A UV imaging objective system with long working distance

Abstract

The invention discloses a long working distance ultraviolet imaging objective lens system, comprising a lens sleeve, and also comprising a positive meniscus lens, a first plano-convex lens, a biconvex lens, a plano-concave lens, and a second plano-convex lens arranged in sequence in the lens sleeve. Both surfaces of the positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens, and the second plano-convex lens are evaporated with anti-reflection films. The element of the invention is easy to obtain and process and manufacture, easy to process with high precision, has a long working distance, and has low stray light.

Description

Technical Field

[0001] The present invention relates to an imaging objective lens system based on a spherical mirror, which is mainly used for Be + The collection and imaging of spontaneously emitted ultraviolet fluorescence of ions. The working distance of the new objective system in this experiment is 67.6mm, and all lenses are double-sided evaporated with 313.1nm anti-reflection film, which is particularly practical with Be + Long-range fluorescence collection and imaging in ion research systems. Background Art

[0002] Trapped ions are trapped in three dimensions by combining AC and DC voltages, which can isolate the background gas and laser cooling. + ,Mg + , Ca + , Yb + It has been widely used in laser spectroscopy, quantum computing, quantum information, and has promoted the development of basic physics, quantum physics, and particle physics. In the research based on these systems, the position, motion state, and quantum state of ions need to be detected by collecting the fluorescence of stimulated ion emission. Therefore, the objective system used for fluorescence collection and imaging is a very critical component in this type of research.

[0003] The simplest collection and imaging system is to use a simple spherical convex lens to converge ion radiation fluorescence. However, due to the large spherical image aberration and small numerical space, the fluorescence image quality and resolution are poor after passing through the vacuum window and spherical mirror in the vacuum system. One solution is to use an aspherical mirror with the corresponding focal length. The aspherical mirror can obtain high-resolution imaging and a large numerical aperture through high-order aberration correction. The disadvantage of the aspherical mirror is that its focal length is generally short, it needs to be close to the imaging object, and it is not suitable for beam splitting of fluorescence. In addition to the simple convex lens imaging method, the microscope objective is also one of the commonly used objects in this field. The microscope objective has the characteristics of short focal length, large field of view, small size, and infinite conjugate imaging. However, its working distance is generally less than 20mm, and it cannot be placed in a vacuum chamber when in use. Therefore, it is generally necessary to use an imaging lens of equal proportion to perform pre-stage imaging first, and then magnify it through the microscope objective. This two-stage structure reduces the performance of the microscope objective and increases the system replication. Summary of the invention

[0004] Aiming at the problems of large imaging aberration, small numerical aperture, complex microscope objective system, short working distance and high cost of traditional spherical mirrors, the present invention provides a long working distance ultraviolet imaging objective lens based on the aberration correction theory of spherical mirrors by optimizing the focal length and spacing of the lenses, which can be applied to Be-based + Quantum physics experiment of ion fluorescence imaging at 313nm wavelength.

[0005] In order to test the above objectives, the present invention is achieved through the following technical solutions:

[0006] A long working distance ultraviolet imaging objective lens system comprises a lens sleeve, and further comprises a positive meniscus lens, a first plano-convex lens, a biconvex lens, a plano-concave lens and a second plano-convex lens which are sequentially arranged in the lens sleeve.

[0007] As described above, both surfaces of the positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens and the second plano-convex lens are evaporated with anti-reflection films.

[0008] The anti-reflection wavelength of the anti-reflection film as described above is 313 nm.

[0009] The refractive index of the positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens and the second plano-convex lens as described above for 313 nm fluorescence is 1.458.

[0010] The positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens and the second plano-convex lens as described above are coaxially arranged.

[0011] The two surfaces of the positive meniscus lens as described above are convex and concave respectively;

[0012] The two surfaces of the first plano-convex lens are respectively a flat surface and a convex surface;

[0013] The two sides of a biconvex lens are convex;

[0014] The two sides of a plano-concave lens are flat and concave;

[0015] The two surfaces of the second plano-convex lens are respectively a flat surface and a convex surface.

