OBJECTIVE LENS AND MICROSCOPE

摘要

An objective lens (OL) according to the present invention comprises, in order from an object side, a first lens group (G1) having positive refractive power, and a second lens group (G2) having negative refractive power. The first lens group (G1) comprises a positive meniscus lens (L1) having a concave surface facing the object side, a positive lens (L2) dispose close to an image of the positive meniscus lens (L1), and a diffractive optical element (DOE) having a diffractive optical surface (D). The second lens group (G2) is composed of three cemented lenses (CL21 to CL23) which are configured with a positive lens and a negative lens cemented each other. When d00 denotes a distance from the object side to the positive meniscus lens (L1), and TL0 denotes a distance from the object side to the objective lens rear end surface, 0.11≦d00/TL0≦0.19 is satisfied.

主权项

1. An objective lens which is configured to comprise, in order from an object side, a first lens group having positive refractive power, and a second lens group having negative refractive power,
the first lens group comprising, in order from the object side, a positive meniscus lens having a concave surface facing the object side, a positive lens disposed close to an image of the positive meniscus lens, and a diffractive optical element in which two diffractive grating elements made of mutually different optical materials are cemented each other and which has a diffractive optical surface in which diffraction grating grooves are formed on a cemented surface thereof, the second lens group being composed of three cemented lenses which are configured with a positive lens and a negative lens cemented each other, and the following conditional expression being satisfied:
0.11≦d00/TL0≦0.19 where d00 denotes a distance on the optical axis from the object side to a surface facing the object side of the positive meniscus lens, and TL0 denotes a distance on the optical axis from the object to a lens rear end surface of the whole objective lens.