JPH0816721B2 - Transmission type phase grating or lens and their manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a transmission type phase grating which is formed of an organic polymer material, has a good transmitted wave front, has a high transmittance, is excellent in mass production, is lightweight, and is inexpensive. The present invention relates to lenses and their manufacturing methods.

(Prior Art) Conventionally, a photosensitive polymer compound is used on a quartz glass or optical glass substrate to draw a phase grating or lens pattern by photolithography, and the pattern is used as it is, or after photolithography, another pattern is used. The compound of
A transmission type phase grating or lens has been obtained by adhering it by a sputtering method or the like.

(Problems to be Solved by the Invention) The transmission type phase grating or lens of the above means has a drawback that it is heavy and expensive because the substrate is glass. Further, the manufacturing method has drawbacks that the process is large and the apparatus is large and expensive. Further, in the method using a photosensitive polymer compound, the adhesion between the glass substrate and the polymer compound was poor. It is easy for those skilled in the art to improve the former defect by using a polymer compound at a low cost.

According to the research conducted by the present inventors, when a photosensitive polymer compound is applied onto a plastic substrate by a spin coating method to form a phase grating or a lens, the interface between the substrate and the polymer compound is formed no matter how carefully the substrate is prepared. It was confirmed that the polymer was immersed in a solvent in which the polymer compound was dissolved, and the transmittance was decreased and the wavefront was drooped.

A first object of the present invention is to provide a phase grating or lens made of an inexpensive organic polymer material.

A second object of the present invention is to provide a phase grating or lens having a good transmission with no transmission wave front squeezing.

A third object of the invention is to provide a durable phase grating or lens.

And another object of the present invention is to provide an industrial manufacturing method of such a phase grating or lens.

(Means for Solving the Problems) According to the study by the present inventors, in a transmission type phase grating or lens formed from a substrate made of an organic polymer material and a phase grating or a lens layer made of an organic polymer material, It has been found that the above problems can be solved by providing at least one or more intermediate layers characterized in that the media have different solvent solubilities between the layers.

That is, the present invention includes 1) (A) a phase grating or a lens layer made of a transparent organic polymer material (a), (B) an organic polymer material having a solvent solubility different from that of the polymer material (a) ( b) at least one intermediate layer, and (C) a substrate made of an organic polymer material (c) different from the polymer material (b) for supporting the phase grating or the lens layer and the intermediate layer. And a phase grating or lens comprising: and a substrate having an organic polymer material (c) having a thickness and strength sufficient to support, and having a solvent solubility different from that of the polymer material. A solution in which the polymer material (b) is dissolved is applied and dried to form an intermediate layer, and then the photosensitive polymer material (a ′) is dissolved in a solvent that does not substantially dissolve the intermediate layer. After applying and drying the prepared solution, the photoreaction process A method of manufacturing a transmission type phase grating or lens, characterized in that the phase grating or lens layer is formed by

As the material constituting the substrate used in the present invention, any organic polymer material having sufficient thickness and strength for supporting can be used, but it is an inexpensive material for the purpose of the invention. It's complicated. Examples of the material (c) include polymethylmethacrylate, polycarbonate, polyester, nylon, polyethylene, polysulfone, and polystyrene. The type of material used is appropriately selected depending on the purpose of use such as required transmittance and the relationship with the material of the intermediate layer, but a methacrylate polymer or a styrene polymer is often used because of its good transparency. .

Known as a photosensitive polymer material (a ') for forming a phase grating or a lens (hereinafter collectively referred to as a phase grating or the like) layer used in the present invention as long as it has sufficient transparency. The material of can be used as it is. Examples of these materials (a ') are photosensitive polymer compounds made of acrylate resins such as polymethylmethacrylate and polycyclohexylmethacrylate, styrene polymers such as polycarbonate, polystyrene and poly α-methylstyrene, Examples thereof include a photosensitive polymer compound composed of a copolymer thereof.