[0016] The lens sleeve as described above is provided with a first lens retaining ring, a second lens retaining ring, a third lens retaining ring, a fourth lens retaining ring, a fifth lens retaining ring and a sixth lens retaining ring in sequence, the positive meniscus lens, the first plano-convex lens and the biconvex lens are clamped between the first lens retaining ring and the second lens retaining ring, the plane of the first plano-convex lens is tangent to the convex surface of the positive meniscus lens, the convex surface of the biconvex lens is tangent to the convex surface of the first plano-convex lens,

[0017] The plano-concave lens is clamped between the third lens clamping ring and the fourth lens clamping ring.

[0018] The second plano-convex lens is clamped between the fifth lens clamping ring and the sixth lens clamping ring.

[0019] The center thickness of the positive meniscus lens and the first plano-convex lens as described above is 7.84 mm.

[0020] The center thickness of the biconvex lens is 6.54mm.

[0021] The center thickness of the plano-concave lens is 2.5 mm.

[0022] The center distance between the concave surface of the plano-concave lens and the convex surface of the biconvex lens is 14.77 mm.

[0023] The center thickness of the second plano-convex lens is 3.7 mm.

[0024] The distance between the plane of the second plano-convex lens and the plane of the plano-concave lens is 51 mm.

[0025] The curvature radii of the concave and convex surfaces of the positive meniscus lens are -46.53mm and -135.25mm respectively.

[0026] The radius of curvature of the convex surface of the first plano-convex lens is -69.01 mm;

[0027] The curvature radii of the two convex surfaces of the biconvex lens are 182.99 mm and -182.99 mm respectively;

[0028] The radius of curvature of the concave surface of the plano-concave lens is -68.85 mm;

[0029] The radius of curvature of the convex surface of the second plano-convex lens is -460.1 mm;

[0030] The positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens and the second plano-convex lens as described above are made of fused quartz.

[0031] As described above, the first lens retaining ring, the second lens retaining ring, the third lens retaining ring, the fourth lens retaining ring, the fifth lens retaining ring and the sixth lens retaining ring are all provided with external threads adapted to the internal threads in the lens barrel in the circumference.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The spherical mirrors used in the present invention are standard positive meniscus lenses with a focal length of 150 mm, biconvex lenses with a focal length of 200 mm, first plano-convex lenses with a focal length of 150 mm, and plano-concave lenses with a focal length of -200 mm. The materials are easy to obtain and process.

[0034] 2. The spherical mirror used in the present invention has a simple surface function and is easy to process with high precision.

[0035] 3. The present invention has a long working distance, that is, the distance between the surface of the lens sleeve and the imaging object is 67.6 mm.

[0036] 4. The present invention adopts the aberration correction principle, has high imaging resolution, and the spatial frequency corresponding to the OTF modulus value of 0.2 is 110lp / mm.

[0037] 5. The present invention adopts the aberration correction principle, and the imaging of near-axis objects is close to the diffraction limit, and the Airy disk is 8.8 microns.

[0038] 6. The positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens and the second plano-convex lens of the present invention are 2-inch spherical mirrors with a large potential field and an object space NA of 0.27.

[0039] 7. The surfaces of the positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens and the second plano-convex lens of the present invention are evaporated with a 313 nm anti-reflection film and the lens sleeve is subjected to black oxidation treatment, so the stray light is small.

[0040] 8. The second plano-convex lens of the present invention uses a 1000mm focal length plano-convex lens to achieve a paraxial magnification of 14.7 times and an angular magnification of 0.31 times for the imaging system.

[0041] 9. The present invention can achieve different magnifications by selecting lenses with different focal lengths as the second plano-convex lens.

[0042] 10. In the practical application of the present invention, the fluorescence radiated by the point light source becomes parallel light after passing through the positive meniscus lens, the first plano-convex lens, the double convex lens, and the plano-concave lens. Therefore, the distance between the plano-concave lens and the second plano-convex lens can be freely adjusted.

[0043] 11. In the present invention, by adding a plane beam splitter between the plano-concave lens and the second plano-convex lens, fluorescence beam splitting can be achieved for different experimental purposes without changing the propagation light path. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of the present invention.

[0045] Figure 2 for Figure 1 Middle AA section view.

[0046] Figure 3 It is a schematic diagram of an embodiment of the present invention.

[0047] Figure 4 This is a charge coupled device imaging in an embodiment of the present invention.

[0048] Figure 5 It is the MTF curve of the imaging system when the detectors of the present invention are coaxial.

[0049] Figure 6 It is the axial aberration curve after optimization of the present invention.

[0050] Figure 7 It is a Seidel aberration diagram of the optical system after optimization of the present invention.

