JPS6195912A - Microlens molding method - Google Patents

Abstract

PURPOSE:To manufacture easily and inexpensively a microlens, by a method wherein a lens material is arranged on a mold having a through hole, press molding is performed under a state wherein the material is softened through heating, a part of the material is extruded within the through hole, which is made to cool and cure. CONSTITUTION:As for a top punch 1 made of a cylindrical metallic component, a predetermined lens surface shape 3 is formed precisely on one end face of the top punch 1. On the one hand, as for a bottom punch 2, a through hole 6 is provided on the central axis of the punch. As for the bottom punch 2, a platinum series metal is filmed on the inside of the through hole 4 and a plane part similarly to the top punch 1. The whole of lens material 5 arranged between the top and bottom punches 1, 2 is heated to a predetermined temperature wherein the lens material can be softened and deformed. Then the predetermined lens surface shape is made to transfer by applying predetermined pressure P to the punches. A part of the material 5 is extruded within the through hole 6, a convex-shaped lens surface 4' is obtained, and then the lens material 5 is made to cool and cure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for molding a microlens.With the recent progress in optical integrated circuits, this type of microlens has been developed by combining, for example, optical fibers and optical fibers. Microlenses are often used as a means for optically coupling a communication system to a fiber between a light emitting source such as a semiconductor laser, or between a light emitting source such as a semiconductor laser and an optical fiber, or as a means for forming an image using optical dots. In particular, the diameter of an optical fiber is Q, 1111 ~
Since it is extremely small at 0.2 mm, it is desirable from the viewpoint of coupling performance (efficiency) to perform optical coupling using a microlens with a diameter of several mm or less.

Conventional configurations and their problems Conventionally, when manufacturing microlenses as described above, there are two methods: (1) A method of polishing a glass material (2) A method of press molding with a mold having a predetermined lens surface (3) Extrusion molding method for plastic materials (4)
This has been done using methods such as injection molding of plastic materials.

However, method 1, that is, polishing the glass material, requires the assistance of a skilled person and is technically an extremely difficult task, so mass production and cost reduction are not very desirable. Also 2
This method has drawbacks such as difficulty in creating a mold having a lens surface shape.

On the other hand, when using plastic materials 3 and 4, the reproducibility is good;
Although this method is suitable for mass production and can reduce costs, it has the inherent drawbacks of plastics, such as the fact that the lens surface is easily scratched.

FIG. 7 is a sectional view of main parts showing the lens molding method of conventional example 2.
This will be explained as an example of trying to obtain a plane lens and a convex lens. A predetermined lens surface shape 3 is formed perpendicularly to the punch axis on one end surface of the upper punch 1 made of a cylindrical metal member.
The lens surface shape 4 of the lower punch 2 forms a surface opposite to the desired lens shape (convex surface), that is, a concave surface. Further, a spherical lens material 6 as shown in the figure is placed on the lens surface shape 4 of the lower punch 2, and the upper punch 1. Lower bunch 2. By heating the entire lens material 6 to a predetermined temperature and applying a predetermined pressure P through the upper punch 1, the lens material 6 is cooled and solidified to form a flat lens surface 3' and a flat lens surface 4 as shown in FIG. The desired molded lenses 7 each having a convex surface are obtained. However, as the outer diameter of the lens becomes smaller (the diameter is 2u or less), it is technically extremely difficult to precisely process the concave lens surface shape 4 such as the lower punch 2, and the manufacturing cost becomes high.

OBJECTS OF THE INVENTION The present invention has been devised to overcome the various drawbacks mentioned above, and proposes a method by which microlenses can be easily and inexpensively manufactured without the use of skilled workers.

Structure of the Invention The microlens molding method of the present invention includes providing a through hole in the pressing surface of at least one of a pair of molds for press molding;
The lens material is prepared by placing the lens material on a mold having the through hole, and press-molding the lens material through the other tm while the lens material is heated and softened to a predetermined temperature. After a part of is extruded into the through hole provided in the mold,
This microlens molding method is characterized in that the lens material extruded into the through hole has a desired lens surface shape by cooling and solidifying the lens material.

A description will be given below with reference to drawings shown as examples. .

Description of Embodiments (First Embodiment) FIGS. 1 and 2 are cross-sectional views of main parts during lens molding in the first embodiment of the present invention, in which an upper punch made of a cylindrical metal member is 1, a predetermined lens surface shape 3 is formed with high precision on one end surface thereof in a shape perpendicular to the punch axis.

In this example, upper punch 1 is used to obtain plane and convex lenses.
The lens surface shape 3 is processed to be flat and mirror-finished, and a film of platinum-based metal is formed by a sputtering method to improve mold releasability from the lens material.

