Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Utilizing plasma – electric – electromagnetic – particulate – or...
Reexamination Certificate
2002-04-19
2004-11-09
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Utilizing plasma, electric, electromagnetic, particulate, or...
C264S001700, C156S099000, C359S741000, C359S362000
Reexamination Certificate
active
06814901
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microlens array typically used in the fields of optical communication and optical packaging for coupling light emitted from a light source to an optical fiber or an optical waveguide, converting light emitted from the optical fiber or the optical waveguide into parallel rays or so focusing light beams to enter the optical fiber or the optical waveguide in an optical coupling system.
2. Related Art of the Invention
The microlens in general represents a fine lens having a lens diameter of not more than a several millimeters. Various methods relating to the microlens array including methods for manufacturing the same have been proposed in the art. The ion exchange diffusion method is widely known as a method for manufacturing the microlens array. In the ion exchange diffusion method, a dopant ion is selectively diffused on a multicomponent glass substrate.
The conventional ion exchange diffusion method will be described below with reference to
FIGS. 14A
to
14
C. As shown in
FIG. 14A
, an ion exchange control membrane
102
is firstly formed on a surface of a multicomponent glass substrate
101
containing a monovalent ion. The ion exchange control membrane
102
may be a metal membrane or a dielectric membrane. Next, an array of circular apertures
103
at a predetermined pitch that is equivalent to that of an LD array or a PD array is formed on the ion exchange control membrane
102
using a photolithographic technique or a etching technique. The diameter of a lens prepared according to this method is determined by each of the apertures
103
, and the apertures function as light-shielding membrans for reducing crosstalk between adjacent channels.
High temperature molten salt
104
shown in
FIG. 14B
containing a dopant ion that will contribute to ascending in refractive index. The dopant ion may include Tl, Ag and Pb, each having a high degree of refractive index. Then, the glass substrate
101
that is coated with the ion exchange control membrane
102
having the circular apertures
103
is immersed in the molten salt
104
so that the dopant ion is selectively diffused on the glass substrate
101
through the apertures
103
on the ion exchange control membrane
102
to thereby form ion exchange areas
105
each having a hemispheric diffusion front. The ion exchange areas
105
serve as distributed refraction type lenses according to a dopant ion distribution. Here, as a result of selecting the dopant ion having the ion radius that is larger than that of the ion contained in the glass substrate
101
, the surface of the substrate
101
is expanded according to the volumetric difference between the ions to form convex lenses
106
shown in
FIG. 14C. A
diameter of each of the convex lenses
106
is typically in a range of from a several tens of microns to a several hundreds of microns.
The above-illustrated ion exchange diffusion method is suitable for forming a microlens having a diameter of from a several tens of microns to a several hundreds of microns; however, problems have been found with the method in manufacture of a microlens having a relatively large lens diameter or a lens effective diameter of from a several hundreds of microns to a several millimeters. More specifically, in order to prepare the relatively large microlens employing the ion exchange diffusion method, a depth of the diffusion must be a several hundreds of microns or more that is about the same as the size of the lens to be produced and it is necessary to conduct a heat treatment at a high temperature for a remarkably long time. Thus, in the ion exchange diffusion method, it is difficult to prepare lenses of a wide range of sizes having diameters from a several tens of microns to a several millimeters and, also, it is impossible to produce a microlens array having a focal length that is about the same as that of the diameter of the lens. Therefore, downsized and high-performance optical coupling elements have not been realized by the use of the ion exchange diffusion method.
SUMMARY OF THE INVENTION
In view of the above problems, an object of the present invention is to provide a method of manufacturing a microlens array that realizes downsized and high-performance optical coupling elements to be used in the fields of optical communication and optical packaging.
One aspect of the present invention is a method of manufacturing a microlens array comprising forming microlenses by dropping or injecting to a plurality of through holes formed on a substrate a liquefied lens material so as to dispose the lens material at each of the through holes, the lens material being curable and has a predetermined transmittivity and a predetermined viscosity.
Another aspect of the present invention is the method of manufacturing a microlens array, wherein a curvature of each of the microlens is varied by adjusting whole or part of (1) configurations or sizes of the through holes of the substrate, (2) wettability between the substrate and the lens material, (3) a viscosity of the lens material and (4) a quantity of lens material in a droplet or in an injection shot.
Still another aspect of the present invention is the method of manufacturing a microlens array, wherein the lens material is dropped or injected substantially simultaneously by using nozzles that can drop or inject the lens material substantially simultaneously to the through holes.
Yet still another aspect of the present invention is the method of manufacturing a microlens array, wherein the lens material is a ultraviolet ray curable resin material, a thermosetting resin material, a thermoplastic material or a glass material.
Still yet another aspect of the present invention is the method of manufacturing a microlens array according to 1st invention, wherein each of the through holes has a truncated conical shape or a step portion.
A further aspect of the present invention is the method of manufacturing a microlens array, wherein the microlenses are convex lenses.
A still further aspect of the present invention is the method of manufacturing a microlens array according to 1st invention, wherein the microlenses are concave lenses.
A yet further aspect of the present invention is the method of manufacturing a microlens array, wherein all refractive indexes and/or a transmittivities of the lens materials to be dropped or injected to the plurality of through holes are not same.
A still yet further aspect of the present invention is the method of manufacturing a microlens array, wherein a whole or a part of the plurality of through holes vary in size, and the lens material is dropped or injected in accordance with the sizes of the through holes.
An additional aspect of the present invention is the method of manufacturing a microlens array, wherein the plurality of through holes are arranged on the substrate to give a closest packed structure, each of the through holes having the shape of a hexagon of a predetermined size.
A still additional aspect of the present invention is the method of manufacturing a microlens array, wherein the substrate is formed from silicone, a plastic material, a glass material, ceramic material, fiber material or a composite material.
A yet additional aspect of the present invention is a microlens multilayer formed by laminating a plurality of microlens arrays produced by the method of manufacturing a microlens array according to any one of 1st to 11th inventions, wherein the plurality of microlens arrays are so laminated that optical axes of the microlenses of each microlens array coincide with the optical axes of the corresponding microlenses of another microlens array.
A still yet additional aspect of the present invention is a microlens array comprising a substrate in which a plurality of through holes are formed and a plurality of microlenses respectively disposed at the through holes in the substrate, wherein
the microlenses are fixed to the through holes of the substrate by way of adhesion or deposition of a microlens material to a sub
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
Vargot Mathieu D.
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