A photosensitive compound that can be dry-developed by the phototocking method is preferable because the process is simple and the substrate made of a polymer material is not damaged by a developing solution or the like. These are, for example, one or more compounds selected from (A) a polymer having a photoreactive carbon-carbon double bond and (B) an unsubstituted or substituted aromatic aldehyde and aromatic ketone. It is a photosensitive polymer material containing.

Here, the photoreactive polymer having a carbon-carbon double bond is a polymer having a carbon-carbon double bond in the molecule in which a reaction with an aldehyde or a ketone proceeds by light. These polymers are, for example, 2-butenol,
It is obtained by reacting a terpene alcohol having a double bond in the molecule such as geraniol with an acrylic acid polymer (polymer esterification reaction). The alcohol having a double bond in the molecule and acrylic acid or methacrylic acid It can also be obtained by polymerizing an acid ester alone or by copolymerizing with an ester of another methacrylic acid.

Representative examples of other methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, and the like, and there is no special constraint on the molecular structure.

The ester consisting of an alcohol having a double bond in the molecule and acrylic acid or methacrylic acid contains a compound having one double bond in the alcohol residue and a non-conjugated carbon-carbon double bond. It is roughly divided into compounds having two or more. As typical examples of the former, allyl methacrylate, crotyl methacrylate, 2-methyl-2-propenyl methacrylate, 3-methyl-3-propenyl methacrylate, 2-methyl-2-butenyl methacrylate, 1,1
-Dimethyl-3-butenyl methacrylate and the like. Typical examples of the latter include geranyl methacrylate and geranyl geranyl methacrylate.

Aromatic ketones are roughly classified into compounds having a carbonyl group and compounds having two or more carbonyl groups. Examples of the former include acetophenone, benzophenone, benzaldehyde and the like. Examples of the latter include 3-benzoylbenzophenone and 3,3'-dibenzoylbenzophenone.

The material (c) used is appropriately selected depending on the purpose of use and the relationship with the intermediate layer.

In the present invention, the introduction of the intermediate layer and the selection of the material (b) constituting the intermediate layer are the most important. It is essential that the organic polymer material (b) has the following properties.

Polymer material forming phase grating or lens layer (a)
Is a material with different solvent solubility.

 The material must have the required transparency.

Be formed from an organic polymer material different from the substrate.

According to the research conducted by the present inventors, it was confirmed that the light transmittance and the transmitted wave front are good by laminating materials having different solvent solubilities. In the present invention, the term “solvent solubility is different” means that when a phase grating layer is formed after the intermediate layer is formed, the photosensitive polymer material (a It means that the solution of ′) can be applied.

In general, the solubility in a solvent can be quantitatively expressed by a solubility parameter defined by Polymer Handbook (2nd edition). In the present invention, the value of the solubility parameter of the organic polymer material (a) forming the phase grating or the lens layer and the value of the solubility parameter of the organic polymer material (b) forming the intermediate layer are 2.0 × 10 ^{− 3}
(J / m ³ ) ^1/2 or more different. The solubility parameter values of both are preferably 2.5 × 10 ^-3 (J / m ³ ) ^1/2 or more apart, and 3.0 × 10 ^-3 (J / m ³ ) ^1/2 or more apart. Is particularly preferable.

According to the present invention, when the intermediate layer is provided, not only the unevenness of the surface of the substrate (support) made of a commercially available organic polymer material is smoothed but also a layer such as a phase grating is essentially laminated. It is possible to achieve the uniformity of the layer such as the phase grating and to reduce the non-uniformity in the phase grating and the like. Therefore, a phase grating made of an organic polymer material can have a good transmitted wavefront and a good light transmittance.

The intermediate layer is not limited as long as it can achieve the above purpose. Therefore, the layer may be a single layer or a laminated structure of two or more layers. A laminated structure of two or more layers is used when higher performance is required than a single layer structure. For example, it is preferable to use a laminated structure of two or more layers for the purpose of improving the adhesiveness between the layers.

