JPH04204902A - Chemical resistant antireflection film - Google Patents

Abstract

PURPOSE:To obtain durability of a chemical-resistant antireflection film against a washing and sterilizing liquid by forming a first layer of ZrO2, Ta2O5, or mixture of these in contact with a glass substrate by ion plating. CONSTITUTION:A BK glass substrate is mounted on an ion plating device. After evacuating the device, O2 gas is introduced (1X10<-5> Torr) to generate O2 plasma, and the first layer comprising vapor deposition of ZrO2, Ta2O5, or mixture of these is formed by ion plating method. Then, the O2 gas is stopped and a MgF2 layer as the second layer, Ta2O5 layer as the third layer, and MgF2 layer as the forth layer are formed by vacuum vapor deposition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a chemical-resistant antireflection film that exhibits durability against cleaning and disinfecting solutions.

[Conventional technology]

In recent years, optical components have come to be used in various fields. Among them, lenses, prisms, etc. used in medical devices are required to maintain a minimum optical performance even when exposed to various cleaning and disinfecting solutions required for medical devices. In particular, medical endoscopes require frequent cleaning because secretions from biological organs and the like adhere to the lens surface.

Commonly used cleaning and disinfecting solutions consist of a wide range of chemicals, ranging from acidic to alkaline. For this purpose, conventionally
It has been common practice to use chemically stable glass material for lenses in parts of the endoscope that are directly exposed to the cleaning solution, such as the distal end of the endoscope. Anti-reflection films formed by conventional vapor deposition were not applied because they would be eroded by the disinfectant solution and would fall off.

[Problem to be solved by the invention]

However, for endoscopes that want to be made smaller by making the optical system as thin as possible, if an anti-reflection film can be applied to the lens, it will be possible to increase the amount of transmitted light, which will be very advantageous in terms of design.

However, conventionally, as described above, an antireflection film was not provided at the tip of an endoscope lens, which caused problems in terms of optical performance and functionality.

The present invention was made in view of such conventional problems, and is a chemical-resistant antireflection film that can be applied to optical glass lenses used in medical equipment, particularly endoscopes, and has durability against cleaning and disinfection solutions. The purpose is to provide

[Means to solve the problem]

Research has revealed that the phenomenon in which films formed by regular vacuum deposition or peeling off due to attack by cleaning or disinfecting solutions is mainly caused by the interface between the glass substrate surface and the film. The above phenomenon occurs in the case of porous (low density) membranes when the cleaning solution is acid.

It was found that this occurs because the alkaline solution permeates through the film and reacts with silicon oxide, the main component of glass, causing the glass to melt at the interface between the glass substrate surface and the film. This was confirmed by experiments where the same film was formed under the same conditions on glass substrates with different silicon oxide contents, and it was found that glass materials with a lower silicon oxide content clearly had higher durability against chemicals. The results were confirmed.

Therefore, we decided to use a chemically stable film material with a high filling rate (film density) for the layer in contact with the glass substrate, and to use a method that could increase the filling rate.

That is, in order to achieve the above object, the present invention has a four-layered chemical-resistant antireflection coating provided on the surface of a glass substrate, and the first layer in contact with the glass substrate is made of zirconium oxide (zirconium oxide) formed by ion plating. The second layer is a magnesium fluoride (MgFt) layer, and the third layer is a Z'02 layer, a Ta205 layer, or a mixture thereof. , the fourth M was made of two MgF layers.

[For production]

In the chemical-resistant antireflection film of the present invention having the above structure, the first layer in contact with the glass substrate contains chemically stable Zr0t, T.
Since we decided to form the film using ion plating, which is a vapor deposition method that can increase the filling rate, using A205 or a mixture of both, it is possible to prevent the cleaning solution and disinfectant from penetrating the glass substrate from the film surface. .

〔Example〕

(Example 1) A BK7 glass substrate was set in an ion plating apparatus, the substrate temperature was set at 250° C., and evacuation was started. When the degree of vacuum reaches I x 10-' Torr, 02 gas is introduced into the device and the vacuum level reaches l x 10-' Torr.
It was set to r. Then, the high frequency output was set to 300 W, 02 plasma was generated, and a Zrot layer was deposited as a first layer using an electron gun until the film thickness shown in Table 1 was obtained. Next, in forming the second layer, the introduction of 02 gas was stopped, and the MgFt layer was deposited by ordinary vacuum deposition using an electron gun until the thickness shown in Table 1 was obtained. Hereinafter, the third Zrot layer was formed using the same means as for the first layer until the thickness shown in Table 1 was obtained, and the fourth layer was formed using the same means as for the second layer until the thickness shown in Table 1 was obtained. Two layers of gP were each deposited.

Table 1 λ=500 nm Table 2 shows the results of immersing the chemical-resistant antireflection film of this example formed as described above in five types of cleaning solutions.

