CN-116466470-B - Telecentric objective lens with low magnification and long working distance

CN116466470BCN 116466470 BCN116466470 BCN 116466470BCN-116466470-B

Abstract

The invention discloses a low-magnification long-working-distance telecentric objective lens, which comprises a first lens group, a second lens group and a third lens group, wherein the first lens group, the second lens group and the third lens group are sequentially arranged along an optical axis, the first lens group has positive refractive power, the second lens group has negative refractive power, the third lens group has positive refractive power, and the conditions that 0.0< |f1/f| <3.3, 0.0< |f2/f| <3.1, 0.0< |f3/f| <3.3, 0.0< |f2/f1| <3.3, 0.0< |f1/f3| <6.1, 0.0< |f2/f3| <3.3 are satisfied, f1 is the focal distance of the objective lens, f2 is the focal distance of the first lens group, and f3 is the focal distance of the second lens group. The invention sets the first lens group, the second lens group and the third lens group, and limits the focal distance of the first lens group, the second lens group and the third lens group, so that the curvature of field, distortion and chromatic aberration of the objective optical system are corrected, and the problems of insufficient working distance, insufficient magnification and telecentricity of the objective are solved.

Inventors

FANG ZHENG
DUAN LIXIN
LIN SHUNHUA
JIANG YUYING
HUANG XIAOHUA
Qiu Zelong

Assignees

麦克奥迪实业集团有限公司

Dates

Publication Date: 20260512
Application Date: 20230407

Claims (10)

1. The low magnification long working distance telecentric objective lens is characterized by comprising a first lens group, a second lens group and a third lens group which are sequentially arranged along an optical axis, wherein the first lens group has positive refractive power, the first lens group comprises a first lens with positive refractive power, the second lens group has negative refractive power, the second lens group comprises 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 which are sequentially arranged from an object side to an image side, the second lens has negative refractive power, the third lens has positive refractive power, the fourth lens has negative refractive power, the fifth lens has positive refractive power, the sixth lens has positive refractive power, the seventh lens has negative refractive power, the eighth lens has positive refractive power, the ninth lens has negative refractive power, the third lens group comprises a tenth lens with positive refractive power, and the following formula is satisfied: 0.0<|f1/f|<3.3; 0.0<|f2/f|<3.1; 0.0<|f3/f|<3.3; 0.0<|f2/f1|<3.3; 0.0<|f1/f3|<6.1; 0.0<|f2/f3|<3.3; Where f is a focal length of the objective lens, f1 is a focal length of the first lens group, f2 is a focal length of the second lens group, and f3 is a focal length of the third lens group.
2.A low magnification long working distance telecentric objective lens according to claim 1, wherein said first lens group is located near the object side.
3. A low magnification long working distance telecentric objective as recited in claim 2, wherein said second lens group has one or more cemented lenses.
4. A low magnification long working distance telecentric objective as recited in claim 3 wherein said second lens group has three cemented lenses.
5. A low magnification long working distance telecentric objective lens according to claim 3, wherein said second lens group satisfies the following conditional expression: 0.0<|f2/f21|<3.6; 0.0<|f2/f22|<6.3; 0.0<|f2/f23|<7.4; 0.0<|f2/f24|<6.7; 0.0<|f2/f25|<6.1; 0.0<|f2/f26|<6.5; 0.0<|f2/f27|<4.6; 0.0<|f2/f28|<3.3; Where f2 is the focal length of the second lens group, f21 is the focal length of the second lens, f22 is the focal length of the third lens, f23 is the focal length of the fourth lens, f24 is the focal length of the fifth lens, f25 is the focal length of the sixth lens, f26 is the focal length of the seventh lens, f27 is the focal length of the eighth lens, and f28 is the focal length of the ninth lens.
6. A low magnification long working distance telecentric lens according to claim 3, wherein said third lens group is located near the image side.
7. The low magnification long working distance telecentric lens of claim 6, wherein each of said first to tenth lenses comprises an object side facing the object side and passing the imaging light and an image side facing the image side and passing the imaging light, wherein said first lens has a convex object side and a convex image side, wherein said second lens has a concave image side and a concave image side, wherein said third lens has a convex object side and a convex image side, wherein said fourth lens has a concave object side and a concave image side, wherein said fifth lens has a convex object side and a concave image side, wherein said sixth lens has a convex object side and a convex image side, wherein said seventh lens has a concave object side and a concave image side, wherein said eighth lens has a convex object side and a convex image side, wherein said ninth lens has a concave object side and a convex image side, and wherein said tenth lens has a concave object side and a convex image side.
8. A low magnification long working distance telecentric objective lens according to claim 6, wherein said first through tenth lenses satisfy the following conditional expression: 1.68≥N11≥1.40;1.49≥N21≥1.45;1.67≤N22≤1.80;1.85≥N23≥1.45;1.72≥N24≥1.40;1.76≥N25≥1.50;1.8≤N26≤1.90;1.5≥N27≥1.45;1.81≤N28≤2.01;1.5≥N31≥1.40; Wherein N11 is the refractive index of the first lens, N21 is the refractive index of the second lens, N22 is the refractive index of the third lens, N23 is the refractive index of the fourth lens, N24 is the refractive index of the fifth lens, N25 is the refractive index of the sixth lens, N26 is the refractive index of the seventh lens, N27 is the refractive index of the eighth lens, N28 is the refractive index of the ninth lens, and N31 is the refractive index of the tenth lens.
9. A low magnification long working distance telecentric objective lens according to claim 6, wherein said first through tenth lenses satisfy the following conditional expression: 81.6≥V11≥30;70.4≤V21≤95;35.3≥V22≥20;32.7≤V23≤95;24.9≤V24≤95;27.5≥V25≥20;30.4≤V26≤95;81.6≤V27≤95;37.9≥V28≥15;81.6≤V31≤95; wherein V11 is the abbe number of the first lens, V21 is the abbe number of the second lens, V22 is the abbe number of the third lens, V23 is the abbe number of the fourth lens, V24 is the abbe number of the fifth lens, V25 is the abbe number of the sixth lens, V26 is the abbe number of the seventh lens, V27 is the abbe number of the eighth lens, V28 is the abbe number of the ninth lens, and V31 is the abbe number of the tenth lens.
10. A low magnification long working distance telecentric objective lens according to claim 6, wherein said first through tenth lenses satisfy the following conditional expression: 1.08<T11/T31<1.58; 0.30<T21/T22<0.70; 0.75<T21/T23<1.25; 0.28<T21/T24<0.78; 0.17<T21/T25<0.67; 0.75<T21/T26<1.25; 0.09<T21/T27<0.59; 0.75<T21/T28<1.25; Wherein T11 is the thickness of the first lens on the optical axis, T31 is the thickness of the tenth lens on the optical axis, T21 is the thickness of the second lens on the optical axis, T22 is the thickness of the third lens on the optical axis, T23 is the thickness of the fourth lens on the optical axis, T24 is the thickness of the fifth lens on the optical axis, T25 is the thickness of the sixth lens on the optical axis, T26 is the thickness of the seventh lens on the optical axis, T27 is the thickness of the eighth lens on the optical axis, and T28 is the thickness of the ninth lens on the optical axis.

