CN114431816A

CN114431816A - Optical fiber endoscope capable of eliminating phase distortion

Info

Publication number: CN114431816A
Application number: CN202111657533.3A
Authority: CN
Inventors: 刘毅
Original assignee: Suzhou Junlin Huihe Information Technology Co ltd
Current assignee: Suzhou Junlin Huihe Information Technology Co ltd
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2022-05-06

Abstract

The invention belongs to the field of medical equipment, in particular to an optical fiber endoscope capable of eliminating phase distortion, aiming at different modes guided in thousands of existing optical fibers, each single optical fiber shows random phase distortion, this hinders the problem of transferring depth information or imaging a focus object, and a solution has been proposed, which comprises a display end, a digital image sensor, an ocular lens, a near-end optical fiber surface, a first coherent optical fiber bundle, a diffuser and a far-end diffraction optical grating, wherein the diffuser is arranged on the far-end diffraction optical grating, the far-beam end diffraction optical grating has the advantages of compactness and low cost, paves a road for a minimally invasive 3D endoscope, and is beneficial to the paradigm conversion of optical imaging application in biomedicine.

Description

Optical fiber endoscope capable of eliminating phase distortion

Technical Field

The invention relates to the technical field of medical equipment, in particular to an optical fiber endoscope capable of eliminating phase distortion.

Background

In order to solve the problem that the conventional 2D endoscope cannot provide depth information without mechanical scanning, an ultra-thin endoscope having a three-dimensional imaging (3D) function is proposed, which can observe weak structures such as visual cortex, cochlea, or capillary vessels. The smallest imaging endoscopes are based on multimode optical fibers and do not require the insertion of bulky optical elements at the distal fiber face. Miniature endoscopes with millimeter resolution, millimeter diameter, and 3D imaging capabilities play an important role in medical imaging and diagnostics. 3D imaging can be achieved by a multimode fiber optic endoscope having a cross-sectional area of about 1mm 2. However, multimode fibers exhibit complex optical transfer functions due to modal mixing and modal dispersion. To achieve imaging, multimode fiber endoscopes rely on calibration of transmission characteristics, such as using a spatial light modulator to precode light on the proximal fiber side to achieve the desired light field distribution and focusing at the distal end of the multimode fiber. But such calibration requires real-time detection. In contrast, a coherent fiber bundle, also known as a multicore fiber, may deliver intensity modes of a hidden region of the distal fiber face to the proximal fiber face instrument, with a lens system at the distal end of the coherent fiber bundle to magnify the core-to-core distance and define resolution. The diameter of the coherent fiber bundle can be up to several millimeters, with minimal invasion of body tissues, but its distal optics increase the footprint of the endoscope, an increase typically in the millimeter range. This greatly limits its use in other applications in the biomedical field. Because coherent fiber bundles incorporate thousands of individual fibers, each individual fiber exhibits arbitrary phase distortion, which prevents the transmission of depth information or the imaging of the focal object;

multimode fibers exhibit complex optical transfer functions due to mode mixing and intermodal dispersion, which are very difficult to achieve in-situ calibration in real time for accurate imaging, and optimization based on this is achieved by guiding different modes in separate fiber cores, so that mode mixing does not occur, but guiding different modes in thousands of fibers, each individual fiber exhibiting arbitrary phase distortion, which prevents the transfer of depth information or the imaging of the focal object.

Disclosure of Invention

The invention aims to solve the defects that in the prior art, thousands of optical fibers guide different modes, and each single optical fiber shows random phase distortion, which hinders the transmission of depth information or the imaging of a focus object, and provides an optical fiber endoscope capable of eliminating the phase distortion.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a can eliminate optical fiber endoscope of phase distortion, includes display end, digital image sensor, eyepiece lens, near-end fiber surface, first coherent fiber bundle, diffuser and far-reaching beam end diffraction optical grating, the diffuser sets up and locates on the far-reaching beam end diffraction optical grating, and the diffuser is connected with first coherent fiber bundle, and first coherent fiber bundle is connected with the near-end fiber surface, and the near-end fiber surface is connected with eyepiece lens, and eyepiece lens is connected with digital image sensor, and digital image sensor is connected with the display end.

Preferably, the diffuser is spaced 500 μm from the first coherent fiber bundle.

Preferably, 50000 cores are arranged in the first coherent optical fiber bundle.

Preferably, the length of the first coherent optical fiber bundle is set to be 10 cm.

Preferably, the diffuser has a diffuser plane facing the fiber side.

Preferably, the far-end diffraction optical grating is composed of thousands of pillars having different heights.

Preferably, the digital image sensor is composed of a CMOS camera.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention uses two-photon polymerization photo-etching method to produce phase conjugate far-beam end diffraction optical grating on coherent optical fiber beam;

2. the invention uses the far-beam end diffraction optical grating with random mode to code the three-dimensional object information into a two-dimensional speckle pattern transmitted along the coherent optical fiber bundle;

the high beam end diffraction optical grating has the advantages of compactness and low cost, paves a way for a minimally invasive 3D endoscope, and is beneficial to the paradigm conversion of optical imaging application in biomedicine.

