A 10x plan apochromatic water immersion objective

Abstract

This invention discloses a 10x flat apochromatic water immersion objective lens, characterized by comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, fixedly set in an aqueous environment and arranged coaxially from the object side to the image side. The first and second lenses form a first cemented lens group with positive optical power, the third and fourth lenses form a second cemented lens group with positive optical power, the fifth and sixth lenses form a third cemented lens group with negative optical power, the seventh and eighth lenses form a fourth cemented lens group with negative optical power, and the ninth lens has positive optical power. Its advantages include using water as the immersion medium, imaging live cells through culture medium, high imaging quality, effectively increasing working distance, good flatness, and a wide chromatic aberration correction range.

Description

Technical Field

[0001] This invention relates to an objective lens structure, and more particularly to a 10x plan apochromatic water immersion objective lens. Background Technology

[0002] As one of the most important components of an optical microscope, the imaging performance of the microscope objective largely determines the microscope's ability to observe samples. In the biomedical field, high-resolution, plan-field, apochromatic microscope objectives are required to better observe samples and distinguish different cell and tissue structures. The resolution of a microscope objective is related to its numerical aperture; the larger the numerical aperture, the higher the objective's resolution. By adding a medium with a refractive index greater than 1 from the tip of the objective to the surface of the sample, the numerical aperture of the objective can be increased, thereby improving the objective's resolution. Commonly used media are oil or water; therefore, oil immersion and water immersion objectives are widely used.

[0003] Imaging of live cells and tissues is crucial for biomedical research. Since live cells are usually in culture media and covered by cell culture medium, direct observation using traditional objectives often results in severe artifacts and other aberrations. Furthermore, the short working distance of oil immersion objectives, which are commonly used in cell observation, is not suitable for imaging live cells through culture media. Additionally, the refractive index of cell culture medium differs from that of oil, and using oil immersion objectives to observe cells in aqueous media can increase other refractive problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a 10x plan apochromatic water immersion objective lens with good planarity and a wide range of chromatic aberration correction.

[0005] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a 10x plan apochromatic water immersion objective lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged coaxially from the object side to the image side, fixedly set in an aqueous environment; the first lens and the second lens form a first cemented lens group with positive optical power and a focal length of 88mm to 106mm; the third lens and the fourth lens form a second cemented lens group with positive optical power. The first lens group has a focal length of 24mm to 26mm; the fifth and sixth lenses form a third cemented lens group with negative optical power and a focal length of -41mm to -38mm; the seventh and eighth lenses form a fourth cemented lens group with negative optical power and a focal length of -40mm to -37mm; the ninth lens has positive optical power and a focal length of 32mm to 34mm; the total focal length of the water immersion objective lens is 19.5mm to 20.5mm, and the total length of the optical system is 59.5mm to 61mm.

[0006] The air gap between the first cemented lens group and the second cemented lens group is 8.1 mm to 9.1 mm; the air gap between the second cemented lens group and the third cemented lens group is 0.1 mm to 0.5 mm; the air gap between the third cemented lens group and the fourth cemented lens group is 2.5 mm to 3.5 mm; and the air gap between the fourth cemented lens group and the ninth lens is 0.1 mm to 0.5 mm.

[0007] The first lens has a focal length of 7mm to 8mm; the second lens has a focal length of -13mm to -11mm; the third lens has a focal length of -115mm to -95mm; the fourth lens has a focal length of 16mm to 18mm; the fifth lens has a focal length of 15mm to 17mm; the sixth lens has a focal length of -9mm to -7mm; the seventh lens has a focal length of -10mm to -8mm; and the eighth lens has a focal length of 17mm to 19mm.

[0008] The first lens has a planar object side and a convex image side; the second lens has a concave object side and a convex image side; the third lens has a convex object side and a concave image side; the fourth lens has a convex object side and a convex image side; the fifth lens has a convex object side and a convex image side; the sixth lens has a concave object side and a concave image side; the seventh lens has a concave object side and a convex image side; the eighth lens has a concave object side and a convex image side; and the ninth lens has a convex object side and a convex image side.

