High-performance GRIN lens rotation scanning endoscopic probe and imaging method

Abstract

The invention provides a high-performance GRIN lens rotary scanning endoscopic probe and an imaging method. The probe comprises an upper tube, a single-mode optical fiber, a glass clamp, a first GRIN lens, an inner tube, an outer tube, a bevel gear, a direct-current brushless motor, a deflection unit and a focusing unit. The upper tube is fixed at the near end of the probe, the single-mode optical fiber is arranged in the upper tube, the glass clamp fixes the single-mode optical fiber at the near end of the probe, the glass clamp and the first GRIN lens are sequentially wrapped at the far end of the upper tube, and the second GRIN lens is arranged at the far end of the upper tube. The inner tube and the outer tube are driven by a direct-current brushless motor to rotate at the same speed in opposite directions through a group of bevel gears, the deflection unit is arranged at the far end of the inner tube, and the focusing unit is arranged in the outer tube. According to the invention, a coupling type optical path of deflection and focusing is abandoned, and the deflection function and the focusing function are decoupled and separated. Independent control of a deflection function and a focusing function is achieved, and high-performance deflection and large-working-distance focusing can be achieved to the maximum extent.

Description

Technical Field

[0001] This application relates to the technical field of optical coherence tomography (OCT), and more particularly, to a high-performance GRIN lens rotational scanning endoscope probe and an imaging method. Background Art

[0002] Optical Coherence Tomography (OCT) imaging technology is a new type of optical imaging technology that can perform non-invasive, non-contact, high-resolution in-vivo imaging of the internal tissue structure and physiological functions of the measured living samples, and has broad application prospects in the fields of early disease diagnosis and in-vivo biopsy. It has been experimentally confirmed that OCT technology has important application value in the research of ophthalmology, dentistry, cardiovascular diseases, early diagnosis of skin cancer, and developmental biology.

[0003] Since the development of optical coherence tomography imaging technology to date, three types have been formed: time-domain OCT systems, spectral-domain OCT systems, and swept-source OCT systems. The early time-domain OCT systems achieved tomographic imaging of biological samples through axial mechanical scanning. The spectral-domain OCT systems and swept-source OCT systems can image without axial scanning, achieving high-speed and high-sensitivity optical coherence tomography imaging. However, for the above three types of OCT systems, since the optical bands used can only penetrate several millimeters in tissues, they cannot directly penetrate the human body outside the body to perform tomographic imaging of internal tissues and organs. Compared with other imaging technologies (such as ultrasonic imaging and CT imaging), the limited imaging depth restricts the imaging and diagnosis of the lesions of human internal tissues and organs by OCT technology.

[0004] To eliminate this restrictive factor, only by developing endoscopy technology based on OCT systems can OCT technology be applied to high-resolution imaging of human internal tissues and organs. Among them, the forward-looking imaging probe can perform 2D scanning, and combined with the depth-resolved imaging ability of OCT, 3D imaging can be essentially achieved. Many foreign research institutions have carried out research in this area. In 2006, Jiang Wu developed a paired-angle rotation scanning OCT (PARS-OCT) probe (Wu J, Conry M, Gu C, etal. Paired-angle-rotation scanning optical coherence tomography forward-imaging probe. Opt Lett, 200631(9): 1265-1267.); In 2008, Shuo Han developed a forward-viewing needle probe for PARS-OCT with a diameter of 820 μm, which is very suitable for assisting vitrectomy (Han S, Sarunic MV, Wu J, et al. Handheld forward-imaging needle endoscope for ophthalmic optical coherence tomography inspection. J Biomed Opt , 2008; 13(2): 020505.); In 2011, Jian Ren et al. developed a forward-viewing needle probe for PARS-OCT with a diameter of 1.6 mm, which can be used to accurately locate the position of the collector channel in the Schlemm's canal during glaucoma surgery (Jian R, Ren H, Henrick K, et al. Ex Vivo Optical Coherence Tomography Imaging of Collector Channels with a Scanning Endoscopic Probe. Invest Ophthalmol Vis Sci , 2011; 52(7): 3921-3925.).

[0005] All of the above methods have the same drawback. In the optical path design, the PARS-OCT probes developed by Jiang Wu, Shuo Han, and Jian Ren utilize two GRIN lenses with wedge angles (usually referred to as gradient lenses, also known as variable refractive index lenses or inhomogeneous medium lenses, which are optical imaging elements designed and manufactured using media with gradient refractive indices) to simultaneously achieve deflection and focusing functions. The coupling of the deflection and focusing functions is not conducive to increasing the working distance of the probe, which in turn affects the scanning range of the probe. In addition, due to the particularly small size and wedge angle of the GRIN lenses used, the processing accuracy of the GRIN prisms also greatly limits the deflection and focusing functions of the probe.

[0006] For clinical surgeries, clinicians would prefer to use a probe with as small a size as possible to obtain a wider scanning range. However, the ratio of the arc length to the probe diameter at the working distance of the reported PARS-OCT probe with the largest effective optical channel area is only 0.637.

[0007] Therefore, how to decouple the deflection function and the focusing function in the optical path design to develop a probe with a high-precision scanning mode and a high-performance large working distance, and then develop a forward-viewing imaging OCT probe with a thinner diameter, a wider scanning range, and more suitable for clinicians to use, has become a major goal in the design of OCT probes.

[0008] In addition, in the fields of biomedical imaging and others, there are requirements for fast and high-precision scanning technology, and at the same time, there are requirements for small size and large scanning range for clinical probes. However, it is difficult for traditional optical path designs and scanning methods to simultaneously meet these indicators. Summary of the Invention

[0009] In view of this, the present application provides a high-performance GRIN lens rotary scanning endoscope probe and an imaging method, so as to decouple and separate the deflection function and the focusing function from the optical path design, and realize a high-precision scanning mode and a high-performance large scanning range through independent control of the deflection function and the focusing function on the premise of a small size.

[0010] To achieve the above object, the technical solution adopted in the present application is as follows: A high-performance GRIN lens rotary scanning endoscope probe, comprising: an upper tube, a single-mode optical fiber, a glass ferrule, a first GRIN lens, an inner tube, an outer tube, bevel gears, a DC brushless motor, a deflection unit, and a focusing unit; the upper tube is fixed at the proximal end of the probe, the single-mode optical fiber is disposed in the upper tube, and the glass ferrule fixes the single-mode optical fiber at the proximal end of the probe. The glass ferrule and the first GRIN lens are sequentially wrapped at the distal end of the upper tube. The inner tube and the outer tube rotate at the same speed in opposite directions under the drive of a DC brushless motor through a set of bevel gears. The deflection unit is disposed at the distal end of the inner tube, the focusing unit is disposed in the outer tube, and the distal end of the inner tube is disposed at the proximal end of the outer tube.

[0011] Further, the deflection unit includes a second GRIN lens and a third GRIN lens, and the second GRIN lens and the third GRIN lens form a double GRIN lens; the second GRIN lens and the third GRIN lens are respectively wrapped at the distal end of the inner tube and the proximal end of the outer tube at a certain interval distance, and the second GRIN lens and the third GRIN lens rotate at the same speed in opposite directions under the drive of a DC brushless motor through a set of bevel gears. The exit end face of the second GRIN lens and the incident end face of the third GRIN lens are polished at a certain wedge angle so that the light beam is deflected twice.

[0012] Further, the focusing unit includes a first quartz lens, a fourth GRIN lens, a second quartz lens, and a fifth GRIN lens; the first quartz lens, the fourth GRIN lens, the second quartz lens, and the fifth GRIN lens are sequentially bonded and then wrapped in the outer tube.

[0013] Further, the length of the first GRIN lens is selected to be 0.25P.

[0014] Further, one end face of the glass ferrule and the first GRIN lens is polished at an 8-degree angle.

