Disclosure of Invention
The embodiment of the invention provides a photoacoustic endoscopic imaging device and system, which aim to solve the problem that the axial resolution of multi-wavelength imaging is reduced due to the fact that a lens is adopted to realize light beam focusing in a photoacoustic endoscopic imaging system based on a nonlinear photoacoustic imaging technology in the prior art, so that the quality of a reconstructed image is low.
In a first aspect, an embodiment of the present invention provides a photoacoustic endoscopic imaging apparatus, including:
the optical fiber bundle comprises a plurality of optical fibers, wherein each optical fiber comprises a signal transmitting end for transmitting an incident optical signal;
the concave surface reflector is coaxial with and opposite to the optical fiber bundle, and a reflecting curved surface is arranged on one side of the concave surface reflector opposite to the optical fiber bundle; the reflecting curved surface reflects incident light signals emitted by the optical fiber bundle to form reflected light signals, and the reflected light signals are converged at an external focus of the reflecting curved surface to form a focusing light ring and irradiate a light receiving area after passing through the focus;
and the annular ultrasonic transducer array is used for receiving photoacoustic signals for ultrasonic imaging excited by the light receiving area under the irradiation of the reflected light signals and outputting electric signals corresponding to the photoacoustic signals.
As a preferred aspect of the first aspect of the present invention, the optical fiber bundle further includes a first matching tube, an inner side of which is connected to the optical fiber bundle;
the side surface of the first matching pipe opposite to the concave reflecting mirror is flush with the signal transmitting end of each optical fiber in the optical fiber bundle.
In a preferred aspect of the first aspect of the present invention, the concave mirror further includes a second matching pipe, one end of the inside of the second matching pipe is connected to the outside of the first matching pipe, and the other end of the inside of the second matching pipe is connected to the outside of the concave mirror;
an annular step-shaped limiting groove is formed in the outer side of the second matching pipe, and the ultrasonic transducer array is arranged at the limiting groove.
As a preferable mode of the first aspect of the present invention, an annular fixing ring for fixing the ultrasound transducer array is further provided at the limiting groove.
In a preferred aspect of the first aspect of the present invention, the second matching tube is made of a hard light-transmitting material.
As a preferable mode of the first aspect of the present invention, the optical fiber bundle further includes a base, and the base is connected to a side of the concave reflecting mirror opposite to the optical fiber bundle;
one side of the base, which is connected with the concave reflector, is provided with an annular edge extending outwards, and the inner side of the edge is also connected with the outer side of the second matching pipe.
As a preferable mode of the first aspect of the present invention, the base is provided with a positioning groove, the concave reflecting mirror is provided with a positioning column adapted to the positioning groove, and the concave reflecting mirror is connected to the base by the installation and matching of the positioning column and the positioning groove.
In a preferred aspect of the first aspect of the present invention, the concave reflecting mirror is an annular reflecting mirror, and the curved reflecting surface is a spherical surface.
In a preferred aspect of the first aspect of the present invention, the optical fiber bundle has a circular ring shape.
In a second aspect, an embodiment of the present invention provides a photoacoustic endoscopic imaging system, including a computer system, further including the photoacoustic endoscopic imaging apparatus according to any one of the first aspect and its preferred embodiments described above;
the computer system is used for sending optical signals to the optical fibers and is also used for collecting and analyzing electric signals output by the ultrasonic transducer array to reconstruct images.
According to the photoacoustic endoscopic imaging device and the photoacoustic endoscopic imaging system, the concave reflecting mirror with the reflecting curved surface is arranged, so that incident light signals emitted by the optical fiber bundle can be reflected to form reflected light signals, the reflected light signals are converged at the external focus of the reflecting curved surface to form a focusing light ring and are irradiated onto the light receiving area after passing through the focus, and the light receiving area is enabled to excite strong photoacoustic signals. The device and the system effectively overcome the inherent defect that the focal position of the converged light beam changes along with the wavelength due to the chromatic aberration of the lens, can obviously improve the axial resolution of the nonlinear photoacoustic endoscopic imaging device and the nonlinear photoacoustic endoscopic imaging system, and can effectively improve the quality of a reconstructed image.