[0009] The Abbe number Vd3 of the third lens and the Abbe number Vd4 of the fourth lens satisfy: 60 ≥ |Vd3 - Vd4| ≥ 40; the Abbe number Vd5 of the fifth lens and the Abbe number Vd6 of the sixth lens satisfy: 60 ≥ |Vd5 - Vd6| ≥ 40; the Abbe number Vd7 of the seventh lens and the Abbe number Vd8 of the eighth lens satisfy: 45 ≥ |Vd7 - Vd8| ≥ 20, where |...| represents the absolute value sign.

[0010] The relative partial dispersion coefficient P of the third lens g.F 3. The relative partial dispersion coefficient P of the fourth lens g.F 4. Satisfies: 0 ≤ |P g.F 3-P g.F 4 | ≤0.03, the relative partial dispersion coefficient P of the fifth lens g.F 5. The relative partial dispersion coefficient P of the sixth lens g.F 6 satisfies: 0 ≤ |P g.F 5-P g.F 6 | ≤ 0.03, the relative partial dispersion coefficient P of the seventh lensg.F 7 and the relative partial dispersion coefficient P of the eighth lens g.F 8 satisfies: 0 ≤ |P g.F 7-P g.F 8 | ≤ 0.01, where |…| represents the absolute value sign.

[0011] Compared with existing technologies, the advantages of this invention lie in using water as the immersion medium. Since the refractive index difference between the cell culture medium and water is small, using a water immersion objective to observe cells in an aqueous medium reduces the effects of refraction, thereby improving image quality, and the working distance reaches approximately 3.5 mm. Furthermore, apochromatic aberration is achieved by controlling the Abbe number relationship of the second, third, and fourth cemented lens groups, and field flatness is achieved by setting the shape and focal length of the fourth cemented lens group and the ninth lens. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the microscope objective in this invention; Figure 2 The field curvature curves are examples of embodiments of the present invention. The vertical axis in the figure represents the angle of the incident light, which can correspond to the field number of the objective lens. The horizontal axis represents the magnitude of the field curvature. The four curves are the field curvature curves of F light (486.1nm), d light (587.5nm), C light (656.3nm), and near-infrared light (800nm). Figure 3 The distortion curve is an example of an embodiment of the present invention. The vertical axis in the figure is the angle of the incident light, which can correspond to the field number of the objective lens, and the horizontal axis is the magnitude of the distortion. Figure 4 The color focus shift curve is an example of an embodiment of the present invention. The vertical axis represents the wavelength of light, in μm, with the wavelength ranging from 0.4358 μm to 0.800 μm. The horizontal axis represents the range of focus shift. Figure 5 This is an example of a 0-field-of-view image-side lateral aberration diagram in an embodiment of the present invention. In the diagram, the horizontal axes PY and PX represent the normalized entrance pupil; the vertical axes EY and EX represent lateral aberrations, where Y represents the meridional direction and X represents the sagittal direction, with units of μm. The maximum value of the vertical axis is 5 μm and the minimum value is -5 μm. The four curves represent F-light (wavelength 486.13 nm), d-light (wavelength 587.56 nm), C-light (wavelength 656.27 nm), and near-infrared light (wavelength 800 nm), respectively. Implementation

[0013] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0014] Example: A 10x plan apochromatic water immersion objective lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, and a ninth lens 9, which are fixedly installed in an aqueous environment and arranged coaxially from the object side to the image side. The first lens 1 and the second lens 2 form a first cemented lens group GL1 with positive optical power and a focal length of 88mm to 106mm; the third lens 3 and the fourth lens 4 form a second cemented lens group GL2 with positive optical power and a focal length of 24mm to 26mm; the fifth lens 5 and the sixth lens 6 form a negative optical power... The third cemented lens group GL3 has a focal length of -41mm to -38mm; the seventh lens 7 and the eighth lens 8 form the fourth cemented lens group GL4 with a negative focal length of -40mm to -37mm; the ninth lens 9 has a positive focal length of 32mm to 34mm; the total focal length of the immersion objective is 19.5mm to 20.5mm, the total length of the optical system is 59.5mm to 61mm, the air gap between the first cemented lens group GL1 and the second cemented lens group GL2 is 8.1mm to 9.1mm, and the air gap between the second cemented lens group GL2 and the third cemented lens group GL3 is... The air gap is 0.1mm to 0.5mm; the air gap between the third cemented lens group GL3 and the fourth cemented lens group GL4 is 2.5mm to 3.5mm; the air gap between the fourth cemented lens group GL4 and the ninth lens 9 is 0.1mm to 0.5mm; the focal length of the first lens 1 is 7mm to 8mm; the focal length of the second lens 2 is -13mm to -11mm; the focal length of the third lens 3 is -115mm to -95mm; the focal length of the fourth lens 4 is 16mm to 18mm; the focal length of the fifth lens 5 is 15mm to 17mm; the focal length of the sixth lens 6 is... -9mm~-7mm; the focal length of the seventh lens 7 is -10mm~-8mm; the focal length of the eighth lens 8 is 17mm~19mm; the object side of the first lens 1 is a plane, and the image side is a convex surface; the object side of the second lens 2 is a concave surface, and the image side is a convex surface; the object side of the third lens 3 is a convex surface, and the image side is a concave surface; the object side of the fourth lens 4 is a convex surface, and the image side is a convex surface; the object side of the fifth lens 5 is a convex surface, and the image side is a convex surface; the object side of the sixth lens 6 is a concave surface, and the image side is a concave surface; the object side of the seventh lens 7 is a concave surface, and the image side is a convex surface; the object side of the eighth lens 8 is a concave surface, and the image side is a convex surface; the object side of the ninth lens 9 is a convex surface, and the image side is a convex surface.

