Abstract:
Exemplary systems, apparatus, methods and computer-accessible medium for generating information regarding at least one sample can be provided. For example, it is possible to receiving first data which is based on at least one first radiation provided to the sample(s) and at least one second radiation provided from the sample(s) that is/are associated with the first radiation(s) It is also possible to generate second data by reducing the influence of first optical effects induced on the first radiation(s) prior to reaching the sample(s), and second optical effects induced on the second radiation(s) after leaving the sample(s).

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is based upon and claims the benefit of priority from U.S. Patent Application Ser. No. 61/509,404 filed Jul. 19, 2011, the entire disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to exemplary optical imaging systems, apparatus, methods and computer-accessible medium, and more particularly to systems, apparatus, methods and computer-accessible medium for reducing the effect of polarization mode dispersion in optical coherence tomography systems, and more particularly for providing polarization-mode dispersion compensation in optical coherence tomography. 
     BACKGROUND INFORMATION 
     A potential of optical coherence tomography (“OCT”) as a diagnostic tool capable of providing high-resolution cross-sectional images of tissue microstructure to depths of 2 mm has been understood for over a decade. Polarization-sensitive-OCT (“PS-OCT”) procedures, systems and techniques can facilitate measurements of sample properties that affect light polarization. However, the presence of polarization mode dispersion (“PMD”) in the OCT instrument can cause noise in PS-OCT measurements. Levels of PMD can at times be reduced and/or minimized, although can rarely be fully eliminated. 
     Accordingly, there may be a need to overcome at least some of the issues and/or deficiencies described herein above. For example, methods, systems and arrangements to minimize the noise impact of PMD on OCT measurements can have a significant value in existing and emerging applications of OCT. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     To address and/or overcome the above-described problems and/or deficiencies, exemplary embodiments of systems, arrangements, methods, apparatus and computer-accessible-medium can be provided which can facilitate deleterious effects of PMD to be reduced. According to one exemplary embodiment, The exemplary PS-OCT system and/or method can be provided with both polarization-diverse detection and simultaneous illumination in two or more polarization states. It is also possible, using such exemplary system and/or method to measure fringe signals form this system, and to apply computational corrections to those fringe signals that reduce the effect of PMD. 
     Thus, according to certain exemplary embodiments of the present disclosure, it is possible to provide exemplary system, apparatus, method and computer-accessible medium so as to generate information regarding at least one sample. For example, using at least one first arrangement, it is possible to receive first data, second data, third data and fourth data. The first data can be associated with a first radiation provided to the sample(s), a second radiation from the sample(s), and at least one further radiation provided from the sample(s) or a reference. The second data can be associated with a third radiation provided to the sample(s), the second radiation, and the further radiation(s) The third data can be associated with the first radiation, a fourth radiation from the sample(s), and the further radiation(s). The fourth data can be associated with the third radiation, the fourth radiation from the sample(s), and the further radiation(s). In this exemplary embodiment, each of the first and third radiations and the second and fourth radiations can have polarizations states that are different from one another. In addition, using a second arrangement, it is possible to generate fifth data by combining at least two of the first, second, third and fourth data, where the combination can reduce the influence of optical effects induced on the first and third radiations prior to reaching the sample(s), and optical effects induced on the second and fourth radiations after leaving the sample(s). 
     In addition, according to another exemplary embodiment, with at least one third arrangement, it is possible to generate (i) an optical frequency shift on the second radiation in relation to the fourth radiation, and/or (ii) an optical delay of the second radiation in relation to the fourth radiation. Using the first arrangement(s), it is also possible to measure characteristics of the sample(s) that influence an optical polarization of a radiation within the sample(s) based on the information. Further, with the first arrangement(s), it is possible to receive sixth data which is associated with signals generated by at least one optical device that is provided in an optical path that excludes the at least one sample. For example, the second arrangement(s) can be used to reduce the influences using the sixth data. The further radiation(s) can be provided from the reference. Further, the first arrangement(s) can be used to resolve the first, second, third and fourth data as a function of an optical wavelengths of at least one of the first, second, third or forth radiations. 
     According to yet another exemplary embodiment of the present disclosure, exemplary systems, apparatus, methods and computer-accessible medium can be provided for generating information regarding at least one sample. For example, it is possible to receiving first data which is based on at least one first radiation provided to the sample(s) and at least one second radiation provided from the sample(s) that is/are associated with the first radiation(s) It is also possible to generate second data by reducing the influence of first optical effects induced on the first radiation(s) prior to reaching the sample(s), and second optical effects induced on the second radiation(s) after leaving the sample(s). 
     For example, the first optical effects and/or the second optical effects can include a wavelength dependent change in polarization of the respective first electromagnetic radiation and/or the respective second electromagnetic radiation. Using the first arrangement(s), it is possible to receive third data which is associated with signals generated by at least one optical device that is provided in an optical path that excludes the sample(s), and using the second arrangement(s), it is possible to reduce the influences using the third data. The information regarding the sample can include optical properties regarding the sample(s) which influence the polarization. The optical properties can include birenfringenece, diattenuation, and/or polarization dependent scattering. Further, using the first arrangement(s), it is possible to resolve the first data as a function of optical wavelengths of the first radiation(s) and/or the second radiation(s). 
     These and other objects, features and advantages of the present invention will become apparent upon reading the following detailed description of embodiments of the disclosure, when taken in conjunction with the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further objects, features and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings showing illustrative embodiments of the present disclosure, in which: 
         FIG. 1  is an illustration of an exemplary PS-OCT system designed to implement a PMD correction according to an exemplary embodiment of the present disclosure; 
         FIG. 2  is a diagram of an exemplary embodiment of a calibrating configuration according to the present disclosure which can be used in the exemplary system shown in  FIG. 1 ; 
         FIG. 3  is an illustration of another exemplary embodiment of a calibrating configuration according to the present disclosure which used in the exemplary system shown in  FIG. 1 ; 
         FIG. 4  is a flow diagram of a method according to an exemplary embodiments of the present disclosure; and 
         FIG. 5  are a set of exemplary images demonstrating an exemplary PMD correction which reduces noise in OCT imaging. 
     
