JP2830406B2 - Telescope optics - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to coding of a telescope optical system.

[Conventional technology]

It is known that when light passes through a lens, surface reflection reduces the amount of transmitted light by 4 to 5% with respect to one lens surface. For this reason, in recent years, telescopes, binoculars, and the like in which a multilayer antireflection film is applied to each lens surface have become widespread in order to improve the transmittance of observation light and brightly observe an object to be observed in the outside world.

Among them, those which reflect light in a wavelength band of a certain color by a multilayer film and color the lens surface to a certain color to give a beautiful appearance are desired.

The human eye can detect 50 even in the visible wavelength range of 400 nm to 700 nm.
It has high sensitivity to light in a wavelength band of about 0 nm to 560 nm, and this wavelength band is defined here as a green wavelength band.

Therefore, in order to stabilize the color of the reflected light and reduce the variation in the color of the reflected light in manufacturing, a multilayer film having residual reflectance characteristics at least for light in the green wavelength band (hereinafter, referred to as a green coat) .) On each side.

For example, if a green coat is applied to binoculars having two telescope optical systems for binocular vision, even if the reflection characteristics of the green coat in both optical systems vary somewhat in manufacturing, the green reflected light will have luminous efficiency. Is the highest, so there is an advantage that the color variation between the two is inconspicuous.

[Problems to be solved by the invention]

By applying the green coat to all surfaces in contact with air in the telescope optical system, various advantages as described above can be obtained.

However, light in the green wavelength band is reflected on each surface and transmitted through the telephoto optical system, and the light component in the green wavelength band is more relative to light components in other surrounding colors (red and violet). As a result, the observed transmitted light is colored magenta (reddish purple).

In addition, by focusing on stabilizing the reflected color and reducing the variation in the color in manufacturing, and increasing the reflectance of light in the green wavelength band in the green coat, the green wavelength band transmitted through the telescope optical system is increased. There is a problem that the light component of the light is greatly reduced.

Therefore, it is difficult to observe the observed object in a natural color.

The present invention has been made in view of the above problems,
It is an object of the present invention to provide a telescope optical system capable of always observing an object to be observed with a natural color brightly with extremely little variation in reflected color during manufacture.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an objective lens O, an eyepiece E for enlarging and observing an object image from the objective lens O, and an objective lens O and an eyepiece as shown in FIG. E and an erecting optical system P for erecting the object image, the telescopic optical system having an erecting optical system P for erecting the object image. Is coated with a first multilayer film having a residual reflectance characteristic with respect to at least light in a green wavelength band in a visible wavelength range, and at least one of which is in contact with air inside the telescope optical system.
On one surface, the reflectance of light in or near the green wavelength band becomes minimum, and the reflectance of light gradually increases toward the short wavelength side and the long wavelength side from the green wavelength band or in the vicinity thereof. The second multi-layer film having the following characteristics is coated.

Based on this basic configuration, the erecting optical system is formed by two right-angle prisms P _1, P _2, among the slopes a _1, a ₂ of the two right-angle prisms P _1, P _2, at least It is preferable that one slope be coated with the second multilayer film.

(Operation)

The first aspect of the present invention is to reflect light in a green wavelength band.
The advantage of the first multilayer film that the visible lens surface is colored green while effectively utilizing the advantages of the multilayer film (green coat), but the light transmission component in the green wavelength band is reduced. The second multilayer film having a reflectance characteristic opposite to that of the first multilayer film is corrected in a well-balanced manner, and light in the green wavelength band from the object to be observed and light in the other color wavelength bands are averaged. It is designed to be guided to the eye point EP with a well-balanced and high transmittance.

Thus, the object to be observed can be brightly observed in an extremely natural color while having a beautiful appearance.

〔Example〕

FIG. 1 is a schematic sectional view of the present embodiment, in which (a) shows a first sectional view, and (b) shows a second sectional view on a plane perpendicular to the paper surface of the first sectional view. FIG. Less than,
This embodiment will be described with reference to FIG.

As shown in the drawing, the telescope optical system according to the present embodiment has, in order from the object side, an objective lens O of a cemented lens cemented with positive and negative lenses, and the slopes of _two right-angle prisms P ₁ and P _2. Erect prism P (erect optical system) arranged orthogonally
And an eyepiece E made up of three lenses: a biconcave positive lens and a cemented lens joined by positive and negative lenses.

FIG. 2 shows the reflectance characteristics of the green coat (first multilayer film). As shown in FIG. 2, the green coat has a short wavelength side 440 nm region and a long wavelength side 640 nm region in the visible wavelength region. Although the reflectance is corrected to be substantially zero in the two regions, it has at least a residual reflection characteristic in an intermediate wavelength band including green and blue of about 460 nm to 580 nm.

Now, the green coat having the residual reflectance characteristic as shown in FIG. 2 is composed of six lens surfaces of the objective lens O and the eyepiece E which are in contact with air, and each of the right-angle prisms P in the erecting prism. _1, the slope a ₁ of P _2, assumed to be applied to a _2.

Then, as shown in FIG. 3, light in the visible wavelength range reaches the eye point EP with a high transmittance of at least 80% or more, so that the object to be observed in the outside world is observed brightly.

However, of the visible light reaching the eye point EP, the transmittance of light in the intermediate wavelength band including blue and green of about 460 nm to 580 nm decreases, while the light in the long wavelength band including red and orange of about 590 nm to 660 nm decreases. As a result, the transmittance of light in the short wavelength band including blue and violet of about 430 nm to 450 nm increases. As a result, as described above, an object image colored in magenta (purplish red) is observed by human eyes.

