JP6979160B2 - Eyepiece optical system and optical equipment - Google Patents

Description

The present invention relates to an eyepiece optical system and an optical device.

Conventionally, an eyepiece optical system having high imaging performance has been proposed (see, for example, Patent Document 1). However, Patent Document 1 has a problem that further improvement in optical performance is required.

Japanese Unexamined Patent Publication No. 2015-07513

The eyepiece optical system according to the first aspect of the present invention has a first lens component having a positive refractive power, a second lens component having a negative refractive power, and a positive refractive power in order from the observation object side. It is composed of substantially four lens components, that is, a third lens component and a fourth lens component having a positive refractive power, and satisfies the condition of the following equation.
0.01 <fe / f4 <0.33
0.58 <D1 / f1 <0.90
However,
fe: Focal length of the entire eyepiece optical system f4: Focal length of the fourth lens component
D1: Air conversion distance from the observation object to the lens surface on the observation object side of the first lens component in the reference diopter.
f1: Focal length of the first lens component The "lens component" means a single lens or a junction lens.

The eyepiece optical system according to the second aspect of the present invention has a first lens component having a positive refractive power, a second lens component having a negative refractive power, and a positive refractive power in order from the observation object side. It is composed of substantially four lens components, that is, a third lens component and a fourth lens component having a positive refractive power, and satisfies the condition of the following equation.
0.01 <fe / f4 <0.33
-0.40 <fe / f23 <-0.15
However,
fe: Focal length of the entire eyepiece optical system f4: Focal length of the 4th lens component f23: Combined focal length of the 2nd lens component and the 3rd lens component The "lens component" is a single lens or a junction lens. It means that.
The eyepiece optical system according to the third aspect of the present invention has a first lens component having a positive refractive power, a second lens component having a negative refractive power, and a positive refractive power in order from the observation object side. It is composed of substantially four lens components, that is, a third lens component and a fourth lens component having a positive refractive power, and the second lens component is a single lens and satisfies the condition of the following equation.
0.259 ≤ fe / f4 <0.33
1.651 ≤ nd2 <1.80
However,
fe: Focal length of the entire system of the eyepiece optical system f4: Focal length of the fourth lens component nd2: Refraction coefficient of the lens element constituting the second lens component with respect to the d line The "lens component" is a single lens. Or it refers to a bonded lens.

It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 1st Example. It is a figure of various aberrations of the eyepiece optical system which concerns on 1st Example. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 2nd Example. It is a figure of various aberrations of the eyepiece optical system which concerns on 2nd Example. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 3rd Example. It is a figure of various aberrations of the eyepiece optical system which concerns on 3rd Example. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 4th Embodiment. It is a figure of various aberrations of the eyepiece optical system which concerns on 4th Embodiment. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 5th Embodiment. 5 is a diagram of various aberrations of the eyepiece optical system according to the fifth embodiment. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 6th Embodiment. 6 is a diagram of various aberrations of the eyepiece optical system according to the sixth embodiment. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 7th Embodiment. It is a diagram of various aberrations of an eyepiece optical system according to a seventh embodiment. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 8th Embodiment. It is a figure of various aberrations of the eyepiece optical system which concerns on 8th Embodiment. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 9th Embodiment. 9 is a diagram of various aberrations of the eyepiece optical system according to the ninth embodiment. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on 10th Embodiment. It is a diagram of various aberrations of an eyepiece optical system according to a tenth embodiment. It is sectional drawing which shows the lens structure of the eyepiece optical system which concerns on eleventh embodiment. 11 is a diagram of various aberrations of the eyepiece optical system according to the eleventh embodiment. It is sectional drawing of the camera equipped with the said eyepiece optical system. It is a flowchart for demonstrating the manufacturing method of the said eyepiece optical system.

Hereinafter, preferred embodiments will be described with reference to the drawings. As shown in FIG. 1, the eyepiece optical system EL according to the present embodiment has a first lens component G1 having a positive refractive power and a negative refractive power in order from the observation object side (also simply referred to as an “object”). It has a second lens component G2 having a positive refractive power, a third lens component G3 having a positive refractive power, and a fourth lens component G4 having a positive refractive power.

The "lens component" means a single lens or a junction lens. Further, the "lens element" refers to each lens constituting a single lens or a junction lens. Further, the "reference diopter" means when the diopter is -1 [1 / m]. Here, with respect to the unit [1 / m], the diopter X [1 / m] is a state in which an image produced by the eyepiece optical system EL can be formed at a position of 1 / X [m (meter)] on the optical axis from the eye point. (The code is positive when the image is formed on the observer side (eye point side) from the eyepiece optical system EL).

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (1) shown below.

0.01 <fe / f4 <0.33 (1)
However,
fe: Focal length of the entire system of the eyepiece optical system EL f4: Focal length of the fourth lens component G4

The conditional expression (1) defines the refractive power of the lens closest to the eye point in order to satisfactorily correct spherical aberration and coma. The fourth lens component G4 on the most eye point side has the greatest effect on spherical aberration and coma. Therefore, if the upper limit of the conditional expression (1) is exceeded, the positive refractive power of the fourth lens component G4 becomes stronger, and spherical aberration and coma are greatly deteriorated, which is not preferable. In order to ensure the effect of the conditional expression (1), it is more desirable to set the upper limit value of the conditional expression (1) to 0.30, further 0.25, and further 0.239. Further, if it is less than the lower limit of the conditional expression (1), it becomes difficult to increase the overall refractive power (power) of the eyepiece optical system EL, and it becomes impossible to increase the observation magnification, which is not preferable. Assuming that the refractive power of the fourth lens component G4 is lower than the lower limit of the conditional expression (1) and the observation magnification is increased, the positive refractive powers of the first lens component G1 and the third lens component G3 are extreme. However, the negative refractive power of the second lens component G2 becomes weaker, which makes it difficult to correct the curvature of field. In order to ensure the effect of the conditional expression (1), it is more desirable to set the lower limit value of the conditional expression (1) to 0.10 and further to 0.15.

Further, in the eyepiece optical system EL according to the present embodiment, if the second lens component G2 is a single lens, the center thickness of the second lens group G2 can be reduced, and the center thickness of the second lens group G2 can be reduced to the eye point side of the second lens group G2. It is possible to reduce the incident height of the light beam, and it is possible to satisfactorily correct the spherical aberration.

Further, in the eyepiece optical system EL according to the present embodiment, when the lens surface on the eyepoint side of the lens on the eyepoint side is formed into a convex surface shape on the eyepoint side, the light beam near the center of the observation object is the most eye. The ejection angle from the lens surface on the eye point side of the lens on the point side becomes small, and the amount of spherical aberration generated can be suppressed. On the other hand, the emission angle of the light beam in the peripheral portion of the screen can be increased, and coma aberration can be corrected.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (2) shown below.

−0.30 <(G2R2-G3R1) / (G2R2 + G3R1) <0.50 (2)
However,
G2R2: Radius of curvature of the lens surface on the most eye point side of the second lens component G2 G3R1: Radius of curvature of the lens surface on the most observed object side of the third lens component G3

Conditional expression (2) defines the shape of the lens surface on the most eye point side of the second lens component G2 and the shape of the lens surface on the most observed object side of the third lens component G3 in order to satisfactorily correct coma. It is a thing. The lens surface on the most eye point side of the second lens component G2 and the lens surface on the most observed object side of the third lens component G3 greatly affect the generation or correction of coma aberration. In order to satisfactorily correct the coma aberration, it is preferable to correct the coma aberration generated on the lens surface on the most eye point side of the second lens component G2 on the lens surface on the most observed object side of the third lens component G3. Further, in order to satisfactorily correct the coma, the shape of the lens surface on the most eye point side of the second lens component G2 and the shape of the lens surface on the most observed object side of the third lens component G3 are made similar to each other. It is desirable to make the coma generated on the lens surface on the most eye point side of the two lens components G2 similar to the coma corrected on the lens surface on the most observed object side of the third lens component G3 to cancel the coma. When it falls below the lower limit of the conditional expression (2), the similarity between the shape of the lens surface on the most eye point side of the second lens component G2 and the shape of the lens surface on the most observed object side of the third lens component G3 is broken. This is not preferable because coma aberration occurs. In order to ensure the effect of the conditional expression (2), it is desirable to set the lower limit value of the conditional expression (2) to −0.25. Further, when the upper limit of the conditional expression (2) is exceeded, the shape of the lens surface on the most eye point side of the second lens component G2 and the shape of the lens surface on the most observed object side of the third lens component G3 become similar. It is not preferable because it collapses and coma aberration occurs. In order to ensure the effect of the conditional expression (2), it is more desirable to set the upper limit value of the conditional expression (2) to 0.25 and further to −0.20.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (3) shown below.

