JPH05323187A - Lens system including compound type aspherical surface lens - Google Patents

Abstract

PURPOSE:To provide the lens system which neither causes its resin layer to turn yellow nor limits its glass material and can excellently correct various aberrations as to a lens system which has at least one compound aspherical surface lens in a lens system consisting of plural lens groups. CONSTITUTION:In the lens system which has at least one aspherical surface lens in the lens system consisting of plural lens groups, the aspherical surface lens is composed of the compound aspherical surface lens 20 provided with a thermosetting resin layer composed of an aspherical surface on one surface of a glass-made lens, and the aspherical surface of the compound aspherical surface lens 20 is arranged on the internal surface of the 1st lens or the external or internal surface of the 2nd lens counted from the front or rear in the optical axis direction of the lens groups.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lens system including an aspherical lens in a constituent lens group.

[0002]

2. Description of the Related Art When an aspherical surface is used in a lens system, it is known that the outermost (frontmost or rearmost) constituent lens is aspherical in terms of aberration correction. This tendency is particularly remarkable in large-diameter lenses or wide-angle lenses.

On the other hand, the aspherical lens has conventionally been constituted by a glass mold lens or a composite type aspherical lens, but the glass mold lens has a problem that the number of glass materials that can be molded is small. Conventionally, as a compound type aspherical lens, a lens having an aspherical UV curable resin on the surface of a glass lens has been widely used, but the UV curable resin tends to absorb ultraviolet rays and turn yellow. is there. For this reason, conventionally, a composite aspherical lens using an ultraviolet curable resin is arranged inside a lens system, and glass having a low transmittance of ultraviolet rays is arranged before and after the lens to prevent yellowing. In other words, in terms of aberration correction, although it is advantageous to make the outermost constituent lenses aspherical, in a lens system in which color reproducibility of transmitted light is a problem, the compound aspherical lens is the outermost lens. It was practically impossible to use it as a lens. In addition, glass with low UV transmittance may deteriorate the color reproducibility due to the glass itself, and since many glass types have a small Abbe number (large dispersion), chromatic aberration can be corrected by arranging it outside the lens system. It is often not suitable for

Therefore, when the outermost constituent lens is made aspherical, a glass mold lens must be used.
As described above, since the glass mold lens is limited in the types of glass materials that can be molded, the aberration correction is limited due to the selectable glass materials. Further, since the diameter of the lens in front of or behind the lens system is likely to be large, the cost of the glass mold is high.

[0005]

SUMMARY OF THE INVENTION The present invention is based on the above-mentioned awareness of the problems of a lens system including an aspherical lens, and the aspherical surface of the aspherical lens can be used as an outermost surface which is advantageous in aberration correction, without the problems of limitation of glass materials and yellowing. It is an object of the present invention to obtain a lens system that can be provided in a lens of (1) or a lens close to the outermost lens.

[0006]

SUMMARY OF THE INVENTION According to the present invention, in a lens system having at least one aspherical lens in a lens system having a plurality of constituent lens groups, an aspherical lens is formed on one surface of a glass lens. It is composed of a composite aspherical lens provided with a thermosetting resin layer, and the aspherical surface of this composite aspherical lens is counted from the front or the rear in the optical axis direction of the constituent lens group, It is characterized in that it is arranged on the side surface or on the outer surface or inner surface of the second lens. The present invention can be applied to any lens system including a plurality of constituent lens groups, but the effect is remarkable in a lens system including five or more lenses. When a filter (parallel plane plate) is fixedly provided on the front surface or the rear surface of the lens system, the filter is also counted as a constituent lens of the present invention.

The thermosetting resin does not have the problem of yellowing unlike the ultraviolet curing resin. Then, if the compound type aspherical lens having this thermosetting resin layer is used as the first or second constituent lens from the outermost side, various aberrations can be effectively corrected. The thermosetting resin has a lower hardness as compared with glass, like the ultraviolet curable resin,
When the first lens is an aspherical surface, the outer surface that may come into contact with foreign matter is not an aspherical surface, but the inner surface is an aspherical surface.

When the second lens is an aspherical surface,
Since there is no possibility that the aspherical surface made of the thermosetting resin layer will come into contact with foreign matter, either the outer surface or the inner surface may be an aspherical surface.

