阅读说明：本技术 一种干涉型光路提高布里渊弹性成像系统信噪比的方法 (Method for improving signal-to-noise ratio of Brillouin elastography system through interference type optical path ) 是由 朱羿叡 张余宝 刘严欢 谢成峰 史久林 何兴道 于 2019-10-18 设计创作，主要内容包括：本发明提供一种干涉型光路提高布里渊弹性成像系统信噪比的方法,该方法采用扫频式F-P干涉仪和光子接收器组成光谱仪系统,由计算机产生驱动程序来控制扫频式F-P干涉仪和光子接收器的同步运行,进而对532nm激光在生物组织中激发出的布里渊散射信号进行高精度的扫描采集,二者结合可以较大程度上提高布里渊散射弹性成像系统中的光谱信息提取的信噪比。本发明的优点是：采用迈克尔逊干涉仪中参考光路干涉相消的原理,通过对散射光中弹性分量的相消干涉来抑制背景噪声,同时结合扫频式F-P干涉仪和光子接收器组成光谱仪系统,提高了布里渊散射系统的信噪比,提高了探测光谱分辨率,增加了布里渊散射光谱弹性成像技术的实际适用性。(The invention provides a method for improving the signal-to-noise ratio of a Brillouin elastography system by an interference type optical path, which adopts a frequency sweep type F-P interferometer and a photon receiver to form a spectrometer system, and a computer generates a driving program to control the synchronous operation of the frequency sweep type F-P interferometer and the photon receiver so as to perform high-precision scanning acquisition on a Brillouin scattering signal excited by 532nm laser in biological tissues, wherein the signal-to-noise ratio of spectral information extraction in the Brillouin elastography system can be improved to a greater extent by combining the frequency sweep type F-P interferometer and the photon receiver. The invention has the advantages that: the principle of reference light path interference cancellation in the Michelson interferometer is adopted, background noise is suppressed through destructive interference of elastic components in scattered light, and meanwhile, a frequency sweeping type F-P interferometer and a photon receiver are combined to form a spectrometer system, so that the signal-to-noise ratio of the Brillouin scattering system is improved, the detection spectrum resolution is improved, and the actual applicability of the elastic imaging technology of the Brillouin scattering spectrum is improved.)

1. A method for improving the signal-to-noise ratio of a Brillouin elastography system by an interference type optical path is characterized in that the specific process of the interference type Brillouin scattering elastography is as follows: the power-adjustable continuous laser (01) emits a laser beam with the wavelength of 532nm, and the laser beam passes through a 50:50 beam splitter (02), is divided into two parts which are perpendicular to each other and have the power ratio of 1: 1, wherein the sample light is emitted by a first reflector (03), focused by a focusing objective lens (04) and then incident to a sample to be measured on a three-dimensional displacement platform (05), excites a Brillouin scattering spectrum, and then is focused by the focusing objective lens (04) and then propagates to a 50:50 beam splitter (02) along an original optical path; reference light enters a second reflecting mirror (07) after passing through an optical compensator (06), the reflecting mirror is controlled by piezoelectric ceramics (08) to move axially, reflected light returns to the beam splitter (02) along an original optical path to interfere with sample light, the second reflecting mirror (07) controlled by the piezoelectric ceramics (08) moves axially to modulate the phase of the reference light, the optical compensator (06) modulates the amplitude of the reference light to realize the destructive suppression of elastic scattering light, namely mirror scattering and Rayleigh scattering, in an interference spectrum, the interference light is focused to a vacuum filter (10) through a convex lens (09) to filter stray light, emergent light enters the focus of the convex lens (11), is changed into parallel light after passing through the convex lens (11), is spatially filtered through a small-hole diaphragm (12) to improve the signal-to-noise ratio, and then is focused through the convex lens (13) to enter a sweep-frequency F-P interferometer (14) arranged at the focus of the convex lens (13), the frequency sweep type F-P interferometer (14) is controlled by a computer (18) to generate a driving program and is used for scanning an optical signal, emergent light enters at the focus of a convex lens III (15), is focused on a single-mode optical fiber (16) through the convex lens III (15) and then is transmitted into a signal receiving end of a photon receiver (17), the photon receiver (17) is controlled by the computer (18) to generate the driving program matched with the frequency sweep F-P and is used for receiving the optical signal, the collection processing of the Brillouin scattering signal after background suppression is completed, and then a corresponding spectrum frequency shift result can be obtained through calculation on the computer (18).

2. The method for improving the signal-to-noise ratio of the Brillouin elastography system through the interferometric optical path according to claim 1, wherein an experimental detection device for implementing the method comprises a power-adjustable 532nm continuous laser (01), a 50:50 spectroscope (02), a 532nm reflector I (03), a focusing objective lens (04), a three-dimensional moving lifting platform (05), an optical compensator (06), a reflector II (07), piezoelectric ceramics (08), a convex lens I (09), a pinhole filter (10), a convex lens II (11), an aperture stop (12), a convex lens III (13), a frequency-sweeping F-P interferometer (14), a convex lens IV (15), a single-mode optical fiber (16), a photon receiver (17) and a computer (18).

3. The method for improving the signal-to-noise ratio of the brillouin elastography system according to claim 1, wherein the method comprises the following steps: the Brillouin scattering frequency shift calculation method is characterized in that a frequency sweep type F-P interferometer (14) is used for receiving Brillouin scattering signals in a scanning mode, the spectral resolution of the frequency sweep F-P interferometer (14) is 67MHz, the free spectral range is 10GHz, the Brillouin scattering signals are collected and processed through a photon receiver (17), and the Brillouin scattering frequency shift calculation is completed through a computer (18).

Technical Field

The invention relates to a method for improving the signal-to-noise ratio of a Brillouin elastography system, in particular to a method for improving the signal-to-noise ratio of the Brillouin elastography system by an interference type optical path.

Background

The Brillouin scattering elastography is used for detecting the bulk elastic modulus of an ophthalmic biological tissue, and has wide application prospects in the fields of diagnosis, treatment and prevention of ophthalmic clinical diseases (myopia, keratoconus and the like), but at present, some technical limitations still exist, mainly the spectral resolution of a detection system is low, and Brillouin frequency shift signals cannot be extracted from strong background noise of specular reflection and Rayleigh scattering with high precision; in addition, most of the existing brillouin scattering imaging technologies adopt a virtual phased array spectrometer (VIPA) to detect brillouin scattering frequency shift signals, the detection accuracy and the scanning time of the brillouin scattering imaging technologies are to be improved, and the brillouin scattering imaging technologies have certain limitations in clinical application.

Because the spectral frequency shift signal of brillouin scattering represents the acousto-optic effect at the molecular level, and different biomechanical properties have different influence degrees on the brillouin scattering spectral frequency shift signal, the brillouin scattering spectral imaging technology for detecting the elastic property of biological tissue has higher resolution, but the Brillouin scattering spectral signal is scanned and detected by adopting a virtual phased array spectrometer (VIPA) in the mainstream technical means at present, the spectral resolution and the detection time of the method are both required to be improved, and the brillouin scattering signal cannot be detected with high precision for biological tissue easily generating complex components of strong specular reflection and Rayleigh scattering.

Disclosure of Invention

The invention aims to provide a method for improving the signal-to-noise ratio of a Brillouin elastic imaging system by an interference type optical path, which mainly suppresses the elastic scattering noise of specular reflection and Rayleigh scattering by the destructive interference of a reference beam in a Michelson interferometer, then adopts a frequency sweep type F-P interferometer and a photon receiver to form a spectrometer to collect and process the Brillouin scattering spectrum of a sample to obtain a spectrum detection result with high signal-to-noise ratio, and then calculates and obtains the bulk elastic modulus of the sample to be detected according to the physical relationship between the signal frequency shift of the Brillouin scattering and the bulk elastic modulus of the sample.

The invention adopts the destructive interference of the reference beam in the Michelson interferometer to inhibit the elastic scattering noise of specular reflection and Rayleigh scattering, then adopts the sweep-frequency F-P interferometer to scan the Brillouin scattering spectrum, then adopts the photon receiver to realize the high-precision acquisition and processing of the spectrum signal, and processes the frequency shift signal of the Brillouin scattering spectrum on the computer to further calculate the bulk elastic modulus of the sample to be detected, and the detection result has important reference value and wide application prospect for solving the diagnosis, treatment and prevention of clinical multiple ophthalmic diseases at present.

