A large-field handheld microscope

Abstract

The present invention relates to the field of miniature microscope technology, specifically to a large-field handheld microscope, comprising a microscope objective lens and a scanner, wherein the rear focal plane of the microscope objective lens is located outside the microscope objective lens, and the scanner is located on the rear focal plane of the microscope objective lens; the microscope objective lens comprises a plurality of lenses connected in sequence; the scanner comprises a photoelectric detector, an ultra-thin sheet, a filter film, and an optical coating connected in sequence. The present solution can be used to obtain a microscope with a low cost, small volume, and a high numerical aperture large-field imaging microscope objective lens.

Description

Technical Field

[0001] The invention relates to the technical field of miniature microscopes, in particular to a large-field handheld microscope. Background Art

[0002] Traditional microscope objective lens is an optical system with large aperture angle and small field angle. Since microscope objective lens is used to provide extremely high resolution (about 200nm, not considering super-resolution technology), its high magnification usually results in a very small field of view. In 2001, Martin Oheim et al. ("Two-photon microscopy in brain tissue: parameters influencing the imaging depth", Journal of Neuroscience Methods. 111: 29-37.) compared the performance of high magnification objective lens and low magnification objective lens with similar numerical aperture, and pointed out that increasing the front aperture of the objective lens is very beneficial for improving the collection efficiency of fluorescence, especially for multi-photon fluorescence excitation in deep parts. The 20-fold magnification 0.95 numerical aperture objective lens of Olympus Corporation of Japan tested in the article can provide more than 10 times the fluorescence collection efficiency relative to the 63-fold magnification 0.9 numerical aperture objective lens.

[0003] Therefore, recently Olympus Corporation of Japan launched a 10x magnification 0.6 numerical aperture objective lens (field of view = 1.8mm, focal length = 18mm, field of view angle 5.725 degrees, exit pupil diameter 16.24mm) and a series of 25x magnification 0.95-1.05 numerical aperture objective lenses (field of view = 0.72mm, focal length = 7.2mm, field of view angle 5.725 degrees, exit pupil diameter 10.83mm). Nikon Corporation of Japan also launched the CFI75 16x magnification 0.8 numerical aperture objective lens (field of view = 1.5625mm, focal length = 12.5mm, field of view angle 7.15 degrees, exit pupil diameter 15mm) and a 25x magnification 1.1 numerical aperture objective lens (field of view = 1mm, focal length = 8mm, field of view angle 7.15 degrees, exit pupil diameter 13.233mm). These low magnification, high numerical aperture objectives rely mainly on increasing the beam diameter, thus bringing the advantages of a large field of view and large light throughput, but their field of view angle remains consistent with the original small beam diameter objective.

[0004] With the development of neuroscience in recent years, the narrow field of view of traditional multiphoton microscopes cannot meet the requirements for functional imaging of massive neural cells. Some research groups have successively realized multiphoton microscopes with ultra-large fields of view. For example, in 2015, PSTsai et al. ("Ultra-large field-of-view two-photon microscopy", Opt Express. 2015Jun 1; 23(11): 13833–13847.) in the United States achieved an ultra-large field of view of 10 mm in diameter by optimizing lens chromatic aberration, but its design was based on a 4x magnification 0.28 numerical aperture objective lens, and the resolution was too low to meet the imaging requirements. In 2016, Gail McConell et al. (“A novel optical microscope for imaging large embryos and tissue volumes with subcellular resolution throughout”, eLife 2016; 5: e18659.) from the UK achieved confocal and nonlinear imaging of 6mm wide and 3mm thick samples, using an incident beam with a diameter of 30mm, custom-made a scanner and a large objective lens Mesolens with a diameter of 63mm. Similarly, in 2016, K. Svoboda et al. (“A large field of viewtwo-photon mesoscope with subcellular resolution for in vivo imaging”, eLife 2016; 5: e14472.) from the United States achieved an ultra-large field of view of 5mm, using an incident beam with a diameter of 20mm, and combining line scanning to improve imaging speed.

[0005] However, the above ultra-large field of view and high numerical aperture objective lenses all rely on increasing the incident light beam diameter to bring the advantages of large field of view and large light throughput, but all have the following disadvantages: the objective lenses are very expensive and have a huge size. Therefore, there is an urgent need for a microscope with a low-cost, small size, and high numerical aperture large field of view imaging microscope objective lens. Summary of the invention

[0006] The present invention aims to provide a large-field handheld microscope, which is low-cost, small in size and has a large-field imaging microscope objective lens with a high numerical aperture.

