JPH01198701A - Colored reflection preventive film - Google Patents

Abstract

PURPOSE:To realize both prevention against surface reflection and the attenuation of light intensity and to easily select optional transmissivity by laminating low-refractive-index dielectric layers, high-refractive-index dielectric layers, and a gray colored layer made of Ni on a transparent substrate. CONSTITUTION:From the side of a light incidence medium, 1st and 5th layers 1 and 5 are low-refractive-index dielectric layers, 2nd, 4th, and 6th layers 2, 4, and 6 are high-refractive-index dielectric layers, and a 3rd layer 3 is the gray colored layer, which is made of Ni. Consequently, the transmissivity can be varied by adjusting the film thickness of the Ni layer regardless of the shape of an optical member which is coated, so the transmissivity is easily set at low cost, and there is not any irregularity which causes variation in the thickness of the optical member. Further, the utilization of Ni nearly flattens the transmissivity in the visual range, so the quantity of light can be attenuated without spoiling a transmitted color tone.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a colored anti-reflection film in which a function is added to the anti-reflection film to attenuate light intensity at a constant rate regardless of wavelength.

Nobiso's Problem Traditionally, optical components such as lenses, filters, and prisms have been coated with a single-layer or multi-layer anti-reflection film to prevent surface reflections.

On the other hand, in order to obtain an appropriate amount of light by weakening the light intensity at a constant rate regardless of the wavelength, a gray colored substrate made of glass containing Co or Ni is used.

As a composite optical member that has both of these functions,
For example, ND (Neutral Density
: Neutral) filters, sunglasses, fashion glasses lenses, etc. These optical members are manufactured by coating a gray colored substrate with a predetermined density with a colorless and transparent antireflection film.

However, setting the transmittance, that is, the density, of the gray colored substrate is done by adjusting the thickness of the substrate having a certain degree of coloring, and this adjustment requires a lot of man-hours, leading to an increase in cost.

In addition, spectacle lenses, especially lenses with a large difference in curvature between the entrance and exit end faces, have the problem that density unevenness occurs within the lens surface due to changes in wall thickness.

By the way, recently CRT (Cathode ray t
(ube) In order to reduce eye strain caused by staring at a display, CRT filters have begun to be used to prevent reflections of ambient light and screen flickering.

Currently used CRT filters include non-glare filters with fine irregularities on the surface, mesh filters made of fibers, etc., but these have the problem of lowering the resolution of images. On the other hand, a CRT filter that uses an anti-reflection film and gray-tinted glass to improve contrast is constructed by sandwiching a circularly polarizing plate and a 1/4 wavelength plate between glass, which requires a lot of man-hours and is expensive. There is a problem.

This invention was made in view of the above-mentioned problems caused by the combination of a gray colored substrate and a colorless and transparent anti-reflection film. It is an object of the present invention to provide a colored antireflection film that has both of the above effects and allows easy selection of arbitrary transmittance.

The colored anti-reflection film according to the present invention has a low refractive index dielectric layer, a high refractive index dielectric layer, and a gray colored layer laminated on a transparent substrate. From the side, the first and fifth layers are low refractive index dielectric layers, the second, fourth and sixth layers are high refractive index dielectric layers, and the third layer is a gray colored layer made of Ni. , aimed at achieving the above objectives.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. Note that the configurations shown in FIGS. 1 and 2 are common to all the examples except for the specific film thickness and the refractive index of the high refractive index dielectric layer.

(First Example) First, as a reference example, the structure of a four-layer antireflection film will be described with reference to FIG.

Here, the transparent substrate B is Bk7 (refractive index n5=1.
521), and dielectric layers having different refractive indexes are laminated on this colorless transparent substrate B by vapor deposition.

Each dielectric layer has a first dielectric layer from the incident medium side. The third layer ■, ■ is a low refractive index dielectric layer, the second layer. The fourth layers (1) and (2) are high refractive index dielectric layers. In this example, M g F (refractive index nL = 1.388) is used as the low refractive index dielectric layer, and a material containing Ta, O, as the main components (refractive index nMu'') is used as the high refractive index dielectric layer. 2.069) is used, and the film thickness of each layer is as shown in Table 1 below.