-0.75 <(G1R2 + G1R1) / (G1R2-G1R1) <0.00 (3)
However,
G1R1: Radius of curvature of the lens surface on the most observed object side of the first lens component G1 G1R2: Radius of curvature of the lens surface on the most eye point side of the first lens component G1

The conditional expression (3) defines the shape of the first lens component G1 in order to increase the observation magnification and satisfactorily correct curvature of field and distortion. The positive refractive power of the first lens component G1 causes curvature of field, but the structure corrects the curvature of field generated by the negative refractive power of the second lens component G2. When the refractive power of the lens surface on the most eye point side of the first lens component G1 is increased, the curvature of field generated by the first lens component G1 becomes large, so that the negative refractive power of the second lens component G2 cannot be corrected. It disappears. On the other hand, in order to increase the observation magnification, it is necessary to increase the positive refractive power of the first lens component G1. Therefore, an appropriate amount of the positive refractive power of the lens surface of the first lens component G1 on the observation object side is appropriate. Must be large. However, if the positive refractive power of the lens surface of the first lens component G1 on the side of the most observed object is made too large, the distortion will be aggravated. If the upper limit of the conditional expression (3) is exceeded, the refractive power of the first lens component G1 becomes too large, and the distortion aberration worsens, which is not preferable. In order to ensure the effect of the conditional expression (3), it is more desirable to set the upper limit value of the conditional expression (3) to −0.20 and further to −0.30. Further, when the value is lower than the lower limit of the conditional expression (3), the refractive power of the first lens component G1 becomes weak and the observation magnification cannot be increased. Further, if the observation magnification is increased while the value is below the lower limit of the conditional expression (3), the refractive power of the lens surface on the most eye point side of the first lens component G1 becomes large, and the curvature of field deteriorates. Not preferred. In order to ensure the effect of the conditional expression (3), it is more desirable to set the lower limit of the conditional expression (3) to -0.57, further to -0.56, and further to -0.50.

Further, in the eyepiece optical system EL according to the present embodiment, distortion can be corrected by making the lens surface on the most observed object side of the first lens component G1 a rotationally symmetric aspherical surface, and the first lens component G1 can be corrected. It is possible to increase the refractive power of the lens surface on the side of the most observed object, which is advantageous for increasing the observation magnification.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (4) shown below.

-1.00 <fe / EnP <-0.48 (4)
However,
fe: Focal length of the entire system of the eyepiece optical system EL EnP: Entrance pupil position of the eyepiece optical system EL at the reference diopter (the reference numeral is positive on the eye point side with respect to the observation object surface).

The conditional expression (4) defines the position of the entrance pupil in order to increase the observation magnification while keeping the eye point long. By increasing the passing height of the main ray with a high image height in the region close to the observation object surface, it becomes easy to increase the observation magnification while keeping the eye point long. In order to increase the passing height of the high image height main ray in the region close to the observation object surface, it is effective to set the entrance pupil distance to a short distance opposite to the eye point side from the observation object surface. If the upper limit of the conditional expression (4) is exceeded, the position of the entrance pupil moves away from the observation object, and the passing height of the main ray having a high image height cannot be increased. It is not preferable because it becomes impossible. In order to ensure the effect of the conditional expression (4), it is desirable to set the upper limit value of the conditional expression (4) to −0.50. Further, when the value is lower than the lower limit of the conditional expression (4), the entrance pupil position is too close to the observation object, so that the main ray passing height of the high image height of the first lens component G1 becomes high and curvature of field is greatly generated. It is not preferable because it will end up. In order to ensure the effect of the conditional expression (4), it is more desirable to set the lower limit value of the conditional expression (4) to -0.70 and further to -0.65.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (5) shown below.

-0.40 <fe / f23 <-0.15 (5)
However,
fe: Focal length of the entire system of the eyepiece optical system EL f23: Combined focal length of the second lens component G2 and the third lens component G3

In the conditional equation (5), the second lens component G2 and the third lens component G3 are manufactured in order to reduce the deterioration of the aberration performance when the optical axes of the second lens component G2 and the third lens component G3 are deviated from each other. It defines the ratio between the combined focal length of the lens and the focal length of the entire eyepiece optical system EL. By reducing the combined focal length of the second lens component G2 and the third lens component G3 with respect to the focal length of the entire eyepiece optical system EL, the light of the second lens component G2 and the third lens component G3 due to a manufacturing error. Even if the axis is deviated, the deterioration of aberration performance can be reduced. Further, it is possible to reduce the deterioration of the optical performance when the refractive index or the radius of curvature of the second lens component G2 and the third lens component G3 changes due to the temperature change. In particular, it is effective when the second lens component G2 and the third lens component G3 are composed of an optical resin. If it is less than the lower limit of the conditional expression (5), the negative combined refractive power of the second lens component G2 and the third lens component G3 becomes strong, and the deterioration of the aberration performance due to the manufacturing error becomes large, which is not preferable. In order to ensure the effect of the conditional expression (5), it is desirable to set the lower limit value of the conditional expression (5) to −0.35. Further, if the upper limit value of the conditional expression (5) is exceeded, the negative refractive power of the second lens component G2 becomes small, and the correction of the curvature of field becomes insufficient, which is not preferable. In order to ensure the effect of the conditional expression (5), it is more desirable to set the upper limit value of the conditional expression (5) to -0.20 and further to -0.25.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (6) shown below.

0.58 <D1 / f1 <0.90 (6)
However,
D1: Air conversion distance from the observed object to the lens surface of the first lens component G1 on the most observed object side in the reference diopter f1: Focal length of the first lens component G1

In the conditional equation (6), in order to satisfactorily correct the coma aberration, the air conversion distance from the observation object at the reference diopter to the lens surface on the most observed object side of the first lens component G1 and the focal length of the first lens component G1. It defines the ratio of. When the air conversion distance from the observation object to the lens surface of the first lens component G1 on the observation object side in the reference diopter becomes large, the luminous flux emitted from one point on the observation surface passes through the first lens component G1. Changes greatly. Therefore, when the air conversion distance D1 from the observation object to the lens surface on the most observation object side of the first lens component G1 becomes large, coma aberration is greatly generated by the positive refractive power of the first lens component G1. It is necessary to reduce the refractive power of G1. On the other hand, in order to increase the refractive power of the first lens component G1 and to reduce the coma aberration generated by the first lens component G1, from the observation object to the lens surface of the first lens component G1 on the observation object side. It is necessary to reduce the air conversion distance D1 of. When the upper limit of the conditional expression (6) is exceeded, the refractive power of the first lens component G1 becomes stronger with respect to the air conversion distance D1 from the observation object to the lens surface on the most observed object side of the first lens component G1, and the coma becomes coma. It is not preferable because the aberration worsens. In order to ensure the effect of the conditional expression (6), it is more desirable to set the upper limit value of the conditional expression (6) to 0.71 and further to 0.68. Further, if it is less than the lower limit of the conditional expression (6), the positive refractive power of the first lens component G1 becomes weak and it becomes impossible to increase the observation magnification, which is not preferable. In order to ensure the effect of the conditional expression (6), it is more desirable to set the lower limit value of the conditional expression (6) to 0.60 and further to 0.63.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (7) shown below. The total length of the eyepiece optical system EL is the distance on the optical axis from the observation object O to the lens surface on the most eyepoint side of the eyepiece optical system EL.

1.50 <TL / fe <1.80 (7)
However,
TL: Overall length of the eyepiece optical system EL fe: Focal length of the entire system of the eyepiece optical system EL

The conditional expression (7) defines the ratio of the total length of the eyepiece optical system EL to the focal length of the entire system in order to satisfactorily correct the curvature of field. If it is less than the lower limit of the conditional expression (7), the overall refractive power of the eyepiece optical system EL becomes weak and the observation magnification cannot be increased, which is not preferable. In order to ensure the effect of the conditional expression (7), it is more desirable to set the lower limit value of the conditional expression (7) to 1.55 and further 1.60. Further, if the upper limit value of the conditional expression (7) is exceeded, the curvature of field deteriorates, which is not preferable. In order to ensure the effect of the conditional expression (7), it is desirable to set the upper limit value of the conditional expression (7) to 1.70.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (8) shown below. When the first lens component G1 is composed of a junction lens and has a plurality of lens elements, at least one of those lens elements satisfies the conditional expression (8).

1.550 <nd1 <1.80 (8)
However,
nd1: Refractive index of the lens element constituting the first lens component G1 with respect to the d-line of the medium.

Conditional expression (8) defines the refractive index of the lens element constituting the first lens component G1 with respect to the d-line in order to satisfactorily correct distortion and curvature of field. If it is less than the lower limit of the conditional expression (8), the first lens component G1 cannot have a refractive power, and it is difficult to maintain the performance and increase the magnification, which is not preferable. In order to ensure the effect of the conditional expression (8), it is more desirable to set the lower limit value of the conditional expression (8) to 1.600 and further 1.700. Further, if the upper limit value of the conditional expression (8) is exceeded, the distortion aberration deteriorates, which is not preferable. In order to ensure the effect of the conditional expression (8), it is desirable to set the upper limit value of the conditional expression (8) to 1.850.