The chemical-resistant antireflection film of this example showed no change at all with respect to the five types of cleaning solutions shown in Table 2.

(Leaving space below) Table 2 *Evaluation after 500 hours of immersion ○: No film peeling △: Partial film peeling ×: Film peeling Also, the reflectance characteristics of the chemical-resistant anti-reflection film of this example are shown in the figure. The figure shows reflectance on the vertical axis and wavelength on the horizontal axis, and the chemical-resistant antireflection film of this example had good reflectance characteristics.

(Example 2) A BK glass substrate was set in an ion plating apparatus, the substrate temperature was set at 250° C., and evacuation was started. When the degree of vacuum reaches I
□ Gas was introduced into the apparatus and set at 1 x 10-'Torr. Then, set the high frequency output to 300W, and
Plasma was generated, and a TatO6 layer was deposited as a first layer using an electron gun until the film thickness as shown in Table 1 was obtained. Next, in forming the second layer, the introduction of 02 gas was stopped, and the ktgFz layer was deposited by normal vacuum deposition using an electron gun until the thickness shown in Table 1 was obtained. Thereafter, the third layer TaaO was formed using the same means as for the first layer until the film thickness shown in Table 1 was obtained.
A fourth layer of MgF 2 was deposited by the same means as for the second layer until the film thickness was as shown in Table 1.

Table 2 shows the results of immersing the chemical-resistant antireflection film of this example, which was formed as described above, in five types of cleaning solutions.

Similarly to Example 1, the chemical-resistant anti-reflection film of this example also had the same properties as shown in Table 2.
No changes were observed with respect to the five types of cleaning solutions shown.

Further, the chemical-resistant antireflection film of this example had good reflectance characteristics as shown in the figure, similar to Example 1.

(Example 3) A BK7 glass substrate was set in an ion plating apparatus, the substrate temperature was set at 250'C, and evacuation was started.

When the degree of vacuum reaches IXIO” Torr,
0. Gas was introduced into the apparatus and set at 1X10-'Torr. Then, set the high frequency output to 300W and
Generate plasma, and as the first layer, ZrO2 and Tax
The weight ratio of ZrO* and Ta205 is 8.
:2 materials were mixed using an electron gun and vapor deposited until the film thickness shown in Table 1 was obtained. Next, in forming the second layer, the introduction of 02 gas was stopped, and two MgF layers were deposited by normal vacuum deposition using an electron gun until the thickness shown in Table 1 was achieved. Hereinafter, the third layer, a mixed layer of ZrL and Ta205, was formed by the same means as for the first layer until the thickness shown in Table 1 was obtained.
A fourth layer of MgF2 was deposited using the same method as for the second layer until the thickness shown in Table 1 was obtained.

Table 2 shows the results of immersing the chemical-resistant antireflection film of this example, which was formed as described above, in five types of cleaning solutions.

Similarly to Example 1, the chemical-resistant anti-reflection film of this example also had the same properties as shown in Table 2.
No changes were observed with respect to the five types of cleaning solutions shown.

Further, the chemical-resistant antireflection film of this example had good reflectance characteristics as shown in the figure, similar to Example 1.

(Comparative example) The first layer and the third layer were formed by normal vacuum evaporation without generating 0□ plasma, and the other conditions were the same as in Example 1 to obtain an antireflection film. Ta.

When the antireflection film of this comparative example was also subjected to a chemical resistance test using the cleaning liquid shown in Table 2 in the same manner as Examples 1 to 3, the film peeled off as shown in the table.

〔Effect of the invention〕

As described above, according to the chemical-resistant antireflection film of the present invention, the first layer in contact with the glass substrate is coated with Z by ion plating.
Since it is formed from rO, Ta205, or a mixture thereof, it has durability against cleaning and disinfecting solutions, and does not cause film peeling. Therefore, it is possible to apply an anti-reflection coating to the endoscope tip lens, which has a great effect on improving the contrast of the endoscope screen and reducing the outer diameter of the endoscope body by increasing the amount of transmitted light and making the optical system more precise. .

[Brief explanation of the drawing]

The figure is a graph showing the reflectance characteristics of the chemical reaction prevention films of Examples 1 to 3 of the present invention. Patent applicant: Olympus Optical Industry Co., Ltd.
1 (nm)

Claims (1)

[Claims] (1) A film with a four-layer structure provided on the surface of a glass substrate, in which the first layer in contact with the glass substrate is made of a zirconium oxide layer, a tantalum oxide layer, or a mixture thereof formed by ion plating, and the second layer is formed by ion plating. A chemical-resistant antireflection film characterized in that the layer is made of a magnesium fluoride layer, the third layer is made of a zirconium oxide layer, a tantalum oxide layer, or a mixture thereof, and the fourth layer is made of a magnesium fluoride layer.