[0015] Further, the lengths of the second GRIN lens and the third GRIN lens are respectively selected as 0.5P and 0.25P.

[0016] Further, the wedge angles of the exit end face of the second GRIN lens and the entrance end face of the third GRIN lens are both 22.5°.

[0017] The imaging method of the high-performance GRIN lens rotary scanning endoscope probe, which is used for the high-performance GRIN lens rotary scanning endoscope probe described in this application, includes: S1: The laser output by the single-mode optical fiber is collimated by the first GRIN lens and output to the deflection unit in the inner tube; S2: The wedge angles of the exit end face of the second GRIN lens and the entrance end face of the third GRIN lens of the deflection unit cause the light beam to deflect twice; S3: The light beam after deflection then enters the focusing unit; S4: The first quartz lens in the focusing unit expands the deflected light beam and converges the light beam on the second quartz lens through the converging property of the fourth GRIN lens; S5: Subsequently, the light beam passes through the expansion of the second quartz lens and the convergence of the fifth GRIN lens, and finally irradiates on the sample to be measured.

[0018] Further, the step S2 may also be: [[ID=ON]] The DC brushless motor makes the second GRIN lens and the third GRIN lens with wedge angles of 22.5° at both end faces rotate in the same speed and opposite directions through a set of bevel gears, so that the light beam is deflected twice by the two wedge-angle end faces, and then a linear B-scan mode is realized at the distal end of the probe.

[0019] Compared with the prior art, the beneficial effects of this application are: 1. This application abandons the coupled optical path of deflection and focusing, decouples and separates the deflection function from the focusing function. The independent control of the deflection function and the focusing function can be realized, and high-performance deflection and large working-distance focusing can be achieved to the greatest extent, greatly improving the ratio of the scanning arc length to the probe diameter of the probe. [[ID=ON]]

[0020] 2. The deflection situation of the deflection unit of this application uses the objective lens and the CCD camera to record the position signal of the scanning trajectory in real time, and further improves the simulation result accuracy of the mathematical model of the rotation angle of the GRIN lens and the light beam deflection angle, so as to realize a higher-quality scanning mode and image reconstruction.

[0021] 3. The focusing unit of the present application focuses the deflected light beam, and realizes a larger working distance with high performance of the probe through the focusing of two groups of quartz lenses and GRIN lenses (the working distance refers to the distance from the position of the focused light spot emitted from the end of the probe to the end of the probe), thereby developing a forward-view imaging OCT probe with a thinner diameter, a wider scanning range and more suitable for clinical doctors to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a structural diagram of the high-performance GRIN lens rotary scanning endoscope probe of the present application.

[0024] Figure 2 It is a schematic optical path diagram of the deflection unit in the present application.

[0025] Figure 3 It is a relationship curve diagram of the light beam deflection angle and the rotation angle difference of the double GRIN lenses in the present application.

[0026] Figure 4 It is a schematic structural diagram of the focusing unit in the present application.

[0027] Figure 5 It is a schematic diagram of the synchronous reverse movement and rotation of GRIN lens two and GRIN lens three of the deflection unit in the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application.

[0029] Such as Figure 1As shown, a high-performance GRIN lens rotary scanning endoscope probe includes: an upper tube 1, a single-mode optical fiber 2, a glass ferrule 3, a first GRIN lens 4, an inner tube 5, an outer tube 6, bevel gears 7, a DC brushless motor 8, a deflection unit 9, and a focusing unit 12; the upper tube 1 is fixed at the proximal end of the probe, the single-mode optical fiber 2 is disposed inside the upper tube 1, and the glass ferrule 3 fixes the single-mode optical fiber 2 at the proximal end of the probe. The glass ferrule 3 and the first GRIN lens 4 are sequentially wrapped at the distal end of the upper tube 1. The inner tube 5 and the outer tube 6 rotate at the same speed in opposite directions under the drive of a set of bevel gears 7 by the DC brushless motor 8. The deflection unit 9 is disposed at the distal end of the inner tube 5, the focusing unit 12 is disposed inside the outer tube 6, and the distal end of the inner tube 5 is disposed at the proximal end of the outer tube 6.

