CN203720071U - Polarization frequency domain optical coherence tomography system based on single detector - Google Patents

Abstract

A polarization frequency domain optical coherence tomography system based on a single detector comprises a low-coherence light source, a first collimator, a polarizer, a Michelson interferometer, a polarization beam splitter, a second collimator, a first optical fiber, a third collimator, a fourth collimator, a second optical fiber, a fifth collimator, a grating, a cylindrical lens and a detector. The utility model discloses a system architecture has been simplified to single detector, has avoided the asynchronous problem of time that exists when two detectors gathered the signal, simultaneously the utility model discloses well two way light all shines the grating with the incident angle of highest diffraction efficiency, and the improvement of diffraction efficiency has increased the SNR of system, has improved image quality.

Description

Polarization Frequency Domain Optical Coherence Tomography System Based on Single Detector

technical field

The utility model relates to a Polarization-sensitive Fourier Domain Optical Coherence Tomography (PS-FD-OCT) system, in particular to a polarization-sensitive Fourier Domain Optical Coherence Tomography system based on a single detector.

Background technique

Optical coherence tomography (Optical Coherence Tomography, OCT) is a technique developed in the past 20 years that can perform tomographic imaging of biological tissues. It has the characteristics of high resolution and non-invasiveness. In traditional OCT, it is believed that the characteristics of the light reflected back to the detector at different depths of the sample are different, and this principle is used to obtain structural information inside the sample. But the polarization of light exists in many biological tissues. When a lesion occurs somewhere in the tissue, the reflectance and birefringence of the tissue will change, thereby changing the intensity and polarization state of the reflected light in the tissue. The contrast of traditional OCT tomographic images of biological tissues with birefringence properties (such as muscles, teeth, etc.) is not ideal, and it cannot show the layered tissue properties of biological tissues with birefringence properties. To this end, Hee et al. developed polarization OCT (Polarization-Sensitive optical coherencetomography, PS-OCT) technology, especially the polarization frequency domain OCT (PS-FD-OCT) developed in recent years, which has fast imaging speed, signal-to-noise Advantages over higher grades. PS-FD-OCT is very sensitive to the polarization characteristics of biological tissue. Using polarized light to image the sample can improve the actual resolution and imaging contrast of the system. Not only can the intensity image of the tissue be obtained, but also the delay image and fast axis of the tissue can be obtained at the same time. The image provides more basis for a better understanding of the internal information of the sample, and can observe the internal structure of the sample more comprehensively.

In the PS-FD-OCT system, the broadband light is transformed into linearly polarized light by the polarizer, and then divided into two beams by the beam splitter, one of which is irradiated on the sample after passing through the wave plate, imaging objective lens, etc., and the other beam After passing through the wave plate and adjustable attenuation plate, it is irradiated onto the reference mirror, and the light reflected from different depths of the sample and the light reflected from the reference mirror are coherently superimposed at the beam splitter, and then the coherent light is split through the polarization beam splitter After that, it is divided into two beams of horizontal polarization and vertical polarization, which are respectively split by the gratings in the two spectrometers and then focused by the lens and recorded by the detector (see prior art [1], E, Baumann B, Pircher M, and Christoph K. Hitzenberger, “Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography”. Optics Express, 2009, 17(25):22704.). The system using dual detectors is complex, and the detector hardware and software triggers of the two spectrometers require high synchronization requirements, otherwise the signal acquisition between the two detectors will cause a time delay. Bernhard et al. used two beams of horizontally polarized light and vertically polarized light to be incident on the grating at the same time, and the light is emitted from the grating at different diffraction angles, and the method of detecting the two signals in the adjacent area of a linear array CCD is used to realize the polarization detection of the sample (see Prior Art [2], Bernhard Baumann, Erich Michael Pircher, and Christoph K. Hitzenberger, "Single camera based spectral domain polarization sensitive optical coherence tomography". Optics Express, 2007, 15(3):1054.). When the light is incident at the Littrow angle, the diffraction efficiency is the highest, but in order to ensure that the two beams of light exit the grating at different appropriate diffraction angles, the incident angles of the two beams of light deviate from the Littrow angle by a certain angle. The OCT signal is relatively weak, and the higher the diffraction efficiency, the better the signal-to-noise ratio of the system. The incidence of light at an angle deviating from the Littrow angle reduces the diffraction efficiency, reduces the system signal-to-noise ratio, and degrades the image quality. In order to ensure horizontally polarized light and vertically polarized light All have relatively high diffraction efficiency, and the deviation angle needs to be calculated accurately and cannot be too large, which increases the difficulty of system adjustment.

