KR100868439B1 - Interference System For Polarization Sensitive Optical Coherence Tomography - Google Patents

Abstract

An interference system for a polarization sensitive optical coherence imaging device (PS OCT) includes a sensing interference unit and a signal analyzer. The sensing interference part includes a second light polarized in the first direction and a second light polarized in the first direction through a first optical path passing through the sample stage after the first portion of the linearly polarized first light provided from the light source is reflected from the sample. A third light polarized in a second direction via a second optical path passing through the reference stage, wherein the second optical path is independent of the first optical path, wherein a polarization direction of the second light and the third light is substantially Orthogonal to each other. The signal analyzer generates an interference signal by compensating the first optical path of the second light and the second optical path of the third light, and converts the interference signal into an electrical signal. The sample stage and the reference stage each comprise a polarization controller and at least one linear polarizer for providing the second and third lights that are substantially orthogonal to each other. The sample measuring stage for the biological sample to be measured may be structurally separated from the signal analyzer, and simply by controlling the polarization state of the two orthogonal polarized signals to obtain the biosignal at high speed using only one measuring stage.

Description

Interference System For Polarization Sensitive Optical Coherence Tomography}

1 is a conceptual diagram illustrating an interference system for polarization sensitive optical coherence tomography according to an embodiment of the present invention.

2 is a conceptual diagram illustrating a principle of a birefringent interferometer using a Wolaston prism for extracting interference signals according to an embodiment of the present invention.

3 and 4 are conceptual diagrams for explaining the principle of the polarization component analysis method.

FIG. 5 is a conceptual diagram illustrating an interference system for polarization sensitive optical coherence tomography according to another embodiment of the present invention.

FIG. 6 is a conceptual diagram illustrating a principle of removing a constant voltage background (DC background) noise signal used as a method for improving a signal-to-noise ratio of a measurement signal.

<Explanation of symbols for the main parts of the drawings>

100: sensing interference unit 110: sample measurement stage

120: sensing interferometer 300: signal analysis unit

310: optical path compensator 350: optical signal detector

The present invention relates to an interferrometer system for Polarization Sensitive Optical Coherence Tomography (PS-OCT), and more specifically, polarization for calculating arrangement information of polarization-related biological tissues. The present invention relates to a polarization-maintaining optical fiber based interference system for sensitive optical coherence.

OCT (Optical Coherence Tomography) is a high-definition image recording technology that detects light reflected from the surface of a biological sample using a low-intensity light source, and obtains an image by performing ultra-high-resolution tomography on the inside of the biological superficial part. It is a technology that allows non-invasive imaging and diagnosis of the structure of biological tissues on the mucous membrane, skin, and the lower surface of the eyeball that cannot be seen by endoscopy.

PS-OCT detects light reflected from a biological sample through two orthogonal polarization channels. The principle of operation of PS-OCT is described in US Pat. No. 6,208,415 (named “Birefringence imaging in biological tissue using polarization sensitive optical coherent tomography”).

PS-OCT can be used for the initial diagnosis of malignant skin cancer, etc. In order to be used for the initial diagnosis of malignant skin cancer, it is required to search to the sub-millimeter depth of the biological sample. Searching up to sub-millimeter depth in the PS-OCT is easily possible in laboratory conditions, but in practical applications in clinical applications, external environments such as bending, twisting and temperature changes of probes used as biometrics Since it is difficult to control the polarization state of two orthogonal polarization channels under the influence of the change, there is a problem in that the polarization state must be adjusted periodically.

US Patent No. 7,016,048 (named “Phase-resolved functional optical coherence tomography: simultaneous imaging of the stokes vectors, structure, blood flow velocity, standard deviation and birefringence in biological samples”) discloses a fiber-based PS-OCT system. have. However, the PS-OCT system disclosed in US Pat. No. 7,016,048 uses a mechanically adjustable fiber loop polarizer to mechanically control the polarization state of two orthogonal polarization channels and obtain a biosignal. It takes a long time to process and can only be used in stable laboratory conditions.

