Abstract
Systems and methods according to exemplary embodiments of the present disclosure can be provided that can efficiently detect the amplitude and phase of a spectral modulation. Such exemplary scheme can be combined with self-interference fluorescence to facilitate a highly sensitive depth localization of self-interfering radiation generated within a sample. The exemplary system and method can facilitate a scan-free depth sensitivity within the focal depth range for microscopy, endoscopy and nanoscopy.
Claims
1. An apparatus which is configured to obtain at least one electro-magnetic radiation from at least one portion of a sample, comprising: at least one optical first arrangement which is configured to receive the at least one electro-magnetic radiation from the at least one portion, and generate at least one first radiation based on the at least one electro-magnetic radiation, wherein the at least one optical first optical arrangement receives, separates and recombines the at least one electro-magnetic radiation to be self-interfered to generate the first radiation; at least one interference second arrangement which is configured to receive, separate and recombine the first radiation so as to self-interfere and generate at least one second radiation; detector elements configured to detect the at least one second radiation; and at least one computer third arrangement which is configured to determine information regarding the at least one portion based on the detected portions of the at least one second radiation.
2. The apparatus according to claim 1, wherein a path-length difference of the separated and recombined at least one electro-magnetic radiation is substantially the same as a path-length difference of the separated and recombined first radiation.
3. The apparatus according to claim 1, wherein the second arrangement generates a plurality of second radiations, and further comprising: at least one combiner fourth arrangement which is configured to recombine at least two of the second radiations to generate a plurality of self-interfered third radiations wherein the detector elements are configured to detect the third radiations.
4. The apparatus according to claim 3, wherein the third arrangement is further configured to generate Fourier-transform data associated with the at least one particular radiation and the third radiations into transformed data, and wherein the transformed data is indicative of amplitude and phase of the self-interfered first radiation.
5. The apparatus according to claim 3, wherein the second and fourth arrangements are optical fiber arrangements.
6. The apparatus according to claim 1, wherein the information includes data regarding a position of a source of the at least one electro-magnetic radiation provided from the at least one portion of the sample.
7. The apparatus according to claim 1, wherein the at least one first arrangement is a catheter arrangement.
8. The apparatus according to claim 7, wherein the at least one first arrangement includes a phase-plate which introduces a path-length difference between portions of the separated and recombined electro-magnetic radiation so as to produce the self-interfered first radiation.
9. The apparatus according to claim 7, further comprising at least one radiation-providing arrangement which is configured to provide a particular radiation having characteristics to excite at least one fluorophore within the at least one portion so as to cause the at least one electro-magnetic radiation to be provided from the at least one portion.
10. The apparatus according to claim 1, wherein the at least one computer third arrangement determines the information regarding the at least one portion by generating the image of the at least one portion.
11. The apparatus according to claim 1, wherein the first and second arrangements are separate from one another.
12. The apparatus according to claim 1, wherein the detector elements include at least three detector elements which provide at least one of a phase or an amplitude of a spectral modulation of the at least one second radiation.
13. A method for obtaining at least one electro-magnetic radiation from at least one portion of a sample, comprising: receiving the at least one electro-magnetic radiation from the at least one portion, and generating at least one first radiation based on the at least one electro-magnetic radiation, wherein the at least one electro-magnetic radiation is separated and recombined with at least one optical arrangement to be self-interfered to generate the first radiation; receiving, separating and recombining the first radiation with at least one interference arrangement so as to further self-interfere and generate at least one second radiation; and with detector elements, detecting portions the at least one second radiation; using at least one computer arrangement, determining information regarding the at least one portion based on the detected portions of the at least one second radiation.
14. The method according to claim 13, wherein a path-length difference of the separated and recombined at least one electro-magnetic radiation is substantially the same as a path-length difference of the separated and recombined first radiation.
15. The method according to claim 13, further comprising: generating a plurality of second radiations; recombining at least two of the second radiations to generate a plurality of self-interfered third radiations; and with the detector elements, detecting the third radiations.
16. The method according to claim 15, further comprising generating Fourier-transform data associated with the at least one particular radiation and the third radiations into transformed data, wherein the transformed data is indicative of amplitude and phase of the self-interfered first radiation.
17. The method according to claim 13, wherein the information includes data regarding a position of a source of the at least one electro-magnetic radiation provided from the at least one portion of the sample.