Contents of the invention

In view of the above problems, the purpose of this utility model is to provide a polarization frequency domain optical coherence tomography system based on a single detector. The problem of time asynchrony, while improving the signal-to-noise ratio of the system, improves the image quality.

The technical solution of the present utility model is as follows:

A polarization-frequency-domain optical coherence tomography system based on a single detector is characterized in that it includes a low-coherence light source, a first collimator, a polarizer, a Michelson interferometer, a polarization beam splitter, and a second collimator The first collimator, the first optical fiber, the third collimator, the fourth collimator, the second optical fiber, the fifth collimator, the grating, the cylindrical lens and the detector; the light emitted by the low-coherence light source passes through the first collimator in sequence , After the polarizer becomes polarized light, it is coupled into the beam splitter of the Michelson interferometer. The beam splitter divides the beam into the reference arm optical path and the sample arm optical path. On the reference mirror, the light from the sample arm passes through the quarter-wave plate and then passes through the two-dimensional vibrating mirror and is focused by the imaging objective lens into the sample to be tested. The reference light reflected back interferes at the beam splitter; the output end of the Michelson interferometer is connected to a polarization beam splitter, which divides the interference beam into two paths of horizontally polarized light and vertically polarized light, The horizontally polarized light is coupled into the first optical fiber through the second collimator, and is incident on the grating in parallel after passing through the third collimator at the other end of the first optical fiber, and the vertically polarized light is collimated through the fourth collimator Coupled into the second optical fiber, the other end of the second optical fiber is parallel incident on the grating after passing through the fifth collimator. After the light is split, it is imaged on different areas of the same detector by the cylindrical lens at the same time, and the horizontal polarization signal and the vertical polarization signal are detected at different positions of the detector at the same time. The two signals are collected by the image acquisition card and sent to the computer for further processing. Data processing to obtain the intensity image, retardation image and fast axis direction image of the sample.

The detector is an area array CCD or other area array detector array with photoelectric signal conversion function and capable of simultaneously detecting at least two signals.

The grating is a transmission grating or a reflection grating.

The low-coherence light source is a broadband light source with a spectral bandwidth of tens of nanometers to hundreds of nanometers, including light-emitting diodes (LEDs) or superluminescent light-emitting diodes (SLDs) or femtosecond lasers or supercontinuum light sources.

The Michelson interferometer has two interference optical paths close to equal optical paths, which are respectively a reference arm and a sample arm, and adopts one of a fiber-optic Michelson interferometer and a spatial Michelson interferometer; the reference arm optical path includes A quarter-wave plate and a reference mirror, the sample arm optical path includes a quarter-wave plate, a two-dimensional vibrating mirror, an imaging objective lens, and a sample; the beam splitter in the Michelson interferometer is a non-polarization-sensitive beam splitter .

The reference mirror adopts an optical device capable of returning the broadband light according to the original propagation path; the imaging objective lens adopts an optical device capable of focusing the broadband light incident on the sample.

The beam splitter connected to the output end of the Michelson interferometer is a polarization sensitive beam splitter, a beam splitting prism or a fiber optic polarization beam splitter.