[0015] The Abbe number Vd3 of the third lens 3 and the Abbe number Vd4 of the fourth lens 4 satisfy: 60 ≥ |Vd3 - Vd4| ≥ 40; the Abbe number Vd5 of the fifth lens 5 and the Abbe number Vd6 of the sixth lens 6 satisfy: 60 ≥ |Vd5 - Vd6| ≥ 40; the Abbe number Vd7 of the seventh lens 7 and the Abbe number Vd8 of the eighth lens 8 satisfy: 45 ≥ |Vd7 - Vd8| ≥ 20, where |...| represents the absolute value sign.

[0016] The relative partial dispersion coefficient P of the third lens 3 g.F The relative partial dispersion coefficient P between lens 3 and the fourth lens 4 g.F 4. Satisfies: 0 ≤ |P g.F 3-P g.F 4 | ≤0.03, the relative partial dispersion coefficient P of the fifth lens 5 g.F The relative partial dispersion coefficient P between lens 5 and the sixth lens 6 g.F 6 satisfies: 0 ≤ |P g.F 5-P g.F 6 | ≤0.03, the relative partial dispersion coefficient P of the seventh lens 7 g.F The relative partial dispersion coefficient P between lens 7 and the eighth lens 8 g.F 8 satisfies: 0 ≤ |P g.F 7-P g.F 8 | ≤ 0.01, where |…| represents the absolute value sign.

[0017] The following is a specific example of this embodiment: In the second cemented doublet spherical lens group, the Abbe number of the third spherical lens is Vd3 = 44.5, the Abbe number of the fourth spherical lens is Vd4 = 94.9, and |Vd3 - Vd4| = 50.4; the relative partial dispersion coefficient P of the third spherical lens is... g.F =3=0.559, the relative partial dispersion coefficient P of the fourth spherical lens g.F 4 = 0.534, |P g.F 3-P g.F 4 | = 0.025; In the third cemented doublet spherical lens group, the Abbe number of the fifth spherical lens is Vd5 = 94.9, the Abbe number of the sixth spherical lens is Vd6 = 44.5, |Vd5 - Vd6| = 50.4; The relative partial dispersion coefficient P of the fifth spherical lens g.F 5 = 0.534, the relative partial dispersion coefficient P of the sixth spherical lens g.F 6 = 0.559, |P g.F 5-P g.F 6 | = 0.025; Both the second and third cemented doublet spherical lens groups use a structural combination where the difference in Abbe number between adjacent spherical lenses is large and the difference in the relative dispersion coefficient is small. Moreover, they use only two materials, which can better correct the second-order spectrum and achieve the function of apochromatic correction. In the fourth cemented doublet spherical lens group, the Abbe number of the seventh spherical lens is Vd7 = 63.4, the Abbe number of the eighth spherical lens is Vd8 = 94.9, and |Vd7 - Vd8| = 31.5; the relative partial dispersion coefficient P of the seventh spherical lens is... g.F 7 = 0.536, the relative partial dispersion coefficient P of the eighth spherical lens g.F 8 = 0.534, |P g.F3-P g.F 4 | = 0.002; The ninth spherical lens is a biconvex spherical lens. The ninth spherical lens is used in combination with the fourth cemented doublet spherical lens group to reduce the Petzval field curvature, thereby obtaining better field flatness.

