JPS6375708A - Manufacture of distributed thickness film - Google Patents

Abstract

PURPOSE:To enable manufacture of a distributed thickness film having a large change of the film shape by producing a difference in the concn. of the photoreaction forming material in a photoreactive material by local photoirradiation and making use of the permeation having the tendency to decrease said concn. difference. CONSTITUTION:This method utilizes the permeation which appears between a solvent and soln. isolated by a semipermeable membrane. Light 3 is projected to the film 1 consisting of the photoreactive material M by using a mask 2. A resultant product (m) of photoreaction is formed from the photoreactive material M in the irradiated region R of the film 1 but an increase in the concn. of the resultant product (m) of photoreaction is caused in the irradiated region R by the photoirradiation if the photoreactive material M has a solvent-like property to the resultant product (m) of photoreaction. The permeation having the tendency to decrease said concn. difference, thereupon, arises at the boundary B between the irradiated region R and the unirradiated region Q so that the photoreactive material M migrates from the region Q to the region R. As a result, a film thickness difference (h) arises between the region R and the region Q.

Description

[Detailed Description of the Invention] [Summary] A method for producing a thickness distribution film, in which a film made of a photoreactive substance is locally irradiated with light, and the photoreaction occurs in the light irradiated area and the non-light irradiated area. It is possible to change the shape of the film at the boundary between the light-irradiated area and the non-light-irradiated area by creating a difference in the concentration of the photoreaction product in the chemical substance, and by an osmosis phenomenon that attempts to reduce the difference in concentration. do.

[Industrial application field]

The present invention relates to a method for manufacturing lenses, optical waveguides, diffraction gratings, etc. used in optical devices for optical communications, and more specifically, to a method for causing changes in their shapes.

Short-focus microlenses such as microlens arrays for sensors and microlenses for CDs are desired for optical devices for optical communication. Further, it is desired that the leading waveguide has a small J] loss and that the diffraction grating has high efficiency. In response to this, a method has been developed in which lenses and the like are manufactured by locally irradiating an organic polymer film with light, but in order to meet the above requirements, it is necessary to increase the change in the shape of the film.

[Conventional technology]

The conventional method for producing film shape distribution films is to locally irradiate a film uniformly mixed with photoreactive substances to create a distribution of photoreaction products, and then remove unreacted photoreactive substances by annealing. Accordingly, there are two methods: one method is to create a thickness distribution film, and the other is a method that utilizes only the diffusion of the photoreactive substance from the non-light irradiated area to the light irradiated area.

The former is used to fabricate optical waveguides, and the latter is used to form holograms, but this method was originally used to make the light distribution the density distribution (refractive index distribution) of the film, and changes in the shape of the film are extremely difficult. small.

[Problem that the invention seeks to solve]

The conventional method described above has the disadvantage that it is not possible to greatly change the shape of the film.

The present invention was created in view of the above points, and an object of the present invention is to provide a method for manufacturing a thickness distribution film having a large change in film shape.

[Means for solving problems] FIG. 1 is a diagram for detailed explanation of the present invention.

In the present invention, as shown in FIG.
is irradiated, and a photoreaction product m is generated from the photoreactive substance M in the light irradiation region R as shown in FIG. 1, thereby forming a thickness distribution film.

[For production]

The effect of the present invention is almost the same as the osmosis phenomenon that occurs when a solvent and a solution are separated by a semipermeable membrane 4, as shown in FIG. 1C, and the difference is that the solute is a chemical change of the solvent. This chemical change is caused by light irradiation, and the semi-permeable membrane action prevents the photoreaction product m from moving in the non-light irradiated region Q.

That is, in FIG. 1, the membrane 1 contains a photoreactive substance M that generates a photoreaction product m upon irradiation with light, and this photoreactive substance M has solvent-like properties for the photoreaction product m. When the photoreaction product m is generated in the light irradiation area R by light irradiation,
As a result, a phenomenon of penetration occurs to dilute this concentration at the boundary B between the light-irradiated region R and the non-irradiated region Q, and the photoreactive substance M is transferred from the non-irradiated region Q to the light-irradiated region. Move to area R. As a result, a difference in film thickness occurs between the light irradiated area R and the non-light irradiated area Q.

〔Example〕

This embodiment will be explained with reference to FIG. The film 1 consists of a photopolymerization reactant iM and a binding polymer P. As the substance M, a substance is selected that diffuses in the film, and a mixture M + m of the substance M and a low polymerization degree polymer m obtained by irradiating the substance with light is a liquid upon irradiation with light.

The polymer P is selected so as to effectively exhibit a semi-permeable membrane action at the boundary B between the light irradiated region R and the non-light irradiated region Q.

By irradiating this with light, the volume of the light irradiated region R will expand until the photopolymerization reaction substance M in the film is exhausted. The volume of the irradiation area R can be increased.

〔Effect of the invention〕

As described above, according to the present invention, a penetration phenomenon occurs due to light irradiation, so a large change in membrane shape can be obtained.
Furthermore, in a system that excludes external forces such as gravity, the volume expansion continues until the photoreactive substance M in the film is depleted, causing a large change in shape. It is possible to form a film with a thickness distribution, and is extremely useful in practical terms.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention in detail. In FIG. 1, 1 is a film, 2 is a mask, 3 is light, M is a photoreactive substance, m is a photoreaction product, and R is light irradiation. area, Q is the unirradiated area, B is the semi-transparent film, and h is the difference in film thickness.

Claims (1)

[Claims] 1. Locally irradiating a film (1) made of at least a photoreactive substance (M) with light;
A difference appears in the concentration of the photoreaction product (m) in the photoreactive substance (M) between the light irradiated area (R) and the non-light irradiated area (Q). A film thickness distribution characterized in that a permeation phenomenon that attempts to reduce the concentration difference appears at the boundary (B) between the light irradiated region (R) and the non-light irradiated region (Q), thereby changing the film shape. Membrane preparation method.