1. A method of generating a tomography image, the method comprising:
performing a depth scan on one spot on a surface of a subject using modulated light received from a spatial light modulator configured to modulate either one or both an intensity and a phase light received from a light source according to a pattern for each of a plurality of patterns of the spatial light modulator;
obtaining depth scan data for each of the plurality of patterns of the spatial light modulator by repeating the depth scan on the spot for each of the plurality of patterns of the spatial light modulator;
forming a matrix R representing a vector space based on a correlation of signal values of the depth scan data for each of the plurality of patterns of the spatial light modulator;
performing a matrix decomposition on the matrix R;
dividing the vector space represented as a sum of subspace components into a noise subspace and a signal subspace based on a threshold and a matrix obtained by the matrix decomposition, wherein the threshold is determined based on characteristics of the subspace components or noise levels of the signal values;
reconstructing a vector space based on either one or both of components of the signal subspace and components of the noise subspace; and
generating the tomography image based on the reconstructed vector space.
2. The method of claim 1, wherein the dividing of the vector space comprises:
determining a noise variance or a signal-to-noise ratio (SNR) as the threshold; and
dividing the vector space into the noise subspace and the signal subspace based on the threshold and the matrix obtained by the matrix decomposition.
3. The method of claim 1, wherein the reconstructing of the vector space comprises reconstructing the vector space based only on the components of the signal subspace.
4. The method of claim 1, wherein the reconstructing of the vector space comprises:
calculating a multiple signal classification (MUSIC) spectrum based on the components of the noise subspace; and
reconstructing the vector space based on the calculated MUSIC spectrum.
5. The method of claim 1, wherein the matrix R is a covariance matrix of signal values of the depth scan data for each of the plurality of patterns of the spatial light modulator.
6. The method of claim 1, wherein the performing of the matrix decomposition on the matrix R comprises performing an eigenvalue decomposition or a singular value decomposition on the matrix R.
7. The method of claim 1, wherein the performing of the matrix decomposition on the matrix R comprises performing an eigenvalue decomposition on the matrix R; and
the dividing of the vector space comprises:
ranking eigenvalues of an eigenvalue matrix obtained by the eigenvalue decomposition in size order, the eigenvalues of the eigenvalue matrix corresponding to eigenvectors of an eigenvector matrix; and
dividing the ranked eigenvalues based on the threshold to divide the vector space into the noise subspace and the signal subspace.
8. The method of claim 1, wherein the performing of the matrix decomposition on the matrix R comprises performing a singular value decomposition on the matrix R; and
the dividing of the vector space comprises:
ranking singular values of a singular value matrix obtained by the matrix decomposition in size order, the singular values of the singular value matrix corresponding to singular vectors of a singular vector matrix; and
dividing the ranked singular values based on the threshold to divide the vector space into the noise subspace and the signal subspace.
9. The method of claim 1, wherein the plurality of patterns of the spatial light modulator are uncorrelated with each other.
10. The method of claim 1, wherein the plurality of patterns of the spatial light modulator are determined based on permutations of a Hadamard pattern.
11. The method of claim 1, wherein the spatial light modulator comprises a digital micromirror device (DMD), or a deformable mirror (DM) device, or a Liquid Crystal on Silicon (LCoS) device.
12. The method of claim 1, wherein the method is an optical coherent tomography (OCT) method or an optical coherent microscopy (OCM) method.
13. A non-transitory computer-readable storage medium storing a computer program for controlling a computer to perform the method of claim 1.
14. An apparatus for generating a tomography image, the apparatus comprising:
a light source configured to emit light;
a spatial light modulator configured to modulate either one or both of an intensity and a phase of the light emitted from the light source according to a pattern;
a modulation controller configured to sequentially apply each of a plurality of patterns to the spatial light modulator;
a depth scanner configured to:
perform a depth scan on one spot on a surface of a subject using modulated light received from the spatial light modulator;
repeat the depth scan on the spot for each of the plurality of patterns of the spatial light modulator; and
obtain light produced by the depth scan for each of the plurality of patterns of the spatial light modulator;
a data detector configured to detect depth scan data for each of the plurality of patterns of the spatial light modulator from the light produced by the depth scan for each of the plurality of patterns of the spatial light modulator obtained by the depth scanner;
a signal processor configured to:
form a matrix R representing a vector space based on a correlation of signal values of the depth scan data for each of the plurality of patterns of the spatial light modulator;
perform a matrix decomposition on the matrix R;
divide the vector space represented as a sum of subspace components into a noise subspace and a signal subspace based on a threshold and a matrix obtained by the matrix decomposition, wherein the threshold is determined based on characteristics of the components of the subspace or noise levels of the signal values; and
reconstruct a vector space based on either one or both of components of the signal subspace and components of the noise subspace; and
an image generator configured to generate the tomography image corresponding to the spot based on the reconstructed vector space.
