Non-oil immersion large numerical aperture microscope objective

Abstract

This invention discloses a non-oil immersion large numerical aperture microscope objective, composed of a first lens group S1, a second lens group S2, a third lens group S3, and a fourth lens group S4. The total length (Lob) of the four lens groups is ≤50mm, and the focal length (EFL) of the microscope objective is... ob The focal length EFL of the first lens group S1 S1 The focal length EFL of the second lens group S2 S2 The focal length EFL of the third lens group S3 S3 The focal length EFL of the fourth lens group S4 S4 Satisfying: -3.40 ≤ EFL S1 / EFL ob ≤-3.90, 5.0≤EFL S2 / EFL ob ≤9.0, 8.0≤EFL S3 / EFL ob ≤21.0, 1.30≤EFL S4 / EFLob≤1.75, HI / EFLob≤0.139, where HI is the height of the observed object. The second lens group S2 can move along the optical axis. Its advantage is that the numerical aperture of the objective lens can be ≥0.95 without oil immersion. By adjusting the distance between the objective lens elements, the imaging blur caused by the processing error of the coverslip can be corrected, and the difference caused by the thickness of the coverslip can be compensated. It has a good effect on correcting chromatic aberration without using special optical materials such as DOE.

Description

Technical Field

[0001] This invention relates to a large numerical aperture microscope objective, and more particularly to a non-oil immersion large numerical aperture microscope objective. Background Technology

[0002] In the field of bioengineering, large numerical aperture microscope objectives are widely used. However, as the numerical aperture of the objective increases, the depth of field of the objective will decrease relatively, making it more sensitive to changes in the thickness of the coverslip. Even small manufacturing errors can cause image blurring.

[0003] Conventional oil immersion objectives, because the refractive index of the immersion oil is close to that of the coverslip, allow for adjustment of the working distance of the objective lens to change the thickness of the oil layer, thus compensating for any deviation in the thickness of the coverslip. However, a major drawback of oil immersion objectives is the inconvenience of cleaning the objective surface before and after each use.

[0004] Furthermore, as the numerical aperture of the objective lens increases, the difficulty of correcting aberrations increases accordingly. Chinese invention patent application CN102959450A discloses a microscope objective lens that uses a diffractive optical element (GD) to correct aberrations. However, diffractive optical elements are rarely used in actual objective lens manufacturing, and few manufacturers have sufficient manufacturing capabilities, thus limiting their application.

[0005] Chinese invention patent application CN108957718A discloses a broadband plan-field apochromatic microscope objective. This objective structure can achieve an aberration NA of 0.95, but the technical solution includes 13 lenses, resulting in relatively high cost. Furthermore, it is not suitable for correcting aberrations caused by coverslips of varying thicknesses. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a non-oil immersion large numerical aperture microscope objective that can correct aberrations caused by different cover glass thicknesses while ensuring that the numerical aperture reaches NA0.95, and has a low cost.

[0007] The technical solution adopted by this invention to solve the above-mentioned technical problem is as follows: a non-oil immersion large numerical aperture microscope objective, composed of a first lens group S1, a second lens group S2, a third lens group S3, and a fourth lens group S4, wherein the total length (Lob) of the first lens group S1, the second lens group S2, the third lens group S3, and the fourth lens group S4 is ≤50mm, and the focal length of the microscope objective is EFL. ob The focal length of the first lens group S1 is EFL. S1 The focal length of the second lens group S2 is EFL. S2The focal length of the third lens group S3 is EFL. S3 The focal length of the fourth lens group S4 is EFL. S4 Each lens satisfies the following condition: -3.90 ≤ EFL S1 / EFL ob ≤-3.40, 5.0≤EFL S2 / EFL ob ≤9.0, 8.0≤EFL S3 / EFL ob ≤21.0, 1.30≤EFL S4 / EFLob≤1.75, HI / EFLob≤0.139, where HI is the height of the observed object. The second lens group S2 can move along the optical axis. The distance between the first surface of the second lens group S2 and the last surface of the first lens group S1 is d11, and the distance between the last surface of the second lens group S2 and the first surface of the third lens group S3 is d12. 3.70mm≤d11+d12≤7.50mm.

[0008] Compared with the prior art, the advantages of the present invention are that the numerical aperture of the objective lens can be ≥0.95 without oil immersion, which can provide the system with good resolution and light transmission. At the same time, the design of the movable lens group of the present invention can correct the imaging blur problem caused by the processing error of the cover glass and compensate for the difference caused by the thickness of the cover glass by adjusting the distance between the objective lens and the lens. It has a good effect on correcting chromatic aberration without using special optical materials such as DOE.