Further, since the thermosetting resin does not have a problem of yellowing due to ultraviolet rays as described above, it is not necessary to dispose lenses having low ultraviolet ray transmittance before and after the yellowing. That is, since a glass lens having a high transmittance of ultraviolet rays can be used, there is an advantage that a glass material is not selected. In particular, in the case of a photographic lens system, S having a low ultraviolet ray transmittance is used to correct chromatic aberration.
Since F type lenses are rarely used outside, thermosetting resins are easier to use for aspherical lenses.

That is, the glass lens positioned outside the aspherical surface is a glass lens having a high transmittance of ultraviolet rays, and its light transmission characteristic is λ _5% <350 nm (where λ
_5% ; wavelength on the short wavelength side where the transmittance is 5%) is desirable. Of course, the glass lens used in the present invention is not limited to a glass material such as a molded lens.

Further, since the thermosetting resin can be thicker than the ultraviolet effect resin, it has an advantage that a desired aspherical shape can be easily obtained. The thermosetting resin is preferably an epoxy resin. As the epoxy resin, bisphenol A type, bisphenol AD type or bisphenol F type epoxy resin can be used. These epoxy resins are cured with acid anhydride type, amine type or other curing agents. Even if the thermosetting resin is directly formed on the glass lens without interposing the silane coupling agent layer or the like as the intermediate layer, sufficient adhesion can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments. [Embodiment 1] FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 shows a composite aspherical lens 2 according to the present invention.
2 is a configuration diagram of the entire lens system having 0, FIG. 2 is a cross-sectional view of the composite aspherical lens 10 alone, and FIG. 3 is a diagram of various aberrations of the entire lens system of FIG.

The composite aspherical lens 20 is formed by adhering an aspherical thermosetting resin layer (bisphenol A type) 23 on a concave spherical surface 22 of a glass lens 21. The thermosetting resin layer 23 is formed by known mold molding. This compound aspherical lens 20 has 13 groups and 15
The aspherical thermosetting resin layer 23 is arranged second from the front of the single lens system and is located on the inner surface (fourth surface) thereof.

Table 1 shows lens data of the lens system shown in FIG. In this lens system, the front surface (10th surface) of the fifth lens from the front is a glass mold aspherical surface. Further, the light transmission characteristics of the glass lens in front of the aspherical surface 23 of this lens system, that is, the first lens and the glass lens 21 are λ _5% = 320 nm and 30 nm, respectively.
It is 0 nm. The five-sided aspherical surface means an aspherical surface attached to the four-sided spherical surface.

[Table 1] F _NO = 1: 2.8 f = 29.0 W = 37.7 f _B = 38.60 No r _No D _No n ν 1 6000.000 2.93 1.80400 46.6 2 -275.847 0.10 − 3 1678.240 2.10 1.72916 54.7 4 32.830 0.75 1.52010 50.8 5 * 32.080 7.46-6 1335.126 2.20 1.72916 54.7 7 47.090 0.20 -8 41.814 4.68 1.84666 23.9 9 97.762 46.82 -10 * 38.726 5.20 1.58913 61.2 11 3650.283 0.25 -12 102.693 1.50 1.80518 25.4 -13 28.807 7.08 1.48749 70.2 14 -47.4 16 -296.449 1.15-17 435.675 3.42 1.80518 25.4 18 -51.367 1.45 1.58913 61.2 19 36.851 3.44 -20 -37.256 1.70 1.58913 61.2 21 -203.259 14.78 -22 748.430 4.43 1.61800 63.4 -23 -29.563 0.10-24 77.601 2.025 -776907 -26 -29.317 1.80 1.80518 25.4 27 99.610 0.87 -28 -675.537 1.50 1.51633 64.1 29 675.537--* is an aspherical surface (5th surface, 10th surface) 5 aspherical surfaces are non-spherical surfaces attached to 4 spherical surfaces Mean sphere To. Aspherical data: 5 surfaces (composite aspherical surface) r = 32.080, K = -0.64345, A4 = 0.0, A
6 = 0.0, A8 = 0.74761 × 10 ^-12 , A10 = -0.140367 × 10 ^-14 ,
Substrate (4th surface) r = 32.83 10 surfaces (glass mold aspherical surface) r = 38.726, K = 0.0, A4 =-
0.29740 × 10 ^-5 , A6 = -0.64387 × 10 ^-9 , A8 = -0.71791 × 10
^-12

From the aberration diagrams of FIG. 3, it is understood that various aberrations are favorably corrected especially by the aspherical thermosetting resin layer 23 (composite aspherical lens 20) on the fourth surface.

[Embodiment 2] FIGS. 4 to 6 show a second embodiment of the present invention. FIG. 4 is a structural diagram of the entire lens system having composite aspherical lenses 30A and 30B according to the present invention. 5 is a cross-sectional view of the composite aspherical lenses 30A and 30B alone, and FIG. 6 is an aberration diagram of the entire lens system of FIG.

The composite aspherical lens 30A is formed by adhering an aspherical thermosetting resin layer (bisphenol A type) 33A on the concave spherical surface 32 of a glass lens 31A. The thermosetting resin layer 33A is formed by known mold molding. This compound type aspherical lens 30A has one
The aspherical thermosetting resin layer 33, which is arranged at the forefront of the lens system of 13 elements in one group, is located on the inner side surface thereof. The composite aspherical lens 30B is formed by adhering and molding a thermosetting resin layer 33B on the convex spherical surface 34 on the front surface of the fourth lens 31B. Thus, it is of course possible to additionally use a composite aspherical surface in order to further eliminate various aberrations.

Table 2 shows lens data of the lens system shown in FIG. The light transmission characteristic of the glass lens in front of the aspherical surface 32 of this lens system, that is, the glass lens 31A is λ.
_5% = 320 nm. The aspherical surfaces of the 3rd and 8th surfaces mean the aspherical surfaces provided on the 2nd and 9th surfaces, respectively.

[Table 2] F _NO = 1: 2.8 f = 29.0 W = 37.8 f _B = 39.75 No r _No D _No n ν 1 143.677 2.10 1.80400 46.6 2 33.001 0.15 1.52010 50.8 3 * 29.507 10.79 − 4 -148.674 2.00 1.77250 49.6 5 85.172 0.20-6 63.293 5.80 1.84666 23.9 7 -7074.614 47.78-8 * 45.298 0.10 1.52010 50.8 9 45.198 4.99 1.56907 71.3 10 1221.832 5.61-11 11 102.779 1.70 1.80518 25.4 12 32.951 6.65 1.48749 70.2 513 -1168.452 0.10 -15 469 5449.48 5.48 2.00 -16 324.915 3.77 1.80518 25.4 17 -40.069 1.60 1.56732 42.8 184 40.069 3.61 -19 -32.631 1.80 1.56732 42.8 20 -133.998 15.01 -21 -182.687 4.23 1.56907 71.3 22 -28.449 0.10 -23 79.343 4.12 1.56907 71.3 -24 -65. -29.006 1.60 1.74000 31.7 26 -106.106-* is an aspherical surface 3 and 8 aspherical surfaces mean aspherical surfaces attached to 2 and 9 spherical surfaces. Aspherical data (3 surfaces); h = 22.5mm, r = 29.507, substrate (2nd surface)
Surface) r = 33.001 K = 0.0, A4 = -0.35442 × 10 ^-4 , A6 = -0.40316 × 10 ^-8 , A8 =
0.30242 × 10 ^-11 , A10 = -0.78164 × 10 ^-14 Aspherical surface data (8 surfaces); h = 17.5mm, r = 45.298, substrate (9th
Surface) r = 45.198, K = 0.0, A4 = -0.28340 × 10 ^-5 , A6 = -0.43644
× 10 ^-9 , A8 = 0.10927 × 10 ^-11 , A10 = -0.24054 × 10 ^-14

According to the aberration diagrams of FIG. 3, the aspherical thermosetting resin layers 33A and 33B, particularly the second surface (and the eighth surface), are shown.
It can be seen that various aberrations are favorably corrected by (composite type aspherical lenses 30A and 30B).

[Third Embodiment] FIGS. 7 to 9 show a third embodiment of the present invention. In this embodiment, the present invention is applied to a rear converter lens RC that is attached to and detached from the master lens ML to change the combined focal length. 7 is a block diagram of the entire rear converter lens RC having the composite aspherical lens 40 according to the present invention, FIG. 8 is a sectional view of the composite aspherical lens 40 alone, and FIG. 9 is various parts of the rear converter lens RC of FIG. It is an aberration diagram. The rear converter lens RC of this embodiment has a magnification of 1.7.

The composite aspherical lens 40 is formed by adhering and molding an aspherical thermosetting resin layer (bisphenol A type) 43 on a convex spherical surface 42 of a glass lens 41. The thermosetting resin layer 43 is formed by known mold molding. This composite type aspherical lens 40 is arranged second from the rear of the lens system of 5 groups and 6 elements, and the aspherical thermosetting resin layer 43 is located on the outer side surface (the 10th surface). .

Table 3 shows the lens data of the entire master lens of FIG. 7 and the lens data of the rear converter lens RC. Further, the light transmission characteristic of the glass lens behind the aspherical surface 43 of this lens system, that is, the glass lens 41 is λ _5% = 300 nm. The 10 aspherical surfaces are
It means an aspherical surface attached on a spherical surface of nine surfaces.

[Table 3] Master lens data F _NO = 1: 1.7 f = 51.8 W = 22.7 f _B = 41.30 Rear converter lens data F _NO = 1: 2.9 f = 88.22 W = 13.8 ° f _B = 41.30 No r _No D _No n ν 1 88.914 3.22 1.64769 33.8 2 -51.505 0.10 − 3 -139.015 1.20 1.88300 40.8 4 17.983 6.69 1.59270 35.3 5 -45.426 1.29 − 6 -24.207 1.20 1.83481 42.7 7 100.325 0.00 − 8 48.492 3.28 1.51454 54.7 -9 -190.565 0.310 * -190.915 0.50 -11 402.828 1.64 1.46450 65.9 12 -402.828 --- * is an aspherical surface (tenth surface) The ten aspherical surface means an aspherical surface attached to nine spherical surfaces. Aspherical data: h = 12mm, K = 0.0, A4 = -0.11935 × 10 ^-4 , A6
= 0.39189 x 10 ^-7 , A8 = -0.23962 x 10 ^-9 , A10 = 0.58710 x
10 ^-12 , substrate (9th surface) r = -190.565

According to the aberration diagrams of FIG. 9, the aspherical thermosetting resin layer 43 (composite aspherical lens 40) on the tenth surface in particular is shown.
Thus, it can be seen that various aberrations are corrected well.

[0024]

As described above, in the lens system having the aspherical lens of the present invention, the aspherical lens is a composite aspherical lens in which a thermosetting resin layer made of an aspherical surface is provided on one surface of a glass lens. The aspherical surface of the composite aspherical lens is arranged on the inner surface of the first lens or on the outer surface or the inner surface of the second lens, counting from the front or rear in the optical axis direction of the constituent lens group. Therefore, it is possible to satisfactorily correct various aberrations without problems such as limitation of glass materials and yellowing.
In particular, it is possible to excellently correct various aberrations of a large-diameter lens and a wide-angle lens.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an entire lens system showing a first embodiment of a lens system having a composite aspherical lens according to the present invention.

FIG. 2 is a cross-sectional view of a single compound aspherical lens included in the lens system of FIG.

FIG. 3 is a diagram of various aberrations of the entire lens system of FIG.

FIG. 4 is a configuration diagram of an entire lens system showing a second embodiment of a lens system having a composite aspherical lens according to the present invention.

5 is a cross-sectional view of a composite type aspherical lens alone included in the lens system of FIG.

FIG. 6 is a diagram of various aberrations of the entire lens system of FIG. It

FIG. 7 is a configuration diagram of an entire rear converter lens system that is attached to and detached from a master lens, showing a third embodiment of a lens system having a composite type aspherical lens according to the present invention.

8 is a cross-sectional view of a composite type aspherical lens alone included in the rear converter lens system of FIG.

FIG. 9 is an aberration diagram of the entire master lens system and rear converter lens system in FIG.

[Explanation of symbols]

 20 30 40 Composite type aspherical lens 23 33 43 Aspherical thermosetting resin layer

Claims (2)

[Claims] 1. A lens system in which at least one aspherical lens is present in a lens system having a plurality of constituent lens groups, wherein the aspherical lens is a thermosetting type in which one surface of a glass lens is an aspherical surface. It is composed of a composite aspherical lens provided with a resin layer, and the aspherical surface of this composite aspherical lens is counted from the front or the rear in the optical axis direction of the above-mentioned constituent lens group, the inner surface of the first lens, Alternatively, a lens system including a compound type aspherical lens, which is arranged on the outer surface or inner surface of the second lens. 2. The glass lens according to claim 1, wherein the glass lens located outside the aspheric surface has a light transmission characteristic of λ _5% <
A lens system that satisfies 350 nm (however, λ _5% ; wavelength on the short wavelength side showing a transmittance of 5%).