The spectral characteristics of this configuration are shown by solid lines (A) in FIGS. 3 and 4. As you can understand from this figure, the reflectance in the visible range is approximately 0.5%, and the transmittance is approximately 100%.
becomes.

Next, the structure of a colored antireflection film according to a first embodiment of the present invention will be explained with reference to FIG.

The colored anti-reflective coating shown in the figure has a 6-layer structure, which maintains the anti-reflection effect of the 4-layer anti-reflective coating shown in Figure 1 and 2, while weakening the amount of transmitted light at a constant rate regardless of the wavelength. , the structure is such that the third layer (3) in FIG. 2 is divided into two and a gray colored layer is inserted in the middle. That is, among all six layers, from the light incident medium side, the first. The fifth layer (■) and (■) are low refractive index dielectric layers, the second layer. 4th. The sixth layers (2), (2), and (2) are high refractive index dielectric layers, and the third layer (M) is a gray colored layer.

The material of the dielectric layer is the same as that of the antireflection film shown in FIG. 2 above, and the gray colored layer is made of Ni (refractive index nil: 1.18
0, absorption coefficient km=1.270).

Ni can be used with other metal films, such as Ag, A Q , Cr, Ti
Unlike the above, even if vacuum evaporation is performed at 250° or exposed to the atmosphere at 180°, the absorption characteristics and electrical conductivity hardly change from those of the low-temperature coating. Therefore, since the dielectric layer can be heated and coated at a high temperature, the dielectric layer does not deteriorate over time, and in this respect, it is more suitable as a gray colored layer than other metals.

The transmittance of the colored antireflection film having the above structure can be set to an arbitrary value by selecting the thickness of the gray colored layer.

Specific values for film thickness are shown in Tables 2 to 4. The reflectance and transmittance according to the configuration in Table 2 are shown by the dotted lines (b) in Figures 3 and 4, and similarly, the spectral characteristics according to the configuration in Table 3 are shown by the two-dot chain line (c), The spectral characteristics according to the configuration in Table 4 are indicated by dashed lines). By the way, wavelength 5
The transmittance for incident light of 00 nm is 7 with the configuration shown in Table 2.
6.1%, 57.5% with the configuration in Table 3, and 45.5% with the configuration in Table 4.

From this, by arbitrarily selecting the deposited film thickness of the gray colored layer (third layer ■) within the range of 0 to 31.78 nm, the transmittance for incident light with a wavelength of 500 ro++ can be increased from 100 to 31.78 nm.
It can be understood that it can be set arbitrarily between 45.5%.

As shown in Figures 3 and 4, in any of the above configurations, the reflectance in the visible range is 0.5%.
It is possible to suppress the transmittance to a certain extent, and it is also possible to obtain flat characteristics in the visible range that are independent of wavelength.

(Second Example) Next, the second example of the present invention will be explained along with the reference example and the fifth and sixth examples.
The explanation will be given according to the table, number 2, and FIG. 6.

In the example shown here, Ti is used as the high refractive index dielectric layer.
Oa (refractive index n H2 = 2.466) is used, and Bk7 and MgF are used as the other substrates and the low refractive index dielectric layer, respectively, as in the first embodiment.

First, the structure of a four-layer antireflection film will be explained as a reference example.

The basic order of lamination is the same as that of the first embodiment shown in FIG. 2, and the thickness of each layer is as shown in Table 5 below.

The spectral characteristics of this configuration are shown by solid lines (A) in FIGS. 5 and 6. As you can understand from this diagram, 50
The reflectance in the range of 0 to 600 n- is approximately 0%, and the transmittance in the visible range is approximately 100%.

Next, a second embodiment of the six-layer colored antireflection film of the present invention will be described. The basic lamination order is the same as that of the first embodiment shown in FIG. 1, and the structure is such that the third layer (3) in FIG. 2 is divided into two and a gray colored layer is inserted in the middle. The thickness of each layer is as shown in Table 6 below.