[0009] Preferably, the first lens group S1 is a first cemented lens CL1 with a negative overall focal length, formed by cementing a biconcave lens L1 and a meniscus lens L2 with a concave object side. The second lens group S2 is a second cemented lens CL2 with a positive overall focal length, formed by cementing a negative lens L3 with a concave object side and a biconvex lens L4, a third cemented lens CL3 with a positive overall focal length, formed by cementing a positive lens L5 with a convex object side and a negative lens L6 with a concave image side. The third lens group S3 is a third cemented lens CL4 with a positive overall focal length, formed by cementing a biconvex positive lens L7, a biconcave negative lens L8, and a biconvex positive lens L9 together. The fourth lens group S4 is a positive lens CL4 with a positive image side, formed by cementing a positive lens L10 with a convex image side, a meniscus lens L11 with a concave object side and positive optical power, and a meniscus lens L12 with a concave object side and positive optical power. The objective lens structure of this invention requires only 12 lenses, which is fewer than the number of lenses used in the contrast lens, resulting in lower cost.

[0010] Preferably, in the first lens group S1, the biconcave lens L1 is crown glass with low refractive index and high dispersion coefficient, and the meniscus lens L2 is flint glass with high refractive index and low dispersion coefficient. In the second lens group S2, the negative lens L3 is crown glass with low refractive index and high dispersion coefficient, the biconvex lens L4 is flint glass with high refractive index and low dispersion coefficient, the positive lens L5 is crown glass with low refractive index and high dispersion coefficient, and the negative lens L6 is flint glass with high refractive index and low dispersion coefficient. In the third lens group S3, the positive lens L7 is crown glass with low refractive index and high dispersion coefficient, the negative lens L8 is flint glass with high refractive index and low dispersion coefficient, and the positive lens L9 is crown glass with low refractive index and high dispersion coefficient. In the fourth lens group S4, the positive lens L10 and the meniscus lens L11 are both crown glass with low refractive index and high dispersion coefficient, and the meniscus lens L12 is flint glass with high refractive index and low dispersion coefficient. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of Example 1 of the present invention;

[0012] Figure 2 This is an axial aberration image of Example 1 of the present invention with a cover glass thickness of 0.11 mm;

[0013] Figure 3 This is an axial aberration image of Example 1 of the present invention with a cover glass thickness of 0.23 mm;

[0014] Figure 4 This is a magnification aberration image of Example 1 of the present invention with a cover glass thickness of 0.11 mm;

[0015] Figure 5 This is a magnification aberration image of Example 1 of Embodiment 1 of the present invention with a cover glass thickness of 0.23 mm;

[0016] Figure 6 This is a light fan pattern of Example 1 of the present invention when the cover glass thickness is 0.11 mm;

[0017] Figure 7 This is a light fan pattern of Example 1 of the present invention when the cover glass thickness is 0.23 mm;

[0018] Figure 8 This is a field curvature diagram of Example 1 of the present invention with a cover glass thickness of 0.11 mm;

[0019] Figure 9 This is a field curvature diagram of Example 1 of the present invention with a cover glass thickness of 0.23 mm;

[0020] Figure 10This is a schematic diagram of the structure of Example 2 of the present invention;

[0021] Figure 11 This is an axial aberration image of Example 2 of the present invention with a cover glass thickness of 0.11 mm;

[0022] Figure 12 This is an axial aberration image of Example 2 of Embodiment 2 of the present invention when the cover glass thickness is 0.23 mm;

[0023] Figure 13 This is a magnification aberration image of Example 2 of the present invention with a cover glass thickness of 0.11 mm;

[0024] Figure 14 This is a magnification aberration image of Example 2 of Embodiment 2 of the present invention when the cover glass thickness is 0.23 mm;

[0025] Figure 15 This is a light fan pattern of Example 2 of the present invention with a cover glass thickness of 0.11 mm;

[0026] Figure 16 This is a light fan pattern of Example 2 of the present invention when the cover glass thickness is 0.23 mm;

[0027] Figure 17 This is a field curvature diagram of Example 2 of the present invention with a cover glass thickness of 0.11 mm;

[0028] Figure 18 This is a field curvature diagram of Example 2 of the present invention with a cover glass thickness of 0.23 mm;

