JP7483399B2 - Observation optical system and observation device - Google Patents

Description

The present invention relates to an observation optical system suitable for observation devices such as binoculars and telescopes.

When observing an object through an observation optical system, the higher the magnification of the optical system, the greater the image blur caused by the user's hand movement. Patent Document 1 discloses an observation optical system that converts an object image formed by an objective lens into an erect image using an erecting prism, and then magnifies and observes the erect image through an eyepiece, and has an anti-vibration function that moves an anti-vibration lens group to reduce image blur.

JP 2016-166907 A

However, in the observation optical system of Patent Document 1, the refractive power of the vibration-proof lens group is weak and its size is large. This is not only disadvantageous to miniaturizing the observation optical system, but also leads to an increase in the size of the mechanism for driving the vibration-proof lens group and increased power consumption.

The present invention provides a compact observation optical system with vibration isolation and an observation device having the same.

An observation optical system according to one aspect of the present invention comprises, arranged in order from the object side to the image side, an objective optical system, an erecting optical system that converts an object image formed by the objective optical system into an erect image, and an eyepiece optical system. The objective optical system comprises, arranged in order from the object side to the image side, a first lens group having positive refractive power and a second lens group having negative refractive power. The second lens group is composed of one negative lens, or one negative lens and one positive lens. Vibration is reduced by moving the second lens group relative to the optical axis of the objective optical system. When the focal length of the objective optical system is f0 and the focal length of the second lens group is f2,
0.03≦−f2/f0≦0.24
The present invention is characterized in that it satisfies the following conditions.

An observation device having the above observation optical system also constitutes another aspect of the present invention.

The present invention makes it possible to realize a compact observation optical system with vibration isolation.

FIG. 2 is a cross-sectional view of the observation optical system according to the first embodiment. 5A to 5C are longitudinal aberration diagrams of the observation optical system of Example 1 when not subjected to image vibration correction. 4A to 4C are lateral aberration diagrams of the observation optical system of Example 1 when not subjected to image vibration correction. 4A to 4C are lateral aberration diagrams of the observation optical system of Example 1 during vibration reduction. FIG. 11 is a cross-sectional view of an observation optical system according to a second embodiment. 11A to 11C are longitudinal aberration diagrams of the observation optical system of Example 2 when not subjected to image vibration correction. 7A to 7C are lateral aberration diagrams of the observation optical system of Example 2 when not subjected to image vibration reduction. 8A to 8C are lateral aberration diagrams of the observation optical system of Example 2 during vibration reduction. FIG. 11 is a cross-sectional view of the observation optical system according to the third embodiment. 13A to 13C are longitudinal aberration diagrams of the observation optical system of Example 3 when not subjected to image vibration correction. 13A to 13C are lateral aberration diagrams of the observation optical system of Example 3 when not subjected to image vibration correction. 13A to 13C are lateral aberration diagrams of the observation optical system of Example 3 during vibration reduction. FIG. 1 is a diagram showing binoculars equipped with the observation optical systems of Examples 1 to 3.

Below, embodiments of the present invention will be described with reference to the drawings. Before describing specific embodiments, matters common to each embodiment will be described using the observation optical system of embodiment 1 shown in FIG. 1.

The observation optical system in each embodiment has, arranged in this order from the object side to the observation side (image side), an objective optical system, an erecting prism (erecting optical system) that converts the object image formed by the objective optical system into an erect image, and an eyepiece optical system. By using an observation optical system having this configuration, the object image can be observed as an erect image. IP in the figure is the eye point, and the object image can be observed by positioning the observer's eye here.

The objective optical system has, from the object side to the observation side, a first lens group L1 with positive refractive power and a second lens group L2 with negative refractive power. When a user's hand shake occurs, the second lens group L2 can be moved (shifted) in a direction perpendicular to the optical axis of the objective optical system (i.e. the observation optical system) to reduce (correct) image shake, i.e., to achieve vibration isolation. By configuring the objective optical system in this way, it is possible to achieve vibration isolation functionality with a simple and compact configuration.

The second lens group L2, which serves as an anti-vibration lens group, is composed of one negative lens, or two lenses: one negative lens and one positive lens. This configuration allows the anti-vibration lens group to be made smaller and lighter, while maintaining good optical performance even during anti-vibration.

