Accused Products
Abstract
An apparatus for the selective transmission or reflection of incident electromagnetic radiation. The apparatus comprises a plurality of dielectric substrates combined so as to form a stack, wherein at least two of the substrates comprise conductive elements extending in first and second directions on a surface of the substrates and at least one of the substrates includes diodes which connect adjacent conductive elements in at least the first direction. The apparatus is electronically controllable between a reflection mode and a transmission mode, wherein in the reflection mode the diodes are reverse-biased and electromagnetic radiation incident on the apparatus is substantially reflected and in the transmission mode the diodes are forward-biased and incident electromagnetic radiation is substantially transmitted. The physical dimensions of the conductive elements of the substrate comprising the diodes is such that in the reflection mode, the apparatus substantially appears as a perfect conductor with respect to the incident energy.
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Citations
42 Claims
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1. A quasi-optical switch comprising:
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a first substrate; a pattern of first conductive elements disposed on a first surface of the first substrate; and means for connecting adjacent first conductive elements in a first direction, said connecting means having a first impedance in a first state when not conducting and a second impedance in a second state when conducting, the conductive elements having an impedance which in response to incident radiation that is polarized in said first direction substantially cancels said first impedance such that the incident radiation is substantially reflected, and which impedance of the conductive elements in combination with said second impedance yields a non-zero, finite value such that the incident radiation is substantially transmitted. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A quasi-optical switch comprising:
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a first pattern of first conductive elements; and diodes interconnecting adjacent first conductive elements in a first direction, the diodes having a first admittance when forward biased, and the diodes having an intrinsic impedance when reversed biased or zero biased, the conductive elements having an inductance for radiation polarized in the first direction incident on the diodes that substantially cancels the intrinsic impedance of the diodes so that the incident radiation is substantially reflected.
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16. A switching means for selectively transmitting or reflecting incident radiation, the switching means comprising:
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a first pattern of conductive elements extending in first and second directions in a substantially planar array, wherein adjacent conductive elements in the first direction of the first pattern are connected by diodes and adjacent conductive elements in the second direction of the first pattern are connected by conductors, the diodes being selectively operable in a first state in which they are not conducting and in a second state in which they are conducting, wherein the physical dimensions of the first pattern of conductive elements are such that, in response to linear polarized incident radiation of a pre-selected frequency having an electric field vector parallel to the first direction of the first pattern of conductive elements, the switching means causes substantial reflection of incident radiation when the diodes are in the first state and substantial transmission of incident radiation when the diodes are in the second state. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A switching means for selectively transmitting or reflecting incident radiation, the switching means comprising:
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a first pattern of conductive elements extending in first and second directions in a substantially planar array, wherein adjacent conductive elements in the first direction of the first pattern are connected by diodes and adjacent conductive elements in the second direction of the first pattern are connected by diodes, the diodes being selectively operable in a first state in which they are not conducting and in a second state in which they are conducting, wherein the physical dimensions of the first pattern of conductive elements are such that, in response to linear polarized incident radiation of a pre-selected frequency having an electric field vector parallel to either the first or second direction of the first pattern of conductive elements, the switching means causes substantial reflection of incident radiation when the diodes parallel to the electric field vector of the incident radiation are in the first state and causes substantial transmission of incident radiation when the diodes are in the second state. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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31. A quasi-optical bandpass filter comprising:
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a first polarizer having a transmission axis parallel to a first direction; a second polarizer having a transmission axis offset an angle θ
from a second direction, the second polarizer disposed in front of the first polarizer; andswitching means for selectively transmitting radiation that is linearly polarized in the first direction and reflecting radiation that is linearly polarized in the second direction, and transmitting radiation that is linearly polarized in the second direction and reflecting radiation that is linearly polarized in the first direction, the switching means including a first pattern of first conductive elements extending in first and second directions in a substantially planar array, wherein adjacent first conductive elements in the first direction are connected by first diodes and adjacent first conductive elements in the second direction are connected by second diodes, the first and second diodes being selectively operable in a first state in which they are not conducting and in a second state in which they are conducting, wherein the physical dimensions of the first pattern of first conductive elements are such that the switching means causes substantial transmission of a first incident radiation linearly polarized in the first direction and reflection of a second incident radiation polarized in the second direction when the first diodes are in the second state and the second diodes are in the first state, and causes substantial transmission of the second incident radiation and reflection of the first incident radiation when the first diodes are in the first state and the second diodes are in the second state. - View Dependent Claims (32)
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33. A millimeter-wave imaging system comprising:
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a receiver array; a means for focusing millimeter wave radiation from a field of view onto the receiver array; a uniform load for providing a noise calibration signal to the receiver array; and switching means for alternately directing the signal from the field of view and from the uniform load onto the receiver array, the switching means comprising, a first substrate, a pattern of first conductive elements disposed on a first surface of the first substrate, and means for connecting adjacent first conductive elements in a first direction, said connecting means having a first impedance in a first state when not conducting and a second impedance in a second state when conducting, the conductive elements having an impedance which in response to incident radiation that is polarized in said first direction substantially cancels said first impedance such that the incident radiation is substantially reflected, and which impedance of the conductive elements in combination with said second impedance yields a non-zero, finite value such that the incident radiation is substantially transmitted.
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34. A switching means for selectively transmitting or reflecting incident radiation, the switching means comprising:
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a first pattern of conductive elements extending in first and second directions in a substantially planar array, wherein adjacent conductive elements in the first direction of the first pattern are connected by diodes and adjacent conductive elements in the second direction of the first pattern are connected by conductors, the diodes being selectively operable in a first state in which they are not conducting and in a second state in which they are conducting, wherein the physical dimensions of the first pattern of conductive elements are such that, in response to linear polarized incident radiation of a preselected frequency having an electric field vector parallel to the first direction of the first pattern of conductive elements, the switching means causes substantial reflection of incident radiation when the diodes are in the first state and substantial transmission of incident radiation when the diodes are in the second state, and a second pattern of conductive elements extending in the first and second directions in a substantially planar array spaced apart from the first pattern, wherein adjacent conductive elements in the first direction of the second pattern are connected by conductors. - View Dependent Claims (35, 36, 37)
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38. A switching means for selectively transmitting or reflecting incident radiation, the switching means comprising:
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a first pattern of conductive elements extending in first and second directions in a substantially planar array, wherein adjacent conductive elements in the first direction of the first pattern are connected by diodes and adjacent conductive elements in the second direction of the first pattern are connected by diodes, the diodes being selectively operable in a first state in which they are not conducting and in a second state in which they are conducting, wherein the physical dimensions of the first pattern of conductive elements are such that, in response to linear polarized incident radiation of a pre-selected frequency having an electric field vector parallel to either the first or second direction of the first pattern of conductive elements, the switching means causes substantial reflection of incident radiation when the diodes parallel to the electric field vector of the incident radiation are in the first state and causes substantial transmission of incident radiation when the diodes are in the second state, and a second pattern of conductive elements extending in the first and second directions in a substantially planar array spaced apart from the first pattern, wherein adjacent conductive elements in the first and second directions are connected by conductors. - View Dependent Claims (39, 40, 41, 42)
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Specification