A large field of view micro-endoscope

Abstract

The present invention relates to the technical field of medical diagnostic imaging devices, and particularly relates to a large field of view microendoscope, which includes a microprobe. The microprobe includes a housing, an objective lens fixed to the housing, and a scanner disposed within the housing. The rear focal plane of the objective lens calculated according to the excitation light wavelength is located outside the objective lens body, and the scanner is located at the rear focal plane position of the objective lens. In this solution, the rear focal plane of the objective lens is located outside the lens body, and by arranging the scanner at the rear focal plane of the objective lens, the field of view angle is increased and the volume of the microprobe of the endoscope is reduced on the premise of keeping the diameter of the incident light beam unchanged, solving the problem in the prior art that the volume of the objective lens and the microprobe increases to achieve a large field of view.

Description

Technical Field

[0001] The present invention relates to the technical field of medical diagnostic imaging devices, and particularly to a large-field-of-view microendoscope. Background Art

[0002] With the development of science and technology, medical endoscopes have been widely used in the medical field and are one of the important tools for humans to observe and treat internal organs. During the development of endoscopes over more than 200 years, the structure has undergone four major improvements. From the initial rigid endoscope, semi-flexible endoscope to fiber endoscope, and then to today's electronic endoscope, the image quality has also achieved a qualitative leap. Nowadays, with LED lighting, endoscopes can obtain color photos or color TV images. At the same time, the images are no longer ordinary images of tissues and organs, but microscopic images observed under a microscope, and minute lesions can be clearly distinguished. According to existing clinical experience, the smaller the volume of the microprobe of the endoscope and the shorter the rigid section, the greater the reduction of the patient's pain. Therefore, endoscopes have been continuously developed towards miniaturization. Currently, endoscopes have a large magnification factor, resulting in a very small field of view.

[0003] With the development of medical diagnosis in recent years, the narrow field of view of traditional endoscopes cannot meet the current needs of medical diagnosis. Currently, there is one design each in the UK and the US that has achieved an ultra-large field of view, and both designs have been commercialized. Both designs rely on greatly increasing the diameter of the incident light beam to achieve a large field of view and a large light throughput. However, these two designs will cause the objective lens of the endoscope microprobe to be very expensive and large in size, which does not conform to the development trend of endoscopes. Summary of the Invention

[0004] The present invention aims to provide a large-field-of-view microendoscope that increases the field of view angle and reduces the volume of the endoscope microprobe while keeping the diameter of the incident light beam unchanged, and solves the problem in the prior art that the objective lens and the volume of the microprobe increase to achieve a large field of view.

[0005] The solution is basically as follows: A large-field-of-view microendoscope includes a microprobe. The microprobe includes a housing, an objective lens fixed to the housing, and a scanner disposed inside the housing. The rear focal plane calculated based on the excitation light wavelength of the objective lens is located outside the objective lens body, and the scanner is located at the position of the rear focal plane of the objective lens.

[0006] Beneficial effects: Compared with the objective lens (scan lens), the present invention has an ultra-short focal length, a high numerical aperture, and a small field of view angle. This solution has a large field of view angle and an external rear focal plane. Since this solution is very different from both ordinary scanning lenses and ordinary microscope objective lenses, it is unique. When in use, when a single uniaxial scanner or a single biaxial scanner is used, the single uniaxial scanner or the single biaxial scanner is located at the rear focal plane of the objective lens; when a set of two uniaxial scanners is used, the rear focal plane of the objective lens is located in the middle of the set of two uniaxial scanners. Since the rear focal plane of the present invention is far from the lens body (usually several millimeters away), there is sufficient space to install the scanner without the need to set a scanning lens and a tube lens between the scanner and the objective lens as in a traditional laser scanning endoscope. The length of the microscope scanning and imaging optical path is greatly shortened. The present invention is used to focus the excitation light beam reflected by the scanner in the sample and collect the emission light signal excited in the sample, and couple it into the optical fiber for transmitting the optical signal or the photodetector for detecting the optical signal through the focusing lens.

[0007] Further, the scanner adopts a dichroic mirror scanner, which includes a driver and several dichroic mirrors. The dichroic mirrors are used to reflect the laser and allow the nonlinear optical signal to pass through; the driver is used to change the angle of the dichroic mirror according to the instruction. The driver includes several lens bodies through which the nonlinear optical signal can transmit, and the dichroic mirror is fixed on the surface of the lens body.

[0008] Compared with the traditional MEMS scanner in the prior art, this dichroic scanner can meet the imaging quality without a scanning lens and a tube lens, reduces the number of lenses in the housing, reduces the volume of the microprobe, and greatly improves the imaging speed at the same time.

[0009] Further, the dichroic mirror includes an ultra-thin sheet, and a dichroic thin film is plated on the ultra-thin sheet.

[0010] The dichroic mirror obtained in this way can be thinner and lighter, which is beneficial to further reducing the volume and weight of the microprobe.

