Observation optical system and optical apparatus

1 . An observation optical system comprising:

a display element; and

an eyepiece lens disposed on an eyepoint side of the display element,

wherein the eyepiece lens consists of four or more lenses, and the eyepiece lens includes a first lens having positive optical power, a second lens having negative optical power, and a third lens consecutively in order from closest to a display element side to the eyepoint side,

in a case where a half value of a longest diameter of a display region in the display element is denoted by H, and a focal length of the eyepiece lens in a state where diopter is −1 diopter is denoted by f, Conditional Expression (1) is satisfied, which is represented by

0.35 <H/f< 0.6  (1), and

in a case where a paraxial curvature radius of a surface of the second lens on the display element side is denoted by R2f, and a paraxial curvature radius of a surface of the second lens on the eyepoint side is denoted by R2r, Conditional Expression (2-1) is satisfied, which is represented by

0.06<( R 2 r+R 2 f )/( R 2 r−R 2 f )<0.65  (2).

2 . The observation optical system according to claim 1 ,

wherein in diopter adjustment, at least three lenses in the eyepiece lens move along an optical axis.

3 . The observation optical system according to claim 1 ,

wherein a lens surface of the first lens on the display element side has a shape in which negative optical power is increased in a direction of separation from an optical axis, or a shape in which positive optical power is decreased in the direction of separation from the optical axis.

4 . The observation optical system according to claim 1 ,

wherein a lens surface of the second lens on the eyepoint side has a shape in which positive optical power is increased in a direction of separation from an optical axis, or a shape in which negative optical power is decreased in the direction of separation from the optical axis.

5 . The observation optical system according to claim 1 ,

wherein the eyepiece lens consists of four lenses.

6 . The observation optical system according to claim 1 ,

wherein in a case where a paraxial curvature radius of a surface of the first lens on the eyepoint side is denoted by R1r, Conditional Expression (3) is satisfied, which is represented by

−0.13<( R 2f−R1r)/( R 2f+R1r)<0.2  (3).

7 . The observation optical system according to claim 1 ,

wherein in a case where a paraxial curvature radius of a surface of the first lens on the display element side is denoted by R1f, and a paraxial curvature radius of a surface of the first lens on the eyepoint side is denoted by R1r, Conditional Expression (4) is satisfied, which is represented by

−5<( R 1 r+R 1 f )/( R 1 r−R 1 f )<−0.2  (4).

8 . The observation optical system according to claim 1 ,

wherein in a case where a paraxial curvature radius of a surface of the third lens on the display element side is denoted by R3f, and a paraxial curvature radius of a surface of the third lens on the eyepoint side is denoted by R3r, Conditional Expression (5) is satisfied, which is represented by

−2.5<( R 3 r+R 3 f )/( R 3 r−R 3 f )<8  (5).

9 . The observation optical system according to claim 1 ,

wherein in a case where a maximum value of refractive indexes of all lenses provided in the eyepiece lens with respect to a d line is denoted by Nmax, Conditional Expression (6) is satisfied, which is represented by

1.61< N max<2.2  (6).

10 . The observation optical system according to claim 1 ,

wherein in a case where a focal length of the second lens is denoted by f2, Conditional Expression (7) is satisfied, which is represented by

−4< f/f 2<−0.9  (7).

11 . The observation optical system according to claim 1 ,

wherein in a case where a combined focal length of the first lens and the second lens in a state where the diopter is −1 diopter is denoted by f12, Conditional Expression (8) is satisfied, which is represented by

−1< f/f 12<0.12  (8).

12 . The observation optical system according to claim 1 ,

wherein in a case where a combined focal length of all lenses on the eyepoint side with respect to the second lens in a state where the diopter is −1 diopter is denoted by fr, Conditional Expression (9) is satisfied, which is represented by

0.83< f/fr< 2  (9).

13 . The observation optical system according to claim 1 ,

wherein in a case where a focal length of the first lens is denoted by f1, and a focal length of the second lens is denoted by f2, Conditional Expression (10) is satisfied, which is represented by

−2.2< f 1/ f 2<−0.73  (10).

14 . The observation optical system according to claim 1 ,

wherein in a case where a focal length of the first lens is denoted by f1, and a combined focal length of all lenses on the eyepoint side with respect to the second lens in a state where the diopter is −1 diopter is denoted by fr, Conditional Expression (11) is satisfied, which is represented by

0.66< f 1/ fr< 1.6  (11).

15 . The observation optical system according to claim 1 ,

wherein in a case where a focal length of the second lens is denoted by f2, and a combined focal length of all lenses on the eyepoint side with respect to the second lens in a state where the diopter is −1 diopter is denoted by fr, Conditional Expression (12) is satisfied, which is represented by

−0.98< f 2/ fr<− 0.4  (12).

16 . The observation optical system according to claim 1 ,

wherein in a case where a paraxial curvature radius of a surface of the third lens on the display element side is denoted by R3f, Conditional Expression (13) is satisfied, which is represented by

−0.6<( R 3 f−R 2 r )/( R 3 f+R 2 r )<9  (13).

17 . The observation optical system according to claim 1 ,

wherein in a case where a distance on an optical axis from a surface of the first lens on the display element side to a lens surface of the eyepiece lens closest to the eyepoint side in a state where the diopter is −1 diopter is denoted by dL, Conditional Expression (14) is satisfied, which is represented by

1.6< dL/f< 2.25  (14).

18 . The observation optical system according to claim 1 ,

wherein in a case where a distance on an optical axis from a surface of the first lens on the display element side to a surface of the second lens on the eyepoint side in a state where the diopter is −1 diopter is denoted by dL12, and a sum of an air conversion distance on the optical axis from a display surface of the display element to the surface of the first lens on the display element side and a distance on the optical axis from the surface of the first lens on the display element side to the surface of the second lens on the eyepoint side in a state where the diopter is −1 diopter is denoted by T2, Conditional Expression (15) is satisfied, which is represented by

0.25< dL 12/ T 2<0.81  (15).

19 . The observation optical system according to claim 1 ,

wherein in a case where a sum of an air conversion distance on an optical axis from a display surface of the display element to a surface of the first lens on the display element side and a distance on the optical axis from the surface of the first lens on the display element side to a lens surface of the eyepiece lens closest to the eyepoint side in a state where the diopter is −1 diopter is denoted by TL, Conditional Expression (16) is satisfied, which is represented by

0.18 <H/TL< 0.65  (16)

20 . The observation optical system according to claim 1 ,

wherein in a case where an air conversion distance on an optical axis from a display surface of the display element to a surface of the first lens on the display element side in a state where the diopter is −1 diopter is denoted by d01, Conditional Expression (17) is satisfied, which is represented by

0.24 <d 01/ f< 0.8  (17).

21 . The observation optical system according to claim 1 ,

wherein in a case where a focal length of the second lens is denoted by f2, Conditional Expression (18) is satisfied, which is represented by

−1.15 <H/f 2<−0.35  (18).

22 . The observation optical system according to claim 1 ,

wherein in a case where a combined focal length of all lenses on the eyepoint side with respect to the second lens in a state where the diopter is −1 diopter is denoted by fr, Conditional Expression (19) is satisfied, which is represented by

0.32 <H/fr< 0.78  (19).

23 . The observation optical system according to claim 1 ,

wherein in a case where a focal length of the first lens is denoted by f1, Conditional Expression (20) is satisfied, which is represented by

0.7< f/f 1<2.2  (20).

24 . The observation optical system according to claim 1 ,

wherein the eyepiece lens includes the first lens, the second lens, the third lens, and a fourth lens consecutively in order from closest to the display element side to the eyepoint side, and

in a case where a paraxial curvature radius of a surface of the fourth lens on the display element side is denoted by R4f, and a paraxial curvature radius of a surface of the third lens on the eyepoint side is denoted by R3r, Conditional Expression (21) is satisfied, which is represented by

−4<( R 4 f−R 3 r )/( R 4 f+R 3 r )<4.2  (21).

