JPS63159811A - Reflecting mirror consisting of multi-layered films and its production - Google Patents

Abstract

PURPOSE:To reflect the entire visible region and to extend the life of a tilted mirror by specifying the materials of a high-refractive index material and low-refractive index material and the central wavelength of a reflection band at the time of providing multi-layered films consisting of alternate layers of the above-mentioned materials on the inside surface of a concave face-shaped glass substrate. CONSTITUTION:The multi-layered films 13 are deposited on the inside surface 12 of the concave face-shaped glass substrate 11 and a light source 14 such as halogen lamp is disposed to the center of the substrate 11. TiO2-SiO2 or the like is used for the multi-layered films 13 in the above-mentioned constitution and the alternate layers having 1/4lambda optical film thickness are formed. Here are specified lambda1=534nm, lambda2=460nm, lambda3=385nm. More specifically, the optical film thickness is specified to 1/4lambda1 when the high-refractive index material consisting of TiO2 is designated as (H) and the low-refractive index material consisting of SiO2 as (L). Such (H) and (L) are alternately deposited 6 times to form 12 layers in total. Further, one layer of (H) is added to deposit the films 13 times so that a 550-800nm wavelength range is reflected. Furthermore, (H) and (L) are alternately provided 6 times to form 12 layer in total to reflect respectively 500-700nm and 400-600nm wavelength ranges.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention (Industrial Application Field) The present invention relates to a multilayer reflective mirror suitable for use in floodlights, etc., and a method for manufacturing the same.

(Prior Art) Multilayer film reflecting mirrors based on cold light mirrors are often used as light sources for store lighting, medical lighting, and the like.

The visible light is reflected and the long-wavelength infrared region is passed through, so that the irradiated object is not heated by the heat rays, and when the heat rays from the light source pass through the multilayer film, more than 80% of the heat rays are transmitted through the substrate. has the characteristic of not being easily heated.

By the way, conventional cold light mirrors have a high refractive index material (H) on the mirror surface.
and a low refractive index material (L), and using two different optical film thicknesses, each of 550 nm'-8
Near infrared wavelength range of 00 nm and 400 nm to 600 nm
reflects the near-ultraviolet wavelength range of 400nm to 800nm for both.
It is configured to reflect the entire visible range of m.

Generally, the larger the ratio of refractive indexes of the laminated materials, the higher the reflectance and the wider the reflection band. Table 1 below shows the combinations of materials used and their refractive index ratios.

Table 1 Na: refractive index of substance a Nb: refractive index of substance a (problem to be solved by the invention) From Table 1 above, in order to obtain high reflection and high reflection band, Z n
It is advantageous to choose a combination of S M g F 2, but if it is applied to a light source that generates high heat, such as a halogen lamp, the multilayer film will peel off due to heating, and the ZnS layer on the surface of the multilayer film will be weathered. It becomes cloudy.

Generally, the heat load when lighting the lamp becomes unusable after 30 hours at a temperature of 350°C and 100 hours at a temperature of 300°C. Furthermore, since the ZnS layer is hygroscopic, the multilayer film will peel off if it is left in an atmosphere at a temperature of 50'C and a humidity of 90% for 50 hours, resulting in poor durability.

On the other hand, as shown in Table 2 below, the TiO2-3iOz alternating layer has a heat load of 150°C at a temperature of 350°C when the lamp is lit.
It has durability of 250 hours at 300℃ and Z
n S M g F It has a significantly longer life than 2 alternating layers, but because of its low refractive index ratio, it cannot reflect the entire visible light range, has a transmission band around 1.096 around 55 Onm, and , with the same number of layers for the overall reflectance, Z n S − M g F 2 is a combination of materials with a large refractive index ratio.
Inferior to alternating layers.

Based on the information in Table 2-1, it is desired to improve the optical properties of a multilayer mirror made of alternating layers of TiO25iOz, which has excellent durability, and to achieve a high reflectance and a wide reflection band.

The object of the present invention is to provide a multilayer reflector that is made of alternating layers of TiO2-3iOz with excellent durability and is capable of reflecting the entire visible range, and a method for manufacturing the same.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a multilayer structure mainly consisting of alternating layers of a high refractive index material (H) and a low refractive index material (L>) on the inner surface of a concave glass substrate. In a multilayer reflective mirror formed of a film, the high refractive index substance (H) is titanium dioxide, the low refractive index substance (L) is silicon dioxide, and the multilayer film a first alternating layer with a wavelength in the range of 430 nm to 510 nm, a second alternating layer with a reflective band center wavelength in the range of 520 nm to 620 nm, and a second alternating layer with a reflective band center wavelength in the range of 650 nm to 750 nm. This is a multilayer film reflecting mirror characterized by comprising three alternating layers.

