JP2006301508A - Eyepiece and optical apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an eyepiece capable of realizing a wide apparent visual field and high performance. <P>SOLUTION: The eyepiece comprising a front lens group having an image surface flattening function and a rear lens group consisting of a plurality of lens groups which are successively arranged from the light incident side and allowing a user to observe an intermediate image formed on an intermediate image forming surface between the front lens group and the rear lens group through the rear lens group includes a refractive optical element of a solid material which satisfies a condition of -2.1×10<SP>-3</SP>×νd+0.693<θgF0.555<θgF<0.9 in an optical path when the refractive indexes of a material for g, F, d, and C rays are respectively Ng, NF, Nd, and NC, an Abbe number is νd, a partial dispersion ratio is θgF. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an eyepiece suitable for observing an object image formed by an objective lens (photographing lens), and an optical apparatus such as a telescope and binoculars (observation optical system), and in particular, has a high resolution and a wide field of view. It is suitable for optical equipment.

  Optical instruments for observation such as telescopes and binoculars are desired to have a wide field of view so that the entire field of view can be observed without difficulty. In such an optical apparatus such as a telescope and binoculars, an image of an objective lens is magnified and observed with an eyepiece. Since the actual angle of view of the objective lens is originally extremely small, in order to realize a high performance and a wide field of view, an eyepiece having a large apparent field of view (viewing angle) is greatly affected.

  Various types of high-performance and wide-field eyepieces have been proposed (for example, Patent Documents 1 to 3).

  The eyepiece lens of Patent Document 1 has, in order from the light incident side to the light exit side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a positive refraction. The lens unit is composed of five lens units, a fourth lens unit having a power and a fifth lens unit having a positive refractive power.

  The eyepiece of Patent Document 2 sequentially forms an intermediate image formed through two lens groups, a first lens group having a negative refractive power and a second lens group having a positive refractive power, from the light incident side to the light exit side. The third lens group having positive refractive power, the fourth lens group having positive refractive power, and the fifth lens group having positive refractive power as a whole are composed of five lens groups.

  The eyepiece disclosed in Patent Document 3 magnifies and observes an intermediate image formed at an intermediate image position through an image plane flattening means comprising a first lens group having a negative refractive power and a second lens group having a positive refractive power. It consists of a lens group.

  In general, as the eyepiece lens has a wider field of view, the optical performance around the observation field tends to deteriorate. In particular, as the field of view becomes wider, the chromatic aberration of magnification increases around the observation field.

  In order to correct the lateral chromatic aberration at this time, there has been proposed an optical system in which achromatization is performed using an optical member made of a liquid material having a relatively high dispersion and a relatively abnormal partial dispersion (Patent Document 3). .

Patent Document 3 corrects chromatic aberration favorably using such a special optical member, and obtains an optical system having high optical performance.
JP 05-119273 A Japanese Patent Laid-Open No. 08-005938 Japanese Patent Laid-Open No. 06-148534 US Pat. No. 5,731,907

  In general, the eye performance of an eyepiece lens tends to deteriorate as the observation field becomes wider.

  In particular, the occurrence of lateral chromatic aberration increases around the observation field. If this lateral chromatic aberration is corrected to improve the optical performance, the eyepiece becomes larger and the lens configuration becomes complicated.

  In order to correct lateral chromatic aberration, it is effective to use a lens made of an optical material having high dispersion and abnormal separation. However, if a lens made of such an optical material is simply provided in the optical system, the lateral chromatic aberration is corrected and good optical performance cannot be obtained.

  An object of the present invention is to provide an eyepiece capable of realizing high performance with a wide visual field and an optical apparatus such as a telescope and binoculars using the eyepiece.

The eyepiece of the present invention is
◎ Sequentially from the light incident side, it has a front lens group having an image plane flattening function and a rear lens group composed of a plurality of lens groups, and is formed on an intermediate image plane between the front lens group and the rear lens group. In the eyepiece for observing the intermediate image through the rear lens group, the refractive indices of the materials for the g-line, F-line, d-line, and C-line are Ng, NF, Nd, and NC, and the Abbe number is νd. The dispersion ratio is θgF,

When in the optical path,
―2.1 × 10 ^-3・ νd +0.693 <θgF
0.555 <θgF <0.9
It is characterized by having a refractive optical element made of a solid material that satisfies the following conditions.

  ◎ An eyepiece for observing an object through an objective lens, wherein the refractive indices of materials for g-line, F-line, d-line, and C-line are Ng, NF, Nd, NC, and Abbe number is νd The dispersion ratio is θgF,

When in the optical path,
―2.1 × 10 ^-3・ νd +0.693 <θgF
0.555 <θgF <0.9
It is characterized by having a refractive optical element made of a solid material that satisfies the following conditions.

  According to the present invention, an eyepiece that can achieve high performance with a wide visual field of view can be obtained.

  FIG. 1 is a lens cross-sectional view of Example 1 of the eyepiece of the present invention, and FIG. 2 is an aberration diagram of Example 1 of the eyepiece of the present invention.

  FIG. 3 is a lens cross-sectional view of the eyepiece according to the second embodiment of the present invention, and FIG. 4 is an aberration diagram of the eyepiece according to the second embodiment of the present invention.

  FIG. 5 is a lens cross-sectional view of the eyepiece according to the third embodiment of the present invention, and FIG. 6 is an aberration diagram of the eyepiece according to the third embodiment of the present invention.

  FIG. 7 is a lens cross-sectional view of an eyepiece according to a fourth embodiment of the present invention. FIG. 8 is an aberration diagram of the eyepiece according to the fourth embodiment of the present invention.

  The eyepiece of each example has an apparent field of view of 64 degrees, a pupil diameter of 4.1, and an eye relief of 16 mm. In the lens cross-sectional view, OCL is an eyepiece lens, IP is an eye point (observation position), MIP is an intermediate image formation position, L1 and L2 are first and second lens groups L3 constituting the front lens group FL of the eyepiece lens OCL. , L4, and L5 are third, fourth, and fifth lens groups that form the rear lens group RL of the eyepiece lens OCL.

  In each embodiment, the lens group includes a single lens or a plurality of lenses. L3n and L3p are a negative lens and a positive lens constituting the third lens group L3, and L5n and L5p are a negative lens and a positive lens constituting the fifth lens group L5. GIT is a refractive optical element made of a solid material having anomalous dispersion, and is provided on the lens surface. In Examples 1 to 4, the refractive optical element GIT is disposed and the lens surfaces are different. Specifically, in Example 1 of FIG. 1, the surface on the intermediate image plane HIP side (eye point IP side) of the second lens unit L2, and in Example 3 of FIG. 3, the intermediate image surface MIP of the third lens unit L3. 5 is a cemented surface in the third lens unit L3 in Example 3 of FIG. 5, and is a surface separated from the intermediate image formation surface MIP of the first lens unit L1 (surface on the light incident side) in Example 4 of FIG. The refractive optical element GIP is disposed on the surface.

  In the longitudinal aberration diagram, the unit is spherical aberration and curvature of field, diopter, distortion is%, and lateral chromatic aberration is degree. In the figure, d, F, C, and g represent the aberrations of the wavelength d-line, F-line, C-line, and g-line, and M and S represent the aberrations of the meridional image surface and the sagittal image surface.

  Next, the lens configuration of each embodiment and the optical action of each lens will be described. The eyepiece lens OCL of each example has an absolute value of the refractive power of an incident surface (a surface on which a light beam from an object side (objective lens side) is incident in order from the incident side (light incident side). The first lens unit L1 in which both lens surfaces stronger than that (the surface from which the light beam incident from the incident surface exits, the same applies below) is a concave negative lens, and the absolute value of the refractive power of the exit surface is that of the incident surface. A third lens unit L2 having a positive refractive power having a convex positive refractive power and an intermediate image position MIP sandwiching the intermediate image position MIP, and a cemented lens having a positive meniscus shape and a positive refractive power as a whole. The lens unit L3, the fourth lens unit L4 having a positive refractive power whose both lens surfaces are convex, and the fifth lens having a positive refractive power made up of a cemented lens whose absolute value of the refractive power of the entrance surface is stronger than that of the exit surface. The lens unit L5 is configured. The front lens group FL composed of the first lens group L1 and the second lens group L2 constitutes an image plane flattening lens group, prevents the expansion of the field curvature generated by the objective lens, and the field curvature of the eyepiece lens OCL. Has the effect of suppressing the occurrence of The front lens group FL is preferably configured to have one or more negative lenses and one or more positive lenses for aberration correction. The first lens unit L1 having negative refractive power is used to flatten the image plane, and off-axis aberrations generated in the first lens unit L1 are corrected by the second lens unit L2.

  Further, deterioration of image performance around the field of view is mitigated by an air lens formed by a negative lens having a concave shape on both lens surfaces constituting the first lens unit L1 and the second lens unit L2. Through the intermediate imaging plane MIP, the third lens unit L3 suppresses the generation of the entire aberration by setting the incident surface facing the second lens unit L2 to have the same curvature as the exit surface of the second lens unit L2.

  Since the eyepiece OCL has a wide field of view, the light flux in the peripheral field of view passes through the peripheral portions of the third lens unit L3 and the fourth lens unit L4 and becomes more susceptible to aberrations such as field curvature. Therefore, the third lens unit L3, the fourth lens unit L4, and the fifth lens unit L5 are all configured to have positive refractive power so that the light beam is gradually refracted and incident on the eye point IP to suppress the occurrence of aberrations. Yes. Further, the positive lens L3p and the fourth lens unit L4 of the third lens unit L3 are made of glass having a high refractive index so as to flatten the field curvature. The fifth lens unit L5 closest to the observation side may be a single lens or a cemented lens. When the fifth lens unit L5 is a cemented lens in order to further correct lateral chromatic aberration, it is preferable that the cemented surface of the cemented lens has a curvature close to the concentric position with respect to the pupil position. According to this, it is possible to reduce the occurrence of aberration with respect to the light flux in the peripheral visual field.

The solid material of the refractive optical element GIT constituting the eyepiece lens has an Abbe number of νd and partial dispersion ratios of θgF and θgd,
−2.1 × 10 ⁻³ · νd +0.693 <θgf (1)
0.555 <θgF <0.9 (2)
-2.407 × 10 ⁻³ · νd + 1.420 <θgd (3)
1.255 <θgd <1.67 (4)
νd <50 (5)
1 or more conditions are satisfied.

Here, Abbe number νd and partial dispersion ratios θgF and θgd are the refraction of the material with respect to g-line (wavelength 435.8 nm), F-line (486.1 nm), d-line (587.6 nm), and C-line (656.3 nm). When the rates are Ng, Nd, NF and NC, respectively
νd = (Nd−1) / (NF−NC)
θgd = (Ng−Nd) / (NF−NC)
θgF = (Ng−NF) / (NF−NC)
It is.

  When the viewing field of the eyepiece is a wide field of view, it is difficult to correct lateral chromatic aberration around the field of view if the entire material is made of glass. In particular, at the short wavelength side, the curvature of lateral chromatic aberration increases as the viewing angle increases. Therefore, the bending of the lateral chromatic aberration around the visual field is corrected by using a fixing material that satisfies the conditional expressions (1) to (5) for some refractive optical elements of the eyepiece. This is because the refractive optical element GIT formed of a solid material that satisfies the conditional expressions (1) to (5) can generate a curve opposite to the curve of the lateral chromatic aberration generated in a lens made of a normal glass material. It is.

  When the refractive optical element GIT is arranged in the front lens group of the eyepiece, the refractive power of the refractive optical element GIT is negative, and when the refractive optical element GIT is arranged in the rear lens group RL, the refractive power is positive. It is good to do.