Further, it is desirable that the eyepiece optical system EL according to the present embodiment satisfies the conditional expression (9) shown below. When the second lens component G2 is composed of a junction lens and has a plurality of lens elements, at least one of those lens elements satisfies the conditional expression (9).

1.640 <nd2 <1.80 (9)
However,
nd2: Refractive index of the lens element constituting the second lens component G2 with respect to the d-line of the medium.

The conditional expression (9) defines the refractive index of the lens element constituting the second lens component G2 with respect to the d-line in order to satisfactorily correct astigmatism. If it is less than the lower limit of the conditional expression (9), the optical performance is deteriorated due to the eccentricity of the second lens component G2, which is not preferable. In order to ensure the effect of the conditional expression (9), it is desirable to set the lower limit value of the conditional expression (9) to 1.650. Further, if the upper limit of the conditional expression (9) is exceeded, it becomes difficult to correct astigmatism, which is not preferable. In order to ensure the effect of the conditional expression (9), it is desirable to set the upper limit value of the conditional expression (9) to 1.750.

Further, the eyepiece optical system EL according to the present embodiment is sufficiently good even if the first lens component G1, the third lens component G3, and the fourth lens component G4 are configured as a single lens and are composed of four single lenses. Aberration performance can be achieved.

Further, the eyepiece optical system EL according to the present embodiment can easily adjust the diopter by moving the entire eyepiece optical system in the optical axis direction.

It should be noted that the conditions and configurations described above are each exerting the above-mentioned effects, and are not limited to those satisfying all the conditions and configurations, and are any of the conditions or configurations, or any of them. It is possible to obtain the above-mentioned effects even if the combination of the above conditions or configurations is satisfied.

Next, a camera, which is an optical device provided with the eyepiece optical system EL according to the present embodiment, will be described with reference to FIG. 23. The camera 1 is a so-called mirrorless camera with an interchangeable lens equipped with an objective lens (shooting lens) OL. In the present camera 1, the light from an object (subject) (not shown) is collected by the objective lens OL and passed through an OLPF (Optical low pass filter) (not shown) on the image pickup surface of the image pickup unit C. Form a subject image. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the image pickup unit C, and the image of the subject is generated. This image is displayed on an electronic viewfinder (EVF) provided in the camera 1. Here, the electronic viewfinder EVF is an eyepiece optical system EL for magnifying and observing an image display element DP such as a liquid crystal display element and an image displayed on the display surface (observation object O described above) of the image display element DP. It is composed of and. Thereby, the photographer can observe the image of the object (subject) formed by the objective lens OL through the eyepiece optical system EL by positioning the eye at the eye point EP.

Further, when the photographer presses the release button (not shown), the image photoelectrically converted by the image pickup unit C is stored in the memory (not shown). In this way, the photographer can shoot the subject with the camera 1. Although an example of a mirrorless camera has been described in the present embodiment, the eyepiece optical system EL according to the present embodiment is used in a single-lens reflex type camera having a quick return mirror in the camera body and observing a subject by a finder optical system. Even when it is mounted, the same effect as that of the camera 1 can be obtained.

As described above, the eyepiece optical system EL according to the present embodiment is an optical system (eyepiece) for magnifying and observing an image. Here, the image is an intermediate image by an objective lens, or a display surface of an image display element such as a liquid crystal display element or an organic EL display, and is particularly preferably a display surface of an organic EL display. Therefore, the eyepiece optical system EL according to the present embodiment is used, for example, as an eyepiece of an electronic binocular for observing an image displayed on a display surface, a head-mounted display, a built-in camera or an external electronic viewfinder. Suitable for.

Although not shown in FIG. 1, an optical member such as a cover glass or a prism is formed between the observation object O (the display surface of the image display element DP shown in FIG. 23) and the first lens component G1. It may be arranged. Further, an optical member such as a cover glass may be arranged between the fourth lens component G4 and the eye point EP.

Hereinafter, an outline of a method for manufacturing the eyepiece optical system EL according to the present embodiment will be described with reference to FIG. 24. First, by arranging each lens, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, a third lens component G3 having a positive refractive power, and a positive refraction A fourth lens component having power and G4 are prepared respectively (step S100). Then, it is arranged so as to satisfy the condition according to the predetermined conditional expression (for example, the above-mentioned conditional expression (1)) (step S200).

Specifically, in the present embodiment, for example, as shown in FIG. 1, a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape in order from the observation object side. The aspherical positive lens L11 is arranged as the first lens component G1, and the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape, and the negative meniscus lens shape with the concave surface facing the observation object side. The aspherical negative lens L12 is arranged as the second lens component G2, and the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape, and a positive meniscus lens shape with a concave surface facing the object side. The aspherical positive lens L31 is arranged as the third lens component G3, and the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape, and the lens surface has a positive meniscus lens shape with the concave surface facing the observation object side. The aspherical positive lens L41 is arranged to be a fourth lens component G4. Each lens component prepared in this way is arranged by the above-mentioned procedure to manufacture an eyepiece optical system EL.

With the above configuration, it is possible to provide an eyepiece optical system EL having a large observation magnification and good optical performance, an optical device having this eyepiece optical system EL, and a method for manufacturing the eyepiece optical system EL.

Hereinafter, each embodiment of the present application will be described with reference to the drawings. In addition, FIG. 1, FIG. 3, FIG. 5, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 15, FIG. 17, FIG. 19 and FIG. 21 are eyepiece optical systems EL (EL1 to EL11) according to each embodiment. It is sectional drawing which shows the structure and the refractive power distribution of.

In these examples, the height of the aspherical surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangent plane of the apex of each aspherical surface to each aspherical surface at the height y. ) Is S (y), the radius of curvature of the reference sphere (near-axis radius of curvature) is r, the conical constant is K, and the nth-order aspherical coefficient is An. To. In the following examples, "En" indicates " ^{x10 -n".}

S (y) = (y ² / r) / {1+ (1-K × y ² / r ² ) ^1/2 }
+ A4 x y ⁴ + A6 x y ⁶ + A8 x y ⁸ + A10 x y ¹⁰ + A12 x y ¹² (a)

In each embodiment, the second-order aspherical coefficient A2 is 0. Further, in the table of each embodiment, the aspherical surface is marked with * on the right side of the surface number.

[First Example]
FIG. 1 is a diagram showing a configuration of an eyepiece optical system EL1 according to the first embodiment. In this eyepiece optical system EL1, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL1, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed to the object side. ing. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL1 is performed by moving the entire eyepiece optical system EL1 in the optical axis direction.

Table 1 below lists the specifications of the eyepiece optical system EL1. In this Table 1, fe shown in the overall specifications indicates the focal length of the entire system, H indicates the maximum object height, and TL indicates the value of the total length. Further, in the first column m of the lens data, the order (plane number) of the lens surfaces from the object side along the traveling direction of the light beam is shown, and in the second column r, the refractive index of each lens plane is shown in the third column. d is the distance (plane spacing) on the optical axis from each optical surface to the next optical surface, and the fourth column nd and the fifth column νd are the refractive index and Abbe number with respect to the d line (λ = 587.6 nm). Is shown. The radius of curvature ∞ indicates a plane, and the refractive index of air 1.00000 is omitted. Further, the object surface indicates the observation object O, and the image surface indicates the eye point EP.

Here, "mm" is generally used as the unit of the focal length f (foe, fEe, etc.), the radius of curvature r, the surface spacing d, and other lengths listed in all the following specification values, but the optical system. Is not limited to this, because the same optical performance can be obtained even if the ratio is expanded or contracted. Further, the description of these reference numerals and the description of the specification table are the same in the following examples.

As described above, although not shown in each of the subsequent examples including this embodiment, between the observation object O and the first lens component G1 and between the fourth lens component G4 and the eye point EP. When an optical member such as a cover glass, a prism, or a display cover glass is arranged, the surface spacing d is the air equivalent length.

(Table 1) First Example [Overall Specifications]
fe = 17.641
H = 6.30
TL = 28.790

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 29.01673 6.95 1.77377 47.25
2 * -11.37822 3.03
3 * -6.74812 1.50 1.63550 23.89
4 * -58.92577 1.25
5 * -48.01803 5.40 1.53110 55.91
6 * -10.14569 0.50
7 * -1037.93340 2.75 1.53110 55.91
8 * -42.12958 D2
Image plane ∞

In this eyepiece optical system EL1, the first surface, the second surface, the third surface, the fourth surface, the fifth surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 2 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 2)
[Aspherical data]
First side K = -1.0414
A4 = -1.29144E-04 A6 = -4.67158E-07 A8 = 1.78024E-08
A10 ＝ -1.65828E-10 A12 ＝ 6.30320E-13
Second side K = -2.2911
A4 = -1.46042E-04 A6 = 1.05047E-06 A8 = -8.71894E-09
A10 = 3.48401E-11 A12 = 0.00000E + 00
Side 3 K = -0.2684
A4 = 3.35859E-04 A6 = -4.37805E-06 A8 = 2.17895E-08
A10 = -4.94107E-11 A12 = 0.00000E + 00
Side 4 K = 5.9869
A4 = 9.81668E-05 A6 = -1.20860E-06 A8 = 6.95819E-09
A10 ＝ -1.72138E-11 A12 ＝ 0.00000E + 00
Side 5 K = 5.9905
A4 = 2.82487E-05 A6 = 1.16190E-06 A8 = -1.23653E-08
A10 = 4.18910E-11 A12 = 0.00000E + 00
Side 6 K = 0.3916
A4 = 1.91131E-04 A6 = -3.21702E-07 A8 = -3.26701E-09
A10 = 2.35655E-11 A12 = 0.00000E + 00
Side 7 K = 1.0000
A4 = -1.52684E-04 A6 = 1.49017E-06 A8 = -1.206061E-08
A10 = 5.44999E-11 A12 = 0.00000E + 00
Side 8 K = 3.6084
A4 = -2.40943E-04 A6 = 2.55221E-06 A8 = -1.68422E-08
A10 = 5.77483E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL1, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 3 below shows the variable intervals and entrance pupil positions for each diopter. The diopter is represented by -1 [1 / m] as "-1 dpt", +2 [1 / m] as "+ 2 dpt", and -4 [1 / m] as "-4 dpt". The same applies to the following examples.

(Table 3)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.41 8.33 6.39
D2 20.60 19.68 21.62
EnP -29.03270 -30.46513 -27.64176

Table 4 below shows the values corresponding to each conditional expression of the eyepiece optical system EL1.

(Table 4)
f4 = 82.602
f23 = -63.706

[Conditional expression correspondence value]
(1) fe / f4 = 0.214
(2) (G2R2-G3R1) / (G2R2 + G3R1) = 0.102
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.437
(4) fe / EnP = -0.608
(5) fe / f23 = -0.277
(6) D1 / f1 = 0.649
(7) TL / fe = 1.632
(8) nd1 = 1.774
(9) nd2 = 1.636

As described above, the eyepiece optical system EL1 satisfies the above conditional expressions (1) to (8).

FIG. 2 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL1. The unit of the horizontal axis of the spherical aberration diagram and the astigmatism diagram is "1 / m", and is indicated by "D" in the figure. Further, the coma aberration diagram and the chromatic aberration of magnification diagram show the minute in the angle unit, and d and g in the figure show the aberration curves on the d line and the g line. In addition, the coma aberration diagram shows an aberration curve for each object height. These explanations are the same in the following examples. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL1 achieves good aberration within the diopter adjustment range.

[Second Example]
FIG. 3 is a diagram showing the configuration of the eyepiece optical system EL2 according to the second embodiment. In this eyepiece optical system EL2, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL2, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed to the object side. ing. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL2 is performed by moving the entire eyepiece optical system EL2 in the optical axis direction.

Table 5 below lists the specifications of the eyepiece optical system EL2.

(Table 5) Second Example [Overall specifications]
fe = 18.135
H = 6.30
TL = 28.100

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 18.29768 7.45 1.53110 55.91
2 * -8.02783 2.40
3 * -5.08738 2.15 1.63550 23.89
4 * -16.13188 0.50
5 * -46.53675 5.00 1.53110 55.91
6 * -9.74321 0.50
7 * -62.07807 2.30 1.53110 55.91
8 * -36.52997 D2
Image plane ∞

In this eyepiece optical system EL2, the first surface, the second surface, the third surface, the fourth surface, the fifth surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 6 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 6)
[Aspherical data]
First side K = 0.4135
A4 = -1.67471E-04 A6 = -2.55937E-06 A8 = 4.54261E-08
A10 ＝ -3.19957E-10 A12 ＝ 1.06400E-12
Second side K = -2.0545
A4 = -3.02431E-04 A6 = 3.45590E-06 A8 = -3.41508E-08
A10 = 1.41269E-10 A12 = 0.00000E + 00
Side 3 K = -0.361
A4 = 5.48726E-04 A6 = -5.11105E-06 A8 = -4.02571E-10
A10 = 6.06422E-11 A12 = 0.00000E + 00
Side 4 K = -3.9720
A4 = 1.64809E-04 A6 = -6.23672E-07 A8 = -3.44304E-09
A10 = 4.26001E-12 A12 = 0.00000E + 00
Side 5 K = 5.8883
A4 = -5.24409E-05 A6 = 5.07414E-07 A8 = 3.77890E-09
A10 ＝ -1.41672E-11 A12 ＝ 0.00000E + 00
Side 6 K = 0.4195
A4 = 2.57996E-04 A6 = -1.85757E-06 A8 = 2.18453E-09
A10 = 5.57891E-11 A12 = 0.00000E + 00
Side 7 K = 4.9451
A4 = -8.67424E-05 A6 = 9.74736E-07 A8 = 5.79036E-09
A10 ＝ -6.53413E-11 A12 ＝ 0.00000E + 00
Side 8 K = 5.7525
A4 = -2.08333E-04 A6 = 2.55741E-06 A8 = -6.33475E-09
A10 ＝ -2.345117E-11 A12 ＝ 0.00000E + 00

In this eyepiece optical system EL2, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 7 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 7)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.80 8.77 6.74
D2 20.60 19.63 21.66
EnP -34.92593 -37.22500 -32.79600

Table 8 below shows the values corresponding to each conditional expression of the eyepiece optical system EL2.

(Table 8)
f4 = 162.068
f23 = -93.824

[Conditional expression correspondence value]
(1) fe / f4 = 0.112
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.485
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.390
(4) fe / EnP = -0.519
(5) fe / f23 = -0.193
(6) D1 / f1 = 0.670
(7) TL / fe = 1.550
(8) nd1 = 1.531
(9) nd2 = 1.636

As described above, the eyepiece optical system EL2 satisfies the above conditional expressions (1), (3) to (7).

FIG. 4 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL2. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL2 achieves good aberration within the diopter adjustment range.

[Third Example]
FIG. 5 is a diagram showing the configuration of the eyepiece optical system EL3 according to the third embodiment. In this eyepiece optical system EL3, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL3, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a biconcave negative lens shape in which the lens surface on the observation object side is formed into an aspherical shape. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a biconvex positive lens shape in which the lens surface on the eye point side is formed into an aspherical shape. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL3 is performed by moving the entire eyepiece optical system EL3 in the optical axis direction.

Table 9 below lists the specifications of the eyepiece optical system EL3.

(Table 9) Third Example [Overall specifications]
fe = 17.654
H = 6.30
TL = 29.118

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 37.20780 7.34 1.82098 42.50
2 * -10.78310 2.69
3 * -6.86450 1.58 1.63550 23.89
4 403.03380 0.98
5 365.51190 5.94 1.53110 55.91
6 * -10.45160 0.50
7 * -40.06410 2.69 1.53110 55.91
8 * -25.10660 D2
Image plane ∞

In this eyepiece optical system EL3, the first surface, the second surface, the third surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 10 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 10)
[Aspherical data]
First side K = 3.5010
A4 ＝ -1.08770E-04 A6 ＝ -7.76264E-07 A8 ＝ 1.84546E-08
A10 ＝ -1.13779E-10 A12 ＝ 3.71750E-13
Second side K = -2.3099
A4 = -1.29893E-04 A6 = 9.59335E-07 A8 = -7.24273E-09
A10 = 3.52620E-11 A12 = 0.00000E + 00
Side 3 K = -0.1511
A4 = 4.02440E-04 A6 = -4.06009E-06 A8 = 2.11556E-08
A10 ＝ -1.51294E-10 A12 ＝ 0.00000E + 00
Side 6 K = 0.5856
A4 = 2.62266E-04 A6 = -6.94589E-07 A8 = -3.75126E-09
A10 = 2.70416E-11 A12 = 0.00000E + 00
Side 7 K = 1.0000
A4 = -1.21897E-04 A6 = 1.25808E-06 A8 = -5.29696E-09
A10 = 4.01375E-11 A12 = 0.00000E + 00
Side 8 K = 0.9506
A4 = -2.35090E-04 A6 = 2.42051E-06 A8 = -1.44574E-08
A10 = 7.36171E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL3, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 11 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 11)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.41 8.34 6.40
D2 20.60 19.67 21.61
EnP -30.17343 -31.78442 -28.65171

Table 12 below shows the values corresponding to each conditional expression of the eyepiece optical system EL3.

(Table 12)
f4 = 119.198
f23 = -70.015

[Conditional expression correspondence value]
(1) fe / f4 = 0.148
(2) (G2R2-G3R1) / (G2R2 + G3R1) = 0.049
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.551
(4) fe / EnP = -0.585
(5) fe / f23 = -0.252
(6) D1 / f1 = 0.678
(7) TL / fe = 1.649
(8) nd1 = 1.821
(9) nd2 = 1.636

As described above, the eyepiece optical system EL3 satisfies the above conditional expressions (1) to (8).

FIG. 6 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL3. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL3 achieves good aberration within the diopter adjustment range.

[Fourth Example]
FIG. 7 is a diagram showing the configuration of the eyepiece optical system EL4 according to the fourth embodiment. In this eyepiece optical system EL4, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL4, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL4 is performed by moving the entire eyepiece optical system EL4 in the optical axis direction.

Table 13 below lists the specifications of the eyepiece optical system EL4.

(Table 13) Fourth Example [Overall specifications]
fe = 17.636
H = 6.30
TL = 29.262

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 24.08699 7.78 1.77377 47.25
2 * -11.23946 2.66
3 * -6.16897 1.50 1.63550 23.89
4 * -35.90996 1.64
5 * -30.97534 4.55 1.53110 55.91
6 * -9.95862 0.50
7 * -2317.28230 2.89 1.53110 55.91
8 * -41.10583 D2
Image plane ∞

In this eyepiece optical system EL4, the first surface, the second surface, the third surface, the fourth surface, the fifth surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 14 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 14)
[Aspherical data]
First side K = 2.7110
A4 ＝ -1.01182E-04 A6 ＝ -1.33523E-06 A8 ＝ 1.97743E-08
A10 ＝ -1.25195E-10 A12 ＝ 4.06080E-13
Second side K = -2.9040
A4 = -1.58180E-04 A6 = 1.29335E-06 A8 = -1.01444E-08
A10 = 4.38226E-11 A12 = 0.00000E + 00
Side 3 K = -0.4456
A4 = 4.04109E-04 A6 = -4.62087E-06 A8 = 2.20818E-08
A10 ＝ -6.21510E-11 A12 ＝ 0.00000E + 00
Side 4 K = -3.9080
A4 = 1.79698E-04 A6 = -1.03102E-06 A8 = -1.74072E-09
A10 = 1.01196E-11 A12 = 0.00000E + 00
Side 5 K = 3.7707
A4 = -3.78236E-06 A6 = 1.16143E-06 A8 = -5.59859E-09
A10 = 1.44702E-12 A12 = 0.00000E + 00
Side 6 K = 0.6581
A4 = 2.55240E-04 A6 = -5.27043E-07 A8 = -3.06199E-10
A10 = 4.00895E-11 A12 = 0.00000E + 00
Side 7 K = 1.0000
A4 = -1.2041E-04 A6 = 1.18792E-06 A8 = -6.17544E-09
A10 = 2.72498E-11 A12 = 0.00000E + 00
Side 8 K = -2.5146
A4 = -2.41805E-04 A6 = 2.45866E-06 A8 = -1.44483E-08
A10 = 5.06379E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL4, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 15 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 15)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.75 8.68 6.74
D2 20.60 19.67 21.61
EnP -28.77738 -30.14404 -27.47277

Table 16 below shows the values corresponding to each conditional expression of the eyepiece optical system EL4.

(Table 16)
f4 = 78.761
f23 = -44.512

[Conditional expression correspondence value]
(1) fe / f4 = 0.224
(2) (G2R2-G3R1) / (G2R2 + G3R1) = 0.074
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.364
(4) fe / EnP = -0.613
(5) fe / f23 = -0.396
(6) D1 / f1 = 0.707
(7) TL / fe = 1.569
(8) nd1 = 1.774
(9) nd2 = 1.636

As described above, the eyepiece optical system EL4 satisfies the above conditional expressions (1) to (8).

FIG. 8 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL4. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL4 achieves good aberration within the diopter adjustment range.

[Fifth Example]
FIG. 9 is a diagram showing the configuration of the eyepiece optical system EL5 according to the fifth embodiment. In this eyepiece optical system EL5, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL5, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL5 is performed by moving the entire eyepiece optical system EL5 in the optical axis direction.

Table 17 below lists the specifications of the eyepiece optical system EL5.

(Table 17) Fifth Example [Overall Specifications]
fe = 18.132
H = 6.30
TL = 27.900

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 18.12430 7.15 1.54392 55.90
2 * -8.93740 2.70
3 * -5.25010 2.10 1.63550 23.89
4 * -15.01890 0.55
5 * -24.00760 4.55 1.54392 55.90
6 * -9.36770 0.55
7 * -2317.28230 2.50 1.54392 55.90
8 * -51.99250 D2
Image plane ∞

In this eyepiece optical system EL5, the first surface, the second surface, the third surface, the fourth surface, the fifth surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 18 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 18)
[Aspherical data]
First side K = 1.5721
A4 = -1.48925E-04 A6 = -2.27684E-06 A8 = 2.76091E-08
A10 ＝ -7.95927E-11 A12 ＝ 1.93700E-15
Second side K = -2.1582
A4 = -2.07700E-04 A6 = 1.44079E-06 A8 = -1.32371E-08
A10 = 7.80799E-11 A12 = 0.00000E + 00
Side 3 K = -0.3642
A4 = 4.11218E-04 A6 = -4.53688E-06 A8 = 1.52134E-08
A10 ＝ -5.51553E-11 A12 ＝ 0.00000E + 00
Side 4 K = -2.1105
A4 = 1.75549E-04 A6 = -6.505035E-07 A8 = -1.17880E-09
A10 ＝ -1.10549E-11 A12 ＝ 0.00000E + 00
Side 5 K = -2.6173
A4 = 3.84318E-05 A6 = 5.26426E-07 A8 = -3.663630E-09
A10 = 1.31408E-11 A12 = 0.00000E + 00
Side 6 K = 0.5270
A4 = 3.06334E-04 A6 = -1.20258E-06 A8 = -2.58312E-09
A10 = 7.29168E-11 A12 = 0.00000E + 00
Side 7 K = 1.0000
A4 = -1.444498E-04 A6 = 6.56846E-07 A8 = 4.58887E-09
A10 ＝ -2.774632E-11 A12 ＝ 0.00000E + 00
Side 8 K = 3.4680
A4 = -2.80056E-04 A6 = 2.69450E-06 A8 = -1.10674E-08
A10 = 1.88829E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL5, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 19 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 19)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.80 8.78 6.74
D2 20.70 19.72 21.76
EnP -34.42818 -36.66472 -32.37294

Table 20 below shows the values corresponding to each conditional expression of the eyepiece optical system EL5.

(Table 20)
f4 = 97.744
f23 = -77.761

[Conditional expression correspondence value]
(1) fe / f4 = 0.186
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.230
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.339
(4) fe / EnP = -0.527
(5) fe / f23 = -0.233
(6) D1 / f1 = 0.643
(7) TL / fe = 1.539
(8) nd1 = 1.544
(9) nd2 = 1.636

As described above, the eyepiece optical system EL5 satisfies the above conditional expressions (1) to (7).

FIG. 10 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL5. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL5 achieves good aberration within the diopter adjustment range.

[Sixth Example]
FIG. 11 is a diagram showing the configuration of the eyepiece optical system EL6 according to the sixth embodiment. In this eyepiece optical system EL6, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL6, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape.

The diopter adjustment in the eyepiece optical system EL6 is performed by moving the entire eyepiece optical system EL6 in the optical axis direction.

Table 21 below lists the specifications of the eyepiece optical system EL6.

(Table 21) 6th Example [Overall specifications]
fe = 18.123
H = 6.30
TL = 28.139

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 16.56700 7.54 1.53110 55.91
2 * -8.36450 2.40
3 * -5.15230 2.11 1.63550 23.89
4 * -15.20140 0.72
5 * -23.94520 4.46 1.53110 55.91
6 * -9.83340 0.50
7 * 153.86920 2.57 1.53110 55.91
8 * -57.12010 D2
Image plane ∞

In this eyepiece optical system EL6, the first surface, the second surface, the third surface, the fourth surface, the fifth surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 22 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 22)
[Aspherical data]
First side K = 0.7228
A4 = -1.63997E-04 A6 = -2.61921E-06 A8 = 3.31813E-08
A10 ＝ -1.23005E-10 A12 ＝ 1.44200E-13
Second side K = -2.0402
A4 = -2.39241E-04 A6 = 1.88690E-06 A8 = -1.74329E-08
A10 = 7.72117E-11 A12 = 0.00000E + 00
Side 3 K = -0.4513
A4 = 4.08176E-04 A6 = -4.24658E-06 A8 = 1.05383E-08
A10 ＝ -4.81073E-11 A12 ＝ 0.00000E + 00
Side 4 K = -2.0834
A4 = 1.95661E-04 A6 = -5.64298E-07 A8 = -2.58247E-09
A10 ＝ -1.66041E-11 A12 ＝ 0.00000E + 00
Side 5 K = -3.9899
A4 = 7.61468E-06 A6 = 4.89100E-07 A8 = 5.08311E-10
A10 ＝ -5.69059E-12 A12 ＝ 0.00000E + 00
Side 6 K = 0.4497
A4 = 2.70507E-04 A6 = -1.61737E-06 A8 = -1.10795E-09
A10 = 7.33076E-11 A12 = 0.00000E + 00
Side 7 K = -4.00
A4 = -1.50783E-04 A6 = 6.32142E-07 A8 = 8.23469E-09
A10 ＝ -5.41717E-11 A12 ＝ 0.00000E + 00
Side 8 K = 4.7540
A4 = -2.61403E-04 A6 = 2.68176E-06 A8 = -9.54981E-09
A10 = 4.35054E-12 A12 = 0.00000E + 00

In this eyepiece optical system EL6, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 23 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 23)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.84 8.82 6.78
D2 20.60 19.62 21.66
EnP -34.03960 -36.20254 -32.04697

Table 24 below shows the values corresponding to each conditional expression of the eyepiece optical system EL6.

(Table 24)
f4 = 78.767
f23 = -49.345

[Conditional expression correspondence value]
(1) fe / f4 = 0.230
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.223
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.329
(4) fe / EnP = -0.532
(5) fe / f23 = -0.367
(6) D1 / f1 = 0.671
(7) TL / fe = 1.553
(8) nd1 = 1.531
(9) nd2 = 1.636

As described above, the eyepiece optical system EL6 satisfies the above conditional expressions (1) to (7).

FIG. 12 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL6. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL6 achieves good aberration within the diopter adjustment range.

[7th Example]
FIG. 13 is a diagram showing the configuration of the eyepiece optical system EL7 according to the seventh embodiment. In this eyepiece optical system EL7, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL7, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side is formed in an aspherical shape and the concave surface is directed toward the observation object side. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the eye point side is formed in an aspherical shape and the concave surface is directed to the observation object side. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape.

The diopter adjustment in the eyepiece optical system EL7 is performed by moving the entire eyepiece optical system EL7 in the optical axis direction.

Table 25 below lists the specifications of the eyepiece optical system EL7.

(Table 25) Example 7 [Overall specifications]
fe = 17.662
H = 6.30
TL = 28.320

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 28.07266 7.30 1.74400 44.80
2 * -10.67758 2.70
3 * -6.63855 1.55 1.63550 23.89
4-144.14719 1.00
5 -167.66045 5.95 1.53110 55.91
6 * -11.29042 0.50
7 * 1712.67070 2.70 1.53110 55.91
8 * -31.84183 D2
Image plane ∞

In this eyepiece optical system EL7, the first surface, the second surface, the third surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 26 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 26)
[Aspherical data]
First side K = -2.0140
A4 = -1.26801E-04 A6 = -7.92018E-07 A8 = 1.72033E-08
A10 ＝ -1.32394E-10 A12 ＝ 5.48090E-13
Second side K = -2.1884
A4 = -1.51405E-04 A6 = 8.63584E-07 A8 = -7.98722E-09
A10 = 2.78537E-11 A12 = 0.00000E + 00
Side 3 K = -0.1010
A4 = 3.80395E-04 A6 = -4.01258E-06 A8 = 2.22431E-08
A10 ＝ -1.81820E-10 A12 ＝ 0.00000E + 00
Side 6 K = 0.6429
A4 = 2.44680E-04 A6 = -7.34170E-07 A8 = -4.187875E-09
A10 = 2.11837E-11 A12 = 0.00000E + 00
Side 7 K = 1.0000
A4 = -1.23377E-04 A6 = 1.23089E-06 A8 = -5.34263E-09
A10 = 3.90858E-11 A12 = 0.00000E + 00
Side 8 K = -0.0905
A4 = -2.34359E-04 A6 = 2.48218E-06 A8 = -1.41661E-08
A10 = 7.75465E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL7, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 27 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 27)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 6.62 7.55 5.61
D2 20.10 19.17 21.11
EnP -30.15672 -31.88364 -28.53315

Table 28 below shows the values corresponding to each conditional expression of the eyepiece optical system EL7.

(Table 28)
f4 = 58.892
f23 = -45.926

[Conditional expression correspondence value]
(1) fe / f4 = 0.300
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.075
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.449
(4) fe / EnP = -0.586
(5) fe / f23 = -0.385
(6) D1 / f1 = 0.586
(7) TL / fe = 1.603
(8) nd1 = 1.744
(9) nd2 = 1.636

As described above, the eyepiece optical system EL7 satisfies the above conditional expressions (1) to (8).

FIG. 14 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL7. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL7 achieves good aberration within the diopter adjustment range.

[Eighth Example]
FIG. 15 is a diagram showing the configuration of the eyepiece optical system EL8 according to the eighth embodiment. In this eyepiece optical system EL8, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL8, the first lens component G1 has an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side has an aspherical shape, and the lens surface on the eye point side having an aspherical shape. It is composed of a bonded lens formed by joining the aspherical positive lens L12 having a positive meniscus lens shape with a concave surface facing the observation object side. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side is formed in an aspherical shape and the concave surface is directed toward the observation object side. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the eye point side is formed in an aspherical shape and the concave surface is directed to the observation object side. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL8 is performed by moving the entire eyepiece optical system EL8 in the optical axis direction.

Table 29 below lists the specifications of the eyepiece optical system EL8.

(Table 29) Example 8 [Overall specifications]
fe = 17.671
H = 6.30
TL = 28.340

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 36.28535 1.50 1.75520 27.57
2-256.85195 5.55 1.74400 44.80
3 * -9.58387 2.70
4 * -6.33627 1.60 1.63550 23.89
5 -309.22499 1.00
6 -340.41004 5.95 1.53110 55.91
7 * -10.20313 0.50
8 * -118.11140 2.70 1.53110 55.91
9 * -33.13998 D2
Image plane ∞

In this eyepiece optical system EL8, the first surface, the third surface, the fourth surface, the seventh surface, the eighth surface, and the ninth surface are formed in an aspherical shape. The following Table 30 shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 30)
[Aspherical data]
First side K = -2.0658
A4 = -1.42501E-04 A6 = -8.76658E-07 A8 = 1.88394E-08
A10 ＝ -1.09268E-10 A12 ＝ 3.68460E-13
Side 3 K = -1.7532
A4 = -1.52859E-04 A6 = 8.23715E-07 A8 = -8.45101E-09
A10 = 3.67563E-11 A12 = 0.00000E + 00
4th side K = -0.2498
A4 = 3.64026E-04 A6 = -4.01765E-06 A8 = 2.07275E-08
A10 ＝ -1.61058E-10 A12 ＝ 0.00000E + 00
Side 7 K = 0.5740
A4 = 2.54149E-04 A6 = -6.372818E-07 A8 = -3.76424E-09
A10 = 2.73994E-11 A12 = 0.00000E + 00
Side 8 K = 1.0000
A4 = -1.19587E-04 A6 = 1.18521E-06 A8 = -5.01478E-09
A10 = 4.10280E-11 A12 = 0.00000E + 00
Side 9 K = 1.4393
A4 = -2.39375E-04 A6 = 2.51700E-06 A8 = -1.48286E-08
A10 = 7.54336E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL8, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 31 below shows the variable intervals and the entrance pupil positions for each diopter.

(Table 31)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 6.84 7.77 5.83
D2 20.10 19.17 21.11
EnP -31.23485 -33.09550 -29.49620

Table 32 below shows the values corresponding to each conditional expression of the eyepiece optical system EL8.

(Table 32)
f4 = 85.790
f23 = -57.363

[Conditional expression correspondence value]
(1) fe / f4 = 0.206
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.048
(3) (G1R2 + G1R1) / (G1R2-G1R1) = -0.582
(4) fe / EnP = -0.566
(5) fe / f23 = -0.308
(6) D1 / f1 = 0.629
(7) TL / fe = 1.604
(8) nd1 = 1.755
(9) nd2 = 1.636

As described above, the eyepiece optical system EL8 satisfies the above conditional expressions (1) to (8).

FIG. 16 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL8. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL8 achieves good aberration within the diopter adjustment range.

[9th Example]
FIG. 17 is a diagram showing the configuration of the eyepiece optical system EL9 according to the ninth embodiment. In this eyepiece optical system EL9, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL9, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L12 having a negative meniscus lens shape in which the lens surface on the observation object side is formed in an aspherical shape and the concave surface is directed toward the observation object side. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the eye point side is formed in an aspherical shape and the concave surface is directed to the observation object side. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL9 is performed by moving the entire eyepiece optical system EL9 in the optical axis direction.

Table 33 below lists the specifications of the eyepiece optical system EL9.

(Table 33) Example 9 [Overall specifications]
fe = 17.664
H = 6.30
TL = 28.440

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 30.06223 7.30 1.74300 49.25
2 * -10.46380 2.70
3 * -6.62848 1.55 1.65093 21.51
4-43.12860 1.00
5 -44.49530 5.95 1.53110 55.91
6 * -10.78420 0.50
7 * -1133.34000 2.70 1.53110 55.91
8 * -34.07780 D2
Image plane ∞

In this eyepiece optical system EL9, the first surface, the second surface, the third surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 34 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 34)
[Aspherical data]
First side K = -1.3191
A4 = -1.08297E-04 A6 = -5.223642E-07 A8 = 1.65142E-08
A10 ＝ -1.39777E-10 A12 ＝ 5.22770E-13
Second side K = -2.1775
A4 ＝ -1.37725E-04 A6 ＝ 9.31664E-07 A8 ＝ -7.77285E-09
A10 = 2.31975E-11 A12 = 0.00000E + 00
Side 3 K = -0.0873
A4 = 3.71838E-04 A6 = -4.12160E-06 A8 = 2.25930E-08
A10 ＝ -1.98410E-10 A12 ＝ 0.00000E + 00
Side 6 K = 0.6318
A4 = 2.37664E-04 A6 = -7.12383E-07 A8 = -4.02440E-09
A10 = 2.46401E-11 A12 = 0.00000E + 00
Side 7 K = 1.0000
A4 = -1.19476E-04 A6 = 1.21154E-06 A8 = -5.10047E-09
A10 = 4.12044E-11 A12 = 0.00000E + 00
Side 8 K = -0.6189
A4 = -2.32309E-04 A6 = 2.50741E-06 A8 = -1.40702E-08
A10 = 7.88020E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL9, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 35 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 35)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 6.74 7.67 5.73
D2 20.00 19.07 20.01
EnP -31.17085 -32.51888 -29.03853

Table 36 below shows the values corresponding to each conditional expression of the eyepiece optical system EL9.

(Table 36)
f4 = 66.097
f23 = -51.032

[Conditional expression correspondence value]
(1) fe / f4 = 0.267
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.016
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.484
(4) fe / EnP = -0.567
(5) fe / f23 = -0.346
(6) D1 / f1 = 0.596
(7) TL / fe = 1.610
(8) nd1 = 1.473
(9) nd2 = 1.651

As described above, the eyepiece optical system EL9 satisfies the above conditional expressions (1) to (9).

FIG. 18 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL9. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL9 achieves good aberration within the diopter adjustment range.

[10th Example]
FIG. 19 is a diagram showing the configuration of the eyepiece optical system EL10 according to the tenth embodiment. In this eyepiece optical system EL10, in order from the observation object side, a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL10, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape. There is. Further, the second lens component G2 is composed of an aspherical negative lens L21 having a negative meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL10 is performed by moving the entire eyepiece optical system EL10 in the optical axis direction.

Table 37 below lists the specifications of the eyepiece optical system EL10.

(Table 37) Example 10 [Overall specifications]
fe = 17.655
H = 6.30
TL = 28.870

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 27.64520 7.35 1.74300 49.25
2 * -10.59980 2.70
3 * -6.62160 1.50 1.66133 20.35
4 * -30.41490 1.00
5 * -33.42740 5.95 1.53110 55.91
6 * -11.06910 0.50
7 * -447.12000 2.70 1.53110 55.91
8 * -33.61500 D2
Image plane ∞

In this eyepiece optical system EL10, the first surface, the second surface, the third surface, the fourth surface, the fifth surface, the sixth surface, the seventh surface, and the eighth surface are formed in an aspherical shape. Table 38 below shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 38)
[Aspherical data]
First side K = 1.8706
A4 ＝ -1.58806E-04 A6 ＝ -6.47977E-07 A8 ＝ 2.00513E-08
A10 ＝ -1.19924E-10 A12 ＝ 3.39780E-13
Second side K = -2.5122
A4 = -1.822335E-04 A6 = 1.26664E-06 A8 = -9.55146E-09
A10 = 4.41287E-11 A12 = 0.00000E + 00
Side 3 K = -0.1010
A4 = 3.59553E-04 A6 = -3.81376E-06 A8 = 2.31702E-08
A10 ＝ -1.65901E-10 A12 ＝ 0.00000E + 00
Side 4 K = 1.2085
A4 = 9.08220E-06 A6 = 4.92684E-09 A8 = 2.99069E-11
A10 = 0.00000E + 00 A12 = 0.00000E + 00
Side 5 K = -0.6362
A4 = 2.08532E-05 A6 = 3.39041E-08 A8 = -4.09295E-10
A10 = 0.00000E + 00 A12 = 0.00000E + 00
Side 6 K = 0.5759
A4 = 2.44689E-04 A6 = -6.87340E-07 A8 = -4.20734E-09
A10 = 2.20759E-11 A12 = 0.00000E + 00
Side 7 K = 1.0000
A4 = -1.28197E-04 A6 = 1.23524E-06 A8 = -5.32987E-09
A10 = 3.98596E-11 A12 = 0.00000E + 00
Side 8 K = 0.3803
A4 = -2.29306E-04 A6 = 2.47452E-06 A8 = -1.42769E-08
A10 = 7.86334E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL10, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 39 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 39)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.17 8.10 6.16
D2 20.10 19.17 21.11
EnP -30.13523 -31.77608 -28.58721

Table 40 below shows the values corresponding to each conditional expression of the eyepiece optical system EL10.

(Table 40)
f4 = 68.284
f23 = -47.435

[Conditional expression correspondence value]
(1) fe / f4 = 0.259
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.047
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.446
(4) fe / EnP = -0.586
(5) fe / f23 = -0.372
(6) D1 / f1 = 0.638
(7) TL / fe = 1.635
(8) nd1 = 1.473
(9) nd2 = 1.661

As described above, the eyepiece optical system EL10 satisfies the above conditional expressions (1) to (9).

FIG. 20 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of this eyepiece optical system EL10. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL10 achieves good aberration within the diopter adjustment range.

[Eleventh Example]
FIG. 21 is a diagram showing the configuration of the eyepiece optical system EL11 according to the eleventh embodiment. The eyepiece optical system EL11 has a first lens component G1 having a positive refractive power, a second lens component G2 having a negative refractive power, and a third lens component G3 having a positive refractive power in this order from the observation object side. And a fourth lens component G4 having a positive refractive power.

In this eyepiece optical system EL11, the first lens component G1 is composed of an aspherical positive lens L11 having a biconvex positive lens shape in which the lens surface on the observation object side is formed into an aspherical shape. Further, in the second lens component G2, both the aspherical negative lens L21 having a biconcave negative lens shape in which the lens surface on the observation object side is formed in an aspherical shape and the lens surface on the eye point side being formed in an aspherical shape. It is composed of a bonded lens in which an aspherical positive lens L22 having a convex regular lens shape is bonded. Further, the third lens component G3 is composed of an aspherical positive lens L31 having a positive meniscus lens shape in which the lens surface on the eye point side is formed in an aspherical shape and the concave surface is directed to the observation object side. Further, the fourth lens component G4 is composed of an aspherical positive lens L41 having a positive meniscus lens shape in which the lens surface on the observation object side and the lens surface on the eye point side are formed in an aspherical shape and the concave surface is directed toward the observation object side. Has been done.

The diopter adjustment in the eyepiece optical system EL11 is performed by moving the entire eyepiece optical system EL11 in the optical axis direction.

The values of the specifications of the eyepiece optical system EL11 are listed in Table 41 below.

(Table 41) 11th Example [Overall specifications]
fe = 17.623
H = 6.30
TL = 30.240

[Lens data]
m r d nd ν d
Paraboloid ∞ D1
1 * 28.78836 7.35 1.82098 42.50
2 -11.25246 2.70
3 * -7.11620 1.50 1.63550 23.89
4 564.01019 1.48 1.53110 55.91
5 * -165.33547 1.00
6 -397.01843 5.95 1.53110 55.91
7 * -11.70908 0.5
8 * -87.51711 2.70 1.53110 55.91
9 * -33.70935 D2
Image plane ∞

In this eyepiece optical system EL11, the first surface, the third surface, the fifth surface, the seventh surface, the eighth surface, and the ninth surface are formed in an aspherical shape. The following Table 42 shows the aspherical data, that is, the conical constant K and the values of the aspherical constants A4 to A12.

(Table 42)
[Aspherical data]
First side K = 4.9064
A4 = -1.05219E-04 A6 = -6.21990E-07 A8 = 1.81446E-08
A10 ＝ -1.14918E-10 A12 ＝ 3.47790E-13
Side 3 K = -2.7141
A4 = -1.22865E-04 A6 = 1.06684E-06 A8 = -6.777704E-09
A10 = 4.48572E-11 A12 = 0.00000E + 00
Side 5 K = -0.1268
A4 = 3.96618E-04 A6 = -3.89261E-06 A8 = 2.32375E-08
A10 ＝ -1.45538E-10 A12 ＝ 0.00000E + 00
Side 7 K = 0.5892
A4 = 2.52841E-04 A6 = -6.999186E-07 A8 = -4.09567E-09
A10 = 2.38163E-11 A12 = 0.00000E + 00
Side 8 K = 1.0000
A4 = -1.15871E-04 A6 = 1.20055E-06 A8 = -5.20908E-09
A10 = 4.32497E-11 A12 = 0.00000E + 00
Side 9 K = 2.7036
A4 = -2.43083E-04 A6 = 2.51325E-06 A8 = -1.39088E-08
A10 = 7.50477E-11 A12 = 0.00000E + 00

In this eyepiece optical system EL11, the axial air gap D1 between the observation object and the first lens component G1 and the axial air gap D2 between the fourth lens component G4 and the eyepoint EP change during diopter adjustment. Further, the entrance pupil position EnP also changes with the change of these intervals. Table 43 below shows the variable intervals and entrance pupil positions for each diopter.