The interference of light in Michelson interferometers is based on the principle of coherent superposition of electromagnetic fields, which provides that the total amplitude E (r, t) of the equal frequencies ω of the two beams at a point r in space is equal to the associated amplitude E ₁And E ₂Is thus the vector sum of

Wherein phi ₁And phi ₂Is the phase of the two beams. Thus, the time-averaged power density or intensity at point r is expressed as:

phase difference delta phi is phi ₂-φ ₁The optical path difference deltaz of the two beams can be expressed as

λ represents the wavelength of light. When the axial amplitudes of the two beams are equal, the total intensity obtained by detection is

Assuming that the two beams are coherent in time and space, the above equation means that destructive interference occurs

m is an integer.

The experimental detection device utilizing the method comprises a power-adjustable 532nm continuous laser, a 50:50 spectroscope, a first reflector, a focusing objective, a three-dimensional moving lifting table, an optical compensator, a second reflector, piezoelectric ceramics, a first convex lens, a pinhole filter, a second convex lens, a small-hole diaphragm, a third convex lens, a sweep frequency F-P interferometer, a fourth convex lens, a single-mode optical fiber, a photon receiver and a computer.

The specific process of the imaging method is that a power-adjustable continuous laser emits laser beams with the wavelength of 532nm, the laser beams pass through a 50:50 beam splitter, and the laser beams are divided into two parts which are perpendicular to each other and have the power ratio of 1: 1, wherein the sample light is emitted by the first reflector, focused by the focusing objective lens and then incident to a sample to be measured on the three-dimensional displacement platform, a Brillouin scattering spectrum is excited, and then the sample light is focused by the focusing objective lens and then propagates to a 50:50 beam splitter along an original light path; the reference light is incident on a second reflecting mirror after passing through the compensator, the second reflecting mirror can axially move under the control of piezoelectric ceramics, and the reflected light returns to the beam splitter along the original light path and interferes with the sample light. The second reflecting mirror controlled by the piezoelectric ceramic moves axially to modulate the phase of the reference light, and the compensator modulates the amplitude of the reference light, so that the suppression of elastic scattering light (specular scattering and Rayleigh scattering) in an interference spectrum is realized.

In the invention, a piezoelectric ceramic (08) is adopted to drive a reflector (07) to complete phase modulation on reference light so as to match phases of specular reflection and Rayleigh scattering in sample light.

In the invention, the compensator is adopted to modulate the amplitude of the reference light so as to match the amplitude of the elastic scattering light in the sample light, and further to perform destructive interference on the elastic scattering noise of specular reflection and Rayleigh scattering in the sample light and the reference light.

Furthermore, a power-adjustable continuous laser 01 with 532nm output wavelength is adopted to generate Brillouin scattering signals, and the frequency-sweeping F-P interferometer and the photon receiver jointly form a spectrometer system.

The working principle is as follows: interference light is focused to a vacuum filter through a convex lens to filter stray light, emergent light is incident at the focus of a convex lens I and is changed into parallel light through the convex lens I, spatial filtering is carried out through an aperture diaphragm, the signal to noise ratio is improved, the parallel light is incident into a frequency sweeping F-P interferometer arranged at the focus of a convex lens II through two focuses of the convex lens, the frequency sweeping F-P interferometer generates a driving program under the control of a computer and is used for scanning optical signals, the free spectral range of the frequency sweeping F-P interferometer is 10GHz, and the spectral resolution is 67 MHz. Emergent light of the F-P interferometer enters the focus of the convex lens III and is focused on the single-mode fiber through the convex lens III, then the single-mode fiber is transmitted to a signal receiving end of the photon receiver, the photon receiver is controlled by a computer to generate a driving program matched with the sweep frequency F-P to receive optical signals, the Brillouin scattering signals after background suppression are acquired and processed, and then corresponding spectral data processing and Brillouin frequency shift calculation are completed in the computer.

The invention has the advantages that: the frequency sweep type F-P interferometer and the photon receiver are adopted to form a spectrometer system, so that the spectral resolution of the Brillouin scattering system is improved, the detection speed is improved, the overall detection time is shortened, and the clinical operability of the Brillouin scattering spectral elastography technology is improved.

Drawings

Fig. 1 is a schematic diagram of the present invention.

FIG. 1 shows: the device comprises a power-adjustable 532nm continuous laser (01), a 50:50 spectroscope (02), a 532nm reflector I (03), a focusing objective lens (04), a three-dimensional moving lifting table (05), an optical compensator (06), a reflector II (07), piezoelectric ceramics (08), a convex lens I (09), a pinhole filter (10), a convex lens II (11), a small-hole diaphragm (12), a convex lens III (13), a sweep frequency F-P interferometer (14), a convex lens IV (15), a single-mode optical fiber (16), a photon receiver (17) and a computer (18).