  When a material with small dispersion is used for the refractive optical element constituting the eyepiece, the amount of power change for obtaining the necessary chromatic aberration increases, and as a result, various aberrations such as spherical aberration change greatly, and correction of chromatic aberration is achieved. Independence weakens. Therefore, it is important for aberration correction that at least one refractive optical element constituting the eyepiece lens is formed of a high dispersion material.

  In addition, since the refractive optical element GIT is used in combination with a general optical material, the partial dispersion ratio of the solid material used for the refractive optical element GIT needs to be different from the partial dispersion ratio of the general optical material. Too much is not good.

  When a refractive optical element made of a material whose partial dispersion ratio is far from that of a general optical material is used, the curvature of the chromatic aberration of the lens surface on the short wavelength side is particularly large. It is difficult to correct the large bend by the chromatic aberration bend generated from the glass.

  For this reason, it is also important that the refractive optical element GIT is a material having a large partial dispersion ratio compared to a general optical material, and that the partial dispersion ratio is not significantly different from that of a general optical material. . Conditional expressions (1) to (5) specify the relationship between the Abbe number νd and the partial dispersion ratios θgF and θgd for satisfactorily correcting chromatic aberration based on the principle of aberration correction.

  It should be noted that a better chromatic aberration correction effect can be expected by setting the numerical range of conditional expression (1) to the following range.

-2.100 × 10 ⁻³ · νd + 0.693 <θgF <
-1.231 × 10 ⁻³ · νd + 0.900 (1a)
More preferably, the range is as follows.

-2.100 × 10 ⁻³ · νd + 0.693 <θgF <
−1.389 × 10 ⁻³ · νd + 0.823 (1b)
More preferably, the range is as follows.

−1.682 × 10 ⁻³ · νd + 0.700 <θgF <
−1.682 × 10 ⁻³ · νd + 0.756 (1c)
If the numerical range of the conditional expression (2) is as follows, a further excellent chromatic aberration correction effect can be expected.

0.555 <θgF <0.86 (2a)
More preferably, the range is as follows.

0.555 <θgF <0.80 (2b)
If the numerical range of the conditional expression (3) is as follows, a further excellent correction effect of chromatic aberration can be expected.

-2.407 × 10 ⁻³ · νd + 1.420 <θgd <
−1.152 × 10 ⁻³ · νd + 1.651 (3a)
More preferably, the range is as follows.

-2.407 × 10 ⁻³ · νd + 1.420 <θgd <
−1.865 × 10 ⁻³ · νd + 1.572 (3b)
More preferably, the range is as follows.

−2.076 × 10 ⁻³ · νd + 1.426 <θgd <
-2.076 × 10 ⁻³ · νd + 1.512 (3c)
If the numerical range of the conditional expression (4) is as follows, a further excellent correction effect of chromatic aberration can be expected.

1.255 <θgd <1.61 (4a)
More preferably, the range is as follows.

1.255 <θgd <1.54 (4b)
Conditional expression (5) is for appropriately setting the Abbe number of the refractive optical element GIT and correcting chromatic aberration satisfactorily. If the conditional expression (5) is not satisfied, it becomes difficult to correct chromatic aberration well over a wide field of view.

  By setting the numerical range of conditional expression (5) to the following range, a further excellent chromatic aberration correction effect can be expected.

νd <45 (5a)
More preferably, the range is as follows.

νd <32 (5b)
As an optical material of the refractive optical element used in each example, when the absolute value of the temperature change of the refractive index of d-line at 0 ° C. to 40 ° C. is | dn / dT |
| Dn / dT | <2.5 × 10 ⁻⁴ (1 / ° C.) (6)
It is good to satisfy the condition.

  If the conditional expression (6) falls outside the range, it becomes difficult to maintain good optical performance in the temperature range of 0 ° C to 40 ° C.

  When the refractive optical element GIT is provided in the optical system in the eyepiece of each embodiment, h is the height of the on-axis ray of the paraxial ray,

Is the height of the off-axis ray with respect to the intermediate image plane,

It is good to provide on the lens surface which satisfies the above.