[0029] Figure 19 This is a schematic diagram of the structure of Example 3 of the present invention;

[0030] Figure 20 This is an axial aberration image of Example 3 of the present invention with a cover glass thickness of 0.11 mm;

[0031] Figure 21 This is an axial aberration image of Example 3 of the present invention with a cover glass thickness of 0.23 mm;

[0032] Figure 22 This is a magnification aberration diagram of Example 3 of the present invention with a cover glass thickness of 0.11 mm;

[0033] Figure 23 This is a magnification aberration image of Example 3 of the present invention with a cover glass thickness of 0.23 mm;

[0034] Figure 24This is a light fan pattern of Example 3 of the present invention with a cover glass thickness of 0.11 mm;

[0035] Figure 25 This is a light fan pattern of Example 3 of the present invention when the cover glass thickness is 0.23 mm;

[0036] Figure 26 This is a field curvature diagram of Example 3 of the present invention with a cover glass thickness of 0.11 mm;

[0037] Figure 27 This is a field curve diagram of Example 3 of the present invention with a cover glass thickness of 0.23 mm.

[0038] In the above figures, F' represents light with a wavelength of 480 nm, C represents light with a wavelength of 656 nm, and e represents light with a wavelength of 546 nm. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0040] Example: Figure 1 , Figure 10 and Figure 19 As shown, a non-oil immersion large numerical aperture microscope objective comprises a first lens group S1, a second lens group S2, a third lens group S3, and a fourth lens group S4. The total length (Lob) of the first lens group S1, the second lens group S2, the third lens group S3, and the fourth lens group S4 is ≤50mm, and the focal length of the microscope objective is EFL. ob The focal length of the first lens group S1 is EFL. S1 The focal length of the second lens group S2 is EFL. S2 The focal length of the third lens group S3 is EFL. S3 The focal length of the fourth lens group S4 is EFL. S4 Each lens satisfies the following condition: -3.90 ≤ EFL S1 / EFL ob ≤-3.40, 5.0≤EFL S2 / EFL ob ≤9.0, 8.0≤EFL S3 / EFL ob ≤21.0, 1.30≤EFL S4 / EFLob≤1.75, HI / EFLob≤0.139, where HI is the height of the observed object. The second lens group S2 can move along the optical axis. The distance between the first surface of the second lens group S2 and the last surface of the first lens group S1 is d11, and the distance between the last surface of the second lens group S2 and the first surface of the third lens group S3 is d12. 3.70mm≤d11+d12≤7.50mm.

[0041] The first lens group S1 is a first cemented lens CL1 with a negative overall focal length, formed by cementing a biconcave lens L1 and a meniscus lens L2 with a concave object side. The second lens group S2 is a second cemented lens CL2 with a positive overall focal length, formed by cementing a negative lens L3 with a concave object side and a biconvex lens L4, a third cemented lens CL3 with a positive overall focal length, formed by cementing a positive lens L5 with a convex object side and a negative lens L6 with a concave image side. The third lens group S3 is a third cemented lens CL4 with a positive overall focal length, formed by cementing a biconvex positive lens L7, a biconcave negative lens L8, and a biconvex positive lens L9 together. The fourth lens group S4 is a positive lens CL4 with a positive overall focal length, formed by cementing a positive lens L10 with a convex image side, a meniscus lens L11 with a concave object side and positive optical power, and a meniscus lens L12 with a concave object side and positive optical power.

[0042] Specific examples are as follows:

[0043] Example 1: Structure as follows Figure 1 As shown, this is a 40x objective lens configuration for use with a commonly used 180mm endoscope system, namely the objective lens EFL. ob =4.37mm,HI=0.55mm,HI / EFL ob =0.126, NA0.95, actual magnification 41.2× objective lens, the specific design parameters are shown in Table 1 when the coverslip is 0.11mm.

[0044] Table 1.

[0045]

[0046]

[0047] The parameters d11 and d12 related to the second lens group S2 under different cover glass thicknesses are shown in Table 2.

[0048] Table 2.

[0049] Cover glass thickness (mm) <![CDATA[d 11 (mm)]]> <![CDATA[d 12 (mm)]]> 0.11 4.3178 0.5400 0.17 3.9702 0.8876 0.23 3.6266 1.2312

[0050] In this example, EFL S1 = -16.27mm, EFL S2 =25.64mm, EFL S3 =44.83mm, EFL S4 =6.54mm, L ob =41.02mm.

[0051] Appendix Figure 2 , 4 6 and 8 represent the performance of axial aberration, magnification aberration, combined aberration, and field curvature in Example 1 at a thickness of 0.11 mm, respectively. (See attached diagram.) Figure 3 , 5 8 and 9 represent the performance of axial aberration, magnification aberration, combined aberration, and field curvature in Example 1 at a thickness of 0.23 mm, respectively. It can be seen that by adjusting the distances of d11 and d12 to adjust the coverslip, the aberration of the observed object surface remains at the same level, without serious degradation.

[0052] Example 2: Structure as follows Figure 10 As shown, this is a 40x objective lens configuration for matching a commonly used 200mm tube lens system, namely the objective lens EFL. ob =4.92mm,HI=0.63mm,HI / EFL ob =0.128, NA0.95, actual magnification 40.6× objective lens, the specific design parameters are shown in Table 3 when the coverslip is 0.11mm.

[0053] Table 3.

[0054]

[0055] The parameters d11 and d12 related to the second lens group S2 under different cover glass thicknesses are shown in Table 4.

[0056] Table 4.

[0057] Cover glass thickness (mm) <![CDATA[d 11 (mm)]]> <![CDATA[d 12 (mm)]]> 0.11 4.7975 0.6000 0.17 4.4113 0.9862 0.23 4.0294 1.3681

[0058] In this example, EFL S1 = -18.20mm, EFL S2 =29.14mm, EFL S3 =40.17mm, EFL S4 =7.3mm, Lob=45.48mm.

[0059] Appendix Figure 11 , 13 15 and 17 represent the performance of axial aberration, magnification aberration, combined aberration, and field curvature in Example 2 at a thickness of 0.11 mm, respectively. (See attached diagram.) Figure 12 , 14 16 and 18 represent the performance of axial aberration, magnification aberration, combined aberration, and field curvature in Example 2 at a thickness of 0.23 mm, respectively. It can be seen that by adjusting the distances of d11 and d12 to adjust the coverslip, the aberration of the observed object surface remains at the same level, without serious degradation.

[0060] Example 3: Structure as follows Figure 19 As shown, this is a 60x objective lens configuration for matching a commonly used 200mm tube lens system, namely the objective lens EFL. ob=3.33mm,HI=0.42mm,HI / EFL ob =0.126NA0.95, with an actual magnification of 60.1× objective lens, the specific design parameters are shown in Table 5 when the coverslip is 0.11mm.

[0061] Table 5.

[0062]

[0063]

[0064] The parameters d11 and d12 related to the second lens group S2 under different cover glass thicknesses are shown in Table 6.

[0065] Table 6.

[0066] Cover glass thickness (mm) <![CDATA[d 11 (mm)]]> <![CDATA[d 12 (mm)]]> 0.11 4.7975 0.6000 0.17 4.4113 0.9862 0.23 4.0294 1.3681

[0067] In this example, EFL S1 = -12.51mm, EFL S2 =26.98mm, EFL S3 =69.85mm, EFL S4 =5.62mm, Lob=47.27mm.

[0068] Appendix Figure 20 , 22 24 and 26 represent the performance of axial aberration, magnification aberration, combined aberration, and field curvature in Example 3 at a thickness of 0.11 mm, respectively. (See attached diagram.) Figure 21 , 23 25 and 27 represent the performance of axial aberration, magnification aberration, combined aberration, and field curvature in Example 3 at a thickness of 0.23 mm, respectively. It can be seen that by adjusting the distances of d11 and d12 to adjust the coverslip, the aberration of the observed object surface remains at the same level, without serious degradation.

Claims

1. A non-oil immersion large numerical aperture microscope objective, comprising a first lens group S1, a second lens group S2, a third lens group S3, and a fourth lens group S4, characterized in that, The total length (Lob) of the first lens group S1, the second lens group S2, the third lens group S3, and the fourth lens group S4 is ≤50mm, and the focal length of the microscope objective is EFL. ob The focal length of the first lens group S1 is EFL. S1 The focal length of the second lens group S2 is EFL. S2 The focal length of the third lens group S3 is EFL. S3 The focal length of the fourth lens group S4 is EFL. S4 Each lens satisfies the following condition: -3.40 ≤ EFL S1 / EFL ob ≤-3.90, 5.0≤EFL S2 / EFL ob ≤9.0, 8.0≤EFL S3 / EFL ob ≤21.0, 1.30≤EFL S4 / EFLob≤1.75, HI / EFLob≤0.139, where HI is the height of the observed object. The second lens group S2 can move along the optical axis. The distance between the first surface of the second lens group S2 and the last surface of the first lens group S1 is d11, and the distance between the last surface of the second lens group S2 and the first surface of the third lens group S3 is d12. 3.70mm≤d11+d12≤7.50mm.

2. The non-oil immersion large numerical aperture microscope objective as described in claim 1, characterized in that, The first lens group S1 is a first cemented lens CL1 formed by cementing a biconcave lens L1 and a meniscus lens L2 with a concave object side, with an overall negative focal length. The second lens group S2 is composed of a second cemented lens CL2 formed by cementing a negative lens L3 with a concave object side and a biconvex positive lens L4, with an overall positive focal length, and a third cemented lens CL3 formed by cementing a positive lens L5 with a convex object side and a negative lens L6 with a concave image side, with an overall positive focal length. The third lens group S3 is a fourth cemented lens CL4 formed by cementing a biconvex positive lens L7, a biconcave negative lens L8, and a biconvex positive lens L9, with an overall positive focal length. The fourth lens group S4 is composed of a positive lens L10 with a convex image side, a meniscus lens L11 with a concave object side and positive optical power, and a meniscus lens L12 with a concave object side and positive optical power.

3. The non-oil immersion large numerical aperture microscope objective as described in claim 2, characterized in that, The first lens group S1 contains a biconcave lens L1 made of crown glass with low refractive index and high dispersion coefficient, and a meniscus lens L2 made of flint glass with high refractive index and low dispersion coefficient. The second lens group S2 contains a negative lens L3 made of crown glass with low refractive index and high dispersion coefficient, a positive lens L4 made of flint glass with high refractive index and low dispersion coefficient, a positive lens L5 made of crown glass with low refractive index and high dispersion coefficient, and a negative lens L6 made of flint glass with high refractive index and low dispersion coefficient. The third lens group S3 contains a positive lens L7 made of crown glass with low refractive index and high dispersion coefficient, a negative lens L8 made of flint glass with high refractive index and low dispersion coefficient, and a positive lens L9 made of crown glass with low refractive index and high dispersion coefficient. The fourth lens group S4 contains a positive lens L10 and a meniscus lens L11 both made of crown glass with low refractive index and high dispersion coefficient, and a meniscus lens L12 made of flint glass with high refractive index and low dispersion coefficient.

4. A non-oil immersion large numerical aperture microscope objective as described in claim 1, 2, or 3, characterized in that, The total length Lob of the first lens group S1, the second lens group S2, the third lens group S3, and the fourth lens group S4 is 41.02 mm, and the focal length EFL of the microscope objective is... ob =4.37mm, the focal length EFL of the first lens group S1 S1 =-16.27mm, the focal length EFL of the second lens group S2 is... S2 =25.64mm, the focal length EFL of the third lens group S3 is... S3 =44.83mm, the focal length EFL of the fourth lens group S4 is... S4 =6.54mm, d11+d12=4.858mm.

5. A non-oil immersion large numerical aperture microscope objective as described in claim 1, 2, or 3, characterized in that, The total length Lob of the first lens group S1, the second lens group S2, the third lens group S3, and the fourth lens group S4 is 45.48 mm, and the focal length EFL of the microscope objective is... ob =4.92mm, the focal length EFL of the first lens group S1 S1 =-18.20mm, the focal length EFL of the second lens group S2 is... S2 =29.14mm, the focal length EFL of the third lens group S3 is... S3 =40.17mm, the focal length EFL of the fourth lens group S4 is... S4 =7.30mm, d11+d12=5.398mm.

6. A non-oil immersion large numerical aperture microscope objective as described in claim 1, 2, or 3, characterized in that, The total length Lob of the first lens group S1, the second lens group S2, the third lens group S3, and the fourth lens group S4 is 47.27 mm, and the focal length EFL of the microscope objective is... ob =3.33mm, the focal length EFL of the first lens group S1 is... S1 =-12.51mm, the focal length EFL of the second lens group S2 is... S2 =26.98mm, the focal length EFL of the third lens group S3 is... S3 =69.85mm, the focal length EFL of the fourth lens group S4 is... S4 =5.62mm, d11+d12=5.398mm.

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