In the observation optical system of each embodiment, when the focal length of the objective optical system is f0 and the focal length of the second lens unit L2 is f2,
0.03≦−f2/f0≦0.24 (1)
The following condition is satisfied. If -f2/f0 exceeds the upper limit of conditional expression (1), the refractive power of the second lens group L2 becomes too weak, which causes the second lens group L2 to become large and the amount of movement (shift) required for vibration reduction to increase, which is not preferable. If -f2/f0 falls below the lower limit of conditional expression (1), the refractive power of the second lens group L2 becomes too strong, which causes a decrease in optical performance during vibration reduction, which is not preferable.

It is more preferable to set the numerical range of conditional expression (1) as follows:
0.04≦−f2/f0≦0.23 (1a)
It is more preferable to set the numerical range of conditional expression (1) as follows:
0.05≦−f2/f0≦0.22 (1b)
It is preferable that the viewing optical system of each embodiment satisfies at least one of the following conditional expressions (2) to (5) in addition to the above-mentioned conditional expression (1).

In the observation optical system of each embodiment, when the distance on the optical axis from the surface closest to the object in the objective optical system to the surface closest to the object in the erect prism is d0, and the distance on the optical axis from the surface closest to the observation in the second lens unit L2 to the surface closest to the object in the erect prism is d02,
0.020≦d02/d0≦0.220 (2)
It is preferable to satisfy the following condition. If d02/d0 exceeds the upper limit of conditional expression (2), the distance between the second lens group L2 and the erect prism becomes too far, which causes the second lens group L2 to become large, which is not preferable. If d02/d0 falls below the lower limit of conditional expression (2), the distance between the second lens group L2 and the erect prism becomes too close, which may cause interference between them, which is not preferable.

In the observation optical system of each embodiment, when the thickness of the second lens unit L2 on the optical axis is t2,
0.010≦t2/d0≦0.110 (3)
It is desirable to satisfy the following condition. If t2/d0 exceeds the upper limit of conditional expression (3), the thickness of the second lens group L2 becomes too thick, the weight of the second lens group L2 increases, and it becomes difficult to drive the second lens group L2 during vibration reduction, which is not preferable. If t2/d0 falls below the lower limit of conditional expression (3), the thickness of the second lens group L2 becomes too thin, and it becomes difficult to manufacture the second lens group L2, which is not preferable.

In the observation optical system of each embodiment, when the lateral magnification of the second lens unit L2 is β2,
1.0≦β2≦5.5 (4)
It is preferable to satisfy the following condition. If β2 exceeds the upper limit of conditional expression (4), the refractive power of the second lens group L2 becomes too strong, which degrades the optical performance during vibration reduction, which is not preferable. Also, if β2 falls below the lower limit of conditional expression (4), the refractive power of the second lens group L2 becomes too weak, which causes the second lens group L2 to become large and the shift amount during vibration reduction to increase, which is not preferable.

In the observation optical system of each embodiment, when the focal length of the eyepiece optical system is fe,
9.0≦f0/fe≦31.0 (5)
It is preferable to satisfy the following condition. If f0/fe exceeds the upper limit of conditional expression (5), the magnification (observation magnification) of the observation optical system becomes too high, making it difficult to observe the object, which is undesirable. If f0/fe falls below the lower limit of conditional expression (5), the observation magnification of the observation optical system becomes too low, making the need for the image stabilization function itself less necessary, which is undesirable.

It is more preferable to set the numerical ranges of the conditional expressions (2) to (5) as follows:
0.025≦d02/d0≦0.215 (2a)
0.013≦t2/d0≦0.100 (3a)
1.4≦β2≦5.2 (4a)
9.5≦f0/fe≦30.0 (5a)
It is even more preferable to set the numerical ranges of the conditional expressions (2) to (5) as follows:
0.030≦d02/d0≦0.210 (2b)
0.015≦t2/d0≦0.090 (3b)
1.8≦β2≦5.0 (4b)
10.0≦f0/fe≦29.0 (5b)
Furthermore, in the observation optical system of each embodiment, the first lens group L1 includes a lens group (positive lens group) L1f having a positive refractive power, and focusing is performed by moving the positive lens group L1f in the optical axis direction. With this configuration, it is possible to realize the focusing function with a simple configuration.