  Here, the surface corresponding to the conditional expression (7) means that it is in the vicinity of the image surface. Under this condition (7), each light beam that forms an image on the intermediate image plane is incident at different heights on the refracting surface, so that it becomes easy to correct the bending of the lateral chromatic aberration.

If an interface is formed by the refractive optical element and an atmosphere such as air, the chromatic aberration can be changed relatively greatly by a slight change in curvature of the interface, so that it is easy to correct the lateral chromatic aberration.
Furthermore, using an aspherical surface for the surface of the refractive optical element GIT that is in contact with the air is effective in correcting the curvature of lateral chromatic aberration and at the same time correcting the curvature of field and the coma that are likely to occur in a wide field of view. There is.

In each of the embodiments, aberration correction is preferably performed, and at least one of the two surfaces of the refractive optical element GIT is aspheric, and at least one of the two surfaces of the refractive optical element GIT. The refractive surface of the refractive optical element GIT is in contact with air, the two refractive surfaces of the refractive optical element GIT are in contact with glass,
It is good to satisfy at least one of the following.

  As a specific example of the solid material (hereinafter also referred to as “optical material”) that satisfies the conditional expressions (1) and (2) described above, there is, for example, a resin. Among various resins, UV curable resin (Nd = 1.635, νd = 22.7, θgF = 0.69) and N-polyvinylcarbazole (Nd = 1.696, νd = 17.7, θgF = 0. 69) is an optical material satisfying conditional expressions (1) and (2). The resin is not limited to these types as long as it satisfies the conditional expressions (1) and (2).

Further, as an optical material having characteristics different from those of general glass materials, there is a mixture in which the following inorganic oxide nanoparticles are dispersed in a synthetic resin. As inorganic oxide nanoparticles, TiO ₂ (Nd = 2.304, νd = 13.8), Nb ₂ O ₅ (Nd = 2.367, νd = 14.0), ITO (Nd = 1.8581, νd = 5.53), Cr ₂ O ₃ (Nd = 2.2178, νd = 13.4), BaTiO ₃ (Nd = 2.4362, νd = 11.3), and the like.

Among these inorganic oxides, when TiO ₂ (Nd = 2.304, νd = 13.8, θgF = 0.87) fine particles are dispersed in a synthetic resin at an appropriate volume ratio, the above conditional expression ( An optical material satisfying 1) and (2) can be obtained.
TiO ₂ is a material used in various applications, and is used as an evaporation material for forming an optical thin film such as an antireflection film in the optical field. In addition, photocatalysts, white pigments and the like, and TiO ₂ fine particles are used as cosmetic materials.

In each example, the average diameter of the TiO ₂ fine particles dispersed in the resin is preferably about ₂ nm to 50 nm in consideration of the influence of scattering and the like, and a dispersant or the like may be added to suppress aggregation. The medium material for dispersing TiO ₂ is preferably a polymer, and high mass productivity can be obtained by photopolymerization molding or thermal polymerization molding using a molding die or the like.

In addition, as a characteristic of the optical constant of the polymer, a polymer having a relatively large partial dispersion ratio or a polymer having a relatively small Abbe number, or a polymer satisfying both, is preferable. N-polyvinylcarbazole, styrene, polymethyl methacrylate (acrylic) ), Etc. are applicable. In the embodiment, a UV curable resin is used as a host polymer for dispersing TiO ₂ fine particles. However, the present invention is not limited to this. The dispersion characteristic N (λ) of the mixture in which the nanoparticles are dispersed can be easily calculated by the following equation derived from the well-known Drude equation. That is, the refractive index N (λ) at the wavelength λ is
N (λ) = [1 + V {N _TiO ² (λ) -1} + (1-V) {N _P ² (λ) -1}] ^1/2
It is.

Here, lambda is an arbitrary _{wavelength, N TiO} is the refractive index of TiO _{2, N P} is the refractive index of the polymer, V is the fraction of the total volume of the TiO ₂ particles to the polymer volume.
Next, the optical characteristics of the solid material that satisfies the conditional expressions (1) and (2) will be specifically shown.
Table 1 shows that UV curable resin 1 and TiO ₂ fine particles were mixed with UV curable resin 2 at a volume ratio of 10%, 20%, and 7% corresponding to Examples 1, 2, 3, and 4 of the eyepiece of the present invention. The values of the refractive index, Abbe number, and partial dispersion ratio for the d-line, g-line, C-line, and F-line of the obtained mixture are shown. Table 2 shows the refractive index, Abbe number, and partial dispersion ratio of the UV curable resin 2 and TiO ₂ constituting the mixture of Table 1 with respect to d-line, g-line, C-line and F-line.

In Examples 1, 2, 3, and 4 of the present invention, the solid material used for the refractive optical element GIT is 10 in volume ratio of UV curable resin 1 in Example 1 and TiO ₂ fine particles in UV curable resin 2 in Example 2. Example 3 is a mixture in which TiO ₂ fine particles are dispersed 20% by volume in the UV curable resin 2, and Example 4 is 7% in TiO ₂ fine particles by 7% by volume in the UV curable resin 2. It is made the mixture.

  FIG. 14 shows the relationship between the ranges of the conditional expressions (1) and (2) and the substances shown in Tables 1 and 2 and general optical glass with respect to the Abbe number νd and the partial dispersion ratio θgF. FIG. 15 shows the relationship between the ranges of conditional expressions (3) and (4), the substances shown in Tables 1 and 2, and general optical glass with respect to the Abbe number νd and the partial dispersion ratio θgd.

An optical material satisfying one or more of the conditional expressions (1) to (7) described above is used for a part of the eyepieces of each example. In each embodiment, an example of using the mixture dispersed in the range of 7-20% by volume of the UV curable resin 1, TiO ₂ fine particles to the UV curable resin 2 as an optical material. Example 1 is an example in which the optical material is used on the surface closest to the intermediate image formation surface MIP in the front lens unit L1 of the eyepiece lens OCL. A UV curable resin 1 is used as an optical material. The second embodiment is an example in which an optical material is used on the surface closest to the intermediate imaging surface MIP in the second lens unit L2 of the eyepiece lens OCL. As the optical material, a mixture in which TiO ₂ fine particles are dispersed in the UV curable resin 2 at a volume ratio of 10% is used.

The third embodiment is an example in which the optical material is used for the cemented surface close to the intermediate image plane MIP in the rear lens group RL of the eyepiece OCL. As an optical material, a mixture in which 20% by volume of TiO ₂ fine particles are dispersed in the UV curable resin 2 is used.

The fourth embodiment is an example in which the first lens unit L1 of the eyepiece OCL is used on the surface farthest from the intermediate image formation surface MIP. As the optical material, a mixture in which TiO ₂ fine particles are dispersed in the UV curable resin 2 at a volume ratio of 7% is used. In Example 1-3, the refractive surface of the optical material is a spherical surface. In Example 4, the refractive surface on the bonding side of the optical material is a spherical surface, and the refractive surface in contact with air is an aspherical surface. In Examples 1, 2, and 4, the refractive optical element GIT has a surface in contact with air so that it effectively functions for aberration correction. In the third embodiment, the refractive optical element GIT is arranged on the cemented surface of the lens so that a surface in contact with air does not occur, and is configured to have high environmental durability.

  By arranging an anomalous dispersive optical material at an appropriate position of the eyepiece, the curvature of lateral chromatic aberration is corrected, and an image without color blur can be observed in the entire field of view. Furthermore, using an aspherical surface as the refractive surface of the optical material is effective in correcting curvature of field and coma.

  FIG. 9 is a lens cross-sectional view of Example 5 at the telephoto end using the eyepiece of Example 1 of the present invention.

  FIG. 10 is an aberration diagram of Example 5.

  FIG. 11 is a lens cross-sectional view of Example 6 at the telephoto end using the eyepiece of Example 2 of the present invention.