Conventional Tugbaev and Myllyla's paper ("Feasibility of a compact fiberoptic prove for real time tracing of subsurface skin birefringence", Proceedings of SPIE, Vol. 5861, 2005) suggests the use of electro-optic switches. It is used to construct a polarization-sensitive biological imaging device. In the conventional Tugbaev and Myllyla papers, since the basic structure uses the Michelson interference method, the position of the electron-liquid-liquid crystal polarizer is positioned at the biological observation terminal, so that the electrons are separated in order to separate the vertical polarization components. -When the light-liquid crystal polarization controller is controlled, the polarization state of light incident on the biological tissue is also changed, which makes it difficult to know the exact polarization-related arrangement information of the biological tissue.

Therefore, in terms of user convenience, instead of mechanically controlling the polarization state, it is possible to simply control it electrically, and in order to know the exact arrangement information of the polarization-related biological tissue, even if the liquid crystal polarization controller is adjusted to the electron-light-liquid crystal polarization controller, There is a need for a PS-OCT system capable of maintaining a constant polarization state of light incident on a target.

Accordingly, an object of the present invention is to provide a polarization-sensitive optical coherence based on a polarization maintaining optical fiber that can structurally separate a sample measuring stage for a biological sample to be measured from a signal analyzing stage and electrically control the polarization state of two orthogonal polarization channels. It is to provide an interference system for a biological imaging device (PS-OCT).

According to one aspect of the present invention for achieving the first object of the present invention, a polarization-maintaining optical fiber-based tandem interferrometer system for polarization sensitive optical coherence tomography is 1). An optical splitter independent of the sample polarization characteristic of distributing the linearly polarized first light provided from the light source into the first and second portions, 2) a mirror reflecting the first portion of the first light, 3) reflected from the mirror A lens for focusing light and irradiating the sample; 4) a sample stage for outputting second light reflected from the sample and polarized in a first direction through a first optical path; and 5) a second portion of the first light The second light path, where the second light path is independent of the first light path, and the third light polarized in the second direction, wherein the polarization directions of the second light and the third light are substantially orthogonal to each other. Output machine 6) a sensing interference part including a polarized light splitter into which the second light and the third light are incident; and 1) compensating the first light path of the second light and the second light path of the third light. A light path compensator for generating an interference signal, 2) a linear polarizer for receiving the interference signal, and 3) a signal analyzer for converting an output of the linear polarizer into an electrical signal to detect an interference pattern. Include. The sample stage and the reference stage may each include a polarization controller and at least one linear polarizer for providing the second and third lights that are substantially orthogonal to each other. The optical signal detector may include a lens connected to the output of the linear polarizer, and a linear detector array configured to detect an interference pattern by converting an output of the lens connected to the output of the linear polarizer into the electrical signal. The low coherence light source may be coupled to a first polarization sustaining optical fiber, the sample end may include a second polarization sustaining optical fiber, and the reference end may include a third polarization sustaining optical fiber. The first, second and third polarization maintaining optical fibers may comprise a flexible cable. The sensing interference unit may further include a quarter-wave retarder for circularly polarizing the light passing through the first polarization maintaining optical fiber. The quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization controller of the sample stage, at least one linear polarizer of the sample stage, at least one linear polarizer of the reference stage, the mirror and the lens May be included in a handheld probe, where the handheld probe is connected to the flexible cable. A quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization controller of the sample stage, at least one linear polarizer of the sample stage, the mirror and the lens are handheld probes, wherein the handheld probe is Connected to the flexible cable. The flexible cable may be an elliptical core polarization maintaining fiber. The polarization controller of the sample stage and the polarization controller of the reference stage may include a bistable ferroelectric liquid crystal rotator operating as a bistable high speed electro-optical switch. The linear detector array calculates a difference between an in-phase interferogram in antiphase and an anti-phase interferogram in antiphase. ), The interference signal can be detected.

In addition, the interference system for Polarization Sensitive Optical Coherence Tomography according to another aspect of the present invention for achieving the first object of the present invention is that the first portion of the linearly polarized first light provided from the light source A second light polarized in a first direction via a first light path that is reflected from the sample and then passes through the sample stage and a second light path where the second portion of the first light passes through the reference stage, wherein the second light path A sensing interference unit providing a third light polarized in a second direction through the first optical path, wherein the polarization directions of the second light and the third light are substantially orthogonal to each other; And a signal analyzer configured to generate an interference signal by compensating the first optical path of the light and the second optical path of the third light, and then converting the signal into an electrical signal. The light source may be coupled to a first polarization maintaining optical fiber, the sample end may include a second polarization maintaining optical fiber, and the reference end may include a third polarization maintaining optical fiber. The sample stage and the reference stage may each include a polarization controller and at least one linear polarizer for providing the second and third lights that are substantially orthogonal to each other. The sensing interference unit focuses a light splitter independent of a sample polarization characteristic of distributing the first light into the first and second portions, a mirror reflecting the first portion of the first light, and light reflected from the mirror. And a sample stage for outputting a lens irradiated to the sample, a second light reflected from the sample and polarized in a first direction through the first optical path, and a second portion of the first light is connected to the second optical path. And a sensing interferometer including a reference terminal for outputting third light polarized in a second direction and a polarized light splitter to which the second light and the third light are incident. The sensing interferometer may further include a quarter-wave retarder for circularly polarizing the light passing through the first polarization maintaining optical fiber. The quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization controller of the sample stage, at least one linear polarizer of the sample stage, at least one linear polarizer of the reference stage, the mirror and the lens May be included in a handheld probe, where the handheld probe is connected to a flexible cable. A quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization regulator of the sample stage, at least one linear polarizer of the sample stage, the mirror and the lens are handheld probes, wherein the handheld probe May be included in the connection to the flexible cable. The signal analyzer may include an optical path compensator configured to generate an interference signal by compensating the first optical path of the second light and the second optical path of the third light by using a Wolaston prism and the interference signal. The linear polarizer may include an optical signal detector configured to detect an interference pattern by converting an output of the linear polarizer into an electrical signal. The interference system may have one sample measuring stage including an optical splitter, the mirror and the lens independent of the sample polarization characteristic.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

1 is a conceptual diagram illustrating an interference system for polarization sensitive optical coherence tomography according to an embodiment of the present invention.

The interference system for the polarization-sensitive optical coherence biological imaging device is largely composed of a sensing interference unit 100 and a signal analyzer 300.

The sensing interference unit 100 includes a light source 10, a polarization maintaining optical fiber 12, a light concentrator 13, a mirror 14, and a sensing interferometer 120. The sensing interferer 100 may be configured in a first direction through a first optical path passing through a sample arm after the first portion of the linearly polarized first light provided from the light source 10 is reflected from the sample 19. The polarized light splitter 25 provides a third light polarized in a second direction through a second optical path through which the second polarized light and the second portion of the first light pass through a reference arm. Here, the polarization directions of the second light and the third light are substantially perpendicular to each other. Here, the second optical path is independent of the first optical path. The sample stage consists of the optical splitter 16 and the components 17 to 25, and the reference stage comprises the optical splitter 16 and the components 26 to 36 and 25. The first light path is after the linearly polarized first light provided from the light source 10 is distributed by the optical splitter 16 independent of the sample polarization properties and after the first portion of the first light is reflected from the sample 19 The optical path through the sample arm and before the polarization optical splitter 25 is shown, and the second optical path is the optical splitter 16 in which the linearly polarized first light provided from the light source 10 is independent of the sample polarization characteristics. And the second portion of the first light passes through the reference arm and before the polarized light splitter 25 is distributed. The sensing interferometer 120 includes components 15, 16, 20, and 35.

The signal analyzer 300 includes an optical path compensator 310, a linear polarizer 39, and an optical signal detector 350. The signal analyzer 300 generates an interference signal by compensating the first optical path of the second light and the second optical path of the third light, and then converts the signal into an electrical signal.

The optical path compensator 310 generates an interference signal by compensating for the first optical path of the second light and the second optical path of the third light by using a Wolaston prism 38. The light path compensator 310 includes a light size expander 37 and a Wolaston prism 38. The linear polarizer 39 receives the interference signal.

The optical signal detector 350 detects the interference pattern by converting the output of the linear polarizer 39 into an electrical signal. The optical signal detector 350 includes lenses 40 and 42 connected to an output of the linear polarizer 39 and a linear detector array 41 for converting an output of the lenses 40 and 42 into the electrical signal to detect an interference pattern. ).