[0018] The specific parameters of each spherical lens are shown in the table below: the focal length of the entire microscope objective is f=20mm, the numerical aperture NA=0.3, the total system length is 59.71mm, and the working distance is 3.5mm.

[0019]

[0020] from Figure 2 Field curve diagram and Figure 3 As can be seen from the distortion curve, the field curvature and distortion in the embodiment are well corrected.

[0021] from Figure 4 The chromatic aberration curve shows that the chromatic aberration along the lens axis is well corrected.

[0022] from Figure 5 As can be seen in the lateral aberration diagram of the 0 field of view image, the aberration balance is good and the imaging is excellent.

Claims

1. A 10x plan apochromatic water immersion objective lens, characterized in that... It consists of a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with positive optical power, all fixedly installed in an aquatic environment and arranged coaxially from the object side to the image side. The first lens has a planar object side and a convex image side; the second lens has a concave object side and a convex image side; the third lens has a convex object side and a concave image side; the fourth lens has a convex object side and a convex image side; the fifth lens has a convex object side and a convex image side; the sixth lens has a concave object side and a concave image side; the seventh lens has a concave object side and a convex image side; and the eighth lens has a concave object side and a convex image side. The ninth lens has a convex object side and a convex image side. The first and second lenses form a first cemented lens group with positive optical power and a focal length of 88mm to 106mm. The third and fourth lenses form a second cemented lens group with positive optical power and a focal length of 24mm to 26mm. The fifth and sixth lenses form a third cemented lens group with negative optical power and a focal length of -41mm to -38mm. The seventh and eighth lenses form a fourth cemented lens group with negative optical power and a focal length of -40mm to -37mm. The ninth lens has a focal length of 32mm to 34mm. The total focal length of the water immersion objective lens is 19.5mm to 20.5mm, and the total length of the optical system is 59.5mm to 61mm.

2. The 10x plan apochromatic water immersion objective lens according to claim 1, characterized in that... The air gap between the first cemented lens group and the second cemented lens group is 8.1 mm to 9.1 mm; the air gap between the second cemented lens group and the third cemented lens group is 0.1 mm to 0.5 mm; the air gap between the third cemented lens group and the fourth cemented lens group is 2.5 mm to 3.5 mm; and the air gap between the fourth cemented lens group and the ninth lens is 0.1 mm to 0.5 mm.

3. A 10x plan apochromatic water immersion objective lens according to claim 1, characterized in that... The first lens has a focal length of 7mm to 8mm; the second lens has a focal length of -13mm to -11mm; the third lens has a focal length of -115mm to -95mm; the fourth lens has a focal length of 16mm to 18mm; the fifth lens has a focal length of 15mm to 17mm; the sixth lens has a focal length of -9mm to -7mm; the seventh lens has a focal length of -10mm to -8mm; and the eighth lens has a focal length of 17mm to 19mm.

4. A 10x plan apochromatic water immersion objective lens according to claim 1, characterized in that... The Abbe number Vd3 of the third lens and the Abbe number Vd4 of the fourth lens satisfy: 60 ≥ |Vd3 - Vd4| ≥ 40; the Abbe number Vd5 of the fifth lens and the Abbe number Vd6 of the sixth lens satisfy: 60 ≥ |Vd5 - Vd6| ≥ 40; the Abbe number Vd7 of the seventh lens and the Abbe number Vd8 of the eighth lens satisfy: 45 ≥ |Vd7 - Vd8| ≥ 20, where |...| represents the absolute value sign.

5. A 10x plan apochromatic water immersion objective lens according to claim 1, characterized in that... The relative partial dispersion coefficients Pg.F3 and Pg.F4 of the third lens and the fourth lens satisfy the following condition: 0 ≤ |Pg.F3 - Pg.F4| ≤ 0.03; the relative partial dispersion coefficients Pg.F5 and Pg.F6 of the fifth lens and the sixth lens satisfy the following condition: 0 ≤ |Pg.F5 - Pg.F6| ≤ 0.03; and the relative partial dispersion coefficients Pg.F7 and Pg.F8 of the seventh lens and the eighth lens satisfy the following condition: 0 ≤ |Pg.F7 - Pg.F8| ≤ 0.01, where |…| represent the absolute value.

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