  FIG. 12 is an aberration diagram of Example 6.

  Each of Examples 5 and 6 is an optical system in which the magnification of the telescope is 10 times and camera shake correction is automatically performed. In the figure, OBJ is an objective lens, L6 and L7 are a sixth lens group and a seventh lens group constituting the objective lens OBJ, VAP is a vertex angle variable prism, and P is an erecting prism. The VAP has a function of making the observation image appear to be stationary by changing the prism apex angle according to the deflection angle of the telescope device by utilizing the feature of the prism apex angle variable. P is a prism that converts an image inverted by the objective lens OBJ into an erect image, and allows the erect image to be observed by the eyepiece OCL. In order to ensure the performance of the telescope, it is necessary to improve the performance of the eyepiece lens OCL and the performance of the objective lens OBJ. In the embodiment, an objective lens having good optical performance is combined.

  FIG. 13 is a schematic diagram of Example 7 of binoculars using a pair of the telescopes of FIG. In the figure, OBJR, VAPR, PR, OCLR, and OAR represent the optical axes of the objective lens, the apex angle variable prism, the erecting prism, the eyepiece lens, and the objective lens, which are arranged on the right side of the binoculars in this order. OBJL, VAPL, PL, and OCLL OAL represent the optical axes of the objective lens, apex variable prism, erecting prism, eyepiece lens, and objective lens arranged on the left side of the binoculars in this order. The left and right objective lenses OBJL and OBJR are erecting prisms arranged on the left and right, respectively. The eye width can be adjusted by rotating the eye. As shown in the longitudinal aberration diagram of FIG. 10, the binoculars of FIG. 13 ensure good performance despite a wide field of view of 10 times and 64 degrees.

  The eyepiece of the present invention can also be used for a microscope. The microscope using the eyepiece lens of the present invention can observe an image that has been satisfactorily corrected for chromatic aberration up to the periphery of the image.

  As described above, according to each embodiment, it is possible to realize an eyepiece of about 10 times having a good performance with very little magnification chromatic aberration up to the periphery of the visual field in spite of a wide field of view of 60 degrees or more, and a telescope and binoculars having the same. .

  Next, numerical examples when the eyepiece of the present invention is used at the telephoto end will be described. In each numerical example, i indicates the order of the surfaces from the object side, Ri is the radius of curvature of the lens surface, Di is the distance between the i-th surface and the (i + 1) -th surface, and Ni and νdi are d-lines, respectively. The refractive index and Abbe number are shown with reference to. θgF and θgd are partial dispersion ratios.

  One surface closest to the image is an eye point.

The aspherical shape is such that the light traveling direction is positive, x is the amount of displacement from the surface apex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, and R is the paraxial radius of curvature. , K is a conic constant, and B to E are aspheric coefficients,
x = (h ² / R) / [1+ {1− (1 + k) (h / R) ² } ^1/2 ]
+ Bh ⁴ + Ch ⁶ + Dh ⁸ + Eh ¹⁰
It is expressed by the following formula.

“E-0X” means “× 10 ^−x ”. f represents a focal length, and ω represents a half angle of view.

  It is clear in FIGS. 14 and 15 described later that the solid materials of the refractive optical elements of Examples 1, 2, 3, and 4 of the eyepiece of the present invention satisfy the conditional expressions (1) to (5). Numerical values corresponding to conditional expression (6) are as follows.

