US 12,189,107 B2
Scanning optical system and scanning-type confocal microscope
Yuki Yoshida, Yokohama (JP); and Fumio Suzuki, Yokohama (JP)
Assigned to Nikon Corporation, Tokyo (JP)
Appl. No. 17/268,464
Filed by Nikon Corporation, Tokyo (JP)
PCT Filed Aug. 27, 2018, PCT No. PCT/JP2018/031614
§ 371(c)(1), (2) Date May 10, 2021,
PCT Pub. No. WO2020/044410, PCT Pub. Date Mar. 5, 2020.
Prior Publication US 2021/0302709 A1, Sep. 30, 2021
Int. Cl. G02B 21/00 (2006.01); G02B 13/00 (2006.01); G02B 21/02 (2006.01); G02B 27/00 (2006.01)
CPC G02B 21/0076 (2013.01) [G02B 13/0045 (2013.01); G02B 21/0032 (2013.01); G02B 21/02 (2013.01); G02B 27/0031 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A scanning optical system provided between an objective lens and a scanning mechanism, consisting of:
a first lens group having a negative refractive power; a second lens group having a positive refractive power; and a third lens group having a negative refractive power, the lens groups being arranged sequentially from a side of the scanning mechanism,
wherein
the first lens group consists of one cemented lens or one single lens,
the third lens group consists of two cemented lenses, and
at least one lens included in any of the first lens group, the second lens group and the third lens group has a positive refractive power, and satisfies the following conditional expression:
νd1>80,
at least one lens included in any of the first lens group, the second lens group and the third lens group has a negative refractive power, and satisfies the following conditional expression:
νd2<50,
the lens having the positive refractive power satisfies the following conditional expression:
θgF1−(−0.00168×νd1)−0.644>0.03
the lens having the negative refractive power satisfies the following conditional expression:
θgF2−(−0.00168×νd2)−0.644<−0.002, and
where vd1: an Abbe number with reference to d-line of the lens having the positive refractive power, defined by the following expression:
νd1=(nd1−1)/(nF1−nC1), and
wherein a refractive index of the lens having the positive refractive power for d-line is nd1, a refractive index of the lens having the positive refractive power for F-line is nF1, and a refractive index of the lens having the positive refractive power for C-line is nC1,
vd2: an Abbe number with reference to d-line of the lens having the negative refractive power, defined by the following expression:
νd2=(nd2−1)/(nF2−nC2),
wherein a refractive index of the lens having the negative refractive power for d-line is nd2, a refractive index of the lens having the negative refractive power for F-line is nF2, and a refractive index of the lens having the negative refractive power for C-line is nC2,
where θgF1: a partial dispersion ratio of the lens having the positive refractive power, defined by the following expression:
θgF1=(ng1−nF1)/(nF1−nC1),
wherein a refractive index of the lens having the positive refractive power for g-line is ng1,
θgF2: a partial dispersion ratio of the lens having the negative refractive power, defined by the following expression:
θgF2=(ng2−nF2)/(nF2−nC2),
wherein a refractive index of the lens having the negative refractive power for g-line is ng2.