JPH09281472A - Production of light reflection plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection plate with no loss which is inevitable for an optical system. SOLUTION: By this method, a source layer 2 containing photopolymerizable acrylate monomers, a photopolymn. initiator and a low mol. liquid crystal is formed on the flat surface of a reflection substrate 1, the layer 2 is irradiated with desired parallel beams at a desired angle to generate static waves in the layer 2 to polymerize the monomers. Thus, a polymer layer having such distribution of liquid crystal microdrops 6 that the number of drops is large in the node part of the static waves is the layer is obtd. In this method, interference between the incident light 4 and the reflected light 5 is used to generate static waves, and thereby, a multilayered structure having different refractive indices is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a light reflecting plate which is useful for the construction of various optical elements and has extremely small loss.

[0002]

2. Description of the Related Art As a lossless reflective film, a multilayer reflective film has been developed by a vapor deposition process under precise film thickness control.
Some have been put to practical use. For this manufacturing method,
Details on the Thin Film Engineering Handbook (2nd Edition), published by Ohmsha, edited by Japan Society for the Promotion of Science, Thin Film 131st Committee.

[0003]

However, in the vapor deposition process under the precise film thickness control, it is essentially a vacuum process, and there is an increase in equipment cost and the complexity of the process unique to vacuum. Therefore, the lossless light reflection plate having a certain area is not widely used in industry.

[0004]

In order to solve the above-mentioned problems, the present invention forms a starting layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal on a reflective substrate plane, By irradiating parallel rays of desired light at a desired angle, the distribution of fine liquid crystal droplets in the polymerized starting layer is distributed by the standing wave generated in the starting layer. A method of manufacturing a light reflection plate which is made large is clarified.
At this time, it is convenient that the light is a laser light because the coherence length can be increased and the spatial distance of standing waves can be increased.

The present invention further comprises forming a source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal on the surface of a substrate which can transmit a desired laser beam, and further comprises a backside of the substrate. Provide a reflective plane that makes a desired angle with the surface, parallel rays of the desired laser light from the surface side of the substrate, irradiate at a desired angle, by standing waves generated in the starting layer, polymerization We propose a method of manufacturing a light reflection plate in which the distribution of minute liquid crystal droplets is enlarged in the nodes of the standing wave in the generated source layer.

A method for increasing the degree of freedom in designing reflection characteristics will be proposed below. The above method is repeated, that is, a source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal is formed on the surface of a substrate that can transmit a desired laser beam, and the substrate is formed. Provide a reflection plane that makes a desired angle with the surface on the back side, irradiate parallel rays of a desired laser beam from the surface side of the substrate at a desired angle, and by a standing wave generated in the starting layer, We present a method of manufacturing a light reflector by repeating the process consisting of obtaining a polymerized layer in which the distribution of fine liquid crystal droplets is enlarged in the nodes of the standing wave in the polymerized source layer. .

Also, another method for adding a degree of freedom to the reflection characteristic is proposed. On the releasable reflective substrate plane,
A standing wave containing a photopolymerizable acrylate monomer, a photopolymerization initiator, and a low-molecular liquid crystal is formed, and a parallel ray of desired light is irradiated at a desired angle to generate a standing wave in the starting layer. A polymerized layer obtained by exfoliating the polymerized source layer from the reflection plane by enlarging the distribution of fine liquid crystal droplets in the node portion of the standing wave in the polymerized source layer, or a desired laser. On the surface of a releasable substrate capable of transmitting light, a source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal is formed, and a desired angle with the surface is formed on the back side of the substrate. Provided with a reflection plane, the parallel rays of the desired laser light from the surface side of the substrate, at a desired angle, by standing waves generated in the starting layer, in the polymerized starting layer. Polymerization by increasing the distribution of minute liquid crystal droplets at the nodes of the standing wave. Was primordial layer polymer layer obtained by peeling from the substrate, the to clarify the method of manufacturing the light reflecting plate as formed by laminating. It is convenient that the above-mentioned light is a laser light because the coherence length is large. Further, it is optically desirable to impregnate the above-mentioned respective polymerized layers with a liquid substantially equivalent to the polymerized acrylate.