The sample measuring stage 110 includes an optical concentrator 13, a mirror 14, a quarter-wave retarder 15, an optical splitter 16 independent of sample polarization characteristics, a mirror 17, A lens 18, a polarizer 20, a linear polarizer 21, an optical concentrator 22, a linear polarizer 26, a mirror 27 and an optical concentrator 28, and a sample 19. Configure a handheld probe to measure.

The low-coherent light source 10 has a linearly polarized output light characteristic and is connected to the optical concentrator 13 by a polarization-maintaining fiber 12.

The output light source from the light concentrator 13 is linearly polarized. For example, the output light source exiting the light collector 13 has a linearly polarized state in a direction perpendicular to the plane of FIG. 1.

The output light in the linearly polarized state is reflected by the mirror 14 and passes through a quarter-wave retarder 15, and then changes in a circularly polarized state. 16).

Half of the light in the circularly polarized state divided by the optical splitter 16 irrespective of the polarization property is the sample 19 having birefringence characteristics through the sample scanning mirror 17 and the focusing lens 18. Is investigated.

Light reflected at each inner boundary of the sample 19 then passes through the optical splitter 16 with an arbitrary polarization state and irrelevant to the polarization characteristics. The light reflected from the sample 19 is then passed through a polarizer 20 that can be adjusted to 45 ° and 0 ° and a linear polarizer 21 that is adjusted to 0 ° and then by the light concentrator 22. The light is focused and transmitted to the polarization maintaining optical fiber 23 and then incident to the polarizing beam combiner 25 by the light concentrator 24. The incident light is polarized at 0 °. According to an embodiment of the present invention, the polarization controller 20 may be adjusted to enable switching between 45 ° and 0 ° using an external driver although not shown in the drawing.

Here, the polarization controller 20 may also be used other polarization controller that can switch the polarization control state between 45 ° and 0 °. For example, the polarization controller 20 may use an electro-optic phase modulator or an electron-liquid-crystal polarization regulator having birefringent properties.

In addition, the other half of the circularly polarized light divided by the optical splitter 16 irrespective of the polarization characteristic passes through the linear polarizer 26 adjusted to 0 ° and then to the mirror 27 and the optical concentrator 28. After the light is focused and transmitted to the polarization maintaining optical fiber 29, the light intensity is properly adjusted while passing through the linear polarizers 31 and 32 by the optical concentrator 30, and then the polarization maintaining optical fiber 34 is again controlled by the optical concentrator 33. After the light is focused and transmitted, the light is incident on the polarization controller 36 and the polarization light splitter 25 which can be adjusted by 45 ° and 0 ° by the optical concentrator 35. At this time, the light incident on the polarization splitter 25 is polarized at 45 °. According to one embodiment of the present invention, the polarization controller 36 may be adjusted to enable switching between 45 ° and 0 ° using an external driver although not shown in the drawing.

Here, the polarization controller 36 may also be used other polarization controller that can switch the polarization control state between 45 ° and 0 °. For example, the polarization regulator 36 may use an electro-optic phase modulator or an electron-liquid-crystal polarization regulator having birefringent properties.

In the polarization splitter 25, the light passing through the sample stage and the light passing through the reference stage are combined and then incident to the birefringent prism 38 through a beam expander 37. One embodiment of the present invention employs a Wolaston prism as the birefringent prism 38.

In addition, the distance between the light concentrator 30 and the light concentrator 33 may be finely adjusted to adjust the overall optical path difference.

In addition, in one embodiment of the present invention using the polarization maintaining optical fibers (12, 23, 29) to ensure easy access to the biological tissue to be actually measured, the sample measuring stage ( 110 may be structurally separated from the signal analysis unit 300. Reference numerals 13 to 18, 20 to 22, and 26 to 28 are placed inside the handheld probe for user convenience, and the handwheel probe is connected to the entire system through the polarization maintaining optical fibers 12, 23, 29. Can be connected.

In an embodiment of the present invention, a Mach-Zehnder interferometer scheme may be used to construct a sensor intersometer of a tandem interferometer.

In addition, in the exemplary embodiment of the present invention, the sample arm of the Mach-Zehnder interferometer is configured using the optical splitter 16 and the components 17 to 25, and the optical splitter 16 The reference arm of the Mach-Zehnder interferometer is configured using the elements 26 to 36 and 25 to form a Mach-Zehnder interferometer.