Therefore, in order to remove this coloring, in the present embodiment, as shown in FIG.
In the green wavelength band of about 60 nm, the reflectance of light is almost zero (minimum), and the reflectance of light gradually increases toward shorter and longer wavelengths than the green wavelength band. A multilayer film having a V-shaped or parabolic reflectance characteristic (hereinafter, referred to as a V-shaped coat) is formed by an erect prism P.
Are applied to the slopes a ₁ and a ₂ of the two right-angle prisms P ₁ and P ₂ .

FIG. 5 shows the transmittance characteristic of visible light reaching the eye point EP at this time. The transmittance curve in this case is
Compared to the case of Fig. 2 where only the green coat is applied to each surface, the transmittance of light in the intermediate wavelength band including blue and green of about 480 nm to 560 nm is improved, and the transmittance curve is compared over the entire visible wavelength range. The target becomes flat.

Therefore, since the transmittance of the light in the entire visible wavelength region is relatively equalized and averaged, it can be seen that the object to be observed can be observed in a bright and very natural color to the observer's eyes.

In this embodiment, the inclined surface of a right-angle prism through which light passes twice
a ₁ and a ₂ are coated with V-shaped coat,
By applying the V-shaped coat, the effect of the double V-shaped coat can be obtained.

Therefore, as a whole of the telescope optical system of the present embodiment, 2
Since the V-shaped coating is applied to each of the inclined surfaces a ₁ and a ₂ of the two right-angle prisms, the V-shaped coating effect for four surfaces is efficiently obtained. Therefore, the number of V-shaped coats coated in a step different from that of the green coat can be reduced, so that manufacturing is easy and cost can be reduced.

In addition, in this embodiment, since the V-shaped coat is applied only to each slope of the right-angle prism constituting the erecting prism, different coatings can be collectively distributed to each optical member requiring the same coating. Therefore, it is advantageous in the manufacturing process, and the cost can be further reduced.

Further, in the present invention, in addition to applying the V-shaped upper surface of each prism surface of the erecting prism as described above, the prism surface may be provided on a lens surface in contact with air inside an objective lens or an eyepiece.

As described above, a green coat is applied to a surface which is easy to see from the outside, and a V-shaped coat is provided to a surface which is relatively invisible from the outside and which is in contact with the air inside the telescope optical system, so that observation in natural colors is possible. , Color variations in manufacturing can be reduced.

Note that, depending on the reflectance characteristics of both the green coat and the V-shaped coat, one of the two right-angle prisms constituting the erecting prism is green-coated on one slope and the other is a V-shaped coat on the slope. Thus, the transmittance may be balanced so that the transmittance in the entire visible wavelength range is relatively equally averaged. Further, in addition to applying a V-shaped coat to both slopes of the two right-angle prisms constituting the erecting prism, a V-shaped coat may be applied to a lens surface which comes into contact with air inside the objective lens or the eyepiece. good.

Further, in the present embodiment, an erect prism having two right-angle prisms is used in order to erect the object image. However, the present invention is not limited to this, and may be a combination of prisms of various shapes. Further, a relay optical system may be used.

〔The invention's effect〕

As described above, according to the present invention, the variation in color during manufacture is small, and the object to be observed is brightened with an extremely natural color while the outer lens surface is colored green to have an aesthetic appearance. Observable telescope optics can be achieved.

Also, even if a green coat with a relatively high residual reflectance in the green wavelength band is applied to further reduce color variations in manufacturing, the V-shaped upper coat balances light in the entire visible wavelength range. Because it can pass well,
The object to be observed can always be observed in a natural color.

In particular, according to the embodiment of the present invention, since the V-shaped coat is applied to each inclined surface of the right-angle prism of the erecting prism through which light passes twice, the coating of the V-shaped coat on one surface enables the two-sided coating. The effect of the double V-shaped coat is obtained.

Therefore, since the number of V-shaped coats to be coated in a step different from that of the green coat can be reduced, manufacturing is easy and cost reduction can be expected.

Moreover, according to the present embodiment, since the V-shaped coat is applied only to each slope of the right-angle prism constituting the erecting prism, different coatings can be collectively distributed to optical members requiring the same coating. Therefore, it is advantageous in the manufacturing process, and the cost can be further reduced.

[Brief description of the drawings]

FIG. 1 shows a schematic configuration of a telescope optical system in the present embodiment. FIG. 2 shows the reflectance characteristics of the green coat in the visible wavelength range. FIG. 3 shows the transmittance characteristics of the entire telescope optical system when only the green coat is applied to each surface of the telescope optical system. FIG. 4 shows the reflectance characteristics of the V-shaped coat in the visible wavelength range. FIG. 5 shows the transmittance characteristics of the entire telescope optical system when a green coat is applied to each lens surface of the objective lens and the eyepiece, and a V-shaped coat is applied to the prism surface of the erecting prism. [Explanation of Signs of Main Parts] O: Objective lens P: Upright prism E: Eyepiece EP: Eye point

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 23/00 G02B 1/10 G02B 5/28

Claims (2)

(57) [Claims] 1. An objective lens, an eyepiece for magnifying and observing an object image from the objective lens, and erecting optics provided between the objective lens and the eyepiece for erecting the object image. And at least the outermost surface of the most object side surface of the objective lens and the most eyepoint side surface of the eyepiece, has a residual reflectance characteristic with respect to light of at least a green wavelength band in a visible wavelength region. And at least one surface of the telescope optical system that is in contact with air has a minimum reflectance of light in or near the green wavelength band, and the green wavelength band Or a second multi-layer film having a characteristic that the reflectance of light gradually increases toward the short wavelength side and the long wavelength side from the vicinity thereof is coated with a second multilayer film. . 2. The erecting optical system is formed of two right-angle prisms, and at least one of the slopes of the two right-angle prisms is coated with the second multilayer film. The telescope optical system according to claim 1, wherein: