JP3312925B2 - Anti-reflection coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner wall of a lens housing (barrel) of an optical machine such as a camera, a telescope or a microscope.
The present invention relates to an antireflection coating formed by using an ion plating method to reduce diffuse reflection.

[0002]

2. Description of the Related Art Conventionally, for example, the inner surface of a lens barrel, which is a lens housing for housing a camera lens, is subjected to black coating or alumite treatment to minimize diffuse reflection as much as possible to improve image clarity. ing. In the alumite treatment, aluminum is anodically oxidized to form a corrosion-resistant oxide film, and the electrolytic solution is oxalic acid, sulfuric acid,
It can be roughly classified into three types of chromic acid aqueous solution, and its coating can also be dyed black or the like.

[0003]

However, when an anti-reflection coating is formed on the inner wall surface of a lens housing such as a lens barrel by this alumite treatment, the reflectance of the coating formed by the alumite treatment with respect to the wavelength is reduced. For example, as shown in FIG. 4, the reflectance suddenly increases at a wavelength of about 700 μm, and when used in a region exceeding the wavelength of 700 μm, irregular reflection becomes remarkable. In addition, there is a problem that the definition (resolution) of the image is remarkably reduced as compared with a region having a wavelength of 700 mμ or less.

The types of light according to the wavelength are generally classified into ultraviolet rays (far ultraviolet rays, near ultraviolet rays), visible rays, and infrared rays (near infrared rays, far infrared rays) as shown in FIG. Since the wavelength is about 760 to 770 mμ or less, an optical machine such as a camera in which an anti-reflection coating formed by alumite treatment is formed on the inner wall surface of the lens housing in the near infrared region where the wavelength in the universe exceeds that is used. In some cases, the irregular reflection was remarkable, and it could not be used. The present invention has been made in view of the above problems, and has as its object to provide an antireflection coating that has a low reflectance in a wavelength region of near infrared rays in addition to ultraviolet rays and visible rays. .

[0005]

Since SUMMARY OF THE INVENTION The present invention to achieve the above object, the antireflection film formed on the inner wall surface of the lens housing portion of the optomechanical by ion plating loading method, the lens housing portion cylindrical And the cylindrical
The composition of the coating formed on the inner wall surface of the lens housing portion is made of titanium, nitrogen, carbon, and oxygen so as to have a black color tone.

[0006]

According to the antireflection coating constructed as described above,
Since it has a low reflectance even in the near-infrared wavelength region, clear images can be obtained even when using an optical machine such as a camera whose film is formed on the inner wall surface of the lens housing in space where the near-infrared wavelength region is used. can get.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a lens barrel which is a lens housing in which an antireflection coating according to the present invention is formed on an inner wall surface.

The anti-reflection coating 10 is a coating formed by using an ion plating method. For example, the inner wall surface 1 of the lens barrel 1 is a cylindrical lens housing as shown in FIG.
a is formed in order to reduce diffuse reflection, and the composition of the coating is composed of titanium (Ti), nitrogen (N), carbon (C), and oxygen (O) and has a black color, and is used for cameras, telescopes, microscopes, etc. It can be widely applied to optical machines as an anti-reflection coating formed on the inner wall surface of the lens housing.

In the example shown in FIG. 1, the lens holder 2 fitted to one end of the lens barrel 1 and the inner wall surfaces 2a and 3a of the lens holder 3 screwed to the other end are similarly used to prevent reflection. A coating 10 is formed. The lens holder 2 is a lens holder for an eyepiece, and holds the lenses 5 and 6 integrally at an interval. The lens holder 3 is an objective lens holder, and holds an objective lens 9 in which lenses 7 and 8 are integrally bonded.

In order to form the antireflection coating 10 on the inner wall surfaces 1a, 2a, 3a of the lens barrel 1 and the lens holders 2, 3, an ion plating apparatus as shown in FIG. 2 is used. In this ion plating apparatus, an evaporating material 15 set on a crucible 13 in a bell jar 11 as a vacuum vessel is evaporated by an evaporating source 20 and the evaporating substance 15 'is ionized. A compound resulting from the reaction between 15 'and the atmospheric gas is attached to the object 16 to form a thin antireflection coating 10.

The bell jar 11 has a substantially cylindrical shape whose upper and lower surfaces are both closed in FIG. 2, and a door (not shown) is attached to a part of the bell jar 11 so as to be openable and closable. An evaporation source 20 provided below the bell jar 11 includes an electron gun 14 and a crucible 13, a probe 12 for generating a plasma state is provided above the evaporation source 20, and a thin film is formed above the probe 12. The processing object 16 is set.

The probe 12 is, for example,
The filament 17 is disposed at a position not blocking the passage of the evaporant 15 ′ evaporated by the evaporation source 20, and the filament 17 is disposed outside the position. The evaporation source 20 is located below the bell jar 11, and the electron gun 1 is attached to the evaporation material 15 set on the crucible 13.
4 irradiates an electron beam to evaporate the evaporating substance 15 '.