15. The apparatus of claim 14, wherein the signal processor is further configured to:
determine a noise variance or a signal-to-noise ratio (SNR) as the threshold; and
divide the vector space into the noise subspace and the signal subspace based on the threshold and the matrix obtained by the matrix decomposition.
16. The apparatus of claim 14, wherein the matrix R is a covariance matrix of signal values of the depth scan data for each of the plurality of patterns of the spatial light modulator.
17. The apparatus of claim 14, wherein the signal processor is further configured to perform an eigenvalue decomposition or a singular value decomposition as the matrix decomposition on the matrix R.
18. The apparatus of claim 14, wherein the signal processor is further configured to:
calculate a multiple signal classification (MUSIC) spectrum based on components of the noise subspace; and
reconstruct the vector space based on the calculated MUSIC spectrum.
19. The apparatus of claim 14, wherein the plurality of patterns of the spatial light modulator are uncorrelated with each other.
20. The apparatus of claim 14, further comprising a light controller configured to horizontally move a location of the spot on the surface on the subject on which the depth scan is performed;
wherein the depth scanner is further configured to repeat the depth scan for each of the plurality of patterns of the spatial light modulator on the moved spot;
the data detector is further configured to obtain depth scan data for the plurality of patterns of the spatial light modulator for the moved spot;
the signal processor is further configured to reconstruct a vector space for the moved spot; and
the image generator is further configured to:
generate a tomography image corresponding to the moved spot based on the reconstructed vector space; and
generate a final tomography image of a region corresponding to all of the spots at which the depth scan was performed by combining the tomography images corresponding to all of the spots.
21. A method of generating a tomography image, the method comprising:
generating a reference light and a measuring light from light emitted from a light source;
modulating any one of the light emitted from the light source, the reference light, and the measuring light with a spatial light modulator configured to modulate either one or both of an intensity and a phase of light according to a pattern for each of a plurality of patterns of the spatial light modulator;
performing a depth scan on one spot on a surface of a subject by applying the measuring light to the spot and receiving a response light from the spot;
repeating the depth scan for each of the plurality of patterns of the spatial light modulator;
obtaining interference light produced by interference of the reference light and the response light;
obtaining depth scan data for each of the plurality of patterns of the spatial light modulator based on the interference light;
forming a matrix R representing a vector space based on a correlation of signal values of the depth scan data for each of the plurality of patterns of the spatial light modulator;
performing a matrix decomposition on the matrix R;
dividing the vector space represented as a sum of subspace components into a noise subspace and a signal subspace based on a threshold and a matrix obtained by the matrix decomposition, wherein the threshold is determined based on characteristics of the components of the subspace or noise levels of the signal values;
reconstructing a vector space based on either one or both of components of the signal subspace and components of the noise subspace; and
generating the tomography image based on the reconstructed vector space.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A transition medium for interfacing a planar medium with a coaxial medium to propagate a primary signal, the transition medium comprising:
a body;
a center conductor extending through the body and electrically connectable with the coaxial medium at a coax interface and the planar medium at a planar interface;
a first cavity extending from the coax interface through a first portion of the body, the first cavity having a substantially circular cross-section,
wherein a first portion of the center conductor is arranged substantially coaxially within the first cavity;
a second cavity extending from the first cavity through a second portion of the body, the second cavity extending the first cavity into the body upward and downward relative to the planar medium,
wherein a second portion of the center conductor is arranged within the second cavity;
wherein the first portion and the second portion of the center conductor are substantially circular and substantially continuous in cross-section;
a pair of planar conductors substantially coplanar with the center conductor and extending along at least a portion of the second cavity and extending from the second cavity to the planar interface,
wherein the pair of planar conductors extend into the second cavity so that a distance from a surface of the second portion of the center conductor to each of the pair of planar conductors is smaller than a distance from a surface of the first portion of the center conductor to a sidewall of the first cavity; and
a planar portion of the center conductor extending from the second cavity to the planar interface,
wherein the planar portion of the center conductor is substantially coplanar with the pair of planar conductors;
wherein the transition medium suppresses excitation of secondary electrical signals by the primary signal when the primary signal is propagated through the transition medium at a frequency below an upper limit.
2. The transition medium of claim 1,
wherein the planar portion of the center conductor extends through free space to the planar medium and includes a height approximately matched to a cross-sectional height of the planar conductors.
3. The transition medium of claim 2, wherein the upper limit of the frequency of the primary signal is determined based on a length of the planar portion of the center conductor that extends through free space.
4. The transition medium of claim 3, wherein the upper limit of the frequency of the primary signal is an inverse of a length of the planar portion of the center conductor that extends through free space.