Detailed Description

A method for improving the signal-to-noise ratio of a Brillouin elastography system through an interference type optical path is characterized in that a 532nm continuous laser 01 with adjustable power emits a laser beam with the wavelength of 532nm, the laser beam is divided into two parts by a 50:50 spectroscope 02 and is mutually vertical, and the power ratio is 1: 1, wherein the sample light is emitted by a first reflector (03), focused by a focusing objective lens (04) and then incident to a sample to be measured on a three-dimensional displacement platform (05), excites a Brillouin scattering spectrum, and then is focused by the focusing objective lens (04) and then propagates to a 50:50 beam splitter (02) along an original optical path; the reference light enters a second reflecting mirror (07) after passing through a compensator (06), the reflecting mirror is controlled by piezoelectric ceramics (08) to move axially, the reflected light returns to the beam splitter (02) along the original light path and interferes with the sample light, and the whole reference light path is used for adjusting the coaxiality of optical elements of all parts of a signal receiving light path of the system. A second reflecting mirror (07) controlled by piezoelectric ceramics (08) moves axially to modulate the phase of the reference light, and a compensator (06) modulates the amplitude of the reference light to realize the destructive suppression of elastic scattering light (mirror scattering and Rayleigh scattering) in an interference spectrum.

Interference light is focused to a vacuum filter (10) through a convex lens (09) to filter stray light, emergent light enters at the focus of a convex lens I (11), becomes parallel light after passing through the convex lens I (11), is subjected to spatial filtering through an aperture diaphragm (12) to improve the signal-to-noise ratio, is focused through a convex lens II (13) to enter a sweep frequency F-P interferometer (14) placed at the focus of the convex lens II (13), the sweep frequency F-P interferometer (14) is controlled by a computer (18) to generate a driving program for scanning an optical signal, the emergent light enters at the focus of the convex lens III (15) and is focused to a single-mode optical fiber (16) through the convex lens III (15), and then is transmitted to a signal receiving end of a photon receiver (17), the photon receiver (17) is controlled by the computer (18) to generate the driving program matched with the sweep frequency F-P for receiving the optical signal, the acquisition process of the brillouin signal after background suppression is completed and then a corresponding spectral frequency shift result can be obtained on a computer (18).

The invention relates to a method for improving the signal-to-noise ratio of a Brillouin elastography system by an interference type optical path, which is characterized in that elastic scattering light of specular reflection and Rayleigh scattering in the Brillouin system is inhibited based on destructive interference of a reference light beam in a Michelson interferometer, so that the aim of reducing background noise of a Brillouin spectrum is fulfilled, and the overall signal-to-noise ratio of the Brillouin elastography system is improved.

The invention relates to a method for improving the signal-to-noise ratio of a Brillouin elastography system by an interference type optical path, which is characterized in that the physical relation between the frequency shift quantity of a Brillouin scattering spectrum and the bulk elastic modulus of biological tissues is utilized, and the bulk elastic modulus of a sample is obtained by scanning and detecting a Brillouin scattering frequency shift signal of the sample.

The invention relates to a method for improving the signal-to-noise ratio of a Brillouin elastic imaging system by using an interference type optical path, which is characterized by adopting an experimental device of a 532nm continuous laser 01 with adjustable power, a 50:50 spectroscope 02, a 532nm reflector I03, a focusing objective 04, a three-dimensional moving lifting platform 05, an optical compensator 06, a reflector II 07, piezoelectric ceramics 08, a convex lens I09, a pinhole filter 10, a convex lens II 11, a small hole diaphragm 12, a convex lens III 13, a sweep frequency F-P interferometer 14, a convex lens IV 15, a single-mode optical fiber 16, a photon receiver 17 and a computer 18.

The invention relates to a method for improving the signal-to-noise ratio of a Brillouin elastography system by an interference type optical path, which is characterized in that a power-adjustable continuous laser 01 with the output wavelength of 532nm is adopted to generate a Brillouin scattering signal, and a frequency sweep type F-P interferometer and a photon receiver jointly form a spectrometer system for realizing high-precision scanning detection of the Brillouin scattering frequency shift signal.

Without being limited thereto, any changes or substitutions that are not thought of through the inventive work should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope defined by the claims.