The system works as follows:

After the light emitted by the low-coherence light source is collimated, it becomes linearly polarized light after passing through a polarizer whose main axis direction is horizontal or vertical, and is coupled into a Michelson interferometer. The non-polarizing beam splitter of the Michelson interferometer divides the light into reference Light path and sample light path. The light in the reference optical path passes through a quarter-wave plate and then irradiates on the reference mirror, and passes through the quarter-wave plate again after being reflected by the reference mirror; the light in the sample optical path passes through a quarter-wave plate and passes through the After the galvanometer and focusing lens are irradiated onto the sample, due to the influence of the random polarization state inside the sample, the polarization state of the light reflected by the sample is a random polarization state, and the reflected light from the sample passes through the sample arm quarter-wave plate again to return to the sample. to the beam splitter. The reference light and the sample light converge at the beam splitter of the Michelson interferometer to generate interference, and are split into two polarized lights, horizontal H and vertical V, through a polarization-sensitive beam splitter. These two polarized lights are respectively coupled into two optical fibers, and then After the other ends of the two optical fibers are collimated by the lens, they can be incident on the upper and lower regions of the same grating at an incident angle with high diffraction efficiency, which are respectively marked as A and B regions. The light split by the grating A and B regions passes through the same Cylindrical lens, because the cylindrical lens only focuses in one direction, so the H and V polarized light respectively form a rectangular light spot after passing through the cylindrical lens, which are respectively detected by the two areas of the detector, which are respectively recorded as H and V area, the detected signals are collected by the image acquisition card and then sent to the computer for data processing. The two signals are respectively recorded as I _H and I _V , and the inverse Fourier transform is performed on the two signals to obtain the A-scan signals, denoted as A _H (z)exp[iΦ _H (z)] and A _V (z)exp[iΦ _V (z)], z is the sample depth coordinate, A _H and A _V are the horizontal and The magnitude of the vertical interference signal, Φ _H and Φ _V are the phases of the horizontal and vertical interference signals, respectively. From this, the intensity image R(z), retardation image δ(z) and fast axis image θ(z) of the birefringent sample can be obtained:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>$

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; .</span>$

The utility model has the following advantages due to the adoption of the above-mentioned technical scheme:

1. Using a single detector, compared with the dual detector system, the system structure is simplified.

2. The utility model does not require synchronous control of the detectors, which can avoid the time asynchronous problem existing when two detectors collect signals.

3. In the utility model, both the horizontally polarized light and the vertically polarized light can be incident on the grating at the angle with the highest diffraction efficiency, and the improvement of the diffraction efficiency increases the signal-to-noise ratio of the system and improves the image quality.

Description of drawings

FIG. 1 is a schematic structural diagram of a polarization frequency domain optical coherence tomography system based on a single detector of the present invention.

Fig. 2 is a schematic diagram of the line light formed by the cylindrical lens in the present invention.

Fig. 3 is a schematic diagram of detector detection signals in the present invention.

Detailed ways

The utility model will be further described below in conjunction with the embodiments and accompanying drawings, but the protection scope of the utility model should not be limited by this embodiment.