In FIG. 2, reference numeral 21 denotes a power supply for evaporation, 22 denotes a DC power supply for a probe, 23 denotes a DC power supply for an object to be processed, and 24 denotes an AC power supply for a filament. Then, using this ion plating apparatus, for example, a lens barrel 1 and lens holders 2 and 3 which are lens housings of the optical machine shown in FIG.
Is formed of a titanium (Ti) material or a titanium alloy, and the anti-reflection coating 1 is formed on each of the inner wall surfaces 1a, 2a, 3a.
In the case of attaching 0, first, the lens barrel 1 and the lens holders 2 and 3 serving as the objects to be processed are attached to the object 16 in FIG.
Attach to the part.

Next, argon gas is injected into the bell jar 11 to maintain the inside at a pressure of 0.005 Torr. In this state, nitrogen gas is injected at a flow rate of 150 cc / min. The titanium (Ti) serving as the evaporating material 15 on the crucible 13 is evaporated by an electron beam from the electron gun 14 of 0.3 A.

By doing so, the inner wall surfaces 1a, 2a and 3a of the lens barrel 1 and the lens holders 2 and 3 have a thickness of about 0.8 μm and a composition of titanium (Ti) and nitrogen (N). A black antireflection coating 10 made of carbon (C) and oxygen (O) and having a glossy color tone is formed. The anti-reflection coating 10 may be adhered to the inner wall surface of the lens housing of another optical machine such as a camera body made of a titanium (Ti) material or a titanium alloy by performing ion plating under the above conditions .

When the members for attaching the coating, such as the lens barrel 1, the lens holders 2, 3 and the camera body, are formed of stainless steel, they are similarly formed on the part to be processed 16 in FIG. Then, argon gas was injected into the bell jar 11 to maintain a pressure of 0.005 Torr. In this state, nitrogen gas was injected at a flow rate of 150 cc / min.
If titanium (Ti) on the crucible 13 is evaporated by an electron beam from the electron gun 14 of 0.3 A, the film thickness is similarly 0.8 μm.
m, glossy black antireflection coating 1
0 can be obtained.

The carbon and oxygen (adsorbed gas) contained in the air effectively act as carbon and oxygen constituting the composition of the antireflection coating 10. By the way, as mentioned earlier, the composition of the antireflection coating 10 is composed of titanium (Ti), nitrogen (N), carbon (C) and oxygen (O). Atomic%) is as shown below. Ti 25 to 35 (atm%) N 25 to 35 (〃) O 15 to 30 (〃) C 15 to 30 (〃)

The optimum values of the composition ratios are 30% titanium, 25% nitrogen, 20% oxygen and 25% carbon.
At this composition ratio, the color tone becomes black, and as shown by the solid line in the "diagram showing the relationship between wavelength and reflectance" shown in FIG. 3, the lowest reflection is obtained for all wavelengths from the ultraviolet to the near infrared wavelength region. Rate of the coating can be obtained.

Therefore, if this anti-reflection coating is formed on the inner wall surface of a lens housing portion of a commercially available camera or the like, irregular reflection in the lens housing portion can be prevented even in the near-infrared wavelength region. A clear image can be obtained even in the (near infrared region). By adjusting and reducing the composition ratio of oxygen and carbon, it is possible to obtain a coating having a grayish black tone shown by a broken line in FIG. 3 or a coating having a light gray black tone shown by an alternate long and short dash line. .

[0020]

As described above, the antireflection coating according to the present invention has a low reflectance characteristic even in the near-infrared wavelength region, so that the coating is formed on the inner wall surface of the lens housing. Even when an optical machine such as a camera is used in outer space, a clear image can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a lens barrel which is a lens housing in which an antireflection coating according to the present invention is formed on an inner wall surface.

FIG. 2 is a configuration diagram showing an ion plating apparatus used when forming the antireflection coating.

FIG. 3 is a graph showing the relationship between the wavelength and the reflectance of an antireflection coating formed by the ion plating apparatus and a coating formed by a conventional alumite treatment.

FIG. 4 is a graph showing the relationship between wavelength and reflectance showing only the characteristics of a film formed by the alumite treatment of FIG. 3;

FIG. 5 is a diagram showing types according to the wavelength of light.

[Explanation of symbols]

1 Lens barrel (lens storage section) 1a, 2a, 3
a inner wall surface 2,3 lens holder 10 anti-reflection coating 11 bell jar 12 probe 13 crucible 14 electron gun 15 evaporating material 17 filament

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-38556 (JP, A) JP-A-3-207869 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 G02B 1/11

Claims (1)

(57) [Claims] 1. An anti-reflection coating formed on the inner wall surface of a lens housing of an optical machine by an ion plating method, wherein the lens housing has a cylindrical shape, and
An anti-reflection coating, wherein the composition of the coating formed on the inner wall surface of the storage compartment is made of titanium, nitrogen, carbon and oxygen and has a black color tone.