CN211155674U - Common-path optical tomography system based on mechanical chirped long-period fiber grating - Google Patents
Common-path optical tomography system based on mechanical chirped long-period fiber grating Download PDFInfo
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- CN211155674U CN211155674U CN201920724395.8U CN201920724395U CN211155674U CN 211155674 U CN211155674 U CN 211155674U CN 201920724395 U CN201920724395 U CN 201920724395U CN 211155674 U CN211155674 U CN 211155674U
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Abstract
The utility model provides a common path optical tomography system based on mechanical system chirp long period fiber grating, includes input light source, optical circulator, OCT common path interference unit and signal processing unit, OCT common path interference unit include MC L PFG, NMF, hollow fiber, fibre core mode reflector and GIF, MC L PFG, NMF regulate and control the light field distribution in the optic fibre through ambient pressure, set up the fibre core mode reflector at NMF and the one end terminal surface of hollow fiber butt fusion, the diameter of hollow fiber centre bore is equal with NMF's fibre core diameter, the outer diameter of hollow fiber is equal with NMF fiber cladding's external diameter, fibre core mode reflector is through the coating film at NMF fiber and the fibre core terminal surface of hollow fiber butt fusion one end to form the speculum, the outgoing beam passes through GIF and focuses on the sample outside the optic fibre and forms the image.
Description
Technical Field
The utility model relates to a biomedical formation of image and medical imaging detection area especially relate to Common Path Optical Coherence Tomography (CPOCT) system field.
Background
Optical Coherence Tomography (OCT) is a broad-spectrum based michelson interferometric low Coherence imaging technique. The OCT imaging technology adopts a broadband light source to realize high-depth imaging, and utilizes a Michelson interference light path to realize high-sensitivity measurement. The OCT imaging technology can acquire the axial depth information of the biological tissue without trauma for imaging, and is widely applied to the fields of medical detection and biological research. Compared with other medical detection technologies, such as confocal microscopic imaging technology, ultrasonic detection technology, nuclear magnetic resonance technology and the like, the OCT imaging technology well makes up the measurement blind area in the aspects of imaging depth and imaging resolution. Meanwhile, the OCT imaging technology has a good development prospect in other detection fields. Such as the field of mechanical quantity measurement, such as the detection of the uniformity of the surface of an object, the detection of coatings, and the like.
Since the technology was proposed by d.huang et al in 1991, OCT systems have been spotlighted and have made great progress. The structure of a traditional OCT system is generally a double-arm structure to realize interference measurement, and the common-path optical coherence imaging technology (CPOCT) realizes the common-path transmission of optical fibers of a reference arm and a measurement arm on the basis of the traditional OCT technology, so that the problems of inter-arm dispersion and polarization disorder caused by the double-arm structure can be relieved. Meanwhile, the problems of length limitation of the measuring arm and complex measuring operation are solved. The common-path OCT system originally proposed by Vakhtin is a discrete system based on a reference mirror; with the further research of the common path OCT system, Wang et al propose a common path OCT system based on a micro electro mechanical system endoscope probe, and a combination structure of an optical fiber and the probe is used for replacing a discrete reflector. With the development of optical fiber technology and the further research of the common-path OCT system, Vairagi et al recently proposed a common-path OCT system based on the bessel beam at the negative-axis tapered optical fiber end, and realized a common-path OCT system with a pure optical fiber structure micro-probe.
At present, the reference light signal of the CPOCT system is mostly generated by Fresnel reflection at the interface of glass and air. The intensity controllability of the reflected light signal is poor, and the stability needs to be further improved. Meanwhile, the probe for the common-path OCT system has high requirement on the manufacturing accuracy, is relatively high in contingency, and still has a relatively large improvement space in the structure.
Disclosure of Invention
In order to overcome the poor, the higher not enough of measurement operation degree of difficulty of formation of image stability of current CPOCT system, the utility model provides a CPOCT system based on mechanical system chirped Fiber grating (mechanical induced L ong-Period Fiber grating, abbreviation MC L PFG) and the inhomogeneous atress optic fibre (the nobuform Stressed Fiber, abbreviation NSF) of modulation light field, the stability of formation of image is good, can reduce the measurement operation degree of difficulty.