[0030] In a preferred embodiment, the length of the first GRIN lens 4 is selected to be 0.25P (2.64 mm), where P represents the pitch. One end face of the glass ferrule 3 and the first GRIN lens 4 is polished at an 8-degree angle.

[0031] Further, the deflection unit 9 includes a second GRIN lens 10 and a third GRIN lens 11, and the second GRIN lens 10 and the third GRIN lens 11 form a double GRIN lens; the second GRIN lens 10 and the third GRIN lens 11 are respectively wrapped at the distal end of the inner tube 5 and the proximal end of the outer tube 6 at a certain interval. The second GRIN lens 10 and the third GRIN lens 11 rotate at the same speed in opposite directions under the drive of a set of bevel gears 7 by the DC brushless motor 8 (as Figure 5 shown), and the exit end face of the second GRIN lens 10 and the incident end face of the third GRIN lens 11 are both polished at a certain wedge angle (for example, 22.5°) so that the light beam is deflected twice, as Figure 2 shown. The angle of the wedge angle can be determined according to specific circumstances.

[0032] Specifically, the drive signal of the DC brushless motor 8 is a PWM signal provided by a function generator, and the real-time speed of the DC brushless motor 8 is controlled by controlling the pulse duty cycle.

[0033] In a preferred embodiment, the DC brushless motor 8 is used in cooperation with a set of bevel gears 7 to make the second GRIN lens 10 and the third GRIN lens 11 with a 22.5° wedge angle at one end rotate in the same speed in opposite directions, so that the light beam is deflected twice by the two wedge end faces, and a linear B-scan mode is realized at the distal end of the probe. This simple drive system can achieve fast and high-precision scanning, reduce the requirements of the system for the motor acceleration and driving ability, and improve the rapidity of scanning.

[0034] This application selects a high-precision dual GRIN lens rotation scanning mode, and the lengths of GRIN lens two and GRIN lens three are respectively selected as appropriate lengths according to the actual situation. In a preferred embodiment, the lengths of the GRIN lens two 10 and the GRIN lens three 11 are respectively selected as 0.5P and 0.25P.

[0035] Refer to Figure 3 , Figure 3 which is a relationship curve graph between the beam deflection angle and the rotation angle difference of the dual GRIN lens in this application, and is calculated according to the following formula: where, θ represents the beam deflection angle, , the wedge angles of the GRIN lenses are both , is the rotation angle difference of the dual GRIN lens, the diameter d of the GRIN lens is 1 mm, the central refractive index is 1.591, the refractive index distribution constant is 0.5947, and the length Z of the GRIN lens three is 0.25P, that is, 2.64 mm.

[0036] The beam deflection angle output from the deflection unit 9 will change with the change of the rotation angle difference of the GRIN lens two 10 and the GRIN lens three 11. After the beam completes the deflection function, it finally passes through the focusing unit 12 and irradiates on the measured sample 13. The dual GRIN lens refers to the GRIN lens two 10 and the GRIN lens three 11.

[0037] Furthermore, as Figure 4 shown, the focusing unit 12 includes a quartz lens one 14, a GRIN lens four 15, a quartz lens two 16 and a GRIN lens five 17; the quartz lens one 14, the GRIN lens four 15, the quartz lens two 16 and the GRIN lens five 17 are adhesively bonded in sequence and then wrapped in the outer tube 6.

[0038] Specifically, the quartz lens one 14, the GRIN lens four 15, the quartz lens two 16 and the GRIN lens five 17 are adhesively bonded in sequence with optical UV glue and then wrapped in the outer tube 6.

