JP2001166117A - Method of producing glass optical elements - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a large number of glass optical elements such as microprisms at a time and to improve the productivity. SOLUTION: The method of producing glass optical elements includes step 201 to press-form a glass material with molding dies including at least an upper die 32 and a lower die 31 to obtain a glass body 40 having first and second faces of a desired form and surface accuracy formed by the upper and lower dies and having a plurality of recesses and projections on at least the first face 40b, and step 203 to cut and separate the glass body into a plurality of products each containing at least one of the recesses and projections of a specified form on the first face 40b and containing at least a part of the second face so as to obtain a plurality of glass optical elements 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing glass optical elements such as microprisms, microlenses, and diffraction gratings used in laser couplers and other optical devices, and more particularly to a glass suitable for improving its mass productivity. The present invention relates to a method for manufacturing an optical element.

[0002]

2. Description of the Related Art Microprisms, microlenses, and diffraction gratings are widely used in laser couplers and other optical devices. FIG. 1 shows an example of a microprism used in a laser coupler or the like. As shown in the figure, the microprism 10 transmits a light incident surface (hereinafter, a light incident surface 11), and transmits at least a part of light incident from the light incident surface 11 and refracted at a predetermined angle, and passes the rest. A reflecting surface (hereinafter, a first reflecting surface 12), a surface transmitting the light reflected by the first reflecting surface 12 (hereinafter, a second reflecting surface 13), and a first reflecting surface 12;
At a predetermined angle (90 degrees in the illustrated example) with respect to
And a surface 15 between the light incident surface 11 and the first reflecting surface 12.

When the microprism 10 is used for a laser coupler, the first and second reflecting surfaces 12 and 13 are used.
A plurality of photodiodes 16 are arranged in parallel with each other, and the state of incident light is detected based on the signal intensity of each photodiode 16.

Conventionally, when manufacturing this kind of microprism, a rectangular rod-shaped glass material having a size close to the external dimensions of the microprism is prepared, and one of the corners is ground and polished to form the light incident surface 11. After formation, it is common practice to separate and cut in the longitudinal direction to obtain a microprism.

[0005]

However, such a conventional method for manufacturing a microprism has the following problems. (1) It is necessary to process the light incident surface 11 for each square rod-shaped glass material, and the productivity is not always high. (2) The processing accuracy of each glass material is not constant due to the processing of each square rod-shaped glass material, and the quality of the manufactured microprisms may vary. Also, the bending or twisting of the square rod-shaped glass material may cause variations in the surface accuracy of the light incident surface 11.

On the other hand, mass production of microlenses and diffraction gratings is also a problem. That is,
The microlenses are manufactured one by one by melting and softening a spherical glass preform and pressing them in a mold having a molding surface along the optical surface of the lens to be produced. Also,
The diffraction grating forms a plurality of concavo-convex patterns by photolithographic etching on a glass substrate (ie, forming a light-shielding film on the glass substrate, exposing the glass to light and exposing the glass, and then etching away the portion). Then, it is manufactured by cutting and separating this into individual diffraction grating units later. Recently, a method of press-forming individual diffraction gratings has also been proposed (for example, Japanese Patent Application Laid-Open No. 10-3).
37734). These manufacturing methods have a problem in the productivity and the uniformity of the quality, similarly to the problems in the above-described conventional method for manufacturing a microprism.

Accordingly, an object of the present invention is to provide a manufacturing method capable of manufacturing a number of glass optical elements such as microprisms at the same time and significantly improving the productivity.

Another object of the present invention is to provide a manufacturing method capable of maintaining a constant quality by simultaneously manufacturing glass optical elements such as a large number of microprisms.

[0009]

According to a method of manufacturing a glass optical element of the present invention, a glass material is formed by press molding a glass material with at least a molding die including an upper die and a lower die. Obtaining a glass body having first and second surfaces having a desired shape and surface accuracy, wherein a plurality of irregularities having a predetermined shape are formed on at least the first surface;
Including at least one irregularity of a predetermined shape on the first surface,
In addition, the method includes a step of obtaining a plurality of glass optical elements by cutting and separating the glass body into a plurality of pieces so as to include a part of the second surface.

In this case, before the step of cutting and separating the glass body into a plurality of pieces, a step of polishing the second surface so that the glass optical element to be obtained has a desired optical function. It is preferred to do so.

Further, the present invention provides a glass body having a first surface and a second surface opposite to the first surface, wherein at least the first surface is provided with a plurality of irregularities of a predetermined shape. Polishing the second surface so that the glass optical element to be obtained has a desired optical function;
A plurality of glass optical elements by cutting and separating the glass body into a plurality of pieces so as to include at least one irregularity of a predetermined shape of the surface and to include a part of the polished second surface. Is obtained.

Here, it is preferable that the glass body is obtained by press-molding a glass material with a molding die having a molding surface corresponding to the irregularities of the predetermined shape.

Further, it is preferable that the glass material to be pressed is obtained by heating and softening a glass plate formed in a predetermined shape in advance.

In the polishing step, the glass body may be
This is performed by flat-polishing one or both of the second surfaces of the glass body in a state where a plurality of the glass bodies are prepared and stacked with the first surface on which the irregularities of the predetermined shape are formed facing inside. preferable.

[0015] In this case, the superimposed state is such that the projections of the irregularities of the predetermined shape on one glass body are overlapped with the concaves of the irregularities of the predetermined shape on the other glass body. be able to.

Further, it is preferable that at least a part of the irregularities having the predetermined shape has an optical function.

[0017] The irregularities having the predetermined shape may be constituted by a first plane and a second plane having a predetermined angle with respect to the first plane.

Further, the glass body preferably has a thickness of 2 mm or less at the convex portion of the predetermined shape, and the glass body after performing the polishing step has a thickness of the convex portion of the predetermined shape. Is preferably 0.7 mm or less.

It is preferable that the glass body has a thickness of 1 mm or less at a concave portion of the irregularities of the predetermined shape.

In the polishing step, the surface accuracy of a plane, which is a functional surface of the optical element, is set to λ / 2 or less (where λ is the wavelength of light incident on the glass optical element to be manufactured). Is preferably polished.

In the present invention, before the polishing step, a heat treatment step of heat-treating the press-molded glass body for a predetermined time may be further provided.

Here, the heat treatment step is preferably carried out at a temperature near the transition point of the glass constituting the glass body.

In the present invention, preferably, the glass optical element is a micro prism.

Preferably, the glass optical element is a micro lens or a diffraction grating.

According to the present invention, after the glass optical element is manufactured by any one of the above methods, the glass optical element and a light receiving element for reading a signal obtained by reflection and / or refraction of light by the glass optical element are further provided. The present invention relates to a method for manufacturing an optical device including a step of combining an element.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on one embodiment shown in the drawings. In the present embodiment, the present invention will be described along a method for manufacturing the microprism shown in FIG. However, the specific shape of the microprism that can be manufactured by the manufacturing method of the present invention is not limited to that shown in FIG. 1, and the manufacturing method of the present invention applies not only to the microprism but also to other glass optics. It can be widely applied to the manufacture of elements such as microlenses and diffraction gratings. