Search

CN-122018132-A - Very low back reflection low power micro objective lens

CN122018132ACN 122018132 ACN122018132 ACN 122018132ACN-122018132-A

Abstract

The invention discloses an extremely low back reflection low power micro-objective lens which is applied to a visible light wave band of 400-700 nm and comprises a first lens group with positive refractive power, a second lens group with negative refractive power and a third lens group with positive refractive power, wherein the first lens group, the second lens group and the third lens group are sequentially arranged along the light path direction of the micro-objective lens, a seventh lens is arranged on one side of the second lens group, which is close to the third lens group, the seventh lens is a biconcave lens, the light transmission aperture of the seventh lens is smaller than that of other lenses of the micro-objective lens, the extremely low back reflection interference of the micro-objective lens is realized through the seventh lens, and the extremely low back reflection interference of the micro-objective lens is realized, so that the requirements of high imaging quality, large field of view and low stray light in the semiconductor field are met.

Inventors

  • YE ZHIJIANG
  • Jiao Linxin
  • FAN HAO

Assignees

  • 茂莱（南京）仪器有限公司

Dates

Publication Date
20260512
Application Date
20260408

Claims (10)

  1. 1. The ultra-low back reflection low power micro-objective lens is characterized by comprising a first lens group (G1) with positive refractive power, a second lens group (G2) with negative refractive power and a third lens group (G3) with positive refractive power, wherein the first lens group (G1) with positive refractive power, the second lens group (G2) with negative refractive power and the third lens group (G3) with positive refractive power are sequentially arranged along the optical path direction of the micro-objective lens, 0.6 is more than or equal to |fG1/fobj is more than or equal to 0.4,0.3 is more than or equal to 0.1,0.5 is more than or equal to |fG3/fobj is more than or equal to 0.3, fG1, fG2 and fG3 respectively represent the focal lengths of the first lens group (G1), the second lens group (G2) and the third lens group (G3), a seventh lens (L7) is arranged on the side close to the first lens group (G3), and the seventh lens (L7) is a concave aperture lens and light passing through is smaller than the light passing aperture of each other micro-objective lens.
  2. 2. The very low back reflection low power micro objective lens according to claim 1, wherein the first lens group (G1) is a cemented doublet lens, and comprises a first lens (L1) with positive optical power and a second lens (L2) with negative optical power, which are sequentially arranged along the optical path direction.
  3. 3. An extremely low back reflection low power micro objective according to claim 2, wherein the first lens (L1) is a biconvex lens and the second lens (L2) is a plano-concave lens.
  4. 4. The very low back reflection low power micro objective of claim 2, wherein the d-ray refractive index and Abbe number of the first lens (L1) are n1 and v1, respectively, 1.6 not less than n1 not less than 1.5,70 not less than v1 not less than 60, and the d-ray refractive index and Abbe number of the second lens (L2) are n2 and v2, respectively, 1.6 not less than n2 not less than 1.5,65 not less than v2 not less than 55.
  5. 5. The very low back reflection low power micro objective lens according to claim 1, wherein the second lens group (G2) is composed of a third lens (L3) of negative power, a fourth lens (L4) of positive power, a fifth lens (L5) of positive power, a sixth lens (L6) of positive power, and a seventh lens (L7) which are sequentially arranged along the optical path direction, wherein the third lens (L3) and the fourth lens (L4) constitute a cemented doublet.
  6. 6. The very low back reflection low power micro objective lens of claim 5, wherein the third lens (L3) is a biconcave lens, the fourth lens (L4) is a meniscus lens, the fifth lens (L5) is a biconvex lens, and the sixth lens (L6) is a plano-convex lens.
  7. 7. The very low back reflection low power micro objective lens according to claim 5, wherein the d-ray refractive index and Abbe number of the third lens (L3) are n3 and v3, respectively, 1.8 not less than n3 not less than 1.7,55 not less than v3 not less than 45, the d-ray refractive index and Abbe number of the fourth lens (L4) are n4 and v4, respectively, 1.6 not less than n4 not less than 1.5,75 not less than v4 not less than 65, the d-ray refractive index and Abbe number of the fifth lens (L5) are n5 and v5,1.55 not less than n5 not less than 1.45,85 not less than v5 not less than 80, the d-ray refractive index and Abbe number of the sixth lens (L6) are n6 and v6, respectively, 1.7 not less than 1.6,35 not less than v6 not less than 30, and the d-ray refractive index and Abbe number of the seventh lens (L7) are n7 and v7, respectively, 1.6 not less than n7 not less than 1.5,60 v7 not less than 50.
  8. 8. The very low back reflection low power micro objective lens according to claim 1, wherein the third lens group (G3) is composed of an eighth lens (L8) and a ninth lens (L9) which are sequentially arranged along the optical path direction, and the eighth lens (L8) and the ninth lens (L9) are positive power lenses.
  9. 9. An extremely low back reflection low power micro objective lens according to claim 8, wherein the eighth lens (L8) is a biconvex lens and the ninth lens (L9) is a meniscus lens.
  10. 10. The very low back reflection low power micro objective lens according to claim 8, wherein the d-ray refractive index and Abbe number of the eighth lens (L8) are n8 and v8, respectively, 1.8 n8 1.7,60 v8 50, respectively, and the d-ray refractive index and Abbe number of the ninth lens (L9) are n9 and v9, respectively, 1.96 n9 1.9,36 v9 33, respectively.

Description

Very low back reflection low power micro objective lens Technical Field The invention relates to the technical field of microobjectives, in particular to an extremely low back reflection low power microobjective. Background In applications such as semiconductor defect detection and micro-nano structure observation, high resolution, large field of view and low stray light imaging are key factors for ensuring detection accuracy and efficiency. At present, although a high-numerical aperture microscope objective can provide higher resolution, the field of view is limited, and the requirement of large-range observation is difficult to meet, while a traditional low-magnification objective has larger field of view, but the conventional low-magnification objective has the problems of smaller normal-factor aperture, insufficient aberration correction and serious back reflection, so that the resolution and contrast of an image are reduced, and the requirement of high-precision semiconductor detection cannot be met. Especially in the optical detection modes such as bright field, dark field, interference imaging and the like, stray light and back reflection of the microscope objective can obviously reduce the signal to noise ratio of images and influence the defect identification capability. The existing low-power objective lens is often not designed to fully combine aberration correction, transmissivity optimization and reflection inhibition, so that the performance is poor when a new-generation semiconductor detection system is matched. Therefore, a high performance microscope objective lens having a large numerical aperture, a large field of view, low stray light, and excellent back reflection suppression capability is required to improve imaging quality and detection reliability. Disclosure of Invention Aiming at the defects of the existing low-power micro-objective lens, the invention discloses an extremely low back reflection low-power micro-objective lens. The technical scheme is that in order to achieve the technical purpose, the invention adopts the following technical scheme: The very low back reflection low power micro objective consists of a first lens group with positive refractive power, a second lens group with negative refractive power and a third lens group with positive refractive power, which are sequentially arranged along the light path direction of the micro objective, wherein 0.6 is more than or equal to |fG1/fobj is more than or equal to 0.4,0.3 is more than or equal to |fG2/fobj is more than or equal to 0.1,0.5 is more than or equal to |fG3/fobj is more than or equal to 0.3, fG1, fG2 and fG3 respectively represent the focal lengths of the first lens group, the second lens group and the third lens group, fobj represents the focal length of the micro objective, a seventh lens is arranged on one side, which is close to the third lens group, and the seventh lens is a biconcave lens with a light passing caliber smaller than the light passing calibers of other lenses of the micro objective. Preferably, the first lens group of the present invention is a cemented lens, and is composed of a first lens of positive power and a second lens of negative power, which are sequentially arranged along the optical path direction. Preferably, the first lens of the present invention is a biconvex lens, and the second lens is a plano-concave lens. Preferably, the d-ray refractive index and the Abbe number of the first lens are respectively n1 and v1,1.6 is larger than or equal to n1 and is larger than or equal to 1.5,70 and is larger than or equal to v1 and is larger than or equal to 60, and the d-ray refractive index and the Abbe number of the second lens are respectively n2 and v2, and 1.6 is larger than or equal to n2 and is larger than or equal to 1.5,65 and is larger than or equal to v2 and is larger than or equal to 55. Preferably, the second lens group of the present invention includes a third lens of negative power, a fourth lens of positive power, a fifth lens of positive power, a sixth lens of positive power, and a seventh lens, which are sequentially disposed along the optical path direction, wherein the third lens and the fourth lens form a double cemented lens. Preferably, the third lens of the present invention is a biconcave lens, the fourth lens is a meniscus lens, the fifth lens is a biconvex lens, and the sixth lens is a plano-convex lens. Preferably, the d-ray refractive index and the Abbe number of the third lens are respectively n3 and v3,1.8 is larger than or equal to n3 and larger than or equal to 1.7,55 is larger than or equal to v3 and larger than or equal to 45, the d-ray refractive index and the Abbe number of the fourth lens are respectively n4 and v4,1.6 is larger than or equal to n4 and larger than or equal to 1.5,75 and larger than or equal to 65, the d-ray refractive index and the Abbe number of the fifth lens are respectively n5 and v5,1.55 is larger than or equal to n5 and larger th