[0039] After deflection, the beam is expanded by the first quartz lens 14 and focused on the second quartz lens 16 through the focusing property of the fourth GRIN lens 15. Then, after being expanded and focused by the second quartz lens 16 and the fifth GRIN lens 17, it finally irradiates on the sample under test 13. Compared with the previous optical path design (in 2008, Shuo Han developed a PARS-OCT forward-looking needle probe with a diameter, and its working distance reached 1.4 mm), the focusing optical path of this application greatly increases the working distance of the probe (2.15 mm) and maintains high lateral resolution (10.45 μm) for scanning imaging, enabling the sample imaging to have a relatively large effective optical channel area.

[0040] In this embodiment, the imaging process of the high-performance GRIN lens rotary scanning endoscope probe is as follows: The laser output from the single-mode optical fiber 2 is collimated by the first GRIN lens 4 and output to the deflection unit 9 in the inner tube 5. The exit end face of the second GRIN lens 10 and the entrance end face of the third GRIN lens 11 are polished at a certain wedge angle so that the beam is deflected twice. After the deflection function is completed, the beam then enters the focusing unit 12, where the first quartz lens 14 is used to expand the deflected beam and the beam is focused on the second quartz lens 16 through the focusing property of the fourth GRIN lens 15. Then, after being expanded and focused by the second quartz lens 16 and the fifth GRIN lens 17, it finally irradiates on the sample to be measured 13. To achieve a large working distance and maintain high lateral resolution for scanning imaging.

[0041] In this application, the deflection function and the focusing function are decoupled and separated in the optical path design, so that the deflection function and the focusing function can be independently controlled, and a high-precision double GRIN lens rotary scanning mode is selected. The single-mode optical fiber is fixed at the proximal end of the probe using a glass clamp, and then combined with GRIN lenses and quartz lenses to achieve illumination of the sample and collection of backscattered light. The probe proposed in this application can achieve a high-precision scanning mode and a high-performance large scanning range through independent control of the deflection function and the focusing function under the premise of a small size.

[0042] This application also provides an imaging method for a high-performance GRIN lens rotary scanning endoscope probe, which is used for the high-performance GRIN lens rotary scanning endoscope probe described in this application, and includes: S1: The laser output from the single-mode optical fiber is collimated by the first GRIN lens and output to the deflection unit in the inner tube; S2: The wedge angles of the exit end face of the second GRIN lens of the deflection unit and the entrance end face of the third GRIN lens cause the beam to be deflected twice; S3: After the deflection is completed, the beam then enters the focusing unit; S4: The first quartz lens in the focusing unit expands the deflected beam and focuses the beam on the second quartz lens through the focusing property of the fourth GRIN lens; S5: Subsequently, the light beam is expanded by the second quartz lens and focused by the fifth GRIN lens, and finally irradiates on the sample to be measured.

[0043] Furthermore, the step S2 can also be: The DC brushless motor drives two GRIN lenses with a 22.5° end face wedge angle, namely the second GRIN lens and the third GRIN lens, to rotate in the same speed but in opposite directions through a set of bevel gears, so that the light beam is deflected twice by the two wedge angle end faces, thereby realizing a linear B-scan mode at the distal end of the probe.

[0044] The high-performance GRIN lens rotating-scanning endoscope probe proposed in this application enables independent control of the deflection function and the focusing function. The single-mode optical fiber is fixed at the proximal end of the probe by using a glass ferrule, and then combined with multiple GRIN lenses and quartz lenses to realize the illumination of the sample and the collection of the backscattered light. The probe proposed in this application can achieve a high-precision scanning mode and a high-performance large scanning range through independent control of the deflection function and the focusing function on the premise of a small size. The probe greatly increases its light passing aperture, and can achieve a large working distance even on the premise of a small-sized probe, thereby ensuring a wide scanning range. For clinical surgery, this kind of endoscope probe with a large effective optical channel area is very clinically practical.

[0045] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application, and all of them should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A high-performance GRIN lens rotating-scanning endoscope probe, characterized in that, Comprising: An upper tube, a single-mode optical fiber, a glass clamp, a GRIN lens 1, an inner tube, an outer tube, bevel gears, a DC brushless motor, a deflection unit, and a focusing unit; the upper tube is fixed to the proximal end of the probe, the single-mode optical fiber is disposed within the upper tube, and the glass clamp fixes the single-mode optical fiber at the proximal end of the probe. The glass clamp and the GRIN lens 1 are sequentially wrapped at the distal end of the upper tube. The inner tube and the outer tube rotate in the same speed and opposite directions under the drive of a set of bevel gears by the DC brushless motor. The deflection unit is disposed at the distal end of the inner tube, the focusing unit is disposed within the outer tube, and the distal end of the inner tube is disposed at the proximal end of the outer tube.

2. The high-performance GRIN lens rotating-scanning endoscope probe according to claim 1, characterized in that, The deflection unit includes a GRIN lens 2 and a GRIN lens 3, and the GRIN lens 2 and the GRIN lens 3 form a double GRIN lens; the GRIN lens 2 and the GRIN lens 3 are respectively wrapped at the distal end of the inner tube and the proximal end of the outer tube at a certain interval distance. The GRIN lens 2 and the GRIN lens 3 rotate in the same speed and opposite directions under the drive of a set of bevel gears by the DC brushless motor. The exit end face of the GRIN lens 2 and the incident end face of the GRIN lens 3 are both polished at a certain wedge angle so that the light beam is deflected twice.

3. The high-performance GRIN lens rotary scanning endoscope probe according to claim 2, characterized in that, The focusing unit includes a quartz lens 1, a GRIN lens 4, a quartz lens 2, and a GRIN lens 5; the quartz lens 1, the GRIN lens 4, the quartz lens 2, and the GRIN lens 5 are sequentially bonded and then wrapped within the outer tube.

4. The high-performance GRIN lens rotary scanning endoscope probe according to claim 3, characterized in that, The length of the GRIN lens 1 is selected to be 0.25P.

5. The high-performance GRIN lens rotational scanning endoscope probe according to claim 3, characterized in that, One end face of the glass clamp and the GRIN lens 1 are both polished at an 8-degree angle.

6. The high-performance GRIN lens rotary scanning endoscope probe according to claim 3, wherein, The lengths of the GRIN lens 2 and the GRIN lens 3 are respectively selected to be 0.5P and 0.25P.

7. The high-performance GRIN lens rotary scanning endoscope probe according to claim 3, characterized in that, The wedge angles of the exit end face of the GRIN lens 2 and the incident end face of the GRIN lens 3 are both 22.5°.

8. Imaging method of a high-performance GRIN lens rotating-scanning endoscope probe, characterized in that, The method is used for the high-performance GRIN lens rotary scanning endoscope probe according to any one of claims 1-7, and includes: S1: The laser output from the single-mode optical fiber is collimated by the GRIN lens 1 and output to the deflection unit in the inner tube. S2: The wedge angle of the exit end face of the GRIN lens 2 and the wedge angle of the incident end face of the GRIN lens 3 of the deflection unit cause the light beam to be deflected twice. S3: The light beam after deflection then enters the focusing unit. S4: The quartz lens 1 in the focusing unit expands the deflected light beam and converges the light beam on the quartz lens 2 through the converging property of the GRIN lens 4. S5: Subsequently, the light beam passes through the expansion of the quartz lens 2 and the convergence of the GRIN lens 5, and finally irradiates on the sample to be measured.

9. The high-performance GRIN lens rotational scanning endoscope probe imaging method according to claim 8, characterized in that, Step S2 may also be: The DC brushless motor rotates the GRIN lens 2 and the GRIN lens 3 with two end face wedge angles of 22.5° in the same speed and opposite directions through a set of bevel gears, so that the light beam is deflected twice by the two wedge angle end faces, thereby realizing a linear B-scan mode at the distal end of the probe.

Images