18. The method according to claim 13, further comprising providing a particular radiation having characteristics to excite at least one fluorophore within the at least one portion so as to cause the at least one electro-magnetic radiation to be provided from the at least one portion.
19. The method according to claims 13, wherein the determination of the information regarding the at least one portion includes generating the image of the at least one portion.
20. The method according to claim 13, wherein the optical and interference arrangements are separate from one another.
21. The method according to claim 13, wherein the detector elements include at least three detector elements, and further comprising providing at least one of a phase or an amplitude of a spectral modulation of the at least one second radiation using the at least three detector elements.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further objects, features and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the present disclosure, in which:
(2) FIG. 1 is an exemplary graph illustrating a typical self-interference spectrum to explain a spectral modulation;
(3) FIG. 2 is an exemplary graph illustrating a dependence of a phase of the self-interference spectrum on the axial position with respect to the focal plane of the objective of a thin emitting layer, whereas each data point in the graph represents the mean phase calculated from 1024 recorded spectra, the error bars indicate ±1 standard deviation, the imaging NA for this measurement was 0.086 and the Rayleigh length zR was 128 μm, and a linear fit of the central section between −2 and 2 zR yields a slope dφ/dz=−1.31 rad/zR;
(4) FIG. 3 is an exemplary graph illustrating a dependence of the standard deviation of a phase measurement on the signal to noise ratio, whereas the dots are the measured standard deviations of 1024 phase measurements, and the solid line is the theoretical curve σ.sub.φ=1/√{square root over (2)}.Math.SNR;
(5) FIGS. 4(a)-4(e) are a set of illustrations of a comparison of SIFM and confocal microscopy on a three-dimensional distribution of fluorescent microspheres;
(6) FIG. 5 is an exemplary SIFM image of microvasculature in a mouse heart, whereas the image represents a 500×500×60 μm volume of tissue, starting at 15 μm below the tissue surface, the depth of the vessels is grayscale/color-coded, and the deepest layers are displayed in violet and the top layers are displayed in a bright shade;
(7) FIG. 6 is an exemplary SIFM image of 100 nm fluorescent beads in agarose gel, whereas the data represents a 40×40×2 μm volume and the grayscale/color coding shows the detected depth;
(8) FIG. 7 is a diagram of a first exemplary embodiment of a system with a free space two-stage interferometer configuration according to the present disclosure.
(9) FIG. 8 is a diagram of a second exemplary embodiment of a fiber based two-stage interferometer in accordance with the present disclosure.
(10) FIG. 9 is a diagram of a third exemplary embodiment of a fiber based two-stage interferometer in accordance with the present disclosure implemented with a 3×3 fiber coupler as the second stage.
(11) FIG. 10(a) is a graph of a simulated detector response for the three output channels of a two-stage interferometer according to the exemplary embodiment shown in FIG. 1 as a function of the phase of the spectral modulation of the input spectrum;
(12) FIG. 10(b) is a graph of the phase information that is obtained from the information of FIG. 10(a) via a discrete Fourier transform;
(13) In particular, FIG. 11 shows the detector response (in counts per second) and the defocus (in micrometer) applied to the microscope sample stage as a function of time applying the exemplary system and method according to the exemplary embodiments of the present disclosure;
(14) FIG. 12 is a graph providing similar or same results as shown in FIG. 11 and instead of an absolute intensity, an exemplary fractional contribution of each channel to the total intensity is shown in order to take out the effect of the confocal point spread function on the signal intensity;
(15) FIG. 13 a graph of the phase obtained by taking the discrete Fourier transform of the normalized channel data from FIG. 12 and applying the exemplary system and method according to the exemplary embodiments of the present disclosure;
(16) FIG. 14 is a diagram of an exemplary embodiment of the apparatus and system according to an exemplary embodiment of the present disclosure that uses a laser scanning microscope, including a phase plate, to collect the modulated SIFM spectrum;
(17) FIG. 15 is a diagram of an exemplary embodiment of the apparatus and system according to an exemplary embodiment of the present disclosure that uses a STED microscope including a stimulated emission depletion beam in order to perform lateral super resolution imaging combined with SIFM depth localization;
(18) FIG. 16 is a diagram of an exemplary embodiment of the apparatus and system according to an exemplary embodiment of the present disclosure that uses a catheter or endoscopic device to collect the SIFM spectrum;
(19) FIG. 17 is a diagram of still another exemplary embodiment of the apparatus and system according to an exemplary embodiment of the present disclosure that uses two GRIN lenses in a catheter or endoscopic device to collect the SIFM spectrum;
(20) FIG. 18 is a diagram of yet another exemplary embodiment of the apparatus and system according to an exemplary embodiment of the present disclosure that uses two separate optical fibers for excitation and detection in a catheter or endoscopic device using to collect the SIFM spectrum;
(21) FIG. 19 is a diagram of an additional exemplary embodiment that scans the fiber for delivery and detection laterally and relays the fiber tip with an optical system to the sample in order to scan the beam across the sample.