[0051] In the figure: 1, lens sleeve, 2, first lens retaining ring, 3, positive meniscus lens, 4, first plano-convex lens, 5, biconvex lens, 6, second lens retaining ring, 7, third lens retaining ring, 8, plano-concave lens, 9, fourth lens retaining ring, 10, fifth lens retaining ring, 11, first plano-convex lens, 12, sixth lens retaining ring.

[0052] 13. Be + Ions, 14. Vacuum chamber, 15. Objective lens system, 16. Charge-coupled device. DETAILED DESCRIPTION

[0053] In order to facilitate those skilled in the art to understand and implement the present invention, the following + The ion fluorescence imaging experimental example further describes the present invention in detail. It should be understood that the implementation examples described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0054] like Figure 1-2 As shown, a long working distance ultraviolet imaging objective lens system includes a lens sleeve 1, and also includes a positive meniscus lens 3, a first plano-convex lens 4, a biconvex lens 5, a plano-concave lens 8, and a second plano-convex lens 11 which are sequentially arranged in the lens sleeve 1. The two sides of the positive meniscus lens 3 are convex and concave respectively; the two sides of the first plano-convex lens 4 are plane and convex respectively; the two sides of the biconvex lens 5 are convex respectively; the two sides of the plano-concave lens 8 are plane and concave respectively; the two sides of the second plano-convex lens 11 are plane and convex respectively. Anti-reflection film is evaporated on both surfaces of the positive meniscus lens 3, the first plano-convex lens 4, the biconvex lens 5, the plano-concave lens 8, and the second plano-convex lens 11.

[0055] The lens tube 1 is provided with a first lens retaining ring 2, a second lens retaining ring 6, a third lens retaining ring 7, a fourth lens retaining ring 9, a fifth lens retaining ring 10 and a sixth lens retaining ring 12 in sequence. The positive meniscus lens 3, the first plano-convex lens 4 and the biconvex lens 5 are clamped between the first lens retaining ring 2 and the second lens retaining ring 6. The plane of the first plano-convex lens 4 is tangent to the convex surface of the positive meniscus lens 3. The convex surface of the biconvex lens 5 is tangent to the convex surface of the first plano-convex lens 4. The plano-concave lens 8 is clamped between the third lens retaining ring 7 and the fourth lens retaining ring 9. The second plano-convex lens 11 is clamped between the fifth lens retaining ring 10 and the sixth lens retaining ring 12. The first lens retaining ring 2, the second lens retaining ring 6, the third lens retaining ring 7, the fourth lens retaining ring 9, the fifth lens retaining ring 10 and the sixth lens retaining ring 12 are all provided with external threads that match the internal threads in the lens tube 1 in the circumferential direction.

[0056] In this embodiment, the lens tube 1 has an outer diameter of 56 mm, an internal SM 2 thread, and a thickness of 100 mm. The inner diameters of the first to sixth lens retaining rings are 48 mm, the circumference is SM 2 thread, and the thickness is 2 mm.

[0057] The center thickness of the positive meniscus lens 3 and the first plano-convex lens 4 is 7.84 mm, the center thickness of the biconvex lens 5 is 6.54 mm, the center thickness of the plano-concave lens 8 is 2.5 mm, the center distance between the concave surface of the plano-concave lens 8 and the convex surface of the biconvex lens 5 is 14.77 mm, and the center thickness of the second plano-convex lens 11 is 3.7 mm.

[0058] The distance between the plane of the second plano-convex lens 11 and the plane of the plano-concave lens 8 is 51 mm, the curvature radii of the concave and convex surfaces of the positive meniscus lens 3 are -46.53 mm and -135.25 mm respectively, the curvature radius of the convex surface of the first plano-convex lens 4 is -69.01 mm, the curvature radii of the two convex surfaces of the biconvex lens 5 are 182.99 mm and -182.99 mm respectively, the curvature radius of the concave surface of the plano-concave lens 8 is -68.85 mm, and the curvature radius of the convex surface of the second plano-convex lens 11 is -460.1 mm.

[0059] The positive and negative signs of the above curvature radius are based on the positive meniscus lens pointing to the direction of the second plano-convex lens, that is, the fluorescence imaging direction is the positive direction. The center of the spherical surface of the lens is located in the positive direction of the lens, and the curvature radius is positive. The center of the circle is located in the negative direction of the lens, and the curvature radius is negative.

