JPS6072927A - Production of polymer microlens - Google Patents

Abstract

PURPOSE:To produce a polymer microlens in good yield, by selectively irradiating with light an optical medium containing a photopolymerizable monomer which, when formed into a polymer, changes in its refractive index. CONSTITUTION:An optical medium 10, i.e. a mixture of a matrix (e.g., bisphenol Z-derived polycarbonate) a photopolymerizable monomer (e.g., methyl acrylate), a solvent (e.g., methylene chloride), a photosensitizer, etc., is poured into a casting container 1 (numeral 2 is a level) and dried to form a sheet-like transparent semi-solid film. A mask 3 whose light transmission is uniformly high outside the circular area 3a, is decreasing toward the center of the circular area, and decreases to nearly zero at the center is laid on the above semi-solid film. Light is transmitted through the mask 3 to polymerize the monomer in response to the intensity of the light. The whole casting container is transferred to a vacuum drier to dry the semisolid film into a flat microlens.

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention The present invention relates to a method for manufacturing microlenses using polymeric materials.

Traditionally, various optical systems have often used lenses with an uneven outer shape, such as convex lenses or concave lenses, but such lenses require a holding mechanism, so it is difficult to use a large number of lenses lined up in a flat shape. In such a case, there are problems in that it takes up a large amount of space and the holding mechanism becomes complicated.

Furthermore, it has not been possible to integrally manufacture a plurality of lenses having such uneven shapes.

Key Points of the Invention The present invention provides a method by which lenses of any size, in any number, and in any arrangement can be manufactured by using a polymeric material.

The method for producing a polymer microlens according to the present invention is to form an optical medium containing a monomer that is polymerized by light irradiation and whose refractive index changes when polymerized into a film, and to apply light intensity in the plane direction on at least one surface of the optical medium. It is characterized by emitting light with a distribution. In order to create a light intensity distribution of irradiation light, it is preferable to use a mask having a light transmittance distribution in the surface direction.

The degree of polymerization of the polymer varies depending on the amount of light irradiation, and the refractive index also varies accordingly. Therefore, the optical medium has a refractive index distribution in its surface direction that corresponds to the light transmittance of the mask. If we create a refractive index distribution where the equirefractive index curve is circular and the refractive index increases toward the center, we can create a lens equivalent to a convex lens that converges light, and conversely, the refractive index decreases toward the center. By doing this, you can create a lens equivalent to a concave lens that diffuses light. Furthermore, it is also possible to manufacture a lens with an elliptical equirefractive index curve, or a lens equivalent to a cylindrical lens with an equirefractive straight line.

It is possible to manufacture lenses of any shape and size depending on the spread of the intensity distribution of the irradiated light, that is, the spread of the light transmittance distribution of the mask, and moreover, it is possible to manufacture a lens of any shape and size according to the spread of the intensity distribution of the irradiated light. Any number of lenses can be fabricated in any combination on top in any arrangement.

DESCRIPTION OF THE EXAMPLE In this example, a monomer is used which has a low refractive index when photopolymerized to form a polymer.

As shown in Figure 1, a base A/Z system where the leading wavepath is formed, f+-*ne-) (PCZ) 70F, methyl acrylate (MA) 42m/m/m as a monomer, and methylene chloride (CH2CI) as a solvent. !2) looof.

Benzoin ethyl ether (BZEE) as a photosensitizer
2.19. Hydroquinone (HQ) 0 as an anti-scattering agent
, 07 f. The amount of solution αQ is adjusted so that the film thickness is 100 μm. This film thickness may be determined depending on the size of the lens to be formed, etc., and can be set to an arbitrary thickness, for example, from about 10 μm to 100 μm. The level (2) is used to adjust the level of the liquid to keep it level.

FIG. 3 shows the change in refractive index (degree of polymerization) with respect to the amount of light irradiation of an optical medium as shown in FIG.