(22) FIG. 20 is a diagram of a further exemplary embodiment of the apparatus and system according to an exemplary embodiment of the present disclosure that rotates the whole assembly of fiber and the imaging optics inside of the catheter sheet in order to scan the beam across the sample.
(23) 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 disclosure 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.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
(24) Thus, detection system and method according to the exemplary embodiment of the present disclosure can be provided, where the phase of a spectral modulation on the spectrum of interest can be obtained with, e.g., only three single point detectors. In addition, the exemplary system according to the present disclosure can include different schemes for an implementation, as well as exemplary methods for processing such data.
(25) FIGS. 4(a)-4(e) show a set of illustrations of a comparison of SIFM and confocal microscopy on a three-dimensional distribution of fluorescent microspheres. For example, FIG. 4(a) illustrates an exemplary SIFM intensity image (100×100 μm), square (4) which can indicate that the area that was compared to a standard confocal stack. FIG. 4(b) illustrates an exemplary SIFM phase image, FIG. 4(c) illustrates an exemplary slice from the SIFM 3D reconstruction, FIG. 4(d) illustrates a corresponding slice from a confocal stack, and FIG. 4(e) shows exemplary SIFM and confocal slices overlapped, with SIFM data displayed in darker and confocal in lighter, and the lightest dots indicating an overlap of both datasets.
(26) In a system according to a first exemplary embodiment of the present disclosure, as shown in FIG. 7, light or other electro-magnetic radiation (10) from a measurement system can be optically processed by a two-stage interferometer to facilitate a determination of both phase and amplitude of a spectral modulation with just three single point detectors. In particular, an electromagnetic spectrum of the light/electro-magnetic radiation (10) can enter the system via a 50/50 beam splitter element (20), and can be partly reflected and partly transmitted. Such spectrum (10) can be transmitted via two mirrors (30), (40) through two variable retarders including rotatable plates (50), (60) onto a second 50/50 beam splitter (70). The retarders (50), (60) can be independently tuned to make it possible to match the optical path difference to the modulation frequency of the input spectrum. The beams/spectrum/radiations exiting the second beam splitter pass through two more variable retarders (80), (90) after which at least one beam is partially transmitted (e.g., about 67%) and partially reflected (e.g., about 33%) by a third beam splitter (100), while the other beam is transmitted to a the last 50/50 beam splitter (120) via a mirror (110). The beam/radiation reflected at the beam splitter 100 can be provided to the beam splitter 120, as well. The three output beams can be provided onto detectors (130), (140), (150).
(27) As shown in FIG. 8 which illustrates another system according to a second exemplary embodiment of the present disclosure, the spectrum of interest can be coupled into the two-stage interferometer via an optical fiber (160). A 50/50 2×2 fiber coupler (170) can couple the light/radiation into two different fibers, at least one of which can extend through a fiber stretcher (180) that can be used to match the optical path difference to the frequency of the spectral modulation on the input spectrum. The light/radiation can be recombined at a second 50/50 2×2 fiber coupler (190). The light/radiation exiting the 2×2 coupler (170) via two fibers then can pass through a 33/67 2×2 coupler (200) and another fiber stretcher (210), respectively, and can be (e.g., partially) recombined at the final 50/50 2×2 fiber coupler (220). The three output fibers can be connected to the detectors (130), (140), (150). The fiber stretchers (180), (210) can be used to tune the optical path lengths OPD1 and OPD2 to the correct value or the desired value.
(28) A first part of the system according to a third exemplary embodiment of the present disclosure is shown in FIG. 9, which can be substantially identical to the system according to the second exemplary embodiment, and instead of two 2×2 couplers (200), (220), a single 33/33/33 3×3 coupler can be used.