    
    
     Throughout the figures, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. Moreover, while the subject invention will now be described in detail with reference to the figures, it is done so in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the subject disclosure as defined by the appended claims. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  shows a polarization-sensitive OCT system designed to numerically compensate for PMD according to an exemplary embodiments of the present disclosure. In this exemplary embodiment, a wavelength swept source  400  can be used, although it should be understood that other sources can be utilized. An electromagnetic radiation (e.g., light) can be split by a coupler  402  to create two or more optical signals, e.g., a reference beam traveling on a fiber  402   b  and a sample beam traveling on a fiber  402   c . The electromagnetic radiation (e.g., light) received from the reference beam can be directed to a first acousto-optic frequency shifter  404 , which can generate an optical frequency shift on such beam. Such electromagnetic radiation (e.g., light) can be directed to an optical coupler  436 , and to a reference mirror  438 . The electromagnetic radiation (e.g., light) reflected from the reference mirror  438  can be directed back to the coupler  436 . The returned electromagnetic radiation (e.g., light) can be partially directed toward a polarization receiver  456 . This electromagnetic radiation (e.g., light) can pass through a polarization controller  440 . Finally such passed electromagnetic radiation (e.g., light) can be collimated by a collimator  442  before it enters the receiver  456 . 
     The sample arm electromagnetic radiation (e.g., light) on the fiber  402   c  can be transmitted through a polarization controller  406  to a frequency multiplexing configuration comprising a first polarization beam splitter  416 . The electromagnetic radiation (e.g., light) can be configured to have a power distributed to both paths. In a first exemplary path, the electromagnetic radiation (e.g., light) can be transmitted through a second acousto-optic frequency shifter  418 , through an optical delay arrangement  420 ,  422 , and to a combining polarization beam splitter  424 . In a second exemplary path, the electromagnetic radiation (e.g., light) can be transmitted through a third acousto-optic frequency shifter  410  to the combining polarization beam combiner  424 . This sample electromagnetic radiation (e.g., light) can be directed to a fiber coupler  426 , then to a polarization controller  428 , and further to a sample and calibration signal configuration  432 . The electromagnetic radiation (e.g., light) returning from such sample and the calibration signal configuration  432  can be returned to the coupler  426 , directed through a polarization controller  434 , and collimated before entering into the polarization diverse receiver  456 . In the polarization diverse receiver  456 , exemplary signals associated with the X-polarized and Y-polarized sample arm electromagnetic radiation (e.g., light) can be detected by and/or via receivers and/or digitizers  450 ,  452 , respectively. The data signals can then be transferred to a digital processing (e.g., hardware) arrangement  454 . 
     An exemplary embodiment of a sample and calibration signal configuration  432  is shown in  FIG. 2 . For example, the electromagnetic radiation (e.g., light) can enter from a fiber  500 , and can be directed to a beam sampler  505 . A portion of this electromagnetic radiation (e.g., light) can pass through the sampler to a beam scanner  510 , through a lens  515 , and to a sample  520 . Such exemplary beam and calibration signal configuration can also comprise a catheter and/or an optical probe. A portion of the beam reflected from the beam sampler  505  can be directed to a first mirror  525 , and then to a first broadband beam splitter  530 . 
     This exemplary setup/configuration can generate two or more beams, e.g., one directed to a second broadband beam splitter  545 . Such second beam splitter  545  can generate two or more signals, e.g., one directed to a first mirror/reflecting arrangement  560 , and a second directed to a second mirror/reflecting arrangement  555  through a first optical element/arrangement  550 . The first optical element  550  can be or include, for example a waveplate, optical retarder, polarizer, or partial polarizer among others. The second beam from the first beam splitter  535  can be directed to a third mirror/reflecting arrangement  540  through a second optical element/arrangement  535 . Again, such second optical element ( 550 ) can be for example a waveplate, optical retarder, polarizer, or partial polarizer among others. The reflected signals from the mirrors/reflecting arrangement  560 ,  555 ,  540  can return to the imaging fiber  500 , and their respective signals are used to determine and/or calculate the correction parameters to be used by the exemplary system, method and arrangement according to the present disclosure. 
     A diagram of another exemplary embodiment for the sample and calibration signal configuration  432  is shown in  FIG. 3 . For example, in the exemplary configuration of  FIG. 3 , a splitter  600  can be used to split the electromagnetic radiation (e.g., light) to be forwarded toward a calibration sample  610  and also toward a sample  620 . The calibration sample  610  is shown in detail in a section  630 , and contains, e.g., two waveplates  640   a ,  640   b , and a mirror  650 . Exemplary signals can be detected from one or more of the five interfaces, including the front and back of the waveplates  640   a ,  640   b  and a mirror/reflecting arrangement  650 . 
     According to an exemplary embodiment of the present disclosure, the digital processing arrangement  454  can include an arrangement and/or a setup designed to reduce the influence of PMD on the digital signals. One exemplary procedure for performing such operation can be to multiply the complex fringe data within the 2×2 matrix M(k) by two correction matrices C in (k) and C out (k) according to, e.g.:
 