In addition, the device has compact structure, further reduces the volume of the photoacoustic imaging probe, and improves the flexibility of the motion posture of the endoscopic imaging catheter.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious 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.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Referring to fig. 1 to 3, an embodiment of the present invention provides a photoacoustic endoscopic imaging apparatus, which mainly includes:
an annular optical fiber bundle 10 composed of a plurality of optical fibers 11, the optical fibers 11 including a signal transmitting end 12-1 for transmitting an incident optical signal 12;
a concave reflector 20 which is coaxial with and opposite to the optical fiber bundle 10, and a reflecting curved surface 21 is arranged on one side of the concave reflector opposite to the optical fiber bundle 10; the reflecting curved surface 21 reflects the incident light signal emitted by the optical fiber bundle 10 to form a reflected light signal 22, and the reflected light signal 22 is converged at the external focal point of the reflecting curved surface 21 to form a focusing light ring 23 and irradiates the light receiving area after passing through the focal point;
and a ring-shaped ultrasonic transducer array 30 for receiving the photoacoustic signal for ultrasonic imaging excited by the light receiving region under the irradiation of the reflected light signal 22 and outputting an electrical signal corresponding to the photoacoustic signal.
In this embodiment, the photoacoustic endoscopic imaging apparatus mainly includes an optical fiber bundle, a concave mirror, and an ultrasonic transducer array. The optical fiber bundle is an annular light source array consisting of a plurality of optical fibers, each optical fiber is provided with a signal transmitting end and is mainly used for transmitting an incident light signal, so that light beams emitted by the optical fiber bundle can form an annular closed light band to realize the excitation of photoacoustic signals in a 360-degree full-field area; the concave reflector is coaxial with and arranged opposite to the optical fiber bundle, a certain interval is formed between the concave reflector and the optical fiber bundle, and a reflecting curved surface is arranged on one side of the concave reflector opposite to the optical fiber bundle and is mainly used for reflecting an incident light signal sent by the optical fiber bundle to form a reflected light signal, the reflected light signal can be converged to an external focus of the reflecting curved surface to form a focusing light ring and further irradiates a light receiving area through the focus to enable the light receiving area to be heated and expanded; the ultrasonic transducer array is mainly used for receiving photoacoustic signals for ultrasonic imaging excited by a light receiving region under the irradiation of reflected light signals, receiving photoacoustic signals generated by a 360-degree full-field-of-view region and then outputting electric signals corresponding to the photoacoustic signals outwards.
The device adopts the ultrasonic transducer array to realize staring type imaging, and compared with a scanning type imaging mode, the staring type imaging mode has remarkable advantages in the aspect of imaging speed and can improve the imaging sensitivity. Meanwhile, the conical mirror which is used for realizing the functions of the existing imaging system is required to be arranged at the position of the front end of the probe, and because the device adopts a mode that the concave mirror reflects incident light signals, the lens which is also required to be arranged at the position of the front end of the probe is abandoned, the problem that the space occupation length is large due to the separated installation of the conical mirror and the lens is avoided, the size of the front end of the probe can be further shortened, and the free movement range of the front end of the imaging catheter is ensured.
In normal use, the photoacoustic endoscopic imaging apparatus is further connected to an external computer system having a function of transmitting an optical signal for photoacoustic imaging and acquiring and analyzing an electrical signal for optical or ultrasonic imaging to reconstruct an image. In general, the optical signal for photoacoustic imaging is a laser beam.
Under external driving, optical signals are transmitted along each optical fiber in the optical fiber bundle, each optical fiber generates incident optical signals at a signal transmitting end, the incident optical signals irradiate the reflecting curved surface of the concave reflecting mirror to be reflected, the irradiation range of the reflected optical signals is gradually reduced along with the increase of the distance until all the reflected optical signals are converged to an external focus of the reflecting curved surface to form a focusing light ring, then the irradiation range of the reflected optical signals is gradually increased after passing through the focus and then is irradiated to the light receiving area, and the light receiving area is enabled to excite strong photoacoustic signals for ultrasonic imaging. At this time, the light intensity signal received by the light receiving area can be changed by moving the light receiving area, and the strongest position of the light intensity signal is the focus position.
The device changes an element for realizing light beam focusing in the prior art into a concave reflector from a lens, utilizes the principle of light ray convergence by the concave reflector, has the advantage of no chromatic aberration, effectively overcomes the inherent defect that the focal position of a converged light beam changes along with the wavelength caused by the chromatic aberration of the lens, and can obviously improve the axial resolution of the nonlinear endoscopic photoacoustic imaging device and system, thereby achieving the purpose of improving the quality of a reconstructed image. Meanwhile, the device has compact structure, further reduces the volume of the photoacoustic imaging probe and improves the flexibility of the motion posture of the endoscopic imaging catheter.