5. The transition medium of claim 1 wherein the planar medium is one of a co-planar waveguide and a microstrip.
6. The transition medium of claim 1, wherein a reflectometer is connectible with the planar medium to send the primary signal to the coaxial medium and receive incident signals from the coaxial medium.
7. The transition medium of claim 6, wherein the reflectometer is a vector network analyzer (VNA).
8. The transition medium of claim 2, wherein the second cavity is an elliptically shaped cavity through which the second portion of the center conductor extends.
9. A vector network analyzer for measuring signal response comprising:
a coax test port;
semiconductor circuitry for generating a primary signal and receiving response signals; and
a transition medium for interfacing the semiconductor circuitry with a coaxial medium associated with the coax test port to propagate the primary signal, the transition medium including
a body;
a center conductor extending through the body and electrically connectable with the coaxial medium at a coax interface and the semiconductor circuitry at a planar interface;
a first cavity extending from the coax interface through a first portion of the body, the first cavity having a substantially circular cross-section,
wherein a first portion of the center conductor is arranged substantially coaxially within the first cavity;
a second cavity extending from the first cavity through a second portion of the body, the second cavity extending the first cavity into the body upward and downward relative to the semiconductor circuitry,
wherein a second portion of the center conductor is arranged within the second cavity;
wherein the first portion and the second portion of the center conductor are substantially circular and substantially continuous in cross-section;
a pair of planar conductors substantially coplanar with the center conductor and extending along at least a portion of the second cavity and extending from the second cavity to the planar interface,
wherein the pair of planar conductors extend into the second cavity so that a distance from a surface of the second portion of the center conductor to each of the pair of planar conductors is smaller than a distance from a surface of the first portion of the center conductor to a sidewall of the first cavity; and
a planar portion of the center conductor extending from the second cavity to the planar interface,
wherein the planar portion of the center conductor is substantially coplanar with the pair of planar conductors;
wherein the transition medium suppresses excitation of secondary electrical signals by the primary signal when the primary signal is propagated through the transition medium at a frequency below an upper limit.
10. The vector network analyzer of claim 9,
wherein the transition medium further includes
a planar medium comprising one of a coplanar waveguide and a microstrip electrically connectable between the frequency-scalable device at the planar interface,
wherein the planar portion of the center conductor extends through free space to the planar medium and includes a height approximately matched to a cross-sectional height of the planar conductors; and
wherein the planar medium is electrically connected with the semiconductor circuitry.
11. The vector network analyzer of claim 10, wherein the upper limit of the frequency of the primary signal is determined based on a length of the planar portion of the center conductor that extends through free space.
12. The vector network analyzer of claim 11, wherein the upper limit of the frequency of the primary signal is an inverse of a length of the planar portion of the center conductor that extends through free space.
13. A method of measuring a signal response in a device under test, the method comprising:
electrically connecting the device under test to a coax test port of a measurement system including a coax-to-planar transition medium;
wherein the coax-to-planar transition medium comprises
a body,
a center conductor extending through the body and electrically connectable with a coaxial medium at a coax interface and a planar medium at a planar interface,
a first cavity extending from the coax interface through a first portion of the body, the first cavity having a substantially circular cross-section,
wherein a first portion of the center conductor is arranged substantially coaxially within the first cavity,
a second cavity extending from the first cavity through a second portion of the body, the second cavity extending the first cavity into the body upward and downward relative to the planar medium,
wherein a second portion of the center conductor is arranged within the second cavity,
wherein the first portion and the second portion of the center conductor are substantially circular and substantially continuous in cross-section,
a pair of planar conductors substantially coplanar with the center conductor and extending along at least a portion of the second cavity and extending from the second cavity to the planar interface,
wherein the pair of planar conductors extend into the second cavity so that a distance from a surface of the second portion of the center conductor to each of the pair of planar conductors is smaller than a distance from a surface of the first portion of the center conductor to a sidewall of the first cavity, and
a planar portion of the center conductor extending from the second cavity to the planar interface,
wherein the planar portion of the center conductor is substantially coplanar with the pair of planar conductors;
generating a signal using the measurement system; and
measuring a response of the device under test to the generated signal;
wherein the transition medium suppresses excitation of secondary electrical signals by the primary signal when the primary signal is propagated through the transition medium at a frequency below an upper limit.
14. The method of claim 13,
wherein the planar portion of the center conductor extends through free space to the planar medium and includes a height approximately matched to a cross-sectional height of the planar conductors.
15. The method of claim 13, wherein the upper limit of the frequency of the primary signal is determined based on a length of the planar portion of the center conductor that extends through free space.
16. The method of claim 15, wherein the upper limit of the frequency of the primary signal is an inverse of a length of the planar portion of the center conductor that extends through free space.
17. The method of claim 13, wherein the measurement system is a vector network analyzer (VNA).