 C   out ( k )· M ( k )· C   in ( k )
 
where the first column of M(k) contains the complex fringe signals associated with the first frequency shifter channel (see, e.g., channel  410  shown in  FIG. 1 ) in each of the two detector channels (see, e.g., channels  452 ,  450  shown in  FIG. 1 ), and the second column of M(k) contains the complex fringe signals associated with the second frequency shifter channel (see, e.g., channel  418  shown in  FIG. 1 ) in each of the two detector channels (see channels  452 ,  450  shown in  FIG. 1 ). The complex fringe signals within M(k) can, for example, be formed by demodulation of the detected interference signals about the RF carrier as described in S. H. Yun et al., “Removing the depth degeneracy in optical frequency domain imaging with frequency shifting”, Optics Express, Vol. 12, No. 20, 2004.
 
     In yet another exemplary embodiment of the present disclosure, the digital processing unit can include an arrangement which can be configured to determine and/or calculate the correction matrices C in (k) and C out (k). Using one exemplary procedure, the exemplary arrangement can determine and/or calculate such correction matrices C in (k) and C out (k) as a function of the calibrating signals generated by the mirrors (see, e.g., mirrors/reflecting arrangements  560 ,  555 ,  540  shown in  FIG. 2 ). For example, the measured fringe signals from a first mirror/reflecting arrangement (see, e.g., mirror/reflecting arrangement  560  shown in  FIG. 2 ), a second mirror/reflecting arrangement  2  (see, e.g., mirror/reflecting arrangement  555  shown in  FIG. 2 ), and a third mirror/reflecting arrangement (see, e.g., mirror/reflecting arrangement  540  shown in  FIG. 2 ) are given by, e.g.:
 
 M   1 ( k )= c   1 ( k ) T   out ( k )· R   1 ( k )· T   in ( k )· K ( k )
 
 M   2 ( k )= c   2 ( k ) T   out ( k )· R   2 ( k )· T   in ( k )· K ( k )
 
 M   3 ( k )= c   3 ( k ) T   out ( k )· R   3 ( k )· T   in ( k )· K ( k )  (Eq. 0)
 
where R 1 (k), R 2 (k) and R 3 (k) describe the optical elements/arrangement within the associated optical paths through the calibration arrangement including, for example, the optical elements/arrangements  535 ,  550  shown in  FIG. 2 .
 