The Mach-Zehnder interferometer for the sample stage configured as described above has several advantages over the conventional method. Since the Michelson interference method is conventionally used, the position of the electron-light-liquid crystal polarization controller is located at the biological observation stage, and when the electron-light-liquid crystal polarization controller is adjusted to separate the vertical polarization component, The polarization state of the light incident on the tissue is also changed, so it is difficult to know the exact polarization arrangement information of the biological tissue.

However, in the tandem interference method used in the embodiment of the present invention, the polarization controller 20 of the sample stage and the polarization controller 36 of the reference stage are irrelevant to the bioobservation stage. Since it is positioned afterwards, the polarization state of the light incident on the biological tissue object may be kept constant regardless of the control of the polarization controllers 20 and 36. Therefore, it is possible to know the arrangement information of the precise polarization-related biological tissue.

2 is a conceptual diagram illustrating a principle of a birefringent interferometer using a Wolaston prism for extracting interference signals according to an embodiment of the present invention.

In an embodiment of the present invention, a birefringent interferometer using a Wolaston prism is configured to construct an interferometer for signal extraction of a tandem interferometer, and in addition, a reference code may be applied to a polarization-sensitive photocoherence biological imaging device (PS-OCT). Use an altered structure consisting of 37 to 42 components.

As shown in FIG. 2, assuming that the sample 19 has a three-layer structure having birefringence characteristics, the light reflected from the sample 19 has an optical path length difference between each other. In addition, the light reflected from the sample 19 has a vertical (or horizontal) polarization state while passing through the optical system of the polarization controller 20 and the linear polarizer 21.

The light reflected from the center of the sample 19 is adjusted to have the same light path as the light from the reference stage, so that the light from the reference stage is reflected from the light reflected from the center plane of the sample 19. Does not have a wide path.

However, the light reflected from the left side of the sample 19 has a light path difference (-τ) corresponding to the light traveling from the reference stage and the left side thickness d of the sample 19. In addition, the light reflected from the right side of the sample has a light path difference (+ τ) corresponding to the thickness d of the right side of the sample and the light propagated from the reference stage.

The optical path difference between the left and right sides and the light propagated at the reference section must be canceled to obtain interference with each other and to obtain thickness information of the sample 19. For this purpose, a vertical polarization characteristic between the light of the sample stage and the light of the reference stage is used. As shown in FIG. 2, the light of the sample stage is all vertically polarized and the light of the reference stage is horizontally polarized.

On the left side (ne <no) of the Wollaston prism 38, the light in the horizontally polarized light proceeds slowly compared to the light in the vertically polarized light, and on the right side (ne> no) the light in the vertically polarized light is It is slower than that. The Wollaston prism 38 is configured such that the thickness ratio of the left and right surfaces having these different characteristics is smaller at the top of the prism 38 and is equal at the center, and becomes larger as it descends to the bottom.

The Wolaston prism 38 serves to compensate the optical path difference.

When the light of the sample stage and the light of the reference stage are irradiated to the Wollaston prism 38 having the birefringence property, the thickness of the left side and the right side of the prism 38 is the same in the exact center of the prism 38. An interference fringe generated by the light reflected from the center plane of the sample 19 without the optical path difference between the light (vertical polarization) and the light at the reference stage (horizontal polarization) and light at the reference stage occurs near the center of the axis.

On the other hand, since the thickness of the left side of the prism is thinner than the thickness of the right side at the top of the prism 38, the light passing through the prism 38 has the light of the sample stage (vertical polarization) than the light of the reference stage (horizontal polarization). Slowly proceeding interference patterns caused by light reflected from the right side of the sample (19) whose light path difference between the light at the sample stage (vertical polarization) and the reference stage (horizontal polarization) is + τ And an interference fringe is generated at the lower end of the axis as the interference fringe passes through the magnification lens 40 as shown in FIG.