The material (b) for forming the intermediate layer is not particularly limited as long as it has the above-mentioned properties, but generally a relatively transparent resin is selected. Examples thereof are cellulose acetate, nitrocellulose, polyvinyl alcohol, polyurethane, epoxy resin, and poly (fluoroalkyl methacrylate). The material (b) to be actually used is arbitrarily selected in consideration of the above-mentioned purpose and the material of the substrate or the phase grating or the lens layer.

Hereinafter, configuration examples and manufacturing examples of the present invention will be described in detail with reference to the drawings.

Fig. 1 shows an example in which the middle layer 2 is a single layer, and Fig. 2 shows the middle layer.
2a and 2b are examples of multiple layers.

In these examples, the substrate 3 has an inexpensive thickness of 0.5 mm to 30 mm, such as polymethylmethacrylate or polycarbonate.
The plastic board is used. The substrate 3 is preferably, but not necessarily, baked at a temperature near the glass transition point (Tg) of the material. In FIG. 1, a material such as cellulose acetate, nitrocellulose, polyvinyl alcohol, etc. is selected for the intermediate layer 2. They are well soluble in solvents that do not dissolve the transparent polymeric materials used as layers for phase gratings, such as water, alcohols, and compounds such as dimethylformamide. Middle layer 2
If there is a problem with the adhesion to the substrate 3 as in the case of polyvinyl alcohol, a second intermediate layer 2b made of polyurethane, for example, is coated as shown in FIG. The solution is to coat layer 2a. The thickness of these intermediate layers 2a and 2b is usually 0.05 to 0.
It is 5 μm. The thickness of these intermediate layers 2a and 2b may be 0.01 to 10 μm depending on the case.

Then, as shown in FIG. 3, the photosensitive polymer compound layer 11 for forming the phase grating layer 1 is coated by a usual method using a solution prepared by dissolving the intermediate layer in a solvent which does not dissolve the intermediate layer. By exposing a pattern such as a desired phase grating and developing it according to the photosensitive polymer used, a transmission type phase grating having good transmitted wavefront and transmittance as shown in FIG. 1 or 2. (Or lens) is obtained. The thickness of the phase grating layer is usually 0.1 to 2 μm, but a wider range, for example, 0.01 to 10 μm can be used.

In the above description, a phase grating having a rectangular relief shape has been described, but a phase grating having any shape such as a sine wave shape or a triangular shape may be used. Further, the phase grating and the like may be of a refractive index distribution type, and include those having a non-linear grating shape such as a Fresnel lens.

In the present invention, the method of applying the intermediate layer 2 and the layer 1 such as the phase grating described above is not limited. A casting method, a bar coating method and the like are exemplified, but a spin coating method is simple and a uniform thickness can be easily controlled to obtain a uniform thin layer.

If desired, the phase grating of the present invention may be provided with an arbitrary upper layer (for example, protective layer 5) as shown in FIG. When the upper layer is applied, it is preferable to apply and dry a solution of a polymer compound dissolved in a solvent that does not substantially dissolve the layer such as the phase grating. When the upper layer is used as a protective layer or the like, a polymer compound having a refractive index different from that of the compound used for the phase grating or the like must be adopted.

Hereinafter, it will be described in more detail with reference to examples. The smoothness (wavefront aberration of transmission) in the examples was measured by a Fizeau interferometer (manufactured by Saigo).

Example 1 First, an equimolar copolymer of methyl methacrylate and crotyl methacrylate was synthesized. The solubility parameter of this copolymer was 19 × 10 ⁻³ (J / m ³ ) ^1/2 . A 4 wt% benzene solution is prepared by adding benzophenone in an equimolar amount to the crotyl methacrylate component in this copolymer, and this is designated as photosensitive resin solution A.