     The matrices T in (k) and T out (k) describe the optical transfer function of the instrument before and after the sample respectively. For example, the scalar factors c 1 (k) c 2 (k), and c 3 (k) includes affects associated with the linear in wave number phase profile of each fringe. It can also include amplitude and phase variations associated with the fringe envelope and transmission loss of each mirror signal. The matrix K(k) describes variations that can occur in the launched polarization states. Only the matrices R 1 (k), R 2 (k), and R 3 (k) are known a priori, and M 1 (k), M 2 (k), and M 3 (k) are measured. An equation for T out (k) can be given as, e.g.: 
                         (         c   1     ⁡     (   k   )           c   2     ⁡     (   k   )         )     ⁢       M   2     ⁡     (   k   )       ⁢       M   1     -   1       ⁡     (   k   )         =           T   out     ⁡     (   k   )       ⁡     [         R   2     ⁡     (   k   )       ⁢       R   1     -   1       ⁡     (   k   )         ]       ⁢       T   out     -   1       ⁡     (   k   )           ⁢     
     ⁢         (         c   1     ⁡     (   k   )           c   3     ⁡     (   k   )         )     ⁢       M   3     ⁡     (   k   )       ⁢       M   1     -   1       ⁡     (   k   )         =           T   out     ⁡     (   k   )       ⁡     [         R   3     ⁡     (   k   )       ⁢       R   1     -   1       ⁡     (   k   )         ]       ⁢       T   out     -   1       ⁡     (   k   )                   (     Eq   .           ⁢   1     )               
where, if c 1 (k) c 2 (k), and c 3 (k) were known, T out (k) can be solved for. To remove c 1 (k) c 2 (k), and c 3 (k) from the equations, it is possible to perform eigenvalue decomposition on [R 2 (k)R 1   −1 (k)] and [R 3 (k)R 1   −1 (k)] and on [M 2 (k)M 1   −1 (k)] and [M 3 (k)M 1   −1 (k)] leaving, e.g.:
 
 M   2 ( k ) M   1   −1 ( k )= U   21 ( k )· d   21 ( k )· U   21   −1 ( k )  (Eq. 2)
 
and
 
 R   2 ( k ) R   1   −1 ( k )= V   21 ( k )· D   21 ( k )· V   21   −1 ( k ).  (Eq. 3)
 
     Further it is possible to construct the expression, because the (c 1 (k)/c 2 (k))[M 2 (k)M 1   −1 (k)] is known as a unitary transformation of [R 2 (k)R 1   −1 (k)] and (c 1 (k)/c 3 (k))[M 3 (k)M 1   −1 (k)] as a unitary transformation of [R 3 (k)R 1   −1 (k)], it is possible to determine and/or calculate (c 1 (k)/c 2 (k))[M 2 (k)M 1   −1 (k)] and (c 1 (k)/c 3 (k))[M 3 (k)M 1   −1 (k)] as, e.g.: 
                       (         c   1     ⁡     (   k   )           c   2     ⁡     (   k   )         )     ⁢       M   2     ⁡     (   k   )       ⁢       M   1     -   1       ⁡     (   k   )         =         U   21     ⁡     (   k   )       ⁢       D   21     ⁡     (   k   )       ⁢       U   21     -   1       ⁡     (   k   )                 (     Eq   .           ⁢   4     )                   (         c   1     ⁡     (   k   )           c   3     ⁡     (   k   )         )     ⁢       M   3     ⁡     (   k   )       ⁢       M   1     -   1       ⁡     (   k   )         =         U   31     ⁡     (   k   )       ⁢       D   31     ⁡     (   k   )       ⁢       U   31     -   1       ⁡     (   k   )                 (     Eq   .           ⁢   5     )               
and it is possible to utilize these values to solve for T out (k). The product T in (k)K(k) can then be solved for from substitution of T out (k) into one of the equations within Eq. 0. Finally, the correction matrices can be calculated as, e.g.:
 
 C   out ( k )= T   out   −1 ( k )
 
 C   in ( k )=[ T   in ( k ) K ( k )] −1 .  (Eq. 6)
 
     According to another exemplary embodiment of the present disclosure, the eigenvectors calculated in Eq. 4 can be compared across a wavelength, and each column within U 21 (k) and/or U 31 (k) can be swapped to ensure continuity of eigenvectors. 
     In a further exemplary embodiment of the present disclosure, the signals M 1 (k), M 2 (k), and M 3 (k) can be derived from the same A-line, where each signal can be associated with one mirror signal, and that signal can be calculated by identifying its spectral peak in its Fourier transformed representation, e.g., by applying a window centered at that peak such that the peaks from other signals are eliminated. The inverse Fourier transformation can be performed to the windows signal. 
     Another method according to still further exemplary embodiment of the present disclosure is shown in a flow diagram of  FIG. 4 . For example, as shown in procedure  900 , frequency dependent Jones matrices T 1 (ω), T 3 (ω) and T 5 (ω) of the calibration samples are measured as follows:
 