On the other hand, the lower bunch 2 is provided with one through hole 6 on the punch center axis. The diameter of this through hole 6 is precisely machined to be the same diameter as the outer diameter of the lens to be obtained, and like the upper punch 1, the inner surface and plane of the through hole 4 of the lower punch 2 is coated with platinum-based metal. The film is formed by sputtering. After placing the flat transparent lens material 5 over the through hole θ of the lower punch 2, the entire molding block, that is, the upper punch 1. The lower bunch 2 and the entire lens material 5 placed between the upper and lower punches are heated to a predetermined temperature at which the lens material can be softened and deformed. Next, a predetermined pressure P is applied via the lens surface shape 3 of the upper punch 1 to transfer the predetermined lens surface shape onto the softened lens material 6. In this case, the lens surface shape 3 of the upper punch 1 is transferred into a flat shape, but on the lower bunch 2 side, a part of the softened lens material 5 is regulated in the radial direction of the through hole 6 and is transferred into the through hole 6. It is extruded to have a convex lens surface 4' as shown in FIG. Thereafter, the lens material 5 is cooled and solidified to complete the lens molding process.

In other words, the function of the through hole 6 is to form the lens surface shape on the lower punch of the conventional example and transfer the lens surface shape to the lens material, whereas in this embodiment, the lens surface shape is transferred to the softened lens material through the upper punch. While applying pressure P and regulating the extruded lens material 6 by the diameter of the through hole 6, inside the through hole 6,
This takes advantage of the fact that the free surface (the surface not in contact with the mold) of the lens material 6 has a convex shape. In the case of this example,
SF-based lead glass with a plate thickness of 1 all is used as the lens material 6, and the diameter of the through hole 6 is 1.01n11, and the pressing temperature is 690°.
Pressure molding was carried out for 6 minutes by applying a C1 pressure of 20Kyf to obtain a molded lens 7 shown in FIG. 3. In the molded lens 7, the lens surface shape 4' in particular is determined by the molding temperature, pressing force, pressing time, the viscosity of the lens material at a predetermined temperature, the thickness, the deformation amount, and the precision of the through hole 6.

Lens surface 3/ of the molded lens obtained as described above
, the shape accuracy of 4/ was measured with a Zygo interferometer and was 1
The roller has a radius of curvature of about 0.6811 with a roller of about λ to 2λ (He-Na laser), and can be sufficiently used as a single lens. For example, when light from a light emitting source 8 such as a semiconductor laser is incident on an optical fiber 9 using a molded lens 7 as shown in FIG. there were.

(Second Embodiment) In the first embodiment, only one through hole was provided in the mold, but in the embodiment shown in FIG. 6, a plurality of through holes are arranged in two rows at a predetermined pitch interval. (not shown) or a mold with a rectangular long through hole (not shown)
Here is an example using . In either case, the doublet lens 12 shown in FIG. 6 and the cylindrical lens 13 shown in FIG. 10
．． It has a cylindrical surface 11. The lens thus obtained can be used as an image forming means (for example, a copying machine) using optical dots. As explained in the above embodiments, by providing through holes on the mold surface, the surface shape of the mold can be changed, and the through holes in the above embodiments can have any shape and arrangement. They may be placed on each mold surface. Also, the through hole may be a hole with a bottom. Furthermore, although glass was chosen as the lens material, it is of course possible to mold transparent resin materials such as acrylic and polycarbonate by selecting the optimal molding temperature.

Effects of the Invention As described above, the present invention allows microlenses to be easily and inexpensively molded using glass materials.

Regardless of the plastic material, stable microlenses can be manufactured by keeping the optimal conditions constant.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of essential parts showing an embodiment of the present invention, FIG. 3 is a diagram showing a molded lens obtained by an embodiment of the present invention, and FIG. 4 is a cross-sectional view of a molded lens obtained by an embodiment of the present invention. Figures 6 and 6 are perspective views of molded lenses obtained according to other embodiments of the present invention, and Figures 7 and 8 are conventional examples. FIG. 1...Upper haunch, 2...Lower punch, 3
, 4... Lens surface shape, 3', 4', 10.1
1... Lens surface, 6... Lens material,
e...Through hole, 7,12゜13...Molded lens, 8...Light source, 9...Fiber.

Claims (3)

[Claims] (1) A lens material is placed on a pair of molds each having a through hole in at least one of the lens material pressing surfaces, and while the lens material is heated to a predetermined temperature at which it can be molded, the lens material is placed through the mold. The lens material is extruded into the through hole by press-molding the lens material, and then cooled and solidified so that the surface shape of the lens material has a desired lens surface shape. Microlens molding method. (2) A microlens molding method according to claim 1, in which a plurality of microlenses are obtained by using a mold having a plurality of through holes arranged therein. (3) A microlens molding method according to claim 1, in which a mold having elongated through holes is used to obtain a cylindrical surface microlens.