阅读说明：本技术 一种全光检测的内窥光声成像系统 (Endoscopic photoacoustic imaging system for all-optical detection ) 是由 张崇磊 杨武 谢振威 袁小聪 于 2019-10-12 设计创作，主要内容包括：本发明公开了一种全光检测的内窥光声成像系统,包括：光源组件、物镜、环形器、光纤探头、探测组件及控制显示器；光源组件包括发射出激发光束的第一激光器和发射出探测光束的第二激光器,激发光束和探测光束经物镜耦合后依次进入环形器、光纤探头；光纤探头包括双包层光纤和设置在双包层光纤远离环形器的端面上的光学共振腔；环形器具有第一端口、第二端口及第三端口,第一端口与物镜对应连接,第二端口与双包层光纤对应连接,第三端口与探测组件对应连接,第一激光器、第二激光器及探测组件均与控制显示器电连接。运用本技术方案解决了现有技术中超声换能器带宽窄、灵敏度低及内窥探头体积大的技术问题,实现了光声成像系统在临床上的内窥检测。(The invention discloses an endoscopic photoacoustic imaging system for all-optical detection, which comprises: the device comprises a light source component, an objective lens, a circulator, an optical fiber probe, a detection component and a control display; the light source component comprises a first laser emitting an excitation beam and a second laser emitting a detection beam, and the excitation beam and the detection beam are coupled by an objective lens and then sequentially enter the circulator and the optical fiber probe; the optical fiber probe comprises a double-clad optical fiber and an optical resonant cavity arranged on the end face of the double-clad optical fiber far away from the circulator; the circulator is provided with a first port, a second port and a third port, the first port is correspondingly connected with the objective lens, the second port is correspondingly connected with the double-clad optical fiber, the third port is correspondingly connected with the detection assembly, and the first laser, the second laser and the detection assembly are electrically connected with the control display. By applying the technical scheme, the technical problems of narrow bandwidth, low sensitivity and large volume of the endoscopic probe of the ultrasonic transducer in the prior art are solved, and the clinical endoscopic detection of the photoacoustic imaging system is realized.)

1. An endoscopic photoacoustic imaging system with plenoptic detection, comprising: the device comprises a light source component, an objective lens, a circulator, an optical fiber probe, a detection component and a control display;

the light source assembly, the objective lens, the circulator and the optical fiber probe are sequentially arranged; the light source component comprises a first laser emitting an excitation beam and a second laser emitting a detection beam, and the excitation beam and the detection beam are coupled by the objective lens and then sequentially enter the circulator and the optical fiber probe; the optical fiber probe comprises a double-clad optical fiber and an optical resonant cavity arranged on the end face of the double-clad optical fiber far away from the circulator; the circulator is provided with a first port, a second port and a third port, the first port is correspondingly connected with the objective lens, the second port is correspondingly connected with the double-clad optical fiber, the third port is correspondingly connected with the detection assembly, and the first laser, the second laser and the detection assembly are electrically connected with the control display.

2. The all-optical inspection endoscopic photoacoustic imaging system according to claim 1, wherein said double-clad optical fiber comprises a core, an inner cladding surrounding said core, and an outer cladding surrounding said inner cladding, said excitation light beam being coupled into said inner cladding through said objective lens, said probe light beam being coupled into said outer cladding through said objective lens.

3. The all-optical detection endoscopic photoacoustic imaging system according to claim 2, wherein the wavelength range of the excitation light beam is 300nm to 1000nm, and the wavelength range of the probe light beam is 400nm to 2200 nm.

4. The all-optical detection endoscopic photoacoustic imaging system according to claim 3, wherein said first laser is a solid-state laser and said second laser is a helium-neon laser.

5. The all-optical detection endoscopic photoacoustic imaging system according to claim 4, wherein said optical resonant cavity is an F-P resonant cavity.

6. The all-optical detection endoscopic photoacoustic imaging system according to claim 5, wherein a gold film is disposed on the end face of the F-P resonant cavity away from the double-clad fiber.

7. The all-optical detection endoscopic photoacoustic imaging system according to claim 6, wherein the fiber probe further comprises a focusing lens disposed on an end surface of the fiber core away from the circulator, and the gold film has a through hole corresponding to the focusing lens.

8. The all-optical detection endoscopic photoacoustic imaging system according to claim 7, wherein the end of the F-P resonant cavity is notched.

9. The plenoptic-detection endoscopic photoacoustic imaging system according to any one of claims 1 to 8, wherein said plenoptic-detection endoscopic photoacoustic imaging system further comprises a slip ring sleeved on the fiber-optic probe, and a rotary motor having an output end connected to the slip ring.