Preferably, and with particular reference to FIG. 2, the bundle 10 is circular.
Particularly, for a staring type imaging system, not only the main propagation direction of a light beam needs to be changed from the axial direction to the radial direction so as to meet the requirements of side-looking imaging application of photoacoustic endoscopy, but also the light beam needs to be shaped into a circular ring, so that the generation area of a photoacoustic signal is matched with the annular detection area of an ultrasonic transducer array, and the sensitivity of the imaging system is improved.
Therefore, the optical fiber bundle is set to be circular, each optical fiber in the optical fiber bundle is used as an independent light-emitting unit, the emergent light beam is reflected through the concave reflector and focused in the outer side area of the ultrasonic transducer array 3, each optical fiber in the optical fiber bundle is focused to form a light spot array after being focused to form a light spot array, and the head and tail area of each light spot in the light spot array is overlapped with the adjacent light spots, so that a focusing light ring continuously distributed in 360 degrees is formed in space. Thus, the above requirements can be effectively satisfied to improve the sensitivity of the imaging system.
Meanwhile, multimode fibers are preferably used as the fibers constituting the optical fiber bundle.
Preferably, the concave reflector 20 is an annular reflector, and the curved reflective surface 21 is a spherical surface.
In particular, the concave reflector is preferably a ring reflector, and the curved reflecting surface on the concave reflector is preferably a spherical surface, so that the incident light signal can be well emitted and converged at the external focal point.
In actual use, the change of the focal point of the reflected light signal can be realized by changing the curvature of the curved surface reflected thereon.
Of course, those skilled in the art can also choose to set the reflecting curved surface to be other aspheric surface shapes according to actual needs, and the technical effects to be achieved by the present invention can also be achieved, which are not listed here.
In addition to the above embodiment, the optical fiber bundle connector further includes a first matching pipe 40, and the inner side of the first matching pipe 40 is connected to the optical fiber bundle 10;
the side of the first matching tube 40 opposite the concave mirror 40 is flush with the signal emitting end 11-1 of each optical fiber 11 in the bundle 10.
In this embodiment, the apparatus further includes a hollow first matching pipe provided outside the optical fiber bundle, and the inside of the first matching pipe is fixedly connected to the outside of the optical fiber bundle by gluing to fix the position of the optical fiber bundle.
Meanwhile, when the first matching pipe is fixed on the outer side of the optical fiber bundle during installation, the side surface of the first matching pipe opposite to the concave surface reflector is required to be flush with the signal transmitting end of each optical fiber in the optical fiber bundle, so that the first matching pipe is prevented from shielding incident light signals transmitted by the signal transmitting end of each optical fiber.
In addition to the above embodiment, the concave mirror further includes a second matching pipe 50, one end of the inside of the second matching pipe 50 is connected to the outside of the first matching pipe 40, and the other end of the inside of the second matching pipe 50 is connected to the outside of the concave mirror 20;
an annular stepped limiting groove 51 is formed on the outer side of the second matching pipe 50, and the ultrasonic transducer array 30 is disposed in the limiting groove 51.
In this embodiment, the apparatus further includes a second hollow matching pipe disposed outside the first matching pipe, and one end of the second matching pipe inside is fixedly connected to the outside of the first matching pipe in a gluing manner, so as to fix the positions of the first matching pipe and the optical fiber bundle; the other end of the inner side of the concave reflector is connected with the outer side of the concave reflector in a gluing mode so as to fix the position of the concave reflector.
Meanwhile, an annular step-shaped limiting groove is formed in the outer side of the second matching pipe, and an annular ultrasonic transducer array is arranged around the outer side of the second matching pipe at the limiting groove. The outer side of the second matching tube is connected with the ultrasonic transducer array in a gluing mode so as to fix the position of the ultrasonic transducer array. The ultrasonic transducer array is arranged close to the light receiving area, so that photoacoustic signals excited by the light receiving area can be conveniently received.
Preferably, an annular fixing ring 60 for fixing the ultrasonic transducer array 30 is further disposed at the limiting groove 51.
Specifically, an annular fixing ring is further arranged at the position of the limiting groove and used for further fixing the ultrasonic transducer array. Therefore, the reinforcing of the axial position is realized through the limiting groove processed on the outer side of the second matching pipe and the fixing ring, and the axial jumping of the ultrasonic transducer array can be effectively prevented.
Preferably, the second matching pipe 50 is made of a hard light-transmitting material.