[0011] Further, the objective lens includes lens one, lens two, lens three, lens four, and lens five through which the outgoing light passes in sequence. Lens one is a concave-convex lens, lens two is a biconvex lens, lens three is a concave-convex lens, lens four is a concave-convex lens, and lens five is a biconvex lens. With this combination, the objective lens can satisfy that the focal plane is outside the lens body.

[0012] Further, the radii of curvature of the first lens' image-side surface S11 and object-side surface S12 are -5.422 mm and -15.096 mm respectively; the radii of curvature of the second lens' image-side surface S21 and object-side surface S22 are 40.057 mm and -119.509 mm respectively; the radii of curvature of the third lens' image-side surface S31 and object-side surface S32 are 18.574 mm and 39.689 mm respectively; the radii of curvature of the fourth lens' image-side surface S41 and object-side surface S42 are 6.873 mm and 8.074 mm respectively; the radii of curvature of the fifth lens' image-side surface S51 and object-side surface S52 are 103.816 mm and -26.042 mm respectively.

[0013] The image-side surface is the surface of the lens farther from the scanning object, and the object-side surface is the surface of the lens closer to the scanning object. With the surface curvatures of each lens set according to the above parameters, the objective lens has a relatively small volume while ensuring a large field of view.

[0014] Further, the thickness of S11 is 14.307 mm, the thickness of S12 is 0.2 mm, the thickness of S21 is 1.5 mm, the thickness of S22 is 0.2 mm, the thickness of S31 is 1.674 mm, the thickness of S32 is 0.2 mm, the thickness of S41 is 6.083 mm, the thickness of S42 is 0.75 mm, the thickness of S51 is 6.083 mm, and the thickness of S52 is 0.75 mm.

[0015] With the above parameters set for the lenses, the axial length of the objective lens is relatively short while ensuring a large field of view.

[0016] Further, the radius of S11 is 6 mm, the radius of S12 is 14 mm, the radius of S21 is 14 mm, the radius of S22 is 14 mm, the radius of S31 is 14 mm, the radius of S32 is 14 mm, the radius of S41 is 12 mm, the radius of S42 is 6.6 mm, the radius of S51 is 7.2 mm, and the radius of S52 is 7.2 mm.

[0017] In this way, when the objective lens meets the requirement of a large field of view, the cross-sectional area of the objective lens formed by the radii of the above-mentioned surfaces is relatively small.

[0018] Further, the materials of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all optical glass or polymer or infrared imaging material. Optical glass or polymer or infrared imaging material is a common material for lenses in this field.

[0019] Further, the numerical aperture of the objective lens is greater than or equal to 0.7.

[0020] Furthermore, the field of view angle of the objective lens is greater than or equal to 15 degrees. Description of the Drawings

[0021] Figure 1 This is a schematic structural diagram of the microprobe of the present invention.

[0022] Figure 2 This is a schematic optical structure diagram of the objective lens of the embodiment of the present invention.

[0023] Figure 3 This is the field curvature and distortion diagram of the excitation light wavelength of the embodiment of the present invention.

[0024] Figure 4 This is the focal plane vignetting diagram of the excitation light wavelength of the embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the scanner of the embodiment of the present invention. Detailed Description of the Invention

[0026] The following is a further detailed description through specific embodiments:

[0027] The reference numerals in the accompanying drawings of the specification include: the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the scanner 6, the laser input optical fiber 90, the laser output optical fiber 91, the driver 22, the dichroic mirror 33, and the microprobe 50.

[0028] The embodiment is basically as follows:

[0029] A large field of view microendoscope, as Figure 1 shown, includes a microprobe 50. The microprobe 50 includes a housing and an objective lens. The housing is a sealed structure made of a polymer material. A scanner 6 and a plurality of lenses are provided inside the housing. The upper end of the housing is connected with a laser input optical fiber 90 and a laser output optical fiber 91. The objective lens is fixed at the lower end of the housing, i.e., the front aperture, and the scanner 6 is located above the objective lens. The scanner 6 is rotatably connected to the housing, so that the scanner 6 can change the angle for scanning. The laser emitted by the output optical fiber is reflected by the dichroic mirror and emitted from the objective lens to irradiate the human tissue.

[0030] As Figure 2 shown, the objective lens includes the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5. The scanner 6 is located on the rear focal plane calculated according to the excitation light wavelength. Among them, the first lens 1 is a concave-convex lens, the second lens 2 is a biconvex lens, the third lens 3 is a convex-concave lens, the fourth lens 4 is a convex-concave lens, and the fifth lens 5 is a biconvex lens.

[0031] Lens 1 has a surface S11 on the image side and a surface S12 on the object side. Lens 2 has a surface S21 on the image side and a surface S22 on the object side. Lens 3 has a surface S31 on the image side and a surface S32 on the object side. Lens 4 has a surface S41 on the image side and a surface S42 on the object side. Lens 5 has a surface S51 on the image side and a surface S52 on the object side.

[0032] The materials of Lens 1, Lens 2, Lens 3, Lens 4, and Lens 5 are optical glass, polymer, or infrared imaging material.

[0033] The data of each lens surface satisfy the following table:

[0034]

[0035] Among them, the excitation light wavelength is 920 nm, and the emission light wavelength is 520 nm.

[0036] Among them, the numerical aperture of the objective lens is 0.7, the working distance is 1 mm, and the field of view diameter is 1.65 mm.

[0037] This embodiment is used for non-linear optical imaging, so the requirement for achromatism is not high.

[0038] Figure 3 The field curvature and distortion diagram of the excitation light wavelength of this embodiment are shown. Since this embodiment is used for in-vivo biological tissue imaging, the requirements for field curvature and distortion are not high.

[0039] Figure 4 The vignetting diagram of the excitation light focal plane of this embodiment is shown. The excitation light wavelength reaches a transmission efficiency greater than 0.5 at the maximum viewing angle.

[0040] As Figure 5 shown, the scanner 6 uses a dichroic mirror scanner. The dichroic mirror scanner includes a driver 22 and several dichroic mirrors 33. The dichroic mirrors 33 are used to reflect laser light and allow non-linear optical signals to pass through. The driver 22 is used to change the angle of the dichroic mirrors 33 according to instructions. The driver 22 includes several mirror bodies through which non-linear optical signals can be transmitted, and the dichroic mirrors 33 are fixed on the surface of the mirror bodies.

[0041] The dichroic mirror 33 includes an ultra-thin sheet, and a dichroic thin film is plated on the ultra-thin sheet. The dichroic mirror 33 can reflect the laser light incident from the incident optical fiber 90 and can transmit the emitted light (such as fluorescent photons) excited by the human tissue. Compared with the traditional MEMS scanner 6 in the prior art, this dichroic scanner 6 can meet the imaging quality without a scanning lens and a sleeve lens, reduces the number of lenses in the housing, reduces the volume of the microprobe 50, and greatly improves the imaging speed at the same time.

[0042] The above are only embodiments of the present invention, and common knowledge such as specific structures and characteristics known in the art are not described in detail herein. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A large field of view microendoscope, comprising a microprobe, the microprobe including a housing, an objective lens fixed to the housing, and a scanner disposed within the housing, characterized in that: the rear focal plane of the objective lens calculated according to the excitation light wavelength is located outside the objective lens body, and the scanner is located at the rear focal plane position of the objective lens, the scanner adopts a dichroic mirror scanner, the dichroic mirror scanner including a driver and a plurality of dichroic mirrors, the dichroic mirrors being used for reflecting laser light and allowing non-linear optical signals to pass through; the driver is used for changing the angles of the dichroic mirrors according to instructions, the driver including a plurality of lens bodies through which non-linear optical signals can transmit, and the dichroic mirrors being fixed on the surfaces of the lens bodies, the dichroic mirrors include ultra-thin sheets, and dichroic thin films are plated on the ultra-thin sheets, the objective lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens through which the outgoing light passes in sequence, the first lens being a concave-convex lens, the second lens being a biconvex lens, the third lens being a convex-concave lens, the fourth lens being a convex-concave lens, and the fifth lens being a biconvex lens, the curvature radii of the opposite image side surface S11 and the opposite object side surface S12 of the first lens are -5.422 mm and -15.096 mm respectively; the curvature radii of the opposite image side surface S21 and the opposite object side surface S22 of the second lens are 40.057 mm and -119.509 mm respectively; the curvature radii of the opposite image side surface S31 and the opposite object side surface S32 of the third lens are 18.574 mm and 39.689 mm respectively; the curvature radii of the opposite image side surface S41 and the opposite object side surface S42 of the fourth lens are 6.873 mm and 8.074 mm respectively; the curvature radii of the opposite image side surface S51 and the opposite object side surface S52 of the fifth lens are 103.816 mm and -26.042 mm respectively, the thickness of S11 is 14.307 mm, the thickness of S12 is 0.2 mm, the thickness of S21 is 1.5 mm, the thickness of S22 is 0.2 mm, the thickness of S31 is 1.674 mm, the thickness of S32 is 0.2 mm, the thickness of S41 is 6.083 mm, the thickness of S42 is 0.75 mm, the thickness of S51 is 6.083 mm, and the thickness of S52 is 0.75 mm, the radius of S11 is 6 mm, the radius of S12 is 14 mm, the radius of S21 is 14 mm, the radius of S22 is 14 mm, the radius of S31 is 14 mm, the radius of S32 is 14 mm, the radius of S41 is 12 mm, the radius of S42 is 6.6 mm, the radius of S51 is 7.2 mm, and the radius of S52 is 7.2 mm, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all lenses made of optical glass or polymer or infrared imaging material, the numerical aperture of the objective lens is equal to 0.7, the field of view angle of the objective lens is equal to 15 degrees.

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