10. The all-optical detection endoscopic photoacoustic imaging system according to claim 1, wherein the detection assembly comprises a high frequency amplifier and a balanced detector, one end of the balanced detector is connected to the third port, the other end of the balanced detector is connected to the control display, and the high frequency amplifier is disposed between the balanced detector and the control display.

Technical Field

The invention relates to the technical field of photoacoustic imaging, in particular to an endoscopic photoacoustic imaging system for all-optical detection.

Background

In recent years, a Photoacoustic Imaging (PAI) based on a Photoacoustic effect has been paid more attention by researchers, and a short pulse laser is irradiated on a biological tissue, and a pigment substance inside the tissue absorbs energy of the laser, so that an ultrasonic wave, that is, a Photoacoustic signal, is generated due to an instantaneous thermoelastic effect. In photoacoustic imaging, since there is no need to mark biological tissue, the biological tissue is not damaged if the energy of the short pulse laser is controlled within a certain range. And different biological tissues have different absorption of the short pulse laser, so that specific observation of the optical absorption characteristics of the tissues can be realized.

Early photoacoustic imaging techniques were based on piezoelectric ceramic transducers. The early photoacoustic tomography has the spatial resolution of 200 mu m, and the subsequent dark field illumination type photoacoustic microscope not only improves the transverse resolution to 50 mu m, but also obviously improves the image quality. The optical resolution photoacoustic microscope achieves micron-scale transverse resolution, and clearly images microcirculation structures including capillary vessels and even red blood cells. In recent years, photoacoustic imaging has achieved sub-wavelength resolution (even breaking through the optical diffraction limit), while greatly increasing the image acquisition rate, and is able to reveal important morphological, functional, and dynamic information on a sub-cellular scale. These photoacoustic imaging techniques based on piezoelectric transducers are not ideal in detection bandwidth and detection sensitivity due to the limitations of the properties of the piezoelectric transducers themselves.

The photoacoustic endoscopic imaging technology is a combination of photoacoustic imaging and endoscopic technology, and can provide structural and functional information of in-situ biological tissues in vivo, and has become a main research and application development direction of the photoacoustic imaging technology due to the potential of clinical practice. The size of the photoacoustic endoscope probe is seriously limited by the volume of an ultrasonic transducer (a piezoelectric ceramic piece), on one hand, the ultrasonic transducer is adopted as an endoscopic ultrasonic probe, power supply and transmission cables are needed, and meanwhile, in order to ensure the stability of a transmission electric signal, insulation shielding protection is needed, which can limit the further reduction of the probe; on the other hand, the volume of the ultrasonic transducer and the detection sensitivity of the ultrasonic signal meet normal correlation, and based on the principle of piezoelectric effect, the larger the deformation amount of the piezoelectric material is, the more net charges are generated, so that in order to ensure the signal-to-noise ratio of the ultrasonic signal detection, the structural size of the ultrasonic transducer must be ensured to be within a certain range and cannot be infinitely reduced; on the other hand, the piezoelectric material commonly used by the existing ultrasonic transducer cannot be compatible with the detection sensitivity in the ultrasonic detection bandwidth, for example, the piezoelectric crystal material PVDF film commonly used by the piezoelectric ultrasonic transducer has the advantages of low acoustic impedance and wide frequency band, but the sensitivity is relatively low; the PZT piezoelectric ceramic material has high sensitivity, but the ultrasonic signal detection bandwidth is narrow.

Disclosure of Invention

The invention mainly aims to provide an endoscopic photoacoustic imaging system for all-optical detection, which solves the technical problems of narrow bandwidth, low sensitivity and large volume of an endoscopic probe of an ultrasonic transducer in the prior art, and enables the photoacoustic imaging system to realize the clinical endoscopic detection.

In order to achieve the above object, the present invention provides an endoscopic photoacoustic imaging system for all-optical detection, comprising: the device comprises a light source component, an objective lens, a circulator, an optical fiber probe, a detection component and a control display; the light source assembly, the objective lens, the circulator and the optical fiber probe are sequentially arranged; the light source component comprises a first laser emitting an excitation beam and a second laser emitting a detection beam, and the excitation beam and the detection beam are coupled by the objective lens and then sequentially enter the circulator and the optical fiber probe; the optical fiber probe comprises a double-clad optical fiber and an optical resonant cavity arranged on the end face of the double-clad optical fiber far away from the circulator; the circulator is provided with a first port, a second port and a third port, the first port is correspondingly connected with the objective lens, the second port is correspondingly connected with the double-clad optical fiber, the third port is correspondingly connected with the detection assembly, and the first laser, the second laser and the detection assembly are electrically connected with the control display.

Further, the double-clad optical fiber comprises a fiber core, an inner cladding layer covering the fiber core and an outer cladding layer covering the inner cladding layer, the excitation light beam is coupled into the inner cladding layer through the objective lens, and the detection light beam is coupled into the outer cladding layer through the objective lens.

