Tomographic systems for spatial and temporal control of an electromagnetic field to image a specimen having regions of different dielectric constants
A tomographic system accurately determines characteristics of a specific region within an inhomogeneous dielectric specimen by guiding an electromagnetic field through the inhomogeneous dielectric specimen in a transverse mode. The system may include a source of electromagnetic energy for generating an electromagnetic waveform, and a transmission line for guiding an electric field of the waveform along a prescribed path that defines a series of spatial regions. The transmission line is provided by a pair or array of conductors, the electric field spanning between two or more of the conductors as the electric field propagates along the prescribed path. The conductors may form part of an external non-contact structure which guides and controls the electromagnetic field both spatially and temporally.
1. A tomographic system comprising:
at least one source of electromagnetic energy that generates an electromagnetic field;
at least one transmission line operably associated with the at least one source of electromagnetic energy and configured to guide the electromagnetic field to propagate in a spatial direction along a prescribed path, the at least one transmission line constituted by electrical conductors disposed externally of and facing the prescribed path and extending contiguously alongside the prescribed path, whereby the electromagnetic field propagates passively from region to region of the prescribed path in the spatial direction; and
electronic means for taking measurements of the electromagnetic energy, indicative of impedance, at each of different locations along a length of each said at least one transmission line as the electromagnetic field generated by the at least one source propagates in the spatial direction along the prescribed path, and
wherein the system is configured to modulate a speed of propagation of the electromagnetic field in the spatial direction along the prescribed path to include a speed at which field lines of an electric field of the electromagnetic field extend in directions orthogonal to the spatial direction.
2. The system of claim 1 , wherein the electrical conductors comprise a conducting plate elongated in the spatial direction and extending contiguously alongside the prescribed path, the conducting plate constituting one transmission line.
3. The system of claim 2 , comprising a computer system operatively connected to the conducting plate and configured to change the speed of propagation of the electromagnetic field as guided by said at least one transmission line in the spatial direction, such that the electronic means is operable to take the measurements at different propagation speeds at each of said locations along the length of said at least one transmission line.
4. The system of claim 3 , wherein the at least one transmission line comprises an array of parallel transmission lines each elongated in the spatial direction, the transmission lines having different structures affecting the speed at which an electromagnetic field is guided therealong, wherein the speed at which an electromagnetic field is guided along one of the transmission lines is different from the speed at which an electromagnetic field is guided along at least one other of the transmission lines.
5. The system of claim 1 , comprising at least one processor; and
a memory storing processor-executable instructions and operatively electronically connected to the at least one processor,
wherein the electronic means comprises a respective sensor disposed at each of said locations, and
the at least one processor is operatively electrically connected to each said sensor and is configured to implement the following operation upon executing the processor-executable instructions:
calculating the speed of propagation of the electromagnetic field.
6. The system of claim 1 , wherein the electrical conductors comprise a conducting plate constituting one transmission line, the electronic means comprises sensors disposed along the length of said one transmission line, a computer system comprising a computer configured to store measurements from the sensors and analyze the measurements, and a multiplexer operatively connected to the sensors and the computer.
7. The system of claim 1 , wherein the electrical conductors comprise a first conducting plate disposed on a side of the prescribed path and having a planar surface facing the prescribed path, and a second conducting plate disposed on another side of the prescribed path and having a planar surface facing the prescribed path and extending parallel to the planar surface of the first conducting plate.
8. The system of claim 7 , wherein the first conducting plate is elongated in the spatial direction.
9. The system of claim 8 , wherein the second conducting plate is elongated in the spatial direction and disposed on the another side of the prescribed path directly across from the first conducting plate.
10. The system of claim 1 , comprising at least one processor operatively electrically connected to the locations in the system where the measurements are taken; and
a memory storing processor-executable instructions and operatively electronically connected to the at least one processor, wherein the at least one processor is configured to implement the following operation upon executing the processor-executable instructions:
based on the measurements, generating a tomograph of a specimen disposed in the prescribed path.
11. The system of claim 1 , wherein the at least one source of electromagnetic energy comprises a radio frequency (RF) or pulse probing signal source.
12. A tomographic system comprising:
at least one transmission line each constituted by a pair or an array of electrical conductors;
a source of electromagnetic energy operatively connected to each said at least one transmission line;
at least one processor; and
a memory storing processor-executable instructions and operatively electronically connected to the at least one processor, wherein the at least one processor is configured to implement the following operations upon executing the processor-executable instructions:
driving the at least one transmission line with a probing signal generated using the source of electromagnetic energy operatively connected thereto such that the probing signal is guided by the at least one transmission line to propagate in a spatial direction along the at least one transmission line;
taking measurements at each of different locations along each said at least one transmission line as the probing signal propagates in the spatial direction along the at least one transmission line;
driving an electromagnetic field as guided by a said pair or array of the electrical conductors in the spatial direction at a speed (Vprop) matching that at which the electromagnetic field propagates intrinsically through a spatial region of an inhomogeneous dielectric specimen situated in an electric field of the electromagnetic field, thereby causing the electromagnetic field to propagate through the spatial region at such the speed in the spatial direction that field lines of the electric field extend in directions orthogonal to the spatial direction and to surfaces of the electrical conductors constituting the at least one transmission line; and
based on the measurements taken when the electromagnetic field is propagating with the field lines of the electric field extending in said directions, generating a tomograph of the inhomogeneous dielectric specimen.
13. The system of claim 12 , wherein the electrical conductors constituting each said at least one transmission line face opposite sides of a prescribed path, such that a series of columnar regions is defined along the prescribed path between respective ones of the electrical conductors, and
the operation of taking measurements comprises taking the measurements at each of locations of the columnar regions.
14. The system of claim 13 , wherein the electrical conductors comprise a first conducting plate disposed on one of the sides of the prescribed path and having a planar surface facing the prescribed path, and a second conducting plate disposed on the other of the sides of the prescribed path and having a planar surface facing the prescribed path and extending parallel to the planar surface of the first conducting plate, the field lines of the electric field extending in directions orthogonal to the planar surfaces.
15. The system of claim 13 , wherein the electrical conductors comprise a first conducting plate elongated in the spatial direction and disposed on one of the sides of the prescribed path, and a second conducting plate elongated in the spatial direction and disposed on the other of the sides of the prescribed path directly across from the first conducting plate.
16. The system of claim 13 , wherein the electrical conductors comprise a two-dimensional array of discrete conducting plates spaced from one another in first and second orthogonal directions along one of the sides of the prescribed path.
17. The system of claim 13 , wherein the at least one transmission line comprises an array of parallel transmission lines each elongated in the spatial direction, the transmission lines having different structures affecting the speed at which an electromagnetic field is guided therealong, wherein the speed at which an electromagnetic field is guided along one of the transmission lines is different from the speed at which an electromagnetic field is guided along at least one other of the transmission lines.
18. The system of claim 13 , wherein the electrical conductors comprise parallel arrays of discrete conducting plates, the conducting plates of each of the arrays spaced from one another in the spatial direction.
19. The system of claim 12 , further comprising field modulating elements discrete from and operatively associated with the electrical conductors, the at least one processor operatively connected to the field modulating elements and configured to implement an operation of controlling the field modulating elements to regulate the speed at which the electromagnetic field propagates in the spatial direction.
20. The system of claim 12 , wherein the source of electromagnetic energy comprises a radio frequency (RF) or pulse probing signal source.