The present invention also provides a method for manufacturing a multilayer reflector in which a multilayer film mainly consisting of alternating layers of a high refractive index material (H) and a low refractive index material (L) is formed on the inner surface of a concave glass substrate.
The total pressure of the atmosphere during the formation of the multilayer film was 10-4 Torr.
When the high refractive index material (H) is titanium dioxide, it is formed in an atmosphere of a mixed gas of oxygen and an inert gas, and when the low refractive index material (L) is silicon dioxide. In case of mixed gas of oxygen and inert gas,
Alternatively, there is a method for manufacturing a multilayer mirror, characterized in that the mirror is formed in an atmosphere containing only an inert gas.

(Function) According to the present invention, it is possible to reflect the entire visible range, and by using alternating layers of T i O2S i O2, anti-peeling properties are improved and the service life can be extended.

(Embodiment) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The multilayer film reflecting mirror of the present invention is constructed as shown in FIG.
is formed. Further, a light source 14 such as a halogen lamp is disposed at the center of the concave glass substrate 11.

The film structure of the multilayer film 13 is as shown in Table 3 below.
Optical thickness 1 consisting of 31 layers of i O2S i 02
/4λ alternating layers (λ11-534n.

They are λ22-460n and λ3-3-385n.

That is, let the high refractive index material made of TiO2 be (H), and 5
When (L) is a low refractive index material made of i02, the optical film thickness is 1/4λ1 levers (H) and (L) alternately 6
times = [12 layers are deposited, and 1 layer of (H) is added to deposit 13 layers to reflect the wavelength range of 550 nm to 800 nm. Furthermore, (H) and (L) were alternately applied 6 times for a total of 12 layers,
The optical film thickness was changed to 1/4λ2, 1/4λ3, respectively, and the layers were deposited to 500nm to 700nm and 400nm, respectively.
It is configured to reflect a wavelength range of ~60 (Jnm).

Table 3 λ1: 534nm λ2: 460nm λ3: 385nm Next, a method for manufacturing a multilayer film reflecting mirror according to the present invention will be explained.

In this invention, the electron beam evaporation apparatus shown in FIG.
The optical film thickness is controlled by several layers per monitor substrate through a wavelength filter 2 having a control wavelength of λnm, and a multilayer film is formed on the reflecting mirror substrate 6.

Note that 5 in the figure is a dome rotation mechanism.

The evaporation method is an electron beam, and a plurality of titanium dioxide and silicon dioxide are accommodated in a plurality of crucibles 7 for accommodating evaporation agents using rotary machine grooves.

Then, an electron beam is excited from the electron gun 8 at an accelerating voltage of, for example, 6 KV, and is deflected by a magnet, for example, by about 270' so as to hit the crucible 7, thereby performing predetermined vapor deposition. The emission current value at this time is, for example, 180 mA in the case of titanium dioxide, and 100 mA in the case of silicon dioxide.
It is A. For vapor deposition of titanium dioxide, reactive vapor deposition is used in which oxygen is also introduced during vapor deposition in order to prevent titanium dioxide from being reduced and becoming a black film.

In addition, the substrate temperature should be adjusted to maximize the film density during vapor deposition.
The temperature is maintained at 300°C by the heater 4. The refractive index of the vapor-deposited film of titanium dioxide obtained is 2.2 to 2.3, and the refractive index of the vapor-deposited film of silicon dioxide is 1.46 to 1.
．． It is 47.

Further, a plurality of substrates 6, for example 100 pieces, are attached to the dome 9, and the dome 9 is rotated one by one by the dome rotation mechanism 5.
3 while rotating at a speed of 900 to 1500 revolutions per hour.
It revolves at a speed of 00 to 500 revolutions, and in order to correct the variation in deposition due to the directivity of the vapor deposition agent when it is scattered, and to suppress the directivity of the vapor deposition molecules as much as possible, a gas such as a mixed gas of oxygen and inert gas argon is used. is introduced, and the total pressure is set to 1, for example.
By maintaining the temperature at about xlO-3 Torr and scattering the vapor deposition molecules by gas molecules, the vapor deposition can be performed uniformly on the curved substrate surface regardless of the substrate position of the dome 9.

However, when the total pressure exceeds 1xlO-2Torr,
The insulation inside the vacuum chamber becomes high, which makes the electron beam unstable and evaporation cannot be performed. On the other hand, the total pressure is 1xlC14
When the temperature is less than Torr, the scattering of the vapor-deposited molecules becomes weaker, and the molecules cannot be uniformly deposited on the substrate surface. Therefore, the total pressure is 1xlO-4 Torr ~ 1x10-2 Torr
limited to r.

FIG. 3 shows the optical characteristics of the multilayer mirror manufactured in this way. Incidentally, when measuring the optical characteristics, a reflective substrate on which no vapor deposition was performed was used as a reference.

Furthermore, as shown in FIG. 3, the transmission band that appeared around 550 nm in the conventional method disappeared, making it possible to reflect the entire visible range, and also improving the reflectance.

Further, the results of the durability test by lamp lighting are shown in Table 2 mentioned above. The heat added by lighting the lamp is 300℃ and 35℃.
This is the case at 0°C. From this Z n S −M g F
It was found that the durability was about three times better than that of the two-layer film.

(Modification) In the third embodiment, the multilayer film has a control wavelength λ1-λ2-λ3.
The lamination order was λ3-λ2-λ.
Similar optical characteristics can be obtained even if the value is changed to 1.

Furthermore, although the above embodiments involve vapor deposition using an electron beam,
Similar effects can also be achieved in vapor deposition by ion blating.

Furthermore, in the above embodiment, as shown in Table 3, the first layer on the substrate side is 5iOz with an optical thickness of 1/4λ1, but the refractive index of 5iOz is the refractive index of the substrate. Therefore, even if the first layer of 5 iOz is omitted or formed with an arbitrary thickness, the spectral characteristics "2" will hardly be affected. Therefore, the configuration in Table 3 is expressed as having substantially 30 layers.

In addition, in the above embodiment, the case where the values of n+, nz, and n3 are respectively 6.3.6 will be explained in detail.
6, n2≧3, and n3≧6, sufficient spectral characteristics as a multilayer film reflecting mirror can be obtained.

By the way, the reason why there are three reflective areas in the above embodiment will be explained.

That is, since the refractive index of the TiO2-8i02 system is low, a transmission band is generated at the two control wavelengths, and Z n S -
It is not possible to maintain optical properties comparable to those of the M g F z system. Therefore, it becomes necessary to use three or more control wavelengths. However, when four or more control wavelengths are used, the number of laminated layers increases and the cost increases.
Since there are problems with practicality from an economical point of view, the number is limited to three.

Also, to explain the reason for limiting the area, a cold light mirror reflects the oral light and allows it to pass through the infrared region, so that the irradiated object is not heated by the heat rays, and the infrared reflection wavelength range is Limited to 8'OOn m. Also,
The substrate used in the multilayer film reflecting mirror of the present invention is an ultraviolet-cut glass substrate, and it is meaningless to widen the reflection band to a short wavelength region using only a multilayer film, and it is considered that it is sufficient to extend the reflection band up to 400 nm. Therefore, the reflection band due to the multilayer film is 400
It is limited without limitation from nm to 800 nm.

The criteria for determining the ends of the reflection band here are that the short wavelength end is a wavelength at which the transmittance drops to 50%, and the long wavelength end is a wavelength at which the transmittance increases to 50%.

Now, optical characteristics when only [H-L12] is deposited are shown using the control wavelength λ1 shown in FIG. In this case,
Reflection band is 534nm to 805nm, bandwidth 251nm
, the peak wavelength is 657 nm. Similarly, the control wavelength λ3
FIG. 5 shows the optical characteristics when only H-L12 was deposited. In this case, the reflection band is 400nm
~591nm, bandwidth 191nm, peak wavelength 474n
It is m. Further, FIG. 6 shows the optical characteristics when both are laminated. A ripple occurs between 530 nm and 640 nm, but in order to remove this ripple, a reflection band of 471 nm to 70 nm is created using a control wavelength λ2 having the optical characteristics shown in FIG.
9 nm, bandwidth 238 nm, peak wavelength 566 nm [
H-L] By using the three layers as spacers, the first
The optical characteristics shown in the figure can be obtained. And 40
In order to reflect wavelengths from 0 nm to 800 nm, it is impossible to do so with an appropriate bandwidth due to the control wavelength. Furthermore, in order to align the ends of the reflection bands, it is not possible to shift the reflection bands due to the control wavelengths λ1 and λ3. Further, although it is possible to shift the reflection band using the control wavelength λ2 of the spacer to some extent, it is not a good idea in terms of manufacturing. Therefore, three areas are limited. Accordingly, the three control wavelengths λ1, λ2, λ3 are also limited to the range of values set forth in claim 1.

Next, the need to use the three control wavelengths λ, λ2, and λ3 can be eliminated by using three control wavelengths in this invention.
This is because optical characteristics comparable to those of the nS-MgFZ system can be obtained.

In addition, the reason for limiting the lamination order is that if the lamination order is changed to another combination, inappropriate interference will occur and predetermined optical characteristics cannot be obtained. limited to only.

[Effect of the invention] According to the invention, TiO is formed on the inner surface of the concave glass substrate.
Since the multilayer film is formed by configuring alternating layers of 2-3iO2 system with three different control wavelengths λlnm, λ2nm, and λ3nm, the heat load when the halogen lamp is turned on is 350℃ for 150 hours, and 300℃ for 150 hours. No peeling occurred for 250 hours, and the lifespan was approximately three times longer than that of ZnS-MgF2. In addition, it has become possible to reflect the entire visible range in terms of optical properties.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a multilayer reflector according to an embodiment of the present invention, and FIG. 2 is a configuration diagram showing an electron beam evaporation apparatus used in a method for manufacturing a multilayer reflector according to an embodiment of the present invention. , FIG. 3 is a characteristic curve diagram showing the optical characteristics of the multilayer film reflecting mirror of the present invention, and FIGS. 4 to 7 are characteristic curve diagrams showing the optical characteristics under various conditions. 11... Concave glass substrate, 13... Multilayer film, 14
···light source. Applicant's agent Patent attorney Takehiko Suzue No. 1 Figure 2 rL Length (nm) Figure 3 Figure 4! L A (nm) Fig. 5 A Moxibustion (nm) Fig. 6

Claims (5)

[Claims] (1) Mainly high refractive index material (
In a multilayer reflector formed of a multilayer film consisting of alternating layers of H) and a low refractive index material (L), the high refractive index material (H) is titanium dioxide, and the low refractive index material (L) is titanium dioxide. is silicon dioxide, and the multilayer film has a reflection band center wavelength of 430 nm to 510 nm.
and the center wavelength of the reflection band is in the range of 52
A multilayer reflector comprising second alternating layers having a wavelength in the range of 0 nm to 620 nm and third alternating layers having a center wavelength of the reflection band in the range of 650 nm to 750 nm. (2) The first alternating layer is [H_1・L_1]^n_1
, if the second alternating layer is [H_2・L_2]^n_2 and the third alternating layer is [H_3・L_3]^n_3, then n_1>n_2, n_3>n_2 (however, n_1, n
The multilayer film reflecting mirror according to claim 1, wherein _2 and n_3 are natural numbers. (3) The multilayer film is formed in the order of the first alternating layer, the second alternating layer, and the third alternating layer from the glass substrate side, or the third alternating layer, the second alternating layer, and the like. 3. The multilayer film reflecting mirror according to claim 1, wherein the multilayer film reflecting mirror is formed in the order of alternating layers and first alternating layers. (4) The multilayer film reflecting mirror according to claims 1 to 3, in which the value of n_1 is 6, the value of n_2 is 3, the value of n_3 is 6, and the number of layers is 30. . (5) Mainly high refractive index material (
In the method for manufacturing a multilayer film reflecting mirror in which a multilayer film is formed of alternating layers of H) and a low refractive index material (L), the total pressure of the atmosphere during formation of the multilayer film is 10^-^4 Torr to 10^ -^2 Torr, when the high refractive index substance (H) is titanium dioxide, it is formed in a mixed gas atmosphere of oxygen and inert gas, and when the low refractive index substance (L) is silicon dioxide, it is formed in a mixed gas atmosphere of oxygen and inert gas. A method for manufacturing a multilayer reflective mirror, characterized in that the mirror is formed in a mixed gas of oxygen and an inert gas, or in an atmosphere of only an inert gas.