Below, specific examples (numerical examples) 1 to 3 of the present invention are described.

Figure 1 shows the configuration of the observation optical system of Example 1 (Numerical Example 1). The details of the configuration are as described above, and the second lens group L2 is composed of a cemented lens of one positive lens and one negative lens. The observation optical system of this example has an observation magnification of about 20.0 times, a pupil diameter of about 2.5 mm, and a half angle of view of about 1.8°.

Figure 2 shows the longitudinal aberrations of the observation optical system of this embodiment, including spherical aberration, astigmatism, distortion, and chromatic aberration, when not vibration-proof (when the center of the second lens group L2 is located on the optical axis). For spherical aberration, the solid line shows spherical aberration for the d-line, and the two-dot chain line shows spherical aberration for the g-line. For astigmatism, the dashed line shows astigmatism at the meridional image plane, and the solid line shows astigmatism at the sagittal image plane. Distortion is for the d-line. Chromatic aberration shows lateral chromatic aberration for the g-line.

Figures 3 and 4 respectively show the lateral aberration for each angle of view of the observation optical system of this embodiment when not anti-vibration and when anti-vibration is performed (when the second lens group L2 is shifted by +1.938 mm to perform anti-vibration with a correction angle of 1.0°). When the half angle of view is ω, each figure shows the lateral aberration for the d-line at the angles of view of +100% (ω = 1.8°), +50% (ω = 0.9°), center (ω = 0°), -50% (ω = -0.9°), and -100% (ω = -1.8°) from the top. The dashed line shows the lateral aberration at the sagittal image plane, and the solid line shows the lateral aberration at the meridional image plane. The explanation of the longitudinal aberration diagram and the lateral aberration diagram is the same for Examples 2 and 3 described later, except for the shift amount of the second lens group L2 during anti-vibration.

Specific values for the observation optical systems in this embodiment and in embodiments 2 and 3 are summarized below.

Figure 2 shows the configuration of the observation optical system of Example 2 (Numerical Example 2). The details of the configuration are as described above, and the second lens group L2 is composed of a cemented lens of one positive lens and one negative lens. The observation optical system of this example has an observation magnification of about 15.0 times, a pupil diameter of about 3.33 mm, and a half angle of view of about 2.4°.

Figure 6 shows the longitudinal aberration of the observation optical system of this embodiment when not vibration-proof. Figures 7 and 8 show the transverse aberration for each angle of view of the observation optical system of this embodiment when not vibration-proof and when vibration-proof (when the second lens group L2 is shifted by +1.862 mm in the direction perpendicular to the optical axis to perform vibration proofing with a correction angle of 1.0°).

9 shows the configuration of the observation optical system of Example 3 (Numerical Example 3). The details of the configuration are as described above, and the second lens group L2 is composed of one negative lens. The objective optical system of this example also has a third lens group composed of one lens on the image side of the second lens group L2. The observation optical system of this example is an observation optical system with an observation magnification of about 12.0 times, a pupil diameter of about 4.18 mm, and a half angle of view of about 2.9°.

Figure 10 shows the longitudinal aberration of the observation optical system of this embodiment when not vibration-proof. Figures 11 and 12 show the transverse aberration for each angle of view of the observation optical system of this embodiment when not vibration-proof and when vibration-proof (when the second lens group L2 is shifted by +1.883 mm and vibration-proofing is performed with a correction angle of 1.0°), respectively.

Numerical examples 1 to 3 are shown below. In each numerical example, ri is the radius of curvature (mm) of the ith surface from the object side, di is the lens thickness or air space (mm) between the ith and (i+1)th surfaces, and ndi is the refractive index at the d-line of the material of the ith optical component (lens and prism). νdi is the Abbe number based on the d-line of the material of the ith optical component.

The Abbe number νd is expressed by the following formula, where Nd, NF, and NC are the refractive indices at the d line (587.6 nm), F line (486.1 nm), and C line (656.3 nm) of the Fraunhofer lines:
νd=(Nd−1)/(NF-NC)
It is expressed as:

An "*" next to a surface number means that the surface has an aspheric shape. The aspheric shape is expressed by the following formula, where the optical axis direction is the X-axis, the direction perpendicular to the optical axis is the H-axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are aspheric coefficients. The "e-x" in the aspheric coefficient means 10 ^-x .

(Numerical example 1)
Unit: mm

Surface data surface number rd nd νd
1 44.966 9.75 1.49700 81.5
2 -645.511 17.86
3 46.689 7.42 1.43875 94.9
4 -59.386 2.70 1.80400 46.6
5 75.307 27.85
6 27.167 2.66 1.48749 70.2
7 72.012 6.17
8 -54.278 3.88 1.77250 49.6
9 -18.417 1.50 1.64000 60.1
10 21.646 6.79
11 ∞ 37.70 1.65844 50.9
12 ∞ 37.70 1.65844 50.9
13∞5.25
14* -9.489 2.12 1.53160 55.8
15 27.611 1.07
16 49.112 7.97 1.84666 23.8
17 -22.630 14.68
18 -103.919 2.00 1.84666 23.8
19 20.323 13.16 1.65160 58.5
20 -33.475 1.00
21 40.835 5.24 1.77250 49.6
22 -211.685 0.29
23 32.252 5.30 1.60311 60.6
24∞20.00

Aspheric data No. 14
K = 0.00000e+000 A4= 1.53388e-004 A6= 2.72143e-006 A8=-4.55814e-008 A10= 5.42766e-010

Various data objective optical systems Start surface 1 End surface 10
Erecting Prism First Surface 11 Last Surface 13
Eyepiece optical system Start surface 14 End surface 24
First lens unit L1: starting surface 1, ending surface 7
Lens group L1f: starting surface 6, ending surface 7
Second lens unit L2: starting surface 8, ending surface 10

(Numerical Example 2)
Unit: mm

Surface data surface number rd nd νd
1 44.506 10.21 1.49700 81.5
2 -342.333 13.71
3 56.382 7.51 1.43875 94.9
4 -58.189 2.70 1.80400 46.6
5 109.473 16.57
6 36.841 3.47 1.48749 70.2
7 104.510 6.47
8 -67.921 2.43 1.77250 49.6
9 -24.593 1.50 1.64000 60.1
10 28.917 10.13
11 ∞ 42.00 1.65844 50.9
12 ∞ 42.00 1.65844 50.9
13∞5.80
14* -10.400 2.12 1.53160 55.8
15 30.857 2.43
16 453.338 10.26 1.84666 23.8
17 -18.743 13.45
18 -178.240 2.00 1.84666 23.8
19 25.953 13.27 1.69680 55.5
20 -37.800 1.00
21 39.700 5.41 1.60311 60.6
22 -378.542 0.29
23 33.731 5.30 1.48749 70.2
24∞20.00

Aspheric data No. 14
K = 0.00000e+000 A4= 1.03277e-004 A6= 1.85689e-006 A8=-2.83912e-008 A10= 2.50449e-010

Various data objective optical systems Start surface 1 End surface 10
Erecting Prism First Surface 11 Last Surface 13
Eyepiece optical system Start surface 14 End surface 24
First lens unit L1: starting surface 1, ending surface 7
Lens group L1f: starting surface 6, ending surface 7
Second lens unit L2: starting surface 8, ending surface 10

(Numerical Example 3)
Unit: mm

Surface data surface number rd nd νd
1 42.953 10.32 1.49700 81.5
2 -509.782 13.23
3 41.042 9.13 1.43875 94.9
4 -63.321 2.70 1.80400 46.6
5 91.372 8.25
6 38.122 2.27 1.48749 70.2
7 52.304 6.32
8 -2466.075 1.50 1.64000 60.1
9 26.334 10.49
10 300.000 1.50 1.48749 70.2
11∞1.50
12 ∞ 43.60 1.65844 50.9
13 ∞ 43.60 1.65844 50.9
14∞5.12
15* -11.511 2.12 1.53160 55.8
16 30.000 1.71
17 96.659 8.75 1.84666 23.8
18 -20.514 12.46
19 -58.504 2.00 1.84666 23.8
20 30.661 14.61 1.69680 55.5
21 -27.837 1.00
22 37.656 8.21 1.60311 60.6
23 -225.736 0.29
24 49.786 5.30 1.48749 70.2
25∞20.00