FIG. 1 is a schematic structural diagram of a polarization frequency domain optical coherence tomography system based on a single detector of the present invention. It can be seen from the figure that the polarization frequency-domain optical coherence tomography system based on a single detector of the present invention includes a low-coherence light source 1, a first collimator 2, a polarizer 3, a Michelson interferometer 4, and a polarization beam splitter 5. Second collimator 6, first optical fiber 7, third collimator 8, fourth collimator 9, second optical fiber 10, fifth collimator 11, grating 12, cylindrical lens 13 and detector 14. The light emitted by the low-coherence light source 1 passes through the first collimator 2 and the polarizer 3 and becomes linearly polarized light coupled into the Michelson interferometer 4, and is divided into the reference arm optical path and the optical path by the non-polarizing beam splitter 41 in the interferometer. Sample arm optical path; the light of the reference arm optical path is irradiated on the reference mirror 43 after passing through the quarter-wave plate 42, and after being reflected by the reference mirror 43, passes through the quarter-wave plate 42 to reach the non-polarizing beam splitter 41 again, and the sample arm The light in the optical path passes through the quarter-wave plate 44, passes through the two-dimensional vibrating mirror 45, and the imaging objective lens 46, and then focuses in the birefringent sample 47. The light with sample information reflected from the sample arm returns along the original path to reach the non-polarized Beam splitter 41; the light reflected from the reference mirror 43 and the sample 47 merges and interferes at the non-polarizing beam splitter 41, and then is divided into two paths of horizontal polarization H and vertical polarization V by the polarization beam splitter 5, respectively denoted It is the H channel and the V channel; the light of the H channel is coupled into the first optical fiber 7 through the collimator 6, and after being collimated by the third collimator 8 at the other end of the first optical fiber 7, it can be irradiated on the grating at the angle of the highest diffraction efficiency 12, the light of the V channel is coupled into the second optical fiber 10 through the fourth collimator 9, and after being collimated by the fifth collimator 11 at the other end of the second optical fiber 10, it can also be irradiated at the angle of the highest diffraction efficiency. The B region of the grating 12, the A region and the B region do not overlap, and are distributed up and down on the grating 12 in this embodiment; the light of the H optical path and the light of the V optical path are split by the grating 12 and then pass through the same cylindrical lens 13 at the same time. The cylindrical lens only focuses in one direction, so the H and V polarized lights respectively form a rectangular light spot after passing through the cylindrical lens 13, and are respectively detected by the two areas of the same detector 14, respectively marked as H and V area. The two signals of H and V are collected by the image acquisition card and then sent to the computer for data processing. The two signals are respectively recorded as I _H and _IV . After inverse Fourier transform of the two signals, the A- scan signal, denoted as A _H (z)exp[iΦ _H (z)] and A _V (z)exp[iΦ _V (z)], z is the sample depth coordinate, A _H and A _V are the horizontal and vertical interference The amplitude of the signal, Φ _H and Φ _V are the phases of the horizontal and vertical interference signals, respectively. From this, the intensity image R(z), retardation image δ(z) and fast axis image θ(z) of the birefringent sample can be obtained:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>$

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

When the dual detector system detects the horizontal and polarization signals, it needs to be controlled synchronously, otherwise there will be a time delay problem in the signals collected by the two detectors. In this embodiment, the polarization frequency-domain optical coherence tomography system uses a cylindrical lens to simultaneously focus the horizontal and polarized two-way light, and only needs to use one detector to detect the horizontal and vertical two-way signals at the same time. Compared with the dual-detector system, the structure is simplified, and there is no time delay problem in the signal; at the same time, the horizontal and polarized light can be incident on the grating at the same angle, and both can be incident at the angle with the highest diffraction efficiency. In prior art 2, the two paths of light from the grating have the largest diffraction efficiency, which improves the system signal-to-noise ratio and image quality.

Fig. 2 is a schematic diagram of forming a line of light by a cylindrical lens.

Fig. 3 is a schematic diagram of the detection signal of the detector. The y-direction shown in the figure is the direction in which light of different wavelengths λ is diffracted by the grating 12 and then focused by the cylindrical lens 13. Since the cylindrical lens only focuses in one direction, it does not act on the light in the x-direction, so The pixels used by the detector to detect signals are rectangular areas as shown in FIG. 3 . The pixel areas for detecting horizontal channels and vertical channels are denoted as H area and V area, respectively. Assuming that the row and column of the pixels in the H area are respectively recorded as i and j (i, j=1, 2, 3...), the light intensity detected by each pixel is I _ij , for each column j, all the row pixels are detected The received light intensity is superimposed and recorded as I _j , then N is the number of lines used by the detection signal in the H area, so the detection signal in the rectangular area is equivalent to the signal detected by the one-dimensional linear array CCD, denoted as I _H . The V area obtains the signal _IV of the vertical channel in the same way. In this way, the detector in the embodiment can realize the simultaneous detection of the two signals of I _H and _IV , and the time asynchronous problem existing in the detection of the two signals can be avoided without synchronous control of the detector.