The greater the amount of light irradiation, the more polymerization progresses and the refractive index changes. It is possible to control changes in the refractive index by adjusting the amount of light irradiation.

FIG. 2 shows an example of a mask used in lens manufacturing. The mask (3) has a circular part (3a) in the center of which the light transmittance is distributed. The light transmittance decreases toward the center within this circular portion (3&), and Gt is almost zero at the center. The isolight transmittance curve T is circular and concentric. Circular part (3
In the outer region of a) the light transmission is maximum and uniform.

After pouring the optical medium a into the cast container (1), the cast container (1) is semi-closed and nitrogen gas is flowed at 100 ml/min for 100 minutes, followed by monomer vapor for 20 minutes to remove the solvent and monomer. A part of it is evaporated to form a sheet-like transparent semi-solid film.

Next, a mask (3) is placed on the sheet-like optical medium αθ,
Uniform parallel light generated from an ultraviolet exposure device is continuously irradiated from above to below the cast container (1) for about 15 minutes. As a result, the circular part (3&
), the part with the lowest light transmittance is hardly irradiated with ultraviolet rays, and the amount of irradiated light increases as it goes to the periphery, so the refractive index is highest in the center (mostly (not polymerized), and as it goes to the periphery, a 7' (roal) layer with a decreased refractive index is formed.Mask (3
) by appropriately determining the light transmission weight distribution of the circular part (3a) of (corresponding to a lens) by considering the graph in Figure 3.
can be obtained. The other portion of the optical medium a[I becomes a substrate with the smallest refractive index.

As a post-processing, after exposure, leave it at room temperature for 30 minutes or more, then transfer the entire cast container to a vacuum dryer and dry at 90℃ for about 5 minutes.
Dry for an hour.

Such a flat lens has a diameter of 10 μm to 1000 μm.
It is possible to fabricate lenses up to the same diameter, and if a mask is used that has a large number of circular parts with a light transmission weight distribution, about 1 to 10 lenses can be lined up on one substrate. A lens substrate with such a large number of lenses arranged is used, for example, when condensing light emitted from an array of light sources (such as an LED array), or to create a light spot on each light receiving element of a light receiving element array. It can be applied in various cases. As shown in FIG. 4, it is also possible to adjust the focal length of the lens by laminating substrates each having a lens (lOβ).

In the above embodiment, light is irradiated from above to below, but the mask (3) is placed outside the bottom of the cast container (11), or the bottom of the cast container ti+ is used as a mask to direct the light from below to above. -You may also irradiate light.If you use a mask with a circular part where the light transmittance increases toward the center, you can create a lens equivalent to a concave lens that diffuses light.Also, you can irradiate light from both the top and bottom sides. It's okay.

In the above embodiments, a monomer whose refractive index decreases when photopolymerized is used, but it is also possible to use a monomer whose refractive index increases. Even by using such a monomer, lenses having both convex lens function and concave lens function can be produced.

Furthermore, it is possible to manufacture lenses having an arbitrary refractive index distribution such as an elliptical refractive index cloth. The refractive index increases toward the center.If you create a lens with an elliptical refractive index curve, you can make light that spreads anisotropically, such as a laser beam emitted from a semiconductor laser, into a perfect circle. It becomes possible.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the manufacturing process of the 4-ear lens according to the present invention.
Fig. 2 is a diagram showing an example of a mask, Fig. 3 is a graph showing changes in refractive index (degree of polymerization) with respect to the amount of light irradiation, and Fig. 4 is a perspective view showing an application example of the lens manufactured according to the present invention. be. (11...Fist cast container, +31-...Mask, (
3m)...Circular part with light transmittance distribution, optical medium, (lOa)...lens. Other 4 people Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) An optical medium containing a monomer that is polymerized by light irradiation and whose refractive index changes when polymerized is formed into a film, and at least one surface of the optical medium is irradiated with light having a light intensity distribution in the surface direction. , a method for manufacturing polymer microlenses. Method for manufacturing molecular microlenses.