Specifically, the second matching tube is made of a hard material with good light transmittance, so that reflected light signals can conveniently pass through the second matching tube.
The second matching pipe is preferably made of optical resin, has better light transmission performance and hardness, and can meet the use requirement,
On the basis of the above embodiment, specifically referring to fig. 3, the optical fiber bundle optical module further includes a base 70, wherein the base 70 is connected to a side of the concave reflecting mirror 20 opposite to the optical fiber bundle 10;
the side of the base 70 connected to the concave reflecting mirror 20 has an annular edge 71 extending outward, and the inner side of the edge 71 is also connected to the outer side of the second matching pipe 50.
In this embodiment, the apparatus further includes a base connected to a side of the concave reflecting mirror opposite to the optical fiber bundle, for encapsulating a structure disposed inside the second matching tube.
And one side of the base, which is connected with the concave reflector, is also provided with an annular edge which extends outwards, and the inner side of the edge is connected with the outer side of the second matching pipe in a gluing mode, so that the packaging of an internal structure is realized.
Preferably, the base 70 is provided with a positioning groove 72, the concave reflecting mirror 20 is provided with a positioning column 24 adapted to the positioning groove 72, and the concave reflecting mirror 20 is connected to the base 70 by the installation and matching of the positioning column 24 and the positioning groove 72.
Specifically, a positioning groove is arranged in the middle of the base, a positioning column matched with the positioning groove is arranged on the concave reflecting mirror, and the positioning column is installed in the positioning groove in a gluing mode so as to fix the position of the concave reflecting mirror and the base.
When the concave reflector is provided with the positioning column, the positioning column can be manufactured into an independent part through machining, and then is connected with the concave reflector in a gluing mode; or, the positioning column can be integrally processed and molded with the bottom surface of the concave reflector.
In addition, an embodiment of the present invention further provides a photoacoustic endoscopic imaging system, including a computer system, further including the photoacoustic endoscopic imaging apparatus according to any one of the above embodiments and preferred embodiments thereof;
the computer system is used for sending optical signals to the optical fiber and is also used for acquiring and analyzing signal electric signals after ultrasonic imaging received and output by the ultrasonic transducer array so as to reconstruct images.
In this embodiment, the photoacoustic endoscopic imaging system includes a computer system and the photoacoustic endoscopic imaging apparatus according to any one of the above embodiments and preferred embodiments thereof.
When the optical fiber bundle is used, an optical signal for photoacoustic imaging is sent to photoacoustic endoscopic imaging through the computer system, transmitted through each optical fiber in the optical fiber bundle of the photoacoustic endoscopic imaging device and finally emitted through the signal emitting end to form an incident optical signal. The incident light signal irradiates the reflecting curved surface of the concave reflecting mirror arranged opposite to the reflecting curved surface for reflection, the reflected emitted light signal is converged on the external focus of the reflecting curved surface to form a focusing light ring, and then the focusing light ring passes through the focus and irradiates the light receiving area to excite the light receiving area to generate a strong photoacoustic signal. And after the photoacoustic signals for ultrasonic imaging excited by the light receiving region are received by the ultrasonic transducer array, the ultrasonic transducer array converts the photoacoustic signals into corresponding electric signals and transmits the electric signals to the computer system. The electric signal is subjected to a series of algorithms in a computer system, and finally image reconstruction is completed, so that the image quality is high.
In summary, the photoacoustic endoscopic imaging apparatus and system according to the embodiments of the present invention can reflect the incident light signal emitted from the optical fiber bundle to form the reflected light signal by providing the concave mirror having the curved reflective surface, and the reflected light signal is converged at the external focal point of the curved reflective surface to form the focused light ring and is irradiated onto the light receiving area after passing through the focal point, so that the light receiving area emits a strong photoacoustic signal. The device and the system effectively overcome the inherent defect that the focal position of the converged light beam changes along with the wavelength due to the chromatic aberration of the lens, can obviously improve the axial resolution of the nonlinear photoacoustic endoscopic imaging device and the nonlinear photoacoustic endoscopic imaging system, and can effectively improve the quality of a reconstructed image.
In addition, the device has compact structure, further reduces the volume of the photoacoustic imaging probe, and improves the flexibility of the motion posture of the endoscopic imaging catheter.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., are based on the directions or positional relationships shown in the drawings, or the directions or positional relationships which are usually placed when the product of the present invention is used, and are only for the convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and thus, cannot be construed as limiting the present invention.
Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," and "connected" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.