Claims (7)

1. the polarization domain optical coherence tomography system based on simple detector, is characterized in that: comprise low-coherence light source (1), first collimator (2), the polarizer (3), Michelson interferometer (4), polarization beam apparatus (5), the second collimating apparatus (6), optical fiber (7), the 3rd collimating apparatus (8), the 4th collimating apparatus (9), optical fiber (10), the 5th collimating apparatus (11), grating (12), cylindrical lens (13), detector (14), the fairing order that low-coherence light source (1) sends is through first collimator (2), after the polarizer (3), become the beam splitter (41) that polarized light is coupled into Michelson interferometer (4), this beam splitter (41) is divided into reference arm light path and sample arm light path by light beam, the light of reference arm is radiated on reference mirror (43) after quarter-wave plate (42), the light of sample arm is imaged object lens (46) through 2-D vibration mirror (45) and focuses in testing sample (47) after quarter-wave plate (44), the light with testing sample information being reflected back from testing sample (47) and the reference light being reflected back from reference mirror (43) interfere at described beam splitter (41), the output terminal of Michelson interferometer (4) connects polarization beam apparatus (5), this polarization beam apparatus (5) is divided into horizontal polarization light (H) and orthogonal polarized light (V) two-way light by interfering beam, horizontal polarization light (H) is coupled in the first optical fiber (7) by the second collimating apparatus (6), the other end parallel inciding on described grating (12) after the 3rd collimating apparatus (8) at the first optical fiber (7), described orthogonal polarized light (V) is coupled in the second optical fiber (10) by the 4th collimating apparatus (9), the other end parallel inciding on described grating (12) after the 5th collimating apparatus (11) at the second optical fiber (10), described horizontal polarization light (H) is different with the position that orthogonal polarized light (V) incides grating (12), after grating (12) light splitting, by described cylindrical lens (13), be imaged in the zones of different of same detector (14) simultaneously, detector diverse location detects horizontal polarization signal and vertical polarization signal simultaneously, this two paths of signals is admitted to computing machine and carries out data processing after image pick-up card collection, obtain the intensity image of sample, delayed image and quick shaft direction image.

2. the polarization domain optical coherence tomography system based on simple detector according to claim 1, is characterized in that: described detector (14) is area array CCD or other have photosignal translation function and can survey at least planar array detector array of two paths of signals simultaneously.

3. the polarization domain optical coherence tomography system based on simple detector according to claim 1, is characterized in that: described grating (12) is transmission grating or reflection grating.

4. the polarization domain optical coherence tomography system based on simple detector according to claim 1, it is characterized in that: described low-coherence light source (1) is wideband light source, its spectral bandwidth is that tens nanometers arrive hundreds of nanometer, comprises light emitting diode (LED) or super-radiance light emitting diode (SLD) or femto-second laser or super continuum source.

5. the polarization domain optical coherence tomography system based on simple detector according to claim 1, it is characterized in that: described Michelson interferometer (4) has two and approaches aplanatic optical interference circuit, be respectively reference arm and sample arm, adopt a kind of in fiberize Michelson interferometer and spatialization Michelson interferometer; Reference arm light path comprises quarter-wave plate (42) and reference mirror (43), and sample arm light path comprises quarter-wave plate (44), 2-D vibration mirror (45), image-forming objective lens (46), sample (47); Beam splitter (41) in described Michelson interferometer (4) is non-polarization-sensitive beam splitter.

6. the polarization domain optical coherence tomography system based on simple detector according to claim 5, is characterized in that: described reference mirror (43) adopts the optical device that can make described broadband light return according to former travel path; Described image-forming objective lens (46) adopts and can make to incide the optical device that the described broadband light on sample focuses on.

7. the polarization domain optical coherence tomography system based on simple detector according to claim 1, it is characterized in that: the beam splitter that described Michelson interferometer (4) output terminal connects is polarization-sensitive beam splitter (5), is the polarization beam apparatus of beam splitting rib piece or fiberize.