Drawings

FIG. 1 is a schematic structural diagram of a fiber optic endoscope capable of eliminating phase distortion according to the present invention;

FIG. 2 is a first flowchart of a process for manufacturing a diffractive optical grating at a distal end of a fiber optic endoscope capable of eliminating phase distortion according to the present invention;

FIG. 3 is a second flowchart of a process for manufacturing a diffractive optical grating at the distal end of a fiber optic endoscope capable of eliminating phase distortion according to the present invention;

fig. 4 is a third flow chart illustrating a manufacturing process of a far-end diffraction optical grating of a fiber endoscope capable of eliminating phase distortion according to the present invention.

In the figure: the optical fiber array comprises a display end 1, a digital image sensor 2, an eyepiece lens 3, a proximal optical fiber surface 4, a first coherent optical fiber bundle 5, a diffuser 6, a far-beam end diffraction optical grating 7, an incident plane light 8, a spatial light modulator 9, an optical field with phase distortion 10, a second coherent optical fiber bundle 11 and a focused optical field 12.

Detailed Description

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.

Referring to fig. 1-4, an optical fiber endoscope capable of eliminating phase distortion includes a display end 1, a digital image sensor 2, an eyepiece lens 3, a proximal optical fiber surface 4, a first coherent optical fiber bundle 5, a diffuser 6 and a distal end diffraction optical grating 7, wherein the diffuser 6 is disposed on the distal end diffraction optical grating 7, the diffuser 6 is connected with the first coherent optical fiber bundle 5, the first coherent optical fiber bundle 5 is connected with the proximal optical fiber surface 4, the proximal optical fiber surface 4 is connected with the eyepiece lens 3, the eyepiece lens 3 is connected with the digital image sensor 2, and the digital image sensor 2 is connected with the display end 1.

In this embodiment, the diffuser 6 is located 500 μm from the first coherent fiber bundle 5.

In this embodiment, 50000 cores are provided in the first coherent optical fiber bundle 5.

In this embodiment, the length of the first coherent optical fiber bundle 5 is set to 10 cm.

In this embodiment, the diffuser 6 has a diffuser plane facing the fiber surface.

In this embodiment, the far-end diffraction optical grating 7 is composed of thousands of pillars having different heights.

In this embodiment, the digital image sensor 2 is composed of one CMOS camera.

In this embodiment, the type of the diffuser 6 is Thorlabs DG10-120-a, the type of the coherent optical fiber bundle 5 is Fujikura, fig-50-1100N, the digital image sensor 2 is uEye, a manufacturing process of a diffraction optical grating for matching phase distortion includes an incident plane light 8, a spatial light modulator 9, a light field 10 with phase distortion, a coherent optical fiber bundle 11 and a focused light field 12, a manufacturing process of the far-end diffraction optical grating 7 is to perform phase distortion compensation on dynamic digital optical phase conjugation by using the spatial light modulator 9 to realize focusing on the far-end fiber side, and then the far-end diffraction optical grating 7 is manufactured by two-photon lithography, the far-end diffraction optical grating 7 can provide a static phase difference of the second coherent optical fiber bundle 11 and is placed in front of the near-end optical fiber to perform focusing and phase matching functions, each post of the far-end diffractive optical grating 7 is directly placed on top of a single optical fiber, and phase distortion can be matched by changing the post height, so that the output light field and the input light field are closely matched, which can realize a stable and low-cost 3D endoscope with a diameter less than 1 mm. Finally, 1mm resolution imaging and reconstruction are realized respectively.

Printing process of the far-end diffraction optical grating 7:

to match the core size, the far-end diffraction optical grating 7 is composed of a cylinder having a diameter of 50 μm and a lateral distance of 10 μm. The phase retardation finally achieved is determined by the height h of the cylinder by the refractive index n of the photopolymer_p1.535 to determine:

h_maxwith a maximum modulation phase of 2 pi at 884nm, a base layer is first printed on the substrate to ensure adhesion, and the high beam end diffractive optical grating 7 is printed by a commercial 3D printer.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. The utility model provides a can eliminate optical fiber endoscope of phase distortion, includes display end (1), digital image sensor (2), eyepiece lens (3), near-end fiber surface (4), first coherent fiber bundle (5), diffuser (6) and far-reaching beam end diffraction optical grating (7), its characterized in that, diffuser (6) set up and locate far-reaching beam end diffraction optical grating (7) on, and diffuser (6) are connected with first coherent fiber bundle (5), and first coherent fiber bundle (5) are connected with near-end fiber surface (4), and near-end fiber surface (4) are connected with eyepiece lens (3), and eyepiece lens (3) are connected with digital image sensor (2), and digital image sensor (2) are connected with display end (1).

2. A phase distortion canceling fiberoptic endoscope according to claim 1, characterized in that the diffuser (6) is located 500 μm from the first coherent fiber bundle (5).

3. A fiber optic endoscope according to claim 1, characterized in that 50000 cores are provided in said first coherent fiber bundle (5).

4. A phase distortion cancelable fibre optic endoscope according to claim 1, characterised in that the length of the first coherent fibre optic bundle (5) is set to 10 cm.

5. A fiber optic endoscope according to claim 1 and characterized by the fact that the diffuser (6) has its diffuser plane facing the fiber optic face.

6. A fiber optic endoscope according to claim 1, characterized in that the distal diffractive optical grating (7) is composed of thousands of struts of different heights.

7. A fiber optic endoscope according to claim 1, characterized in that said digital image sensor (2) consists of a CMOS camera.