The utility model provides a technical scheme that its technical problem adopted is:
a common-path Optical tomography system based on a mechanically chirped long-period Fiber grating comprises an input light source, an Optical circulator, an OCT common-path interference unit and a signal processing unit, wherein the OCT common-path interference unit comprises MC L PFG, NSF, a Hollow Optical Fiber (HOF), a Fiber core mode reflector and GIF (Graded IndexFiber), the MC L PFG and NSF regulate and control Optical field distribution in the Optical Fiber through external pressure, the Fiber core mode reflector is arranged on the end face of one end, where the NSF is welded with the Hollow Optical Fiber, the diameter of a central hole of the Hollow Optical Fiber is equal to the diameter of a Fiber core of the NSF, the diameter of an outer layer of the Hollow Optical Fiber is equal to the outer diameter of a cladding of the NSF, the Fiber core mode reflector is formed by coating on the end face of the Fiber core, where the NSF is welded with one end of the Hollow Optical Fiber, so as to form a reflector, and emitted light beams are focused on a sample outside the Optical Fiber through the GIF to form images.
Further, the coating film for the core mode reflector includes a metal film and a dielectric film.
Still further, the signal processing unit comprises a photoelectric conversion module and a computer image processing module.
Preferably, the photoelectric conversion module is a spectrometer or a double balanced detector.
The input light source is a broad spectrum light source or sweep frequency laser, and the optical circulator is a conventional optical circulator or a one-way optical coupler.
The utility model provides a CPOCT system based on MC L PFG and NSF light field regulation and control has the advantages such as light field is controllable, simple manufacture, stable in structure, preparation time are short for current CPOCT structure, the utility model discloses utilize chirped fiber grating's filtering characteristic, realize the syntropy coupling beam splitting of cladding and fibre core in optic fibre, replace the beam splitter among the traditional system to realize sharing route transmission measurement optical signal and reference light signal, when MC L PFG's filter wavelength width is greater than light source spectral width, light source light signal is through MC L PFG, its light signal all satisfies the resonance wavelength requirement, control the coupling efficiency that light signal couples to the cladding from the fibre core through pressure change, realize the syntropy separation of light signal, then light signal further obtains suitable mode field distribution through NSF regulation and control light field, the coating film is realized the reflection of fibre core after NSF, as reference light signal utilize Gradient Index Fiber (GIF) to replace the lens in the traditional cladding system, realize the focusing of light signal in realizing the measurement light signal for PFG and reducing the PFG and the reflection of the fibre core light signal returns to the optical signal through the reflection of the cladding in the HOF in the optical fiber core, the sample reflection and the reflection of the optical fiber core, the reflection of the optical signal returns to take place the optical fiber core through the optical fiber in the empty core in the core and the optical signal processing, the optical signal processing unit, the optical fiber of the optical signal of the optical fiber.
The technical idea of the utility model is that C L PFG is used to replace the optical splitter to realize the common-path transmission of the measuring optical signal and the reference optical signal, GIF is used to replace the traditional probe to realize the focusing of the measuring optical signal, and MC L PFG NSF GIF is used to construct a new CPOCT structure.
The beneficial effects of the utility model are that 1) the reference light signal of present CPOCT system is provided by the fresnel reflection of glass and air, and the controllability and the stability of its signal remain to be improved the utility model discloses in utilize MC L PFG as beam splitting device, realize the reflection of reference light signal through the fibre core coating film, reflection signal stability is high, can realize the regulation and control of light signal intensity through the change of external pressure 2) realize measuring the self-focusing of light signal through the gradual change refracting index optic fibre, realized the full optic fibre of probe, miniaturized probe can adapt to more complicated measuring environment 3) the utility model discloses a MC L PFG and NSF, through the change of pressure in order to realize the controllability modulation in optic fibre light field to realize optimizing imaging quality, and for current CPOCT probe, its preparation time is short, and cost of manufacture and the preparation technological requirement are not high.
Drawings
Fig. 1 is a schematic structural diagram of a common-path interference unit of a CPOCT system based on MC L PFG.
Fig. 2 is a schematic diagram of the overall structure of the CPOCT operation.
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
Referring to fig. 1 and 2, a common-path optical tomography system based on a mechanically chirped long-period fiber grating comprises an input light source 1, an optical circulator 2, an OCT common-path interference unit 4 and signal processing units 5 and 6, wherein the OCT common-path interference unit comprises a mechanically chirped long-period fiber grating (MC L PFG)401, a non-uniform stress fiber (NSF)402, a core mode reflector 405, a hollow core fiber (HOF)403 and a Graded Index Fiber (GIF)404, the core radius of the NSF402 is equal to that of the MC L PFG401, the core radius of the HOF403 is equal to that of the NSF402, and the fiber cladding outer diameters of the MC L PFG401, the NSF402, the HOF403 and the GIF404 are equal.