As the substrate 3, a polymethylmethacrylate plate having a thickness of 1 mm and a transmission flatness of 5 mm × 5 mm and a wavelength of 0.01λ (rms) was used. After washing with isopropanol, baking was performed at 110 ° C. for 1 hour, and the plate was allowed to cool. Solubility parameter 2 as the middle layer 2
A solution of 4.5 × 10 ⁻³ (J / m ³ ) ^1/2 of cellulose acetate dissolved in dimethylformamide was spin-coated and dried. At this time, the thickness of the intermediate layer 2 was 0.05 μm. Next, the photosensitive resin solution A was applied in a thickness of 0.9 μm, and then, using a 10 μm line-and-space mask as a photomask 4, irradiation was performed with a 500 W ultra-high pressure mercury lamp for 20 minutes to react the photosensitive polymer. Rear 0.2mm Hg, 100 ℃
A sublimation type phase grating was produced by sublimating benzophenone in the unreacted part exposed to light with a mask under the condition of. At this time, the transmittance of He-Ne light was 92.5% when all diffracted lights were combined, which was the same as that of the substrate 1 alone. Also, the transmitted wavefront aberration is 0.01λ (rm
s) was good and the adhesion was also good.

Example 2 Geranyl methacrylate having a solubility parameter of 18.8 × 10 ⁻³ (J / m ³ ) ^1/2 instead of the copolymer of crotyl methacrylate and methyl methacrylate in Example 1
In molar ratio of methyl methacrylate and α-methylstyrene
When a 1: 2: 1 copolymer was synthesized and a similar experiment was conducted, the same result was obtained.

Example 3 In Example 1, a solution prepared by dissolving nitrocellulose having a solubility parameter of 22.0 × 10 ⁻³ (J / m ³ ) ^1/2 in place of cellulose acetate in an intermediate layer 2 in a mixed solvent of isopropanol / dimethylformamide was spun. When the same operation was performed after coating and drying, the same result was obtained with a transmittance of 92.5%.

Comparative Example 1 When the same operation as in Example 1 was performed without coating the intermediate layer 2, the thickness of the phase grating layer was 0.9.
The thickness was not uniform up to 1.2 μm, and the transmitted wavefront aberration was 0.1λ (rms) or more in the range of 5 mm × 5 mm, which was a defect.

(Effects of the Invention) According to the present invention, although it is a phase grating made of an inexpensive plastic material, it is possible to provide a phase grating or a lens having good transmitted wavefront and transmittance. And, compared with the conventional glass substrate, the weight can be reduced to half or less, and further, the glass substrate requires polishing, which makes it difficult to process it into an arbitrary shape. Since the phase grating or the lens layer is also made of synthetic resin, the shape processing is very easy, and the phase grating or the lens having a very low cost can be obtained.

[Brief description of drawings]

1 to 4 are schematic sectional views of a phase grating or a lens according to the present invention. In the figure, 1 is a phase grating or a lens layer,
2, 2a and 2b are intermediate layers, 3 is a substrate, 4 is a photomask, and 5 is an upper protective layer.

Claims (3)

[Claims] 1. A phase grating or lens layer comprising (A) a transparent organic polymer material (a) (B) a solubility parameter value of the polymer material (a) is 2.0 × 10 ⁻³ (J / m ³ ) At least one or more intermediate layers made of organic polymer materials (b) having different solubility parameters by ^1/2 or more (C) The polymer material (b) for supporting the phase grating or the lens layer and the intermediate layer. And a transparent type phase grating or lens comprising a substrate made of an organic polymer material (c) different from the above. 2. The phase grating or lens according to claim 1, wherein the intermediate layer has a laminated structure of a layer for increasing adhesion and a layer for smoothing the surface. 3. A solution in which an organic polymer material (b) different from the polymer material (c) is dissolved on a substrate composed of the organic polymer material (c) having a sufficient thickness and strength for supporting. It was obtained by coating and drying to form an intermediate layer, and then dissolving the photosensitive polymer material (a ′) in a solvent.
The value of the solubility parameter of the polymer material (b) is 2.0
× 10 ^-3 (J / m ³ ) ^1/2 or more A solution having different solubility parameters is applied and dried, and then a phase grating or lens layer is formed by a photoreaction process. Manufacturing method.