As a light source, that is, a light source, it is necessary that the wavelength region of light is narrow because a standing wave is generated by interference, and a laser, a high or low pressure mercury lamp or a sodium lamp is preferable. The reflection wavelength band of the resulting reflector is, of course, almost determined by the wavelength of the standing wave. Therefore, the usable light source is somewhat limited. Of course, the laser light is in TEM ₀₀ mode.

Argon ion lasers and helium-cadmium lasers are preferred as the lasers to be used because of the mature technology in this regard. However, at this time, it is necessary to use a suitable photopolymerization initiator depending on the laser wavelength used. The low-molecular liquid crystals described so far refer to nematic liquid crystals, smectic liquid crystals, discotic liquid crystals, and the like.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The coherence length between incident light and reflected light from a reflector is about 1 μm for light from a high or low pressure mercury lamp or a sodium lamp. When laser light is used, the coherence length is improved. This is something that is routinely experienced with the photolithography method.

In order to obtain a light-reflecting plate without loss, it is possible to easily obtain a multi-layered reflecting plate in air without using vacuum deposition or the like. In the present invention, what corresponds to this multilayer film is due to the periodic distribution of the fine liquid crystal droplets in the cross section of the polymerized starting layer, that is, in the cross section of the polymerized layer. This period corresponds exactly to the standing wave of light or laser light. That is, it corresponds to the wavelength, and the control of the period is automatic.
However, when forming a multi-layer film by vapor deposition or the like, strict control of the film thickness is required, which is a production limitation.

The basic concept of the present invention is shown in a sectional configuration view in FIGS. In FIG. 1, 1 is a reflective substrate, and 2 is a source layer, which becomes a polymerized layer by light energy. Reference numeral 3 is a normal line of the reflective substrate, 4 is incident light, 5 is emitted light, and 6 is a minute liquid crystal droplet segregated in layers. In FIG. 2, 7 is a transparent substrate, and 8 is a source layer, which becomes a polymerized layer by light energy. Reference numeral 9 is an angled reflective substrate, 10 is a normal line of the translucent substrate, 11 is a normal line of the reflective substrate, 12 is an incident laser beam, 13 is an emitted laser beam, and 14 is a minute liquid crystal droplet segregated in layers. Is.

The essence of the present invention is as follows. The present invention resides in that a standing wave is generated by the interference of incident light and reflected light within a coherence length, whereby minute liquid crystal droplets are deposited in layers at the node portion of the low standing wave. This is a very simple method in principle. Therefore, in the cross section, a periodic distribution of the refractive index is formed by the distribution of the acrylic polymer layer, the fine liquid crystal droplets, and the layer composed of the acrylic polymer, and the reflection is selectively caused by the Bragg reflection condition.

The deposition of fine liquid crystal droplets in layers has been confirmed with a scanning electron microscope of the cross section of the polymerized layer. From other experimental evidence, small liquid crystal droplets are segregated at the nodes of standing waves. This is because the acrylate monomer rapidly crosslinks and polymerizes in the abdomen of the standing wave with high energy, and the diacrylate monomer in other places diffuses into this abdomen, and conversely, the non-reactive low-molecular liquid crystal is located in this region. It is thought that it will be kicked out of. Further, it is necessary to make the diameter of the micro liquid crystal droplet smaller than the wavelength of light. To this end, the polymerization rate of the acrylic monomer is adjusted to be relatively high. This results in a large ratio of fast reacting diacrylate monomer to monoacrylate monomer.

The wavelength of the light that is selectively reflected by the light reflecting plate depends on the spatial period of the structure of the cross section of the polymer layer. Therefore, this cycle should be set arbitrarily. This is because the spatial period can be varied by making incident light incident obliquely when manufacturing the light reflecting plate of the present invention.

That is, when the spatial period d and the angle formed by the incident light and the normal line of the reflective substrate are θ, d = λ / 2 × (1 / cos θ). Therefore, when θ is 0 °, d can be minimized.

In addition, it is necessary to design whether the maximum direction of the light reflection intensity is in the front or at an angle. This is achieved by making an angle between the surface of the source layer and the reflective substrate during manufacturing so that the normal of the source layer and the normal of the reflective substrate are different. This is shown in FIG. That is, the micro liquid crystal droplet layer is perpendicular to the normal line of the reflective substrate. That is, the angle of strong reflection of the finished light reflector is in the oblique direction, that is, the angle α from the normal.
Direction.

Another essence of the present invention is that a precise light reflecting plate can be formed by a simple system utilizing the interference between incident light and reflected light. This is apparent in FIGS. For a single periodic distribution of minute liquid crystal droplets in the cross section of the polymerized layer, the wavelength range of selective reflection is
It is about 50 nm. Often, more broadband reflection is required. On the other hand, this can be answered by stacking a plurality of polymerized layers having different periodic distributions of minute liquid crystal droplets in the cross section. For this purpose, there is a method in which each polymerized layer is manufactured and laminated, or each polymerized layer is sequentially formed on a substrate.

Example 1 Polished quartz glass substrate A
Aluminum is vapor-deposited on the main surface. On this, hexamethyldisiloxane obtained from Shin-Etsu Silicone Co., Ltd. is formed into a peelable surface by glow discharge at a vacuum degree of 0.5 mmHg. Similar peeling treatment is performed on the main surface of the other quartz glass substrate B. The pair of glass substrates were bonded together with their releasable surfaces facing each other with a gap of about 5 μm.
This gap was defined by a Mylar film having a thickness of about 5 μm. Diacrylate monomer, product name, light acrylate DCP-, obtained from Kyoeisha Chemical Co., Ltd.
About 65% by weight of A and a monoacrylate monomer, HOA-HH, about 35% by weight, which were also obtained from Kyoeisha Chemical Co., Ltd., were mixed to prepare an acrylate monomer resin.

About 85% by weight of this acrylate monomer resin, about 15% by weight of a cyanoterphenyl nematic liquid crystal (BL-008 manufactured by Merck & Co., Inc.), and a photopolymerization initiator IRGAQUA 651 (manufactured by Ciba-Geigy Co.) were used. 4% by weight was mixed to obtain a resin. The resin was impregnated into the gap and filled to form a starting layer.
The light irradiation was performed by an exposure device using a high pressure mercury lamp manufactured by Mikasa Co., Ltd. Collimated light is obtained in the range of about 15 cm diameter. The wavelength of light was about 360 nm. In FIG. 1, light irradiation is performed from the back surface side of the quartz glass substrate B, and θ
To about 30 °. The exposure time was about 5 minutes to obtain a polymerized layer. However, the quartz glass substrate B is omitted in FIG.

After that, the polymer layer was peeled from both substrates and taken out for optical measurement. The reflection was about 420 nm.
Centered on the wavelength band of about 50 nm. It appears blue to the naked eye. When the cross section of the polymer film was observed with a scanning electron microscope, liquid crystal droplets were localized in layers, and the diameter of the liquid crystal droplets was 100 nm or less.

(Example 2) A reflective substrate having a cross section with an angle as shown in FIG. 2 was prepared from stainless steel whose surface was polished. The angle α was about 15 °. The surface of this reflective substrate was covered with aluminum by a vapor deposition method. Further, the quartz glass substrate C and the other quartz glass substrate D were subjected to the same release treatment surface as in Example 1 and bonded to each other with a gap of about 3 μm so that the release surfaces face each other. This gap was secured by a liquid crystal spacer.