The MC L PFG401 is generated by applying pressure periodically changing with a certain chirp coefficient C from the outside, the coupling efficiency of the MC L PFG401 is adjusted and controlled by changing the pressure, the NSF402 is applied with a certain angle pressure from the outside to adjust and control the optical fiber optical field, and the optical fiber mode reflector 405 is formed by coating a film on the fiber core at one end of the NSF402 and the hollow optical fiber HOF403 in a welding mode to form a reflecting end face.
Referring to FIG. 1, the operation and principle of the CPOCT system is such that the input light source inputs a broad spectrum signal 411 through the fiber, the end field distribution of which in the transmission fiber is shown at 407, the optical signal will satisfy the harmonic through the MC L PFG401Light of vibration condition is coupled from core mode to cladding mode L P1mThe end surface field distribution is shown as 408, the filter bandwidth of the MC L PFG401 is larger than the spectral width of the light source, the optical signal distribution of the fiber core and the cladding is respectively shown as 412 and 413, the mode fields in the fiber core and the cladding are regulated and controlled by the NSF402, so that the mode field distribution in the fiber core and the cladding is shown as 409, the optical signal in the fiber core passes through the fiber core mode reflector 405 and is reflected back to the fiber core of the NSF402 as a reference optical signal, the regulated cladding mode 410 is continuously transmitted through the HOF403 as a measurement optical signal, then the measurement optical signal is focused into a measurement sample 406 through the GIF404, the reflected optical signal carrying the sample information is coupled back to the cladding mode through the GIF404, the measurement optical signal is transmitted from a new return MC L PFG401 through the HOF403 and is re-coupled back to the fiber core through the MC L PFG401 and generates low interference with the reference optical signal, so as to form an interference signal as 414, and finally the interference signal information of the sample is demodulated by the signal processing unit so as.
The embodiment is as in fig. 1 and fig. 2, and the light emitted from the input light source 1 enters the circulator 2 through the single mode fiber, and then enters the CPOCT common-path interference unit 4 through the fiber. The whole CPOCT common-circuit interference unit 4 can be deeply inserted into tissues or workpieces through the rotation of the micromotor 3, and the information of the sample 406 can be detected in all directions. The backscattered light from each depth of the sample returns together, and undergoes michelson interference with the light reflected by the core mode reflector 405, the interference spectrum image is collected by the photoelectric conversion module 5, and the entire image information in the depth direction of the sample to be measured is recovered by the image processing module 6 through processing such as spectrum calibration, linear interpolation, fourier transform, and the like.
Claims (5)
1. A common-path optical tomography system based on a mechanically chirped long-period fiber grating is characterized by comprising an input light source, an optical circulator, an OCT common-path interference unit and a signal processing unit, wherein the OCT common-path interference unit comprises MC L PFG, NMF, a hollow fiber, a fiber core mode reflector and GIF, the MC L PFG and the NMF regulate and control light field distribution in the fiber through external pressure, the fiber core mode reflector is arranged on the end face of one end, welded to the hollow fiber, of the NMF, the diameter of a central hole of the hollow fiber is equal to the diameter of a fiber core of the NMF, the outer diameter of an outer layer of the hollow fiber is equal to the outer diameter of a cladding of the NMF, the fiber core mode reflector is formed by coating the end face of the fiber core, welded to the hollow fiber, of the NMF fiber and the end face of the fiber core, and emergent light beams are focused on a sample outside the fiber through the GIF to.
2. The mechanically chirped long period fiber grating-based common-path optical tomography system of claim 1, wherein the coating for the core mode reflector comprises a metal film and a dielectric film.
3. The system according to claim 1 or 2, wherein the signal processing unit comprises a photoelectric conversion module and a computer image processing module.
4. The mechanically chirped long-period fiber grating-based common-path optical tomography system of claim 3, wherein the photoelectric conversion module is a spectrometer or a double balanced detector.
5. The co-path optical tomography system based on the mechanically chirped long-period fiber grating according to claim 1 or 2, wherein the input light source is a broad spectrum light source or a swept-frequency laser, and the optical circulator is a one-way optical coupler.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110215181A (en) * | 2019-05-20 | 2019-09-10 | 浙江工业大学 | Common-path optical chromatographic imaging system based on mechanical chirp long period optic fiber grating processed |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110215181A (en) * | 2019-05-20 | 2019-09-10 | 浙江工业大学 | Common-path optical chromatographic imaging system based on mechanical chirp long period optic fiber grating processed |
| CN110215181B (en) * | 2019-05-20 | 2024-05-07 | 浙江工业大学 | Common-path optical tomography system based on mechanical chirped long-period fiber grating |
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