Lens cross-sectional view of eyepiece Example 1 of the present invention Longitudinal aberration diagram of the eyepiece Example 1 of the present invention Lens cross section of the eyepiece Example 2 of the present invention Longitudinal aberration diagram of the eyepiece Example 2 of the present invention Lens cross section of the eyepiece Example 3 of the present invention Longitudinal aberration diagram of the eyepiece Example 3 of the present invention Lens cross-sectional view of eyepiece Example 4 of the present invention Longitudinal aberration diagram of the eyepiece Example 4 of the present invention Lens sectional view of Example 5 of the telescope lens of the present invention Longitudinal aberration diagram of Example 5 of the telescope of the present invention Cross section of lens of Embodiment 6 at the telephoto end of the present invention Longitudinal aberration diagram of Example 6 of the telescope of the present invention The figure which shows the optical system of the binoculars which used Example 5 of the telescope of this invention one pair The figure explaining the range of conditional expressions (1) and (2) according to the present invention The figure explaining the range of conditional expressions (3) and (4) according to the present invention

Explanation of symbols

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group L6 6th lens group L7 7th lens group GIT refractive optical element MIP intermediate image plane OBJ, OBJR, OBJL Objective Lens VAP, VAPR, VAPL Vertical angle variable prism P, PR, PL Erecting prism OCL, OCLR, OCLL Eyepiece OAR, OAL Objective lens optical axis FL Front lens group RL Rear lens group

Claims (14)

In order from the light incident side, a front lens group having an image plane flattening function and a rear lens group composed of a plurality of lens groups are formed on an intermediate imaging plane between the front lens group and the rear lens group. In an eyepiece that observes an intermediate image through the rear lens group, the refractive indexes of materials for g-line, F-line, d-line, and C-line are Ng, NF, Nd, and NC in this order, Abbe number is νd, and partial dispersion Let the ratio be θgF,
When in the optical path,
―2.1 × 10 ^-3・ νd +0.693 <θgF
0.555 <θgF <0.9
An eyepiece having a refractive optical element made of a solid material that satisfies the following conditions. The partial dispersion ratio of the refractive optical element is θgd,
And when
-2.407 × 10 ⁻³ · νd + 1.420 <θgd
1.255 <θgd <1.67
The eyepiece according to claim 1, wherein the following condition is satisfied.   The eyepiece according to claim 1 or 2, wherein the front lens group includes one or more negative lenses and one or more positive lenses.   The eyepiece according to claim 1, wherein the refractive optical element has a negative refractive power and is disposed in the front lens group.   5. The eyepiece according to claim 1, wherein the refractive optical element has a positive refractive power and is disposed in the rear lens group. The refractive optical element has a height h of an on-axis ray of a paraxial ray passing through the intermediate imaging plane and a height of an off-axis ray.
And when
The eyepiece lens according to claim 1, wherein the eyepiece lens is provided on a surface that satisfies the following condition. When the absolute value of the rate of change of the refractive index of the d-line with respect to the temperature is | dn / dT | in the temperature range of 0 ° C. to 40 ° C., | dn / dT | <2.5 × 10 ⁻⁴ / ° C
The eyepiece according to claim 1, wherein the following condition is satisfied.   The eyepiece according to any one of claims 1 to 7, wherein at least one of the two surfaces of the refractive optical element on the light incident side and the light emitting side has an aspherical shape.   9. The eyepiece according to claim 1, wherein at least one of two surfaces of the refractive optical element on the light incident side and the light emitting side is in contact with air.   The eyepiece lens according to any one of claims 1 to 8, wherein the two surfaces of the refractive optical element on the light incident side and the light emitting side are in contact with a surface made of a glass material. An eyepiece for observing a subject via an objective lens, wherein the refractive indices of materials for g-line, F-line, d-line, and C-line are Ng, NF, Nd, and NC in this order, Abbe number is νd, and partial dispersion Let the ratio be θgF,
When in the optical path,
―2.1 × 10 ^-3・ νd +0.693 <θgF
0.555 <θgF <0.9
An eyepiece having a refractive optical element made of a solid material that satisfies the following conditions. The partial dispersion ratio of the refractive optical element is θgd,
And when
-2.407 × 10 ⁻³ · νd + 1.420 <θgd
1.255 <θgd <1.67
The eyepiece according to claim 11, wherein the following condition is satisfied. νd <50
The eyepiece according to claim 1, wherein the following condition is satisfied.   An optical apparatus characterized by observing a subject using an objective lens and the eyepiece according to any one of claims 1 to 13.