25 . The observation optical system according to claim 1 ,

wherein the eyepiece lens includes the first lens, the second lens, the third lens, and a fourth lens consecutively in order from closest to the display element side to the eyepoint side, and

in a case where a paraxial curvature radius of a surface of the fourth lens on the display element side is denoted by R4f, and a paraxial curvature radius of a surface of the fourth lens on the eyepoint side is denoted by R4r, Conditional Expression (22) is satisfied, which is represented by

−15<( R 4 r+R 4 f )/( R 4 r−R 4 f )<0.5  (22).

26 . The observation optical system according to claim 1 ,

wherein in a case where a distance on an optical axis from a surface of the first lens on the eyepoint side to a surface of the second lens on the display element side in a state where the diopter is −1 diopter is denoted by d12, and a thickness of the second lens on the optical axis is denoted by d2, Conditional Expression (23) is satisfied, which is represented by

0.15< d 12/d2<5.8  (23).

27 . The observation optical system according to claim 1 ,

wherein in a case where a distance on an optical axis from a surface of the first lens on the eyepoint side to a surface of the second lens on the display element side in a state where the diopter is −1 diopter is denoted by d12, and a sum of an air conversion distance on the optical axis from a display surface of the display element to a surface of the first lens on the display element side and a distance on the optical axis from the surface of the first lens on the display element side to a lens surface of the eyepiece lens closest to the eyepoint side in a state where the diopter is −1 diopter is denoted by TL, Conditional Expression (24) is satisfied, which is represented by

0.01< d 12/ TL< 0.16  (24).

28 . The observation optical system according to claim 1 ,

wherein in a case where a focal length of the first lens is denoted by f1, Conditional Expression (25) is satisfied, which is represented by

0.25< H/f 1<0.9  (25).

29 . The observation optical system according to claim 1 ,

wherein Conditional Expression (1-1) is satisfied, which is represented by

0.37< H/f< 0.5  (1-1).

30 . The observation optical system according to claim 1 ,

wherein in a case where a paraxial curvature radius of a surface of the first lens on the display element side is denoted by R1f, and a paraxial curvature radius of a surface of the first lens on the eyepoint side is denoted by R1r, Conditional Expression (4-1) is satisfied, which is represented by

−3<( R 1 r+R 1 f )/( R 1 r−R 1 f )<−0.4  (4-1).

31 . The observation optical system according to claim 1 ,

wherein in a case where a paraxial curvature radius of a surface of the third lens on the display element side is denoted by R3f, and a paraxial curvature radius of a surface of the third lens on the eyepoint side is denoted by R3r, Conditional Expression (5-1) is satisfied, which is represented by

−1.5<( R 3 r+R 3 f )/( R 3 r−R 3 f )<5  (5-1).

32 . The observation optical system according to claim 1 ,

wherein in a case where a maximum value of refractive indexes of all lenses provided in the eyepiece lens with respect to a d line is denoted by Nmax, Conditional Expression (6-1) is satisfied, which is represented by

1.66< N max<2  (6-1).

33 . An optical apparatus comprising the observation optical system according to claim 1 .

34 . An observation optical system comprising:

a display element; and

an eyepiece lens disposed on an eyepoint side of the display element,

wherein the eyepiece lens consists of four or more lenses, and the eyepiece lens includes a first lens having positive optical power, a second lens having negative optical power, and a third lens consecutively in order from closest to a display element side to the eyepoint side,

in a case where a half value of a longest diameter of a display region in the display element is denoted by H, and a focal length of the eyepiece lens in a state where diopter is −1 diopter is denoted by f, Conditional Expression (1) is satisfied, which is represented by

0.35 <H/f< 0.6  (1), and

in a case where a paraxial curvature radius of a surface of the second lens on the display element side is denoted by R2f, and a paraxial curvature radius of a surface of the first lens on the eyepoint side is denoted by R1r, Conditional Expression (3-1) is satisfied, which is represented by

−0.09<( R 2 f−R 1 r )/( R 2 f+R 1 r )<0.14  (3-1).