[0007] The present invention provides a basic solution: a large-field handheld microscope, comprising a microscope objective lens and a scanner, wherein the rear focal plane of the microscope objective lens is located outside the microscope objective lens, and the scanner is located on the rear focal plane of the microscope objective lens; the microscope objective lens comprises a plurality of lenses connected in sequence.

[0008] Working principle and beneficial effects of the basic scheme: In a traditional laser scanning microscope, a scanning lens and a tube lens must be installed between the scanner and the objective lens. Since the rear focal plane of the microscope objective lens is located outside the microscope objective lens, there is enough space to install the scanner, and there is no need to install a scanning lens and a tube lens, thereby reducing the optical components in the microscope and further reducing the size of the microscope. Secondly, the length of the scanning and imaging optical path in the microscope is shortened, which can further reduce the size of the microscope. The microscope objective lens includes a number of lenses connected in sequence, and a high numerical aperture and a large field of view are achieved through the combination of lenses, thereby obtaining a high numerical aperture and a large field of view imaging microscope objective lens, and then obtaining a low-cost, small-volume microscope with a high numerical aperture and a large field of view imaging microscope objective lens.

[0009] Furthermore, the scanner is a single-axis scanner. Beneficial effects: The single-axis scanner has a simple structure, is easy to use, is easy to obtain, and has a low cost.

[0010] Furthermore, the scanner is a biaxial scanner. Beneficial effect: The biaxial scanner can be combined with line scanning to improve imaging speed.

[0011] Furthermore, the number of the scanners is two, and the back focal plane of the microscope objective lens is located between the two scanners. Beneficial effect: The back focal plane of the microscope objective lens is located between the two scanners, thereby reducing the volume of the microscope objective lens, and further reducing the volume of the microscope.

[0012] Furthermore, the rear focal plane of the microscope objective lens is located in the middle of the two scanners. Beneficial effect: The rear focal plane of the microscope objective lens is located in the middle of the two scanners, so that the final imaging effect is better.

[0013] Furthermore, the lens is an optical element made of one of optical glass, high molecular polymer, and infrared imaging material. Beneficial effects: Optical elements made of optical glass, high molecular polymer, infrared imaging material, etc. are easy to obtain and have low cost.

[0014] Furthermore, the number of the lenses is five. Beneficial effect: Through the combination of the five lenses, the microscope objective lens has a high numerical aperture and a large field of view.

[0015] Furthermore, it also includes an objective lens housing, which covers all lenses. Beneficial effect: The setting of the objective lens housing can protect the lenses and prevent them from being damaged.

[0016] Furthermore, it also includes a microscope housing for hand-held use, wherein the microscope objective lens and the scanner are both arranged in the microscope housing. Beneficial effect: The arrangement of the microscope housing protects the optical elements in the microscope.

[0017] Furthermore, the scanner includes a photoelectric detector, an ultra-thin sheet, a filter film, and an optical coating connected in sequence. Beneficial effect: The setting of the optical coating can separate the excitation light and the emission light. The setting of the ultra-thin sheet and the filter film can filter out the excitation light. The setting of the photoelectric detector can perform photoelectric conversion on the emission light passing through the optical coating, the filter film, and the ultra-thin sheet. The setting of the photoelectric detector, the ultra-thin sheet, the filter film, and the optical coating can achieve multiple functions, that is, it can replace multiple optical components, reduce the volume and weight of the microscope by reducing the number of components in the microscope, and thus make its application more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the optical path of a first embodiment of a large-field handheld microscope of the present invention;

[0019] Figure 2 A field curvature and distortion diagram of the excitation light wavelength of a first embodiment of a large-field handheld microscope of the present invention;

[0020] Figure 3 This is a vignetting diagram of the focal plane of the excitation light of Embodiment 1 of a large-field handheld microscope of the present invention;

[0021] Figure 4 This is a schematic structural diagram of a dichroic mirror scanner according to Embodiment 5 of a large-field-of-view handheld microscope of the present invention. DETAILED DESCRIPTION

[0022] The following is further described in detail through specific implementation methods:

[0023] The reference numerals in the drawings of the specification include: a first lens 1 , a second lens 2 , a third lens 3 , a fourth lens 4 , a fifth lens 5 , a scanner 6 , a photodetector 11 , a first driver 12 , an optical coating 13 , a filter film 14 , and an ultra-thin sheet 15 .