[0060] The positive meniscus lens 3 , the first plano-convex lens 4 , the biconvex lens 5 , the plano-concave lens 8 and the second plano-convex lens 11 are made of fused quartz.

[0061] The anti-reflection wavelength of the anti-reflection film is 313 nm. The refractive index of the positive meniscus lens 3, the first plano-convex lens 4, the biconvex lens 5, the plano-concave lens 8 and the second plano-convex lens 11 for 313 nm fluorescence is 1.458.

[0062] Assemble the above objective lens system, screw the first lens retaining ring 2 to the bottom of the lens tube 1, and the first lens retaining ring 2 is parallel to the cross section of the lens tube 1. Place the positive meniscus lens 3, the first plano-convex lens 4, and the biconvex lens 5 in sequence, and place the second lens retaining ring 6 into the lens tube 1 and screw it to the surface of the biconvex lens 5. Fix the positions of the first plano-convex lens 4 and the biconvex lens 5 by the second lens retaining ring 6. Place the third lens retaining ring 7 into the lens tube 1, and the distance between the third lens retaining ring 7 and the second lens retaining ring 6 is 10.77 mm. Afterwards, place the plano-concave lens 8 into the lens tube 1, and the plano-concave lens 8 contacts the third lens retaining ring 7. Then use the fourth lens retaining ring 9 to fix the position of the plano-concave lens 8. The distance between the fifth lens retaining ring 10 and the fourth lens retaining ring 9 is 47 mm. The second plano-convex lens 11 contacts the fifth lens retaining ring 10. The sixth lens retaining ring 12 fixes the second plano-convex lens 11. The positive meniscus lens 3, the first plano-convex lens 4, the biconvex lens 5, the plano-concave lens 8 and the second plano-convex lens 11 are coaxially arranged.

[0063] The object side numerical aperture NA of the objective lens system of the present invention is 0.27, the effective focal length is 84.3 mm, and the working distance is 67.6 mm. The lens sleeve and each lens retaining ring are made of aluminum alloy, and the surface is subjected to black oxidation treatment.

[0064] The total length of the objective lens system of the present invention is 100 mm. The focal length of the positive meniscus lens is 150 mm, the focal length of the biconvex lens is 200 mm, the focal length of the first plano-convex lens is 150 mm, the focal length of the plano-concave lens is -200 mm, the focal length of the second plano-convex lens is 1000 mm, and the positive meniscus lens, the first plano-convex lens, the biconvex lens, the plano-concave lens, and the second plano-convex lens are 2-inch spherical mirrors.

[0065] Preferably, a plane beam splitter is added between the plano-concave lens and the second plano-convex lens.

[0066] like Figure 3 As shown. + Example of ion fluorescence imaging. Adjusting Be + The relative positions between the ion 13 and the objective lens system 15, and between the objective lens system 15 and the charge coupled element 16, enable a clear and sharp real image to appear on the charge coupled element 16, as shown in FIG. Figure 4 shown.

[0067] In this embodiment, Be + The ion 13, the objective lens system 15, and the charge coupled device 16 are coaxially arranged.

[0068] In this embodiment, ionizing radiation is 2 S- 2 Transition between P energy levels, the fluorescence wavelength is 313.1nm.

[0069] In this embodiment, Be + The ions radiate fluorescence, which passes through the vacuum chamber 14, the positive meniscus lens 3, the first plano-convex lens 4, the biconvex lens 5, and the plano-concave lens 8 in sequence to form parallel light, which is then converged to the charge-coupled element 16 through the second plano-convex lens 11. The charge-coupled element 16 is a photosensitive device that senses and images the incident light.

[0070] like Figure 4 In this embodiment, the trapped ions are 4 Be + When the ions are detected, the fluorescence emitted by them is collected by the objective lens system of the present invention, and a high-resolution image can be formed on the charge-coupled device. The pixel size of the horizontal axis distance between two adjacent ions is 60 pixels, and the distance between the ions after magnification is about 780 microns.

[0071] like Figure 5As shown, the axial modulation and demodulation function of the objective lens system of the present invention is close to the diffraction limit, and the spatial frequency corresponding to the 0.2 modulus value is about 93 cycles / mm.

