Method and apparatus for imaging using polarimetry and matrix based image reconstruction
First Claim
1. A method for producing images of an object or region of interest of the object, comprising the steps of:
- a) producing an incident beam of light in a pre-selected polarization state and scanning said incident earn of light point by point across an object or region of interest of the object;
b) detecting light intensity signals corresponding to beams of light in a pre-selected number of polarization states reflected point by point from the object or region of interest of the object and storing electronic signals corresponding to the detected light intensity signals;
c) repeating steps a) and b) for an effective number of pre-selected polarization states of the incident beam of light;
d) constructing a spatially resolved matrix of the object point by point from the detected light intensity signals and from said spatially resolved matrix constructing spatially resolved images of the object or region of interest of the object for a set of theoretical polarization states of the incident beam of light in addition to those input states generated in the incident beam of light, said matrix being selected to describe the effect of the object on the polarization properties of light;
e) characterizing image quality of each image in accordance with an effective image quality parameter and based upon said characterization selecting a best image of said object or region of said object; and
f) visually displaying said best image.
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Abstract
The present invention provides a method and apparatus for improving the signal to noise ratio, the contrast and the resolution in images recorded using an optical imaging system which produces a spatially resolved image. The method is based on the incorporation of a polarimeter into the setup and polarization calculations to produce better images. After calculating the spatially resolved Mueller matrix of a sample, images for incident light with different states of polarization were reconstructed. In a shorter method, only a polarization generator is used and the first row of the Mueller matrix is calculated. In each method, both the best and the worst images were computed. In both reflection and transmission microscope and Macroscope and ophthalmoscope modes, the best images are better than any of the original images recorded. In contrast, the worst images are poorer. This technique is useful in different fields such as confocal microscopy, Macroscopy and retinal imaging.
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Citations
40 Claims
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1. A method for producing images of an object or region of interest of the object, comprising the steps of:
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a) producing an incident beam of light in a pre-selected polarization state and scanning said incident earn of light point by point across an object or region of interest of the object;
b) detecting light intensity signals corresponding to beams of light in a pre-selected number of polarization states reflected point by point from the object or region of interest of the object and storing electronic signals corresponding to the detected light intensity signals;
c) repeating steps a) and b) for an effective number of pre-selected polarization states of the incident beam of light;
d) constructing a spatially resolved matrix of the object point by point from the detected light intensity signals and from said spatially resolved matrix constructing spatially resolved images of the object or region of interest of the object for a set of theoretical polarization states of the incident beam of light in addition to those input states generated in the incident beam of light, said matrix being selected to describe the effect of the object on the polarization properties of light;
e) characterizing image quality of each image in accordance with an effective image quality parameter and based upon said characterization selecting a best image of said object or region of said object; and
f) visually displaying said best image. - View Dependent Claims (2, 3, 4)
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5. A method for producing images of an object or region of interest of the object, comprising the steps of:
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a) producing an incident beam of tight in a pre-selected polarization state and scanning said incident beam of light point by point across an object or region of interest of the object;
b) detecting light intensity signals corresponding to beams of light reflected point by point from the object or region of interest of the object and storing electronic signals corresponding to the detected light intensity signals;
c) repeating steps a) and b) for an effective number of pre-selected polarization states of the incident beam of light;
d) constructing a spatially resolved vector of the object point by point from the detected light intensity signals and from said spatially resolved vector constructing spatially resolved images of the object or region of interest of the object for a set of theoretical polarization states of the incident beam of light in addition to those input states generated in the incident beam of light, said vector comprised of independent elements of a matrix being selected to describe the effect of the object on the polarization properties of light;
e) characterizing image quality of each image in accordance with an effective image quality parameter and based upon said characterization selecting a best image of said object; and
f) visually displaying said best image. - View Dependent Claims (6, 7, 8)
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9. A method for producing images of an object or region of interest of the object, comprising the steps of:
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a) producing an incident beam of light in a pre-selected polarization state and illuminating an object or region of interest of the object with the selectively polarized beam of light;
b) detecting an array of light intensity signals reflected from spatially distinct points of the object or region of interest of the object and storing electronic signals corresponding to said detected array of light signals;
c) repeating steps a) and b) for an effective number of pre-selected polarization states of the incident beam of light;
d) constructing a spatially resolved vector comprised of independent elements of a spatially resolved matrix of the object point by point from the detected light intensity signals and from said spatially resolved vector constructing spatially resolved images of the object or region of interest of the object for a set of theoretical polarization states of the incident beam of light in addition to those input states generated in the incident beam of light, said matrix being selected to describe the effect of the object on the polarization properties of light;
e) characterizing image quality of each image in accordance with an effective image quality parameter and based upon said characterization selecting a best image of said object; and
f) visually displaying said best image. - View Dependent Claims (10, 11, 12, 13)
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14. A method for producing images of an object or region of interest of the object, comprising the steps of:
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a) producing an incident beam of light in a pre-selected polarization state and illuminating an object or region of interest of the object with the selectively polarized beam of light;
b) detecting an array of light intensity signals reflected from spatially distinct points of the object or region of interest of the object and storing electronic signals corresponding to said detected array of light signals;
c) repeating steps a) and b) for an effective number of pre-selected polarization states of the incident beam of light;
d) constructing a spatially resolved matrix of the object from the detected light intensity signals and from said spatially resolved matrix constructing spatially resolved images of the object or region of interest of the object for a set of theoretical polarization states of the incident beam of light in addition to those input states generated in the incident beam of light, said matrix being selected to describe the effect of the object on the polarization properties of light;
e) characterizing image quality of each image in accordance with an effective image quality parameter and based upon said characterization selecting a best image of said object; and
f) visually displaying said bet image. - View Dependent Claims (15, 16, 17, 18)
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19. A method for producing images of an object using confocal scanning laser microscopy, comprising the steps of:
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a) calibrating a confocal scanning laser microscope modified to include a polarization generator and a polarization analyzer to obtain a Mueller matrix
of the instrument in the incoming direction, wherein a matrix of 16 intensity values results from intensity measurements with a rotating ¼
wave plate located in said generator positioned in each of four positions including 45 degrees, 0 degrees, 30 degrees and 60 degrees, while a ¼
wave plate located in said analyzer is placed in each of the same four positions;
b) calibrating said modified confocal scanning instrument to obtain a Mueller matrix
of the instrument in the outgoing direction, wherein a matrix of 16 intensity values results from intensity measurements with a rotating ¼
wave plate located in said generator positioned in each of four positions including 45 degrees, 0 degrees, 30 degrees and 60 degrees, while a ¼
wave plate located in said analyzer is placed in each of the same four positions;
c) placing said object in said modified confocal scanning apparatus and focusing light onto said object and recording sixteen gray scale images with the object in place for each of four generator states with a ¼
wave plate at 45, 0, 30 and 60 degrees combined with each of the four analyzer states 1/4 wave plate at 45, 0, 30 and 60 degrees;
d) placing said sixteen grey scale values for each pixel into a spatially resolved matrix, I(mn), which is a first element of a Stokes vector,
reaching the photodetector;
e) from I(mn) calculate Mout from equation 2, given by f) from equation 3, given by
calculate M, the spatially resolved Mueller matrix of the object;
g) choosing values of an incident Stokes vector, SIN, around a Poincaré
sphere in predetermined increments of χ and
φ
which represent, respectively, the azimuth and ellipticity of the incident Stokes vector on the Poincaré
sphere;
h) applying equation 4, given by
to reconstruct images, I(out), pixel by pixel for each incident Stokes vector;
i) for each image, calculate the image quality measure of choice, for example SNR as defined in equation 7, given by
andj) display the image with best value of the image quality measure. - View Dependent Claims (20, 21, 22)
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23. An optical scanning apparatus for producing images of an object, comprising:
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a) a light source for producing a light beam;
b) polarization generator for producing selected polarization states in the light beam upon passage of the light beam through said polarization generator to produce a selectively polarized light beam;
c) scanning mechanism for receiving the selectively polarized light beam and spatially scanning the selectively polarized light beam in two dimensions across an object point by point;
d) polarization analyzer for transmitting light beams of selected polarization, including directing and focusing optics for directing the reflected light beams reflected point by point from the object to said polarization analyzer;
e) detector and light shaping and focusing optics for directing and focusing the reflected or transmitted light beams of selected polarization onto said detector;
f) computer processor connected to said detector, said computer processor including image analysis means for processing signals from said detector due to the reflected light beams of selected polarization detected by said detector and producing therefrom images of the object; and
g) display means for displaying an image of the object produced by said processing means. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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31. An optical scanning apparatus for producing images of an object, comprising:
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a) a light source for producing a light beam;
b) polarization generator means for producing selected polarization states in the light beam upon passage of the light beam through said polarization generator means to produce a selectively polarized light beam;
c) a beam splitter for transmitting the selectively polarized light beam;
d) scanning means for receiving the selectively polarized light beam from said beam splitter and spatially scanning the selectively polarized light beam in two dimensions across an object point by point and receiving light beams reflected back from different positions on the object and directing the reflected light beams to said beam splitter;
e) polarization analyzer means positioned to receive reflected light beams reflected from said beam splitter for transmitting reflected light beams of selected polarization;
f) detection means and light shaping and focusing means for directing and focusing the reflected light beams of selected polarization onto said detection means;
g) computer processing means connected to said detection means, said computer processing means including image analysis means for processing signals from the detector due to the reflected light beams of selected polarization detected by said detection means and producing therefrom images of the object; and
h) display means for displaying an image of the object produced by said processing means. - View Dependent Claims (32, 33, 34, 35, 36)
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37. A method for producing images of an object or region of interest of the object, comprising the steps of:
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a) producing an incident beam of light in a pre-selected polarization state and scanning said incident beam of light point by point across and/or along an object or region of interest of the object;
b) detecting light intensity signals corresponding to beams of light in a pre-selected number of polarization states reflected or transmitted point by point from the object or region of interest of the object and storing electronic signals corresponding to the detected light intensity signals;
c) repeating steps a) and b) for an effective number of pre-selected polarization states of the incident beam of light;
d) constructing a spatially resolved matrix of the object point by point from the detected light intensity signals and from said spatially resolved matrix constructing spatially resolved images of the object or region of interest of the object for a set of theoretical polarization states of the incident beam of light in addition to those input states generated in the incident beam of light, said matrix being selected to describe the effect of the object on the polarization properties of light;
e) characterizing image quality of each image in accordance with an effective image quality parameter and based upon said characterization selecting a best image of said object or region of said object; and
f) visually displaying said best image.