The reflectance and transmittance according to the structure of Table 6 are shown in Figures 5 and 6.
As can be understood from Figure 0, which is indicated by the dotted line (b) in the figure, the reflectance in the visible range can be suppressed to within 0.7%, and flat transmittance characteristics that are independent of wavelength can also be obtained in the visible range. . Incidentally, the transmittance for incident light with a wavelength of 500 nm is 45.5%.

(Third Embodiment) Next, the third embodiment of the present invention will be explained as well as the seventh and eighth embodiments together with the reference example.
This will be explained according to the table and FIGS. 7 and 8.

In the example shown here, Zr is used as the high refractive index dielectric layer.
Oz (refractive index n 83 = 1.918),
As the other substrates and the low refractive index dielectric layer, Bk7 and MgF are used, respectively, as in the first embodiment.

First, the structure of a four-layer antireflection film will be explained as a reference example.

The basic stacking order is the same as that of the first embodiment shown in FIG. 2, and the thickness of each layer is as shown in Table 7 below.

The spectral characteristics of this configuration are shown by solid lines (A) in FIGS. 7 and 8. As can be understood from this figure, the reflectance in the visible range is within 1%, and the transmittance is approximately 100%.

Next, a third embodiment of the six-layer colored antireflection film of the present invention will be described. The basic lamination order is the same as that of the first embodiment shown in FIG. 1, and the structure is such that the third layer (3) in FIG. 2 is divided into two and a gray colored layer is inserted in the middle. The thickness of each layer is as shown in Table 8 below.

The reflectance and transmittance according to the structure of Table 8 are shown in Figures 7 and 8.
As can be understood from Figure 0, which is indicated by the dotted line (B) in the figure, the reflectance in the visible range is suppressed to within 0.4%, and flat transmittance characteristics that are independent of wavelength in the visible range are also obtained. . Incidentally, the transmittance for incident light with a wavelength of 500 nm is 49.5%.

As explained above, according to the colored antireflection coating of the present invention, regardless of the shape of the optical member to be coated, N
Since the transmittance can be changed by adjusting the thickness of the i-layer, it is easier and cheaper to set the transmittance than by adjusting the thickness of a colored substrate, and it is also possible to change the transmittance by adjusting the thickness of the optical member. Density unevenness due to changes does not occur.

In addition, by using N1, the transmittance in the visible range can be made almost flat, so the amount of light can be attenuated without impairing the transmitted color tone, and the colored antireflection film of the present invention can be formed on a colorless transparent substrate. By this, an ND filter can be constructed.

Furthermore, when this configuration is applied to a CRT filter, in addition to the gray coloring effect and antireflection effect, the antistatic effect of the Ni layer can be expected, and an inexpensive and useful product can be provided.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of a colored antireflection film according to the present invention, and FIG. 2 is an explanatory diagram showing the structure of a four-layer antireflection film. FIG. 3 is a graph showing reflectance according to the film thickness structure shown in the first embodiment, and FIG. 4 is a graph showing similar transmittance. FIG. 5 is a graph showing reflectance according to the film thickness structure shown in the second embodiment, and FIG. 6 is a graph showing similar transmittance. FIG. 7 is a graph showing reflectance according to the film thickness structure shown in the third embodiment, and FIG. 8 is a graph showing similar transmittance. B...Transparent substrate ■~■...1st to 6th layers Figure 1 Figure 2 Figure 3 Figure 4 Agent 5 Figure 6

Claims (1)

[Claims] A colored anti-reflection film formed by laminating a low refractive index dielectric layer, a high refractive index dielectric layer, and a gray colored layer on a transparent substrate, wherein of the total six layers, the one on the light incident medium side The first and fifth layers were the low refractive index dielectric layers, the second, fourth and sixth layers were the high refractive index dielectric layers, and the third layer was the gray colored layer made of Ni. A colored antireflection film characterized by: