Imaging lenses and microscopes

Abstract

An image formation lens (1L) for a microscope has a negative lens, and a positive lens (L13) that satisfies the following conditional expressions.　-0.002×(νdP-35)+0.602-θgFP < 0 and 23 < νdP < 65 where νdP is the Abbe number of the positive lens, and θgFP is the partial dispersion ratio of the positive lens, and is defined by the following expression: θgFP = (ngP-nFP) / (nFP-nCP) where ngP is the refractive index for the g line of the positive lens, nFP is the refractive index for the F line of the positive lens, and nCP is the refractive index for the C line of the positive lens.

Claims

1. An imaging lens for a microscope that forms an image from light from the objective lens, It consists of a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power, arranged in order from the objective lens side. The second lens group consists of one lens component having negative refractive power, The third lens group consists of one lens component having a positive refractive power, An imaging lens having a positive lens and a negative lens that satisfy the following condition. -0.002×(νdP-35)+0.602-θgFP<0 23 < νdP < 65 -0.0033×(νdN-35)+0.593-θgFN<0 20 < νdN < 37 However, νdP: Abbe number of the positive lens θgFP: This is the partial dispersion ratio of the positive lens, and is defined by the following equation, where ngP is the refractive index of the positive lens with respect to the g line, nFP is the refractive index of the positive lens with respect to the F line, and nCP is the refractive index of the positive lens with respect to the C line. θgFP=(ngP-nFP) / (nFP-nCP) νdN: Abbe number of the negative lens θgFN: This is the partial dispersion ratio of the negative lens, and is defined by the following equation, where ngN is the refractive index of the negative lens with respect to the g line, nFN is the refractive index of the negative lens with respect to the F line, and nCN is the refractive index of the negative lens with respect to the C line. θgFN=(ngN-nFN) / (nFN-nCN)

2. The first lens group has a cemented lens on the image side of the first lens group, The image-forming lens according to claim 1, wherein the cemented lens includes the positive lens.

3. The negative lens is the imaging lens according to claim 1, wherein the negative lens of the imaging lens is positioned furthest towards the image side.

4. The imaging lens according to claim 1, wherein the positive lens satisfies the following condition. 1.55<ndP<1.79 However, ndP: refractive index of the positive lens with respect to the d line.

5. The imaging lens according to claim 1, wherein the negative lens satisfies the following condition. ndN < 1.78 However, ndN: refractive index of the negative lens with respect to the d line.

6. The imaging lens according to claim 1, wherein the positive lens satisfies the following condition. 0.4<fP / f<1.2 However, fP: focal length of the positive lens. f: Focal length of the imaging lens

7. The imaging lens according to claim 1, wherein the negative lens satisfies the following condition. -1.1<fN / f<-0.2 However, fN: focal length of the negative lens. f: Focal length of the imaging lens

8. The imaging lens according to claim 1, satisfying the following conditional expression. 0.2<Bf / TL<0.6 However, Bf: Back focus of the imaging lens TL: Total length of the imaging lens

9. The imaging lens according to claim 1, satisfying the following conditional expression. 0.45<f1 / f3<2.4 However, f1: focal length of the first lens group f3: Focal length of the third lens group

10. The imaging lens according to claim 1, satisfying the following conditional expression. -2.5<f1 / f2<-0.6 However, f1: focal length of the first lens group f2: Focal length of the second lens group

11. A microscope apparatus having an objective lens that receives light from an object and converts it into parallel light, and an imaging lens as described in claim 1.

12. The microscope apparatus according to claim 11, satisfying the following conditional expression. 0.3<DA / TL<0.6 However, DA: distance along the optical axis from the image-side lens surface of the objective lens to the object-side lens surface of the imaging lens. TL: Total length of the imaging lens

13. The microscope apparatus according to claim 11, satisfying the following conditional expression. 0.1<FDN / f<0.18 However, FDN: Field of view of the microscope device. f: Focal length of the imaging lens

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