About 90% by weight of the same acrylate monomer resin as in Example 1, about 10% by weight of a cyanoterphenyl nematic liquid crystal (BL-008 manufactured by Merck),
Photopolymerization initiator, IRGAQUA 369 (manufactured by Ciba Geigy)
Was mixed so as to be 0.2% by weight to obtain a resin. As in Example 1, the resin was filled in this gap. This filling was placed on the reflective substrate as shown in FIG.

Irradiation is performed as shown in FIG. However, in the figure
However, the quartz glass substrate D is omitted. In the figure
Therefore, α is about 15 ° and θ is about 30 °. As a light source
Is a helium-cadmium laser manufactured by Kinmen Co., Ltd.
About 441.6nm TEM ₀₀Laser light by oscillation
used. The irradiation time was about 1 minute.

After that, the polymer layer was separated from both substrates, and the polymer layer was taken out and subjected to an optical measurement. As a result, the reflection was the largest from about 30 ° obliquely from the front, and about 520 nm was centered in a wavelength band of about 60 nm. Happened. 30 diagonally from the front
It looks green when observed with the naked eye. When the cross section of the polymer film was observed with a scanning electron microscope, liquid crystal droplets were localized in layers, and the diameter of the liquid crystal droplets was 100 nm or less.

(Embodiment 3) Similar to Embodiment 2, except that
The reflective substrate is made of stainless steel whose surface is coated with aluminum. Further, θ in FIG. 2 is set to 0 °. By doing so, the polymerized layer a is obtained.

Further, the polymerized layer b obtained from Example 1 is obtained. Two polymer layers are laminated to obtain a laminate. Butyl carbitol (hereinafter referred to as BC), which has almost the same refractive index, was impregnated between the polymerized layer a and the polymerized layer b.

When the optical characteristics of this laminate were measured, selective reflection was observed in the region of about 390 nm to about 470 nm. The naked eye showed a clear blue color. Note that B
Without C, it was dark.

Example 4 A reflective substrate having a cross section shown in FIG. 2 was made of stainless steel. The angle α was about 5 °. The surface of this reflective substrate was coated with silver by a vapor deposition method. Further, the quartz glass substrate E and another quartz glass substrate F were subjected to the same release treatment surface as in Example 1 and bonded to each other in a gap of about 3 μm so that the release surfaces face each other. This gap was secured by a liquid crystal spacer.

The same acrylate monomer resin as in Example 1 was used in an amount of about 90% by weight, and a cyanoterphenyl nematic liquid crystal (BL-008 manufactured by Merck & Co., Inc.) was used in an amount of about 10% by weight.
Photopolymerization initiator, IRGAQUA 369 (manufactured by Ciba Geigy)
Was mixed so as to be 0.2% by weight to obtain a resin. As in Example 1, the resin was filled in this gap. This filling was placed on the reflective substrate as shown in FIG.

Irradiation is performed as shown in FIG. However, the quartz glass substrate F is omitted in FIG. In the figure, α is about 5 ° and θ is about 30 °. Light source: Coherent, Argon Laser, INNO
TEM ₀₀ of about 514.5 nm by VA 200-25
Laser light was used by oscillation. The irradiation time was about 1 minute. Next, the quartz glass substrate F is peeled off, and the polymerized layer c
Quartz glass E was obtained.

The quartz glass substrate F is washed, and then the quartz glass substrate F is again held on the quartz glass substrate E and the polymerized layer c to form a gap of about 3 μm as described above, and the resin is filled. To do. This filling was placed on the reflective substrate as shown in FIG.

Irradiation is performed as shown in FIG. However, the quartz glass substrate F is omitted in FIG. In the figure, α is about 5 ° and θ is about 40 °. Light source: Coherent, Argon Laser, INNO
TEM ₀₀ of about 514.5 nm by VA 200-25
Laser light was used by oscillation. The irradiation time was about 1 minute. Next, the quartz glass substrate E and the glass substrate F were peeled off to obtain a laminate.

When the optical characteristics of this laminate were measured, selective reflection was observed in the region of about 570 nm to about 710 nm. The naked eye showed a clear red color.

[0035]

INDUSTRIAL APPLICABILITY As described above, the present invention provides a lossless reflector which is indispensable for an optical system, and its industrial value is enormous.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of a light reflecting plate according to an embodiment of the invention.

FIG. 2 is a structural cross-sectional view of a light reflecting plate according to another embodiment of the present invention.

[Explanation of symbols]

 1 Reflective Substrate 2 Initiating Layer (Polymerized Layer After Irradiation of Light Energy) 3 Reflective Substrate Normal Line 4 Incident Light 5 Outgoing Light 6 Layered Micro Liquid Crystal Droplets 7 Translucent Substrate 8 Initiating Layer (Light Energy) After irradiation, polymerized layer) 9 Angled reflective substrate 10 Normal line of translucent substrate 11 Normal line of reflective substrate 12 Incident laser beam 13 Emitted laser beam 14 Minute liquid crystal droplets segregated in layers

Claims (6)

[Claims] 1. A starting source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator, and a low-molecular liquid crystal is formed on a plane of a reflective substrate, and a parallel ray of desired light is irradiated at a desired angle to obtain the initial light. The standing wave generated in the source layer provides a polymerized layer in which the distribution of the fine liquid crystal droplets is enlarged in the nodes of the standing wave in the polymerized starting layer to obtain a polymerized layer. Production method. 2. A source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal is formed on the surface of a substrate that can transmit a desired laser beam, and the surface is formed on the back side of the substrate. And a reflection plane that makes a desired angle are provided, and a parallel light beam of a desired laser beam is irradiated from the surface side of the substrate at a desired angle, and a standing wave generated by the standing wave generated in the starting layer is polymerized. A method for producing a light reflection plate, characterized in that a polymerized layer is obtained in which the distribution of fine liquid crystal droplets is enlarged in the nodes of the standing wave in the layer. 3. A source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal is formed on the surface of a substrate that can transmit a desired laser beam, and the surface is formed on the back side of the substrate. By providing a reflection plane that makes a desired angle with a parallel beam of a desired laser beam from the surface side of the substrate, irradiating at a desired angle, by a standing wave generated in the starting layer,
A method of manufacturing a light reflecting plate, characterized in that a step of obtaining a polymerized layer in which a distribution of fine liquid crystal droplets is enlarged in a node portion of a standing wave in a polymerized source layer is repeated a plurality of times. . 4. A source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal is formed on a releasable reflective substrate plane, and parallel rays of desired light are emitted at desired angles. ,
Irradiation causes the standing wave generated in the starting layer to reflect the superposition of the starting layer in which the distribution of micro liquid crystal droplets is enlarged to the nodes of the standing wave in the superposed starting layer. On the surface of a polymerized layer obtained by peeling from a flat surface or a releasable substrate capable of transmitting a desired laser beam, a source layer containing a photopolymerizable acrylate monomer, a photopolymerization initiator and a low molecular weight liquid crystal is formed. Further, a reflection plane forming a desired angle with the front surface is provided on the back surface side of the substrate, and a parallel light beam of a desired laser beam is irradiated from the front surface side of the substrate at a desired angle to generate in the source layer. By the standing wave generated by the above, the polymerized layer obtained by peeling the polymerized source layer formed by enlarging the distribution of the fine liquid crystal droplets in the section of the standing wave in the polymerized source layer from the substrate is formed. A method of manufacturing a light reflecting plate, which is characterized by being laminated. 5. The method for manufacturing a light reflection plate according to claim 1, wherein the light is laser light. 6. The method according to claim 4, wherein a liquid substantially equivalent to the polymerized acrylate is impregnated between the polymerized layers.
A method for producing the light reflection plate described.