Description

Telecentric objective lens with low magnification and long working distance Technical Field The invention relates to the technical field of optical imaging, in particular to a low-magnification long-working-distance telecentric objective lens. Background With the high-speed development of the biological industry and the electronic industry in recent years, the optical microscope plays an important role in various fields such as biomedicine, and particularly in the aspects of structure of industrial materials, surface defects of devices, machine vision detection, microscopic real-time observation and the like, the optical system with the low-magnification long-working-distance telecentric objective lens can provide more and quicker possibilities for the optical microscope. In the microscopic imaging field, the low magnification and long working distance are particularly important, and the telecentric objective lens in the detection industry is more irreplaceable, so that the common microscope objective lens cannot achieve the effects of low magnification, long working distance and telecentricity. Meanwhile, the objective lens with low magnification and long working distance and object space telecentricity is difficult, and the optical system needs to meet the requirement of integral high-resolution imaging, and low on-axis aberration, low magnification, small magnification chromatic aberration, small field curvature and small distortion are more difficult to realize. For example, the prior art with application publication number CN115343832a discloses a large field flat field telecentric microscope objective with a focal length of 50.12mm, which is not large enough, i.e. not low enough magnification. Therefore, how to provide a low-magnification long-working-distance telecentric objective lens is a technical problem that needs to be solved by those skilled in the art. Disclosure of Invention The invention aims to provide a low-magnification long-working-distance telecentric objective lens, which aims to solve the problems of insufficient working distance, insufficient magnification and telecentricity of the objective lens. In order to achieve the above purpose, the present invention adopts the following technical scheme: The low magnification long working distance telecentric objective lens comprises a first lens group, a second lens group and a third lens group which are sequentially arranged along an optical axis, wherein the first lens group has positive refractive power, the second lens group has negative refractive power, and the third lens group has positive refractive power and meets the following conditional expression: 0.0<|f1/f|<3.3;0.0<|f2/f|<3.1;0.0<|f3/f|<3.3; 0.0<|f2/f1|<3.3;0.0<|f1/f3|<6.1;0.0<|f2/f3|<3.3; Where f is a focal length of the objective lens, f1 is a focal length of the first lens group, f2 is a focal length of the second lens group, and f3 is a focal length of the third lens group. Further, the first lens group is near the object side, and the first lens group includes a first lens having a positive refractive power. Further, the second lens group has one or more cemented lenses, the second lens group includes 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 that are disposed in order from an object side to an image side, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a negative refractive power, the fifth lens has a positive refractive power, the sixth lens has a positive refractive power, the seventh lens has a negative refractive power, the eighth lens has a positive refractive power, and the ninth lens has a negative refractive power. Further, the second lens group has three cemented lenses. Further, the second lens group satisfies the following conditional expression: 0.0<|f2/f21|<3.6; 0.0<|f2/f22|<6.3; 0.0<|f2/f23|<7.4; 0.0<|f2/f24|<6.7; 0.0<|f2/f25|<6.1; 0.0<|f2/f26|<6.5; 0.0<|f2/f27|<4.6; 0.0<|f2/f28|<3.3; Where f2 is the focal length of the second lens group, f21 is the focal length of the second lens, f22 is the focal length of the third lens, f23 is the focal length of the fourth lens, f24 is the focal length of the fifth lens, f25 is the focal length of the sixth lens, f26 is the focal length of the seventh lens, f27 is the focal length of the eighth lens, and f28 is the focal length of the ninth lens. Further, the third lens group is close to the image side, and includes a tenth lens having a positive refractive power. Further, each of the first lens element to the tenth lens element includes an object-side surface facing the object-side surface and through which the image-forming light passes, and an image-side surface facing the image-side surface and through which the image-forming light passes, wherein the object-side surface of the first lens element is convex, the image-side surface of the second lens element is concave, t