JP2010286755A5 - - Google Patents

Description

In order to achieve such an object, the objective lens for a parallel system stereomicroscope according to the present invention converts light from an object into a parallel light beam, and then guides it to two subsequent variable magnification optical systems for both left and right eyes. a objective lens system stereomicroscope, the aligned from the variable power optical system side in order toward the object side, a negative single lens having a concave surface facing the variable magnification optical system side, at least one or more positive The first lens group having a single lens and the second lens group having two or more cemented lenses and having a positive refractive power as a whole, the most object side constituting the second lens group from the object plane The distance on the optical axis to the lens is DO, the focal length of the objective lens is F, and satisfies the following formula 0.55 <DO / F <0.90, and in the second lens group, The Abbe number of the negative lens component constituting the cemented lens is ν 2 is n, the following conditional expression is satisfied: 39 <ν2n <60.

In the objective lens for parallel system stereomicroscope according to the present invention, the partial dispersion ratio of the negative lens component constituting the cemented lens is θgF (n), and the partial dispersion ratio of the positive lens component constituting the cemented lens is θgF (p ), It is preferable that all the cemented lenses in the second lens group satisfy the following condition: 0.00 <θgF (n) −θgF (p) <0.04.
However, the partial dispersion ratio θgF is expressed by the following formula θgF = (ng), where ng is the refractive index of the glass material with respect to g-line, nF is the refractive index of glass material with respect to F-line, and nC is the refractive index of glass material with respect to C-line. -NF) / (nF-nC).

The objective lens for a parallel system stereomicroscope according to the present invention preferably satisfies the following condition: 2.0 <| f1 / F | <4.0 when the focal length of the first lens group is f1. .
In the objective lens for a parallel system stereomicroscope according to the present invention, when the radius of curvature of the cemented surface of the cemented lens located closest to the object side in the second lens group is r2b, the following expression 0.65 <| r2b / F It is preferable to satisfy the condition of | <0.90.

In the objective lens for a parallel system stereomicroscope according to the present invention, the objective lens is preferably made of a glass material having an internal transmittance of 90% or more at a wavelength of 380 nm that does not include a reflection loss at a thickness of 10 mm.

Claims (5)

An object lens for a parallel system stereomicroscope that converts light from an object into parallel luminous fluxes and then guides it to two variable power optical systems for the left and right eyes,
A first lens group having a negative single lens having a concave surface facing the variable magnification optical system and at least one positive single lens, which are arranged in order from the variable magnification optical system to the object side ; ,
The second lens group has two or more cemented lenses and has a positive refractive power as a whole.
The distance on the optical axis from the object surface to the most object side lens constituting the second lens group and DO, the focal length of the objective lens is F, the following equation 0.55 <DO / F <0.90
While satisfying the conditions of
When the Nyu2n the Abbe number of the negative lens component constituting the cemented lens in the second lens group, the following formula 39 <ν2n <60
An objective lens for a parallel stereomicroscope characterized by satisfying the following conditions. When the partial dispersion ratio of the negative lens component constituting the cemented lens is θgF (n) and the partial dispersion ratio of the positive lens component constituting the cemented lens is θgF (p), all of the second lens group The cemented lens of the following formula
0.00 <θgF (n) −θgF (p) <0.04
The objective lens for a parallel stereomicroscope according to claim 1, wherein the following condition is satisfied.
However, the partial dispersion ratio θgF is expressed by the following formula θgF = (ng), where ng is the refractive index of the glass material with respect to g-line, nF is the refractive index of glass material with respect to F-line, and nC is the refractive index of glass material with respect to C-line. -NF) / (nF-nC). When the focal length of the first lens group is f1, the following formula
2.0 <| f1 / F | <4.0
The objective lens for a parallel stereomicroscope according to claim 1 or 2, wherein the following condition is satisfied. When the radius of curvature of the cemented surface of the cemented lens located closest to the object side in the second lens group is r2b,
0.65 <| r2b / F | <0.90
The objective lens for a parallel system stereomicroscope according to any one of claims 1 to 3, wherein the following condition is satisfied. The lenses of the objective lens, according to claim 1-4 any one of the internal transmittance at a wavelength of 380nm without the reflection loss in the thickness of 10mm is characterized in that it is a glass material is 90% or more Objective lens for parallel system stereomicroscope described in 1.