In addition, since the thickness of the left side of the prism is thicker than the thickness of the right side at the lower end of the prism 38, the light passing through the prism 38 has the light of the sample stage (vertical polarization) than the light of the reference stage (horizontal polarization). As soon as the optical path difference between the light at the sample stage (vertical polarization) and the light at the reference stage (horizontal polarization) is -τ, the interference pattern caused by the reflected light from the left side of the sample and the light at the reference stage is the prism (38). ), And the interference fringe is generated at the upper end of the axis while passing through the magnification lens 40 as shown in FIG. 2.

Referring back to FIG. 1, each of the interference fringes generated as described above is concentrated in one direction by the lens 42 to increase the signal-to-noise ratio, and then is applied to the linear detector array 41. Is converted into an electrical signal and measured. The linear detector array 41 may be, for example, a CCD detector array.

3 and 4 are conceptual diagrams for explaining the principle of the polarization component analysis method. In order to investigate the birefringence characteristic of the sample 19, the polarization component of the light reflected from the sample is irradiated by dividing it into a vertical (V) component and a horizontal (H) component. To this end, in an embodiment of the present invention, the electron-light-liquid crystal polarization controller 20 and the linear polarizer 21 which can adjust the polarization state of light to 45 ° and 0 ° are used.

First, as shown in FIG. 3, when the electron-light-liquid crystal polarization controller 20 is set to 45 ° and then passed through the light 43 reflected from the sample 19, the horizontal (H) component of the light 43 is vertically lighted. The light 44 whose vertical (V) component of (43) is horizontally adjusted in polarization state comes out. The light 44 passing through the electron-light-liquid crystal controller 20 passes through the linear polarizer 21 set to 0 ° again, filtering only the horizontal component and reflecting the vertical (V) of the light 43 reflected from the first sample. ) Only components remain.

Similarly, as shown in FIG. 4, when the electron-light-liquid crystal polarization controller 20 is set to 0 ° and then passed through the light 43 reflected from the sample 19, the horizontal (H) component of the light 43 is perpendicular to the horizontal (H) component. The intensity of the light passes through it and the light 44 'changes only in the entire axial direction. The light 44 ′ passing through the electron-light-liquid crystal polarizer 20 passes through the linear polarizer 21 which is set to 0 ° again, filtering only the vertical components and reflecting the horizontality of the light 43 reflected from the first sample. Only the H) component remains.

Therefore, in one embodiment of the present invention, the polarization control state of the electron-light-liquid crystal polarization controller 20 may be electrically controlled at 45 ° and 0 ° to separate and extract the polarization component of the sample.

FIG. 5 is a conceptual diagram illustrating an interference system for polarization sensitive optical coherence tomography according to another embodiment of the present invention.

Referring to FIG. 5, basically, a combination of an optical fiber optical signal distributor 25a, polarization maintaining optical fibers 25b, 25c, and an optical concentrator 25d may be applied instead of the polarization optical splitter 25 of FIG. To ensure the stability. Furthermore, in order to construct a more efficient biosignal measurement stage, the positions and configurations of some optical systems were changed in the structure of FIG. 1. That is, the quarter wavelength retarder 15 is replaced with the position of the quarter wavelength retarder 15a, and the linear illuminator 26 is replaced with the position of the linear illuminator 26a. ) Is replaced by the combination of the light concentrator 37a and the lens 37b. The rest of the rest is the same as the configuration of FIG.

FIG. 6 is a conceptual diagram illustrating a principle of removing a constant voltage background (DC background) noise signal used as a method for improving a signal-to-noise ratio of a measurement signal.

The electron-light-liquid crystal polarization regulator 36, which is a component of the present invention, can be phase-adjusted by half wavelength of light, and by using this, a linear detector array according to the polarization control state of the electron-light-liquid crystal polarization regulator 36 As shown in the second and third graphs of FIG. 6, the signal measured in FIG. 41 obtains an in-phase interferogram in antiphase and an anti-phase interferogram in antiphase. In this case, since the DC noise of the background is constant regardless of the interference pattern measurement signal of the positive phase type and the interference pattern measurement signal of the antiphase type, when the two signals are subtracted from each other, the fourth graph of FIG. Similarly, the surrounding constant voltage noise signal is removed and only the interference fringe signal remains. Therefore, it is possible to obtain a bio-image without additional signal processing of Fourier signal conversion for bio-image reconstruction and without distortion of the signal.

According to embodiments of the present invention, it has several advantages as described above.

First, in the case of the conventional polarization-sensitive photocoherence biological imaging device (PS-OCT), two independent measurement stages are used to distinguish and measure the vertically polarized components of light. However, in the embodiments of the present invention, instead of using two measurement stages, the polarization component may be separated using the electron-light-liquid crystal polarization controller 20 and the linear polarizer 21 so that only one measurement stage may be used. It can be measured.

Second, in the embodiments of the present invention, polarization maintaining optical fibers 12, 23, and 34 may be used to secure easy access to the biological tissue to be measured, and the sample measuring stage may be provided to ensure the ease of use of the end user. It is structurally separated from the signal analyzer.

Third, in the embodiments of the present invention, the fast switching of the polarization control state is possible by using only the electrical signal using the electron-light-liquid crystal polarization controller 20, thereby enabling the fast biosignal acquisition.

Fourth, the embodiments of the present invention remove the constant voltage ambient noise signal used as a method for improving the signal-to-noise ratio of the measurement signal, so that the bio-image may be removed without additional signal processing and signal distortion during Fourier signal conversion for reconstruction of the bio-image. To get it.

According to the interference system for a polarization-sensitive optical coherence imaging device (PS-OCT) as described above, the sample measuring stage for the biological sample to be measured is structurally separated from the signal analyzer and the electron-light-liquid crystal polarization controller 20 is By using only an electrical signal can be controlled to quickly switch the polarization state of the two orthogonal polarization channels it is possible to obtain a bio-signal at high speed.

In addition, in the case of the interference system for polarization-sensitive optical coherence imaging device (PS-OCT) using the Michelson interference method in which the position of the existing electron-light-liquid crystal polarization controller is located at the biological observation stage, To solve the problem of difficult to know the arrangement information of the biological tissue, the position of the polarization controller 20 and the polarization controller 36 of the reference stage is positioned after the polarization irrelevant light splitter 16 irrelevant to the biological observation stage In this case, the light path through the sample stage and the light path through the reference stage can be independently controlled. Therefore, irrespective of the control of the polarization controllers 20 and 36, the polarization state of the light incident on the biological tissue object can be kept constant and accurate array information of the polarization-related biological tissue can be known.

In addition, unlike in the case of the conventional polarization-sensitive optical coherence imaging device (PS-OCT), instead of using two independent measurement stages to distinguish and measure the vertically polarized components, instead of the two measurement stages, -The polarization component can be separated by using the light-liquid crystal polarizer and the linear polarizer, so it can be measured with only one measuring stage.

In addition, by removing the constant voltage ambient noise signal used as a method for improving the signal-to-noise ratio of the measured bio-signals, a bio-image may be obtained without additional signal processing and signal distortion during Fourier signal conversion for bio-image restoration.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (20)