[0024] Embodiment 1

[0025] A large-field handheld microscope includes a microscope objective lens and a scanner 6. The back focal plane of the microscope objective lens is calculated according to the wavelength of the excitation light. The back focal plane of the microscope objective lens is located outside the microscope objective lens body. The scanner 6 is located on the back focal plane of the microscope objective lens. The scanner 6 can use an existing uniaxial scanner 6 or an existing biaxial scanner 6. In this embodiment, the scanner 6 is preferably a uniaxial scanner 6. The microscope objective lens includes a plurality of lenses connected in sequence. The lenses are optical elements made of one of optical glass, high molecular polymer, and infrared imaging material. In this embodiment, the lenses are preferably spherical lenses made of optical glass.

[0026] As attached Figure 1As shown, specifically, in this embodiment, the number of lenses is five for illustration. For the convenience of distinction, the lenses are defined as a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5. The side close to the image is defined as the image side, and the side close to the experimental sample is defined as the object side. Figure 1 The left side is the image side, and the right side is the object side. Along the direction from the image side to the object side, the first lens 1 to the fifth lens 5 are arranged in sequence, and the left side of the first lens 1 is defined as the first image side, and the right side is defined as the first object side. The left side of the second lens 2 is defined as the second image side, and the right side is defined as the second object side; the left side of the third lens 3 is defined as the third image side, and the right side is defined as the third object side; the left side of the fourth lens 4 is defined as the fourth image side, and the right side is defined as the fourth object side; the left side of the fifth lens 5 is defined as the fifth image side, and the right side is defined as the fifth object side. Detailed parameters of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 are shown in Table 1.

[0027] Table 1 Lens parameter table

[0028]

[0029]

[0030] The present invention adopts the design concept of keeping the incident light beam diameter unchanged, increasing the field of view angle, and placing the rear focal plane of the objective lens externally, providing a low-cost, small-volume, high numerical aperture, large field of view imaging microscope objective lens for standard desktop multiphoton microscopes. When the excitation light wavelength is 920 nanometers and the emission light wavelength is 520 nanometers, its numerical aperture is 0.7, the working distance is 1 millimeter, and the field of view diameter is 1.65 millimeters. This embodiment is used for nonlinear optical imaging, so the requirements for achromatism are not high. When used for imaging of living biological tissues, the requirements for the distortion of field curvature are not high. The field curvature and distortion diagrams of the excitation light wavelength are shown in the attached figure. Figure 2 When the excitation light wavelength reaches a transmission efficiency greater than 0.5 at the maximum viewing angle, the excitation light focal plane vignetting diagram is shown in the attached figure. Figure 3 shown.

[0031] Embodiment 2

[0032] The difference between this embodiment and the first embodiment is that the number of scanners 6 is two, and the back focal plane of the microscope objective lens is located before the two scanners 6 . In this embodiment, the back focal plane of the microscope objective lens is located between the two scanners 6 .

[0033] Embodiment 3

[0034] The difference between this embodiment and the first embodiment is that: it further comprises an objective lens housing, and the objective lens housing covers all the lenses.

[0035] Embodiment 4

[0036] The difference between this embodiment and the first embodiment is that it further comprises a microscope housing for hand-holding, and the microscope objective lens and the scanner 6 are both arranged in the microscope housing.

[0037] Embodiment 5

[0038] The difference between this embodiment and the above embodiment is that: Figure 4 As shown, the scanner 6 includes a mirror body and a first driver 12 capable of driving the mirror body. The first driver 12 is fixedly connected to the mirror body. In this embodiment, the first driver 12 is welded to the mirror body. A mirror surface is provided on the mirror body. The shape of the mirror surface is an axisymmetric figure, such as a polygon, a circle, or an ellipse. In this embodiment, the shape of the mirror surface is a circle. A photodetector 11, an ultra-thin sheet 15, a filter film 14, and an optical coating 13 are sequentially connected to the mirror surface. The photodetector 11, the ultra-thin sheet 15, the filter film 14, and the optical coating 13 match the shape of the mirror surface. The photodetector 11 is one of a photodiode, a phototransistor, a photomultiplier tube, a charge coupled device, and a metal semiconductor oxide device. In this embodiment, the photodetector 11 is preferably a photodiode. The photodetector 11 is connected to an external computer. The connection method thereof is referred to the connection between a photodiode and a computer in the prior art, so it is not repeated here.

[0039] The optical coating 13 is one of a polarization beam splitter film and a dichroic mirror film. When the scanner 6 is applied to a micro scanning microscope, etc., and the excitation light and the emission light of the observed object have different wavelengths, the dichroic mirror film is used to reflect the excitation light to the observed object, and the emission light excited by the observed object passes through the dichroic mirror film. The filter film 14 is used to filter out the remaining excitation light, and the photodetector 11 receives the emission light passing through the filter film 14 to realize photoelectric conversion. When the scanning detector is applied to a micro laser radar module, the S linear polarized light emitted by the external light source is collimated by the external lens, reflected by the polarization beam splitter film, and then the polarization direction of the linear polarized light is changed by the external wave plate. After being reflected by the experimental sample, it passes through the external wave plate again to make the polarization direction of most of the reflected light in the P direction. The polarization beam splitter film reflects the S linear polarized light and transmits the P linear polarized light. Finally, the P linear polarized light passes through the ultra-thin sheet 15 and the filter and is collected by the photodetector 11. In this embodiment, the optical coating 13 is preferably a polarization beam splitter film. The microscope also includes other optical elements for constructing the light path, which can adopt existing technologies and are therefore not described in detail.

[0040] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A large-field handheld microscope, comprising a microscope objective lens and a scanner, characterized in that: The rear focal plane of the microscope objective lens is located outside the microscope objective lens, and the scanner is located on the rear focal plane of the microscope objective lens; the microscope objective lens includes a plurality of lenses connected in sequence; The number of the lenses is five; the five lenses are defined as a first lens, a second lens, a third lens, a fourth lens, and a fifth lens respectively; a side close to the image is defined as an image side, and a side close to the experimental sample is defined as an object side; along the image side to the object side direction, the first lens to the fifth lens are sequentially arranged, the left side of the first lens is defined as a first image side, and the right side is defined as a first object side, and the left side of the second lens is defined as a second image side, and the right side is defined as a second object side; the left side of the third lens is defined as a third image side, and the right side is defined as a third object side; the left side of the fourth lens is defined as a fourth image side, and the right side is defined as a fourth object side; the left side of the fifth lens is defined as a fifth image side, and the right side is defined as a fifth object side; The radius of curvature of the first image side is -5.422 mm, the radius of curvature of the first object side is -15.096 mm, the thickness of the first lens is 14.307 mm; the distance between the first lens and the second lens is 0.2 mm; The curvature radius of the second image side is 40.057 mm, and the curvature radius of the second object side is -119.509 mm; the thickness of the second lens is 1.5 mm; the distance between the second lens and the third lens is 0.2 mm; The curvature radius of the third image side is 18.574 mm, and the curvature radius of the third object side is 39.689 mm; the thickness of the third lens is 1.674 mm; the distance between the third lens and the fourth lens is 0.2 mm; The curvature radius of the fourth image side is 6.873 mm, and the curvature radius of the fourth object side is 8.074 mm; the thickness of the fourth lens is 6.083 mm; the distance between the fourth lens and the fifth lens is 0.75 mm; The curvature radius of the fifth image side is 103.816 mm, and the curvature radius of the fifth object side is -26.042 mm; the thickness of the fifth lens is 0.85 mm; the distance between the fifth lens and the biological sample is 2 mm; The distance from the rear focal plane to the first image side is 6 mm; The diameter of the first image side is 6 mm; the diameters of the first object side, the second image side, the second object side, the third image side, and the third object side are all 14 mm; the diameter of the fourth image side is 12 mm, and the diameter of the fourth object side is 6.6 mm; the diameters of the fifth image side and the fifth object side are both 7.2 mm.

2. A large-field-of-view handheld microscope according to claim 1, characterized in that: The scanner is a single-axis scanner.

3. A large-field-of-view handheld microscope according to claim 1, characterized in that: The scanner is a biaxial scanner.

4. A large-field-of-view handheld microscope according to claim 1, characterized in that: The lens is an optical element made of one of optical glass, high molecular polymer and infrared imaging material.

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