Aspheric data No. 15
K = 0.00000e+000 A4 = 1.56384e-004 A6 = -1.46641e-007 A8 = 4.27699e-009 A10 = 1.91538e-011

Various data objective optical systems Start surface 1 End surface 11
Erecting Prism Start surface 12 End surface 14
Eyepiece optical system: starting surface 15, ending surface 25
First lens unit L1: starting surface 1, ending surface 7
Lens group L1f: starting surface 6, ending surface 7
Second lens unit L2: starting surface 8, ending surface 9
Third lens group: starting surface 10, ending surface 11

Table 1 shows the values of conditional expressions (1) to (5) in each embodiment (numerical example) .

Figure 13 shows binoculars as an observation device using the observation optical systems of Examples 1 to 3 above. Each symbol in Figure 13 corresponds to the symbol in Figure 1.

In FIG. 13, 1R is an observation optical system for the right eye, and 1L is an observation optical system for the left eye. The shake sensor 1 is a vibration gyroscope or the like, and includes a pitch shake sensor that detects vertical shake and a yaw shake sensor that detects horizontal shake. The sensitivity axes of these two shake sensors are perpendicular to each other. The shake sensor 1 detects the shake (angular acceleration) of the binoculars and outputs the information to the microcomputer 2. The microcomputer 2 calculates the drive amount of the second lens group L2 for shake correction based on the angular acceleration information, and outputs it to the lens actuator 3. The lens actuator 3 translates the second lens group L2 in a direction perpendicular to the optical axis or rotates it around a point on the optical axis according to the drive amount from the microcomputer 2. The position sensor 4 detects the position of the second lens group L2 and outputs the result to the microcomputer 2. When the detected position coincides with the position corresponding to the drive amount calculated by the calculation, the microcomputer 2 stops the drive of the second lens group L2 by the lens actuator 3. This reduces image blur caused by the shake of the binoculars.

In this way, by using the observation optical systems of Examples 1 to 3, it is possible to realize binoculars that are small and have good optical performance even when vibration is reduced.

The observation optical systems of Examples 1 to 3 can be used not only in binoculars, but also in various observation devices such as telescopes and optical finders for cameras.

The embodiments described above are merely representative examples, and various modifications and alterations are possible when implementing the present invention.

L1: first lens unit L1f: positive lens unit L2: second lens unit IP: eye point

Claims (7)

An observation optical system having an objective optical system, an erecting optical system for making an object image formed by the objective optical system into an erect image, and an eyepiece optical system, which are arranged in this order from an object side to an image side,
The objective optical system is arranged in order from the object side to the image side,
a first lens group having a positive refractive power;
a second lens group having a negative refractive power,
the second lens group is composed of one negative lens, or one negative lens and one positive lens,
The second lens group is moved relative to the optical axis of the objective optical system to perform vibration isolation.
When the focal length of the objective optical system is f0 and the focal length of the second lens group is f2,
0.03≦−f2/f0≦0.24
An observation optical system characterized in that the following conditions are satisfied. When the distance on the optical axis from the surface closest to the object in the objective optical system to the surface closest to the object in the erect optical system is d0, and the distance on the optical axis from the surface closest to the image in the second lens group to the surface closest to the object in the erect optical system is d02,
0.020≦d02/d0≦0.220
2. The viewing optical system according to claim 1, which satisfies the following condition: When the thickness of the second lens group on the optical axis is t2,
0.010≦t2/d0≦0.110
3. The viewing optical system according to claim 1, wherein the following condition is satisfied: When the lateral magnification of the second lens group is β2,
1.0≦β2≦5.5
4. The viewing optical system according to claim 1, wherein the following condition is satisfied: When the focal length of the eyepiece optical system is fe,
9.0≦f0/fe≦31.0
5. The viewing optical system according to claim 1, wherein the following condition is satisfied: The observation optical system according to any one of claims 1 to 5, characterized in that the first lens group has a positive lens group, and the positive lens group moves in the optical axis direction for focusing. An observation device having an observation optical system according to any one of claims 1 to 6.