In a polarization-maintaining optical fiber based tandem interferrometer system for polarization sensitive optical coherence tomography, 1) a light splitter independent of the sample polarization characteristic of distributing the linearly polarized first light provided from the light source into the first and second portions, 2) a mirror reflecting the first portion of the first light, 3) from the mirror A lens for focusing the reflected light and irradiating the sample; 4) a sample stage for outputting a second light reflected from the sample and polarized in a first direction through a first optical path; 5) a second portion of the first light A third light polarized in a second direction via the second optical path, wherein the second optical path is independent of the first optical path, wherein the polarization directions of the second light and the third light are orthogonal to each other; 6) a sensing interference unit including a polarization optical splitter to which the second light and the third light are incident; And 1) an optical path compensator for generating an interference signal by compensating the first optical path of the second light and the second optical path of the third light, 2) a linear polarizer receiving the interference signal, and 3) the linear polarizer Tandem interference system comprising a signal analysis unit including an optical signal detection unit for converting the output of the signal to an electrical signal to detect the interference pattern. The tandem interference system of claim 1, wherein the sample stage and the reference stage each comprise a polarization controller and at least one linear polarizer for providing the second and third light orthogonal to each other. The method of claim 2, wherein the optical signal detector A lens coupled to the output of the linear polarizer; And And a linear detector array configured to detect an interference pattern by converting an output of a lens connected to the output of the linear polarizer into the electrical signal. The tandem interference system of claim 3, wherein the light source is coupled to a first polarization sustaining optical fiber, the sample end comprises a second polarization sustaining optical fiber, and the reference end comprises a third polarization sustaining optical fiber. . The tandem interference system of claim 4, wherein the first, second and third polarization maintaining optical fibers comprise a flexible cable. The tandem interference system of claim 5, wherein the sensing interference unit further comprises a quarter-wave retarder for circularly polarizing the light passing through the first polarization maintaining optical fiber. 7. The apparatus of claim 6, wherein the quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization controller of the sample stage, at least one linear polarizer of the sample stage, and at least one linear polarizer of the reference stage The mirror and the lens are included in a handheld probe, And the hand held probe is coupled to the flexible cable. The handheld probe of claim 6, wherein a quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization controller of the sample stage, at least one linear polarizer of the sample stage, the mirror, and the lens are a handheld probe. Included in And the hand held probe is coupled to the flexible cable. 6. The tandem interference system of claim 5, wherein the flexible cable is an elliptic core polarization maintaining fiber optic fiber. 10. The method of claim 9, wherein the polarization controller of the sample stage and the polarization controller of the reference stage comprise a bistable ferroelectric liquid crystal rotator operating as a bistable high speed electro-optical switch. Tandem interference system. The background detector of claim 3, wherein the linear detector array obtains a difference between an in-phase interferogram in antiphase and an anti-phase interferogram in antiphase. And a tandem interference system for detecting the interference signal by removing a constant voltage noise signal. The first portion of the linearly polarized first light provided from the light source is reflected from the sample and then the second light polarized in the first direction through the first optical path passing through the sample stage and the second portion of the first light A third light polarized in a second direction via a second light path passing through, wherein the second light path is independent of the first light path, wherein the polarization directions of the second light and the third light are perpendicular to each other; Sensing interference unit for providing; And And a signal analyzer for compensating the first optical path of the second light and the second optical path of the third light to generate an interference signal and converting the signal into an electrical signal. Interference system for Polarization Sensitive Optical Coherence Tomography. The polarization sensitive light of claim 12, wherein the light source is coupled to a first polarization maintaining optical fiber, the sample end comprises a second polarization maintaining optical fiber, and the reference end comprises a third polarization maintaining optical fiber. Coherence system for biological imaging equipment. The polarization-sensitive photocoherence biological image of claim 13, wherein each of the sample stage and the reference stage includes a polarization controller and at least one linear polarizer for providing the second and third light orthogonal to each other. Interference system for equipment. The method of claim 14, wherein the sensing interference unit An optical splitter independent of sample polarization characteristics for distributing the first light to the first and second portions, a mirror for reflecting the first portion of the first light, and the light reflected from the mirror to focus on the sample; A lens for irradiating, a sample stage for outputting second light reflected from the sample and polarized in a first direction through the first optical path, and a second portion of the first light passing through the second optical path in a second direction And a sensing interferometer including a reference stage for outputting the third polarized light and a polarized light splitter to which the second light and the third light are incident. 2. 16. The interference system of claim 15, wherein the sensing interferometer further comprises a quarter-wave retarder for circularly polarizing the light passing through the first polarization maintaining optical fiber. 17. The system of claim 16, wherein the quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization controller of the sample stage, at least one linear polarizer of the sample stage, and at least one linear polarizer of the reference stage. The mirror and the lens are included in a handheld probe, And said hand-held probe is connected to a flexible cable. 17. The handheld probe of claim 16, wherein a quarter-wave retarder, an optical splitter independent of the sample polarization characteristic, a polarization regulator of the sample stage, at least one linear polarizer of the sample stage, the mirror and the lens are handheld probes. Included in And said hand-held probe is connected to a flexible cable. The method of claim 14, wherein the signal analysis unit An optical path compensator configured to generate an interference signal by compensating the first optical path of the second light and the second optical path of the third light by using a Wolaston prism; A linear polarizer receiving the interference signal; And an optical signal detector for converting an output of the linear polarizer into an electrical signal to detect an interference pattern. 15. The interference system of claim 14, wherein the interference system has one sample measuring stage including an optical splitter, the mirror, and the lens irrelevant to the sample polarization characteristic.

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