[0072] like Figure 6 As shown, the optical path difference from the object plane to the image plane of the objective lens system of the present invention under a 313nm light source is 0.2 wavelengths in the vertical axis coordinate axis width. The results show that the optical path difference is less than 0.065 wavelengths.

[0073] like Figure 7 As shown, different lens surfaces of the objective lens system of the present invention have different values ​​for different aberration types, and some are positive and some are negative. The aberration is particularly significant, and the concave surface of the plano-concave lens 8 has a large negative aberration, which can offset the positive aberration introduced by the positive meniscus lens, the first plano-convex lens and the biconvex lens, as well as the vacuum glass window in actual use.

[0074] The above embodiments are only for illustrating the specific implementation of the technology of the present invention, and their purpose is to enable professionals who intend to understand this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention.

Claims

1. A long working distance ultraviolet imaging objective lens system, comprising a lens sleeve (1), characterized in that: It also includes a positive meniscus lens (3), a first plano-convex lens (4), a biconvex lens (5), a plano-concave lens (8), and a second plano-convex lens (11), which are sequentially arranged in the lens sleeve (1). Anti-reflection films are deposited on both surfaces of the positive meniscus lens (3), the first plano-convex lens (4), the biconvex lens (5), the plano-concave lens (8) and the second plano-convex lens (11). The anti-reflection wavelength of the anti-reflection film is 313 nm. The refractive index of the positive meniscus lens (3), the first plano-convex lens (4), the biconvex lens (5), the plano-concave lens (8) and the second plano-convex lens (11) for 313 nm fluorescence is 1.

458. The positive meniscus lens (3), the first plano-convex lens (4), the biconvex lens (5), the plano-concave lens (8) and the second plano-convex lens (11) are coaxially arranged. The two surfaces of the positive meniscus lens (3) are respectively a convex surface and a concave surface; The two surfaces of the first plano-convex lens (4) are respectively a flat surface and a convex surface; The two sides of the biconvex lens (5) are convex surfaces; The two surfaces of the plano-concave lens (8) are respectively a plane surface and a concave surface; The two surfaces of the second plano-convex lens (11) are respectively a flat surface and a convex surface. The lens sleeve (1) is provided with a first lens retaining ring (2), a second lens retaining ring (6), a third lens retaining ring (7), a fourth lens retaining ring (9), a fifth lens retaining ring (10) and a sixth lens retaining ring (12) in sequence; the positive meniscus lens (3), the first plano-convex lens (4) and the biconvex lens (5) are clamped between the first lens retaining ring (2) and the second lens retaining ring (6); the plane of the first plano-convex lens (4) is tangent to the convex surface of the positive meniscus lens (3); the convex surface of the biconvex lens (5) is tangent to the convex surface of the first plano-convex lens (4); The plano-concave lens (8) is clamped between the third lens clamping ring (7) and the fourth lens clamping ring (9). The second plano-convex lens (11) is clamped between the fifth lens clamping ring (10) and the sixth lens clamping ring (12). The center thickness of the positive meniscus lens (3) and the first plano-convex lens (4) is 7.84 mm. The center thickness of the biconvex lens (5) is 6.54 mm. The center thickness of the plano-concave lens (8) is 2.5 mm. The center distance between the concave surface of the plano-concave lens (8) and the convex surface of the biconvex lens (5) is 14.77 mm. The center thickness of the second plano-convex lens (11) is 3.7 mm. The distance between the plane of the second plano-convex lens (11) and the plane of the plano-concave lens (8) is 51 mm. The curvature radii of the concave and convex surfaces of the positive meniscus lens (3) are -46.53 mm and -135.25 mm respectively. The radius of curvature of the convex surface of the first plano-convex lens (4) is -69.01 mm; The curvature radii of the two convex surfaces of the biconvex lens (5) are 182.99 mm and -182.99 mm respectively; The curvature radius of the concave surface of the plano-concave lens (8) is -68.85 mm; The radius of curvature of the convex surface of the second plano-convex lens (11) is -460.1 mm. The positive meniscus lens (3), the first plano-convex lens (4), the biconvex lens (5), the plano-concave lens (8) and the second plano-convex lens (11) are made of fused quartz. The first lens retaining ring (2), the second lens retaining ring (6), the third lens retaining ring (7), the fourth lens retaining ring (9), the fifth lens retaining ring (10) and the sixth lens retaining ring (12) are all provided with external threads adapted to the internal threads in the lens sleeve (1) in the circumferential direction.

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