(Table 43)
[Variable interval data]
Diopter -1dpt + 2dpt -4dpt
D1 7.06 7.98 6.04
D2 20.10 19.18 21.12
EnP -27.40929 -28.67303 -26.17269

Table 44 below shows the values corresponding to each conditional expression of the eyepiece optical system EL11.

(Table 44)
f4 = 101.468
f23 = -66.090

[Conditional expression correspondence value]
(1) fe / f4 = 0.174
(2) (G2R2-G3R1) / (G2R2 + G3R1) = -0.412
(3) (G1R2 + G1R1) / (G1R2-G1R1) =-0.438
(4) fe / EnP = -0.643
(5) fe / f23 = -0.267
(6) D1 / f1 = 0.657
(7) TL / fe = 1.716
(8) nd1 = 1.821
(9) nd2 = 1.636

As described above, the eyepiece optical system EL 11 satisfies the above conditional expressions (1) , (3) to (8).

FIG. 22 shows a spherical aberration diagram, an astigmatism diagram, a distortion diagram, and a coma aberration diagram at a reference diopter (-1 dpt) of the eyepiece optical system EL11. From each of these aberration diagrams, it can be seen that the eyepiece optical system EL11 achieves good aberration within the diopter adjustment range.

The contents described below can be appropriately adopted as long as the optical performance is not impaired.

In the present embodiment, the configuration of four lens components is shown as a numerical example of the eyepiece optical system EL, but it can also be applied to other lens configurations such as five lens components. Further, the configuration in which the lens component is added to the most object side or the configuration in which the lens component is added to the most eye point side may be used.

In addition, one or more lens components are moved so as to have a displacement component in the direction orthogonal to the optical axis, or rotationally moved (swing) in the in-plane direction including the optical axis to correct image shake caused by camera shake. It may be a group of anti-vibration lenses. In particular, it is preferable that the third lens component G3 is a vibration-proof lens group.

Further, the lens surface of the lens (lens component, lens element) constituting the eyepiece optical system EL of the present embodiment may be a spherical surface or a flat surface, or may be an aspherical surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented, which is preferable. Further, even if the image plane is displaced, the deterioration of the depiction performance is small, which is preferable. When the lens surface is an aspherical surface, it is either an aspherical surface formed by grinding, a glass mold aspherical surface formed by molding glass into an aspherical shape, or a composite aspherical surface formed by forming a resin provided on the surface of the glass into an aspherical shape. But it may be. Further, the lens surface may be a diffraction surface, and the lens may be a refractive index distribution type lens (GRIN lens) or a plastic lens.

Further, on the lens surface of the lens (lens component, lens element) constituting the eyepiece optical system EL of the present embodiment, in order to reduce flare and ghost and achieve high optical performance with high contrast, in a wide wavelength range. An antireflection film having a high transmittance may be applied.

Further, in the eyepiece optical system EL of the present embodiment, the first lens component G1, the second lens component G2, the third lens component G3, and the fourth lens component G4 move integrally, or the entire eyepiece optical system EL moves integrally. The configuration for adjusting the diopter is shown, but the lens component on the most eye point side is fixed, and the entire lens component on the observation object side of the lens component is moved integrally, or the first lens component G1 and the first lens component are the first. At least a part of the lens components of the two lens component G2, the third lens component G3, and the fourth lens component G4 may be moved. In particular, it is preferable to move the first lens component G1 and fix the position of the other lens components with respect to the image plane at the time of diopter adjustment. The diopter adjustment lens group is preferably composed of a single lens.

EL (EL1 to EL11) Eyepiece optical system G1 1st lens component G2 2nd lens component G3 3rd lens component G4 4th lens component 1 Camera (optical equipment)

Claims (16)

From the observation object side,
The first lens component with positive refractive power and
A second lens component with negative refractive power,
A third lens component with positive refractive power,
It consists of substantially four lens components with a fourth lens component having a positive refractive power.
An eyepiece optical system that satisfies the following conditions.
0.01 <fe / f4 <0.33
0.58 <D1 / f1 <0.90
However,
fe: Focal length of the entire system of the eyepiece optical system f4: Focal length of the fourth lens component D1: Air conversion from the observed object to the lens surface of the first lens component on the most observed object side in the reference diopter. Distance f1: Focal length of the first lens component The "lens component" means a single lens or a junction lens. From the observation object side,
The first lens component with positive refractive power and
A second lens component with negative refractive power,
A third lens component with positive refractive power,
It consists of substantially four lens components with a fourth lens component having a positive refractive power.
An eyepiece optical system that satisfies the following conditions.
0.01 <fe / f4 <0.33
-0.40 <fe / f23 <-0.15
However,
fe: Focal length of the entire system of the eyepiece optical system f4: Focal length of the fourth lens component f23: Composite focal length of the second lens component and the third lens component The "lens component" is a single lens. Or it refers to a bonded lens. From the observation object side,
The first lens component with positive refractive power and
A second lens component with negative refractive power,
A third lens component with positive refractive power,
It consists of substantially four lens components with a fourth lens component having a positive refractive power.
The second lens component is a single lens.
An eyepiece optical system that satisfies the following conditions.
0.259 ≤ fe / f4 <0.33
1.651 ≤ nd2 <1.80
However,
fe: Focal length of the entire system of the eyepiece optical system f4: Focal length of the fourth lens component nd2: Refraction coefficient of the lens element constituting the second lens component with respect to the d line The “lens component” is A single lens or a junction lens. The eyepiece optical system according to claim 2, which satisfies the conditions of the following equation.
0.58 <D1 / f1 <0.90
However,
D1: Air conversion distance from the observed object to the lens surface of the first lens component on the most observed object side in the reference diopter f1: Focal length of the first lens component The eyepiece optical system according to any one of claims 1, 2 and 4, wherein the second lens component is a single lens. The eyepiece optical system according to any one of claims 1, 2, 4, and 5, which satisfies the conditions of the following equation.
1.640 <nd2 <1.80
However,
nd2: Refractive index of the lens element constituting the second lens component with respect to the d-line of the medium. The eyepiece optical system according to any one of claims 1 to 6, wherein the lens surface on the eyepoint side of the lens on the most eyepoint side is convex toward the eyepoint side. The eyepiece optical system according to any one of claims 1 to 7, which satisfies the conditions of the following equation.
−0.30 <(G2R2-G3R1) / (G2R2 + G3R1) <0.50
However,
G2R2: Radius of curvature of the lens surface on the most eye point side of the second lens component G3R1: Radius of curvature of the lens surface on the most observed object side of the third lens component The eyepiece optical system according to any one of claims 1 to 8, which satisfies the conditions of the following equation.
-0.75 <(G1R2 + G1R1) / (G1R2-G1R1) <0.00
However,
G1R1: Radius of curvature of the lens surface on the most observed object side of the first lens component G1R2: Radius of curvature of the lens surface on the most eye point side of the first lens component The eyepiece optical system according to any one of claims 1 to 9, which satisfies the conditions of the following equation.
-1.00 <fe / EnP <-0.48
However,
fe: Focal length of the entire system of the eyepiece optical system EnP: Entrance pupil position of the eyepiece optical system at the reference diopter (the sign is positive on the eye point side with respect to the observation object surface). The eyepiece optical system according to any one of claims 1 to 10, which satisfies the conditions of the following equation.
1.50 <TL / fe <1.80
However,
TL: Overall length of the eyepiece optical system fe: Focal length of the entire system of the eyepiece optical system The eyepiece optical system according to any one of claims 1 to 11, which satisfies the conditions of the following equation.
1.550 <nd1 <1.80
However,
nd1: Refractive index of the lens element constituting the first lens component with respect to the d-line of the medium. The eyepiece optical system according to any one of claims 1 to 12, wherein each of the first lens component, the third lens component, and the fourth lens component is a single lens. The eyepiece optical system according to any one of claims 1 to 13, wherein the diopter is adjusted by moving the entire eyepiece optical system in the optical axis direction. The eyepiece optical system according to any one of claims 1 to 14, wherein the second lens component has a negative meniscus lens shape with a concave surface facing the observation object side. An optical device having the eyepiece optical system according to any one of claims 1 to 15.

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