Further, the wavelength range of the excitation light beam is 300nm-1000nm, and the wavelength range of the detection light beam is 400nm-2200 nm.

Further, the first laser is a solid laser, and the second laser is a helium-neon laser.

Further, the optical resonant cavity is an F-P resonant cavity.

Furthermore, a gold film is arranged on the end face of the F-P resonant cavity far away from the double-clad optical fiber.

Furthermore, the optical fiber probe also comprises a focusing lens, the focusing lens is arranged on the end face of the fiber core far away from the circulator, and a through hole corresponding to the focusing lens is formed in the gold film.

Furthermore, a gap is formed at the end part of the F-P resonant cavity.

Furthermore, the all-optical detection endoscopic photoacoustic imaging system further comprises a slip ring and a rotary motor, wherein the slip ring is sleeved on the optical fiber probe, and the output end of the rotary motor is connected with the slip ring.

Furthermore, the detection assembly comprises a high-frequency amplifier and a balance detector, one end of the balance detector is connected with the third port, the other end of the balance detector is connected with the control display, and the high-frequency amplifier is arranged between the balance detector and the control display.

The invention provides an endoscopic photoacoustic imaging system for all-optical detection, which has the beneficial effects that: the controller controls the first laser to emit an excitation beam and the second laser to emit a detection beam, the excitation beam and the detection beam enter the optical fiber probe from the circulator through the objective coupling, the excitation beam penetrates through the optical resonant cavity and strikes on a sample, the sample absorbs pulse energy to generate a photoacoustic signal, the refractive index of the interface of the cavity film of the optical resonant cavity and the sample is changed, the light intensity change of the detection beam returned is further influenced, the detection beam reflected after the optical resonant cavity interferes for multiple times passes through the detection assembly after being split by the circulator, and finally an image is constructed through a reconstruction program of the controller. By applying the technical scheme, the technical problems of narrow bandwidth, low sensitivity and large volume of the endoscopic probe of the ultrasonic transducer in the prior art are solved, so that the photoacoustic imaging system can realize the clinical endoscopic detection.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a block diagram schematically illustrating the structure of an endoscopic photoacoustic imaging system for all-optical detection according to the present invention;

FIG. 2 is a schematic structural diagram of a fiber-optic probe according to the present invention;

fig. 3 is a cross-sectional view of fig. 2.

Wherein the figures include the following reference numerals:

11. a first laser; 12. a second laser; 20. an objective lens; 31. a circulator; 311. a first port; 312. a second port; 313. a third port; 40. a fiber optic probe; 41. a double-clad optical fiber; 411. a fiber core; 412. an inner cladding; 413. an outer cladding; 42. an F-P resonant cavity; 421. a notch; 43. a focusing lens; 51. a balance detector; 52. a high-frequency amplifier; 60. controlling the display; 61. a data acquisition card; 70. a collimating lens group.

Detailed Description

In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 and fig. 2, an endoscopic photoacoustic imaging system with all-optical detection includes: light source assembly, objective lens 20, circulator 31, fiber probe 40, detection assembly and control display 60; the light source component, the objective lens 20, the circulator 31 and the optical fiber probe 40 are arranged in sequence; the light source component comprises a first laser 11 emitting an excitation beam and a second laser 12 emitting a detection beam, wherein the excitation beam and the detection beam are coupled by an objective lens 20 and then sequentially enter the circulator 31 and the optical fiber probe 40; the fiber probe 40 includes a double-clad fiber 41 and an optical resonant cavity provided on an end face of the double-clad fiber 41 remote from the circulator 31; the circulator 31 has a first port 311, a second port 312 and a third port 313, the first port 311 is correspondingly connected to the objective lens 20, the second port 312 is correspondingly connected to the double-clad fiber 41, the third port 313 is correspondingly connected to the detection component, and the first laser 11, the second laser 12 and the detection component are electrically connected to the control display 60.

In the invention, the controller controls the first laser 11 to emit an excitation beam and the second laser 12 to emit a detection beam, the excitation beam and the detection beam are coupled by the objective lens 20 and enter the fiber probe 40 from the circulator 31, the excitation beam passes through the optical resonant cavity and strikes on the sample, the sample absorbs the pulse energy to generate a photoacoustic signal, the refractive index of the interface between the cavity film of the optical resonant cavity and the sample is changed, the light intensity change of the detection beam returning is further influenced, the detection beam reflected after the multiple interference of the optical resonant cavity is split by the circulator 31 and then passes through the detection assembly, and finally the image is constructed through the reconstruction program of the control display 60. By applying the technical scheme, the technical problems of narrow bandwidth, low sensitivity and large volume of the endoscopic probe of the ultrasonic transducer in the prior art are solved, so that the photoacoustic imaging system can realize the clinical endoscopic detection.