 T   1 (ω)= T   out (ω)· T   w1   ·T   in (ω)
 
 T   3 (ω)= T   out (ω)· T   w3   ·T   in (ω)
 
 T   5 (ω)= T   out (ω)· T   w5   ·T   in (ω)
 
where Tw 1 , Tw 3 , Tw 5  are known Jones matrices from calibration samples; Tin (ω) and Tout (ω) are frequency dependent Jones matrices of two exemplary lumped PMD section in the exemplary system: from, e.g., a laser source to the sample, and from sample back to the detector, respectively.
 
     Then, in procedure  901  of  FIG. 4 , an instrumentation PMD in the exemplary system can be calculated by solving for T in (ω) and T out (ω). Further, in procedure  902 , the continuity of T in (ω) and T out (ω) is checked. The sample Jones matrix is measured, e.g., T s   _   measured (ω)=T out (ω)·T s (ω)·T in (ω); and the actual T s (ω) is recovered by taking inverse of T in (ω) and T out (ω) in procedure  903 . Then, in procedure  904 , a compensated electric field of X and Y, polarized light E x (ω) and E y (ω) from the sample Jones matrix T s (ω) can be calculated. Further, in procedure  905 , a standard polarization sensitive optical coherence tomography (PS-OCT) data processing is utilized to calculate sample&#39;s birefringence. 
     The exemplary result(s) of the exemplary correcting instrument/arrangement/system/method PMD is/are shown in  FIG. 5 . For example, the exemplary system can be used to image an intralipid sample. An exemplary OCT structural image  800   a  is presented illustrating three lines associated with the three calibrating signals which are described herein with reference to  FIG. 2 , and the intralipid sample below those lines. A local birefringence image  800   b  is provided without a PMD correction. A local birefringence image  800   c  is provided with PMD correction as described herein. An exemplary image  800   d  is provided which is generated when PMD is physically removed form the exemplary system. The similarity of the images  800   c  and  800   d  can confirm that the described approach reduces the influence of PMD on PS-OCT image noise. 
     In light of these technological advancement and exemplary measurements, the exemplary apparatus, system, arrangement and method according to the exemplary embodiments of the present disclosure can facilitate ophthalmic research and patient care since they can provide, among other things, non-invasive, non-contact and microscopic information on ocular properties in situ. For example, a PS-OCT arrangement can be a useful diagnostic tool, e.g., possibly facilitating early diagnosis, screening of at-risk patients, monitoring therapeutic responses, developing novel approaches for treatment, and understanding pathogenesis. 
     The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. Indeed, the arrangements, systems and methods according to the exemplary embodiments of the present disclosure can be used with and/or implement any OCT system, OFDI system, SD-OCT system or other imaging systems, and for example with those described in International Patent Application PCT/US2004/029148, filed Sep. 8, 2004 which published as International Patent Publication No. WO 2005/047813 on May 26, 2005, U.S. patent application Ser. No. 11/266,779, filed Nov. 2, 2005 which published as U.S. Patent Publication No. 2006/0093276 on May 4, 2006, and U.S. patent application Ser. No. 10/501,276, filed Jul. 9, 2004 which published as U.S. Patent Publication No. 2005/0018201 on Jan. 27, 2005, and U.S. Patent Publication No. 2002/0122246, published on May 9, 2002, the disclosures of which are incorporated by reference herein in their entireties. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures which, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. In addition, all publications and references referred to above can be incorporated herein by reference in their entireties. It should be understood that the exemplary procedures described herein can be stored on any computer accessible medium, including a hard drive, RAM, ROM, removable disks, CD-ROM, memory sticks, etc., and executed by a processing arrangement and/or computing arrangement which can be and/or include a hardware processors, microprocessor, mini, macro, mainframe, etc., including a plurality and/or combination thereof. In addition, certain terms used in the present disclosure, including the specification, drawings and claims thereof, can be used synonymously in certain instances, including, but not limited to, e.g., data and information. It should be understood that, while these words, and/or other words that can be synonymous to one another, can be used synonymously herein, that there can be instances when such words can be intended to not be used synonymously. Further, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it can be explicitly being incorporated herein in its entirety. All publications referenced above can be incorporated herein by reference in their entireties.