US 12,455,432 B2
Infinity-corrected microscope objective
Kenichiro Abe, Tatsuno-machi (JP); and Shinya Sakata, Tatsuno-machi (JP)
Assigned to Evident Corporation, Nagano (JP)
Filed by Evident Corporation, Tatsuno-machi (JP)
Filed on Dec. 7, 2022, as Appl. No. 18/076,918.
Claims priority of application No. 2021-202596 (JP), filed on Dec. 14, 2021.
Prior Publication US 2023/0185055 A1, Jun. 15, 2023
Int. Cl. G02B 9/12 (2006.01); G02B 9/14 (2006.01); G02B 9/22 (2006.01); G02B 21/02 (2006.01)
CPC G02B 9/12 (2013.01) [G02B 9/14 (2013.01); G02B 9/22 (2013.01); G02B 21/02 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An objective comprising, in order from an object side:
a first lens group having positive refractive power;
a second lens group including a pair of lens components having concave surfaces facing each other; and
a third lens group having positive refractive power;
wherein:
each of the pair of lens components is a cemented lens,
the first lens group consists of one positive lens,
the third lens group consists of one positive lens, and
conditional expressions
0.20≤d2/L≤0.5  (1)
−20≤f/fU21≤−0.5  (4)
−6≤f/fU22≤1  (5)
0.7≤L12/fG1≤2.1  (6)
are satisfied, where f is a focal length of the objective, d2 is a distance on an optical axis between a surface that is situated closest to an image side in a first lens component and a surface that is situated closest to the object side in a second lens component, the first lens component being a lens component situated on the object side of the pair of lens components, the second lens component being a lens component situated on the image side of the pair of lens components, L is a distance on an optical axis between a surface that is situated closest to the object side in the objective and a surface that is situated closest to the image side in the objective, fu21 is a focal length of the first lens component, fu22 is a focal length of the second lens component, L12 is a distance on an optical axis between a surface that is situated closest to the image side in the first lens group and the surface that is situated closest to the object side in the second lens component, and fG1 is a focal length of the first lens group.