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38. A method for producing images of an object or region of interest of the object, comprising the steps of:
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a) producing an incident beam of light in a pre-selected polarization state and scanning said incident beam of light point by point across an object or region or along an object or a region of interest of the object by moving the object with respect to the incident beam or by moving the object in 1 dimension with respect to the incident beam and scanning the beam in a perpendicular direction with respect to the object;
b) detecting light intensity signals corresponding to beams of light reflected or transmitted point by point from the object or region of interest of the object and storing electronic signals corresponding to the detected light intensity signals;
c) repeating steps a) and b) for an effective number of pre-selected polarization states of the incident beam of light;
d) constructing a spatially resolved vector of the object point by point from the detected light intensity signals and from said spatially resolved vector constructing spatially resolved images of the object or region of interest of the object for a set of theoretical polarization states of the incident beam of light in addition to those input states generated in the incident beam of light, said vector comprised of independent elements of a matrix being selected to describe the effect of the object on the polarization properties of light;
e) characterizing image quality of each image in accordance with an effective image quality parameter and based upon said characterization selecting a best image of said object; and
f) visually displaying said best image.
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39. A method for producing images of an object using scanning laser microscopy or macroscopy, in transmission mode, comprising the steps of:
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a) calibrating a scanning laser microscope or macroscope modified to include a polarization generator and a polarization analyzer to obtain a Mueller matrix MSCN(1), of the instrument in the incoming direction, wherein a matrix of 16 intensity values results from intensity measurements with a rotating ¼
wave plate located in said generator positioned in each of four positions including 45 degrees, 0 degrees, 30 degrees and 60 degrees, while a ¼
wave plate located in said analyzer is placed in each of the same four positions;
b) placing said object in said modified confocal scanning apparatus and focusing light onto said object and recording sixteen gray scale images with the object in place for each of four generator states with a ¼
wave plate at 45, 0, 30 and 60 degrees combined with each of the four analyzer states ¼
wave plate at 45, 0, 30 and 60 degrees;
c) placing said sixteen grey scale values for each pixel into a spatially resolved matrix, I(mn), which is a first element of a Stokes vector,
reaching the photodetector;
d) from I(mn) calculate Mout from equation 2, given by e) from equation 5, given by
calculate M, the spatially resolved Mueller matrix of the object;
f) choosing values of an incident Stokes vector, SIN, around a Poincaré
sphere in predetermined increments of χ and
φ
which represent, respectively, the azimuth and ellipticity of the incident Stokes vector on the Poincaré
sphere;
g) applying equation 6, given by
to reconstruct images, I(out), pixel by pixel for each incident Stokes vector;
h) for each image, calculating the image quality measure of choice, for example SNR as defined in equation 7, given by
andi) displaying the image with best value of the image quality measure.
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40. An optical scanning apparatus for producing images of an object, comprising;
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a) a light source for producing a light beam;
b) polarization generator means for producing selected polarization states in the light beam upon passage of the light beam through said polarization generator means to produce a selectively polarized light beam;
c) scanning means for receiving the selectively polarized light beam and spatially scanning the selectively polarized light beam in two dimensions across an object point by point scanning the sample with respect to the laser beam or scanning the beam in 1 or 2 dimensions and the sample in the perpendicular direction;
d) polarization analyzer means for transmitting light beams of selected polarization, including directing and focusing optics for directing the reflected light beams reflected point by point from the object to said polarization analyzer means;
e) detection means and light shaping and focusing means for directing and focusing the reflected light beams of selected polarization onto said detection means;
f) computer processing means connected to said detection means, said computer processing means including image analysis means for processing signals from said detector due to the reflected light beams of selected polarization detected by said detection means and producing therefrom images of the object; and
g) display means for displaying an image of the object produced by said processing means.
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Specification