(29) FIG. 10(a) shows a graph of an exemplary simulated detector response for the three output channels of a two-stage interferometer according to the exemplary embodiment shown in FIG. 1 as a function of the phase of the spectral modulation of the input spectrum. FIG. 10(b) is a graph of the phase information that is obtained from the information of FIG. 10(a) via a discrete Fourier transform. Thus, FIGS. 10(a) and 10(b) illustrate a simulation of the spectrally integrated detector signals provided by the exemplary system of the first exemplary embodiment of the present disclosure illustrated in FIG. 7, as the phase of the spectral modulation of the input spectrum is varied. For each input phase, e.g., the three detectors can contribute different ratios to the total signal.
(30) By treating these exemplary ratios as three samples in a short signal, the phase and amplitude of the modulation can be obtained in a complex representation as either the second or the third sample in the discrete Fourier transform of this signal (e.g., which can carry the same information since they are complex conjugates of one another). The calculation/determination of this complex number representing the amplitude and phase of the modulation can also be expressed as a sum of the three channels following multiplication of the channels signals by the three discrete complex exponentials 1,
(31)
respectively:
(32)
where I.sub.k is the relative intensity on channel k. The squared magnitude and phase can now be obtained by conversion of the complex number z to the polar representation.
(33) FIGS. 11-13 illustrate a set of exemplary graphs for applying the exemplary system and method according to the exemplary embodiments of the present disclosure to a depth sensitive fluorescence detection with Self Interference Fluorescence Microscopy, as described in, e.g., U.S. Pat. No. 8,040,608.
(34) For example, as shown in the graph of FIG. 11, the measured detector response (in counts per second) and the defocus (in micrometer) is applied to the microscope sample stage as a function of time. This measurement was obtained with a 20× objective from a thin layer of fluorescent dye (a 5 μl drop of a 25 μM LiCor IrDye-800CW solution with 0.1% bovine serum albumin in phosphate buffered saline between cover slips). The sample was scanned in depth by applying a voltage to the z-drive of a piezo-driven microscope stage. The amplitude of the modulation was 45 μm. The sample was excited with a 785 nm laser and the power at the sample was 10 μW. The signals were detected with a 4 channel photon counting module (Excelitas SPCM-AQ4C). The three channels were acquired in parallel at a sampling rate of 10 Hz. The sampling rate was limited by the speed of the piezo stage only, in principle much higher sampling rates of 1 MHz or more can easily be achieved. The spectral modulation on the input spectrum was induced using a coverslip with a 4 mm diameter hole positioned in the back-focal plane of the microscope objective, similar to the description provided in M. De Groot et al. “Self-interference fluorescence microscopy: three dimensional fluorescence imaging without depth scanning,” Optics Express, 20, 15253 (2012).
(35) FIG. 12 shows a graph providing the same or substantially the same results as provided FIG. 11. Further, instead of the absolute intensity, the fractional contribution of each channel to the total intensity is shown in order to take out the effect of the confocal point spread function on the signal intensity. For each time point provided in the illustration of FIG. 6, the sum of the signals of the three channels was calculated, and the signal of each channel was divided by this sum. This exemplary graph illustration of FIG. 12 shows the phase differences in the signals for the three channels which is approximately 120 degrees.
(36) FIG. 13 shows a graph providing the phase obtained by taking the discrete Fourier transform of the normalized channel data from FIG. 12 as described above. The phase can be unambiguously mapped to a certain depth. The phase response may not be completely linear, which is partly due to the imperfect balance between the three channels. This can be improved by better/further alignment and or post processing of the data if required) and partly this is a characteristic of Self-Interference Fluorescence Microscopy. Thus, as shown therein, the phase can be unambiguously mapped to a certain depth.
(37) FIG. 14 shows a diagram of the system according to a fourth exemplary embodiment of the present disclosure. For example, with the exemplary system illustrated in FIG. 14, the SIFM spectrum can be obtained via a laser scanning microscope. An excitation beam/radiation (330) can be deflected by a dichroic mirror (340) to an X,Y scanner (350). The beam/radiation can then be transmitted via a scan lens (360), a folding mirror (370), and a tube lens (380) to a microscope objective (390). The beam/radiation focused on the sample (320) can excite the fluorophores, and the emitted fluorescence can be collected and descanned in the opposite direction. The emission beam/radiation then passes the dichroic mirror, and is transmitted via a SIFM phase plate (280) and a lens (400) through a spatial filter (410) toward the detection interferometer.
(38) The system according to a fifth exemplary embodiment of the present disclosure is shown in FIG. 15. With this exemplary system, the SIFM spectrum can be obtained via a stimulated emission depletion microscope. For example, an excitation beam (330) can be deflected by a dichroic mirror (340). The beam/radiation can then be combined with a second beam (335) that passes through a phase plate (337) to create a donut beam for stimulated emission depletion. Both beams/radiations together can pass through an X,Y scanner (350), and may be transmitted via a scan lens (360) a folding mirror (370) and a tube lens (380) to a microscope objective (390). The two beams/radiations focused together onto the sample can induce fluorescence only from a spot smaller than the diffraction limit. The emitted fluorescence can be collected and descanned in the opposite direction. The emission beam/radiation can then pass the dichroic mirror, and may be transmitted via a SIFM phase plate (280) and a lens (400) through a spatial filter (410) towards the detection interferometer.
(39) FIG. 16 shows the system according to a sixth exemplary embodiment of the present disclosure. With this exemplary system of FIG. 16, the SIFM spectrum can be obtained via a catheter or endoscopic device. For example, a catheter housing (240) can host and/or include an optical fiber (250) that can be used both for excitation and detection. The optical fiber can be a standard single mode fiber or a multiclad fiber that provides light guidance both through the core and multiple claddings. The excitation light/radiation can be provided through the cladding or through the core. The detected fluorescence can be guided through the core to provide the SIFM signal, and the light guided through the claddings can provide additional information on the total fluorescence of the sample. An optional spacer (260) can facilitate the imaging beam/radiation exciting the fiber (320) to expand before it passes through a GRIN lens (270) and a SIFM phase plate (280). Thereafter, the beam/radiation can be deflected by a rotating mirror (290) mounted on a micromechanical motor (300). An end cap (310) can seal the catheter housing.
(40) FIG. 17 illustrates the system according to a seventh exemplary embodiment of the present disclosure. With this exemplary system, the SIFM spectrum can be obtained via a similar catheter or endoscopic device and instead of a single GRIN lens that focuses the beam/radiation, this exemplary system can use two GRIN lenses (270), (285) to focus the beam/radiation onto the sample which can provide a collimated beam at the SIFM phase plate (280).
(41) FIG. 18 shows the system according to an eighth exemplary embodiment of the present disclosure. With this exemplary system, the SIFM spectrum can be obtained via a similar catheter or endoscopic device, and instead of a single optical fiber, two separate fibers can be used for an excitation (285) and detection (280). This configuration uses, e.g., three GRIN lenses (270), (275), (285), and facilitates a separation according to the wavelength with two dichroic mirrors (282), (283).
(42) FIG. 19 illustrates the system according to a ninth exemplary embodiment of the present disclosure. With this exemplary system, the SIFM spectrum can be obtained via a catheter or endoscopic device similar to the exemplary system of the fifth exemplary embodiment, and instead of a rotating mirror that scans the beam/radiation across the sample, the fiber for delivery and detection (250) can be laterally scanned and relayed to the sample with an optical system consisting of two lenses (272), (315) in order to scan the beam/radiation across the sample.
(43) FIG. 20 shows the system according to a further exemplary embodiment of the present disclosure. With this exemplary system, the SIFM spectrum can be obtained via a catheter or endoscopic device similar to the exemplary system of the fifth exemplary embodiment described herein, and instead of a rotating mirror that scans the beam across the sample, the whole assembly of fiber and imaging optics can be rotated inside the stationary catheter housing to scan the beam/radiation across the sample. At least part of the assembly can include an optional spacer (287) and a polished ball lens (292) that can be used to deflect and focus the beam/radiation onto the sample.
(44) The foregoing merely illustrates the principles of the present 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 imaging systems, and for example with those described in U.S. Pat. No. 8,040,608, the disclosure of which is 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 methods which, although not explicitly shown or described herein, embody the principles of the present disclosure and are thus within the spirit and scope of the present disclosure. In addition, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly being incorporated herein in its entirety. All publications referenced herein above are incorporated herein by reference in their entireties.