The effect of the circulator 31 is better than that of adding the semi-transparent semi-return lens at the front end of the coupling part of the objective lens 20, the loss is low, and the reflected signal is easy to collect; the circulator 31 may also be replaced by a coupler which functions to split the light path for collection by the detection assembly.

Further, the double-clad optical fiber 41 includes a core 411, an inner cladding 412 covering the core 411, and an outer cladding 413 covering the inner cladding 412, wherein the excitation beam is coupled into the inner cladding 412 through the objective lens 20, and the detection beam is coupled into the outer cladding 413 through the objective lens 20. The first laser 11 emits an excitation beam to generate a signal, the second laser 12 emits a detection beam, the excitation beam and the detection beam are coupled into the double-clad optical fiber 41, all-optical detection can be achieved, and the structure volume of the optical fiber probe 40 is smaller, so that the optical fiber probe can replace a traditional piezoelectric ultrasonic transducer, and the sensitivity of the optical fiber probe is improved by 1-2 orders of magnitude compared with that of the traditional piezoelectric ultrasonic transducer.

The wavelength range of the excitation light beam is 300nm-1000nm, the wavelength range of the detection light beam is 400nm-2200nm, and the wavelengths of the excitation light beam and the detection light beam can be changed for different samples, wherein the maximum absorption coefficient of the sample and the maximum generated photoacoustic signal are used as the standard. Preferably, in the present technical solution, a wavelength of the excitation beam is 532nm, and a wavelength of the detection beam is 633nm, and further, the first laser 11 is a solid-state laser, and the second laser 12 is a he-ne laser.

The optical resonant cavity can be selected from micro-ring, micro-tube, micro-cavity, bragg grating, etc., and in this embodiment, the optical resonant cavity is selected from F-P resonant cavity 42. Further, a gold film is disposed on the end surface of the F-P resonant cavity 42 away from the double-clad fiber 41 to enhance the signal of the refractive index change of the sample, and of course, the end surface of the F-P resonant cavity 42 may be plated with films of different materials as long as it can enhance the signal of the refractive index change of the sample interface.

Referring to fig. 3, preferably, the fiber probe 40 further includes a focusing lens 43, the focusing lens 43 is disposed on an end surface of the fiber core 411 away from the circulator 31, a through hole corresponding to the focusing lens 43 is formed in the gold film, and the focusing lens 43 is disposed on the end surface of the fiber core 411 to focus the excitation beam to enable the sample to generate the ultrasonic signal.

Further, a notch 421 is formed at an end of the F-P resonant cavity 42, in the present technical solution, the F-P resonant cavity 42 is directly processed on an end surface of the double-clad optical fiber 41 by a two-photon three-dimensional lithography machine, and the notch 421 is formed at the end of the F-P resonant cavity 42 so that the inside glue can flow out during the lithography process, it should be noted that the material of the F-P resonant cavity 42 is not limited to the photoresist.

Preferably, the endoscopic photoacoustic imaging system with all-optical detection further comprises a slip ring and a rotary motor, the slip ring is sleeved on the fiber-optic probe 40, and the output end of the rotary motor is connected with the slip ring. The 360-degree large-field imaging of the endoscopic photoacoustic imaging system can be realized by controlling the rotation of the slip ring through the rotary motor.

Referring to fig. 1, the detection assembly includes a high frequency amplifier 52 and a balance detector 51, one end of the balance detector 51 is connected to the third port 313, the other end of the balance detector 51 is connected to the control display 60, and the high frequency amplifier 52 is disposed between the balance detector 51 and the control display 60. The signals collected by the balance detector 51 are first amplified by the high frequency amplifier 52 and then collected by the data acquisition card 61 in the control display 60, and the collected data are reconstructed into an image by the reconstruction program on the control display 60.

Further, a collimating lens group 70 is disposed between the light source assembly and the objective lens 20, and collimates and expands the excitation light from the first laser 11 and the detection light from the second laser 12 for subsequent coupling.

The technical scheme is that a double-clad optical fiber 41 is utilized, an F-P resonant cavity 42 is processed on the end face of the double-clad optical fiber 41, two laser beams are coupled into the double-clad optical fiber 41, one laser beam is used as exciting light, the other laser beam is used as detecting light, a double-light-source endoscopic photoacoustic imaging mode of all-optical detection and self-emission and self-collection is realized, and the optical absorption characteristic of biological tissues is closely related to the change of physiological functions, so that the endoscopic photoacoustic imaging system can be closer to clinical application.

The above description is provided for the all-optical detection endoscopic photoacoustic imaging system, and for those skilled in the art, there may be variations in the specific implementation and application scope according to the concepts of the embodiments of the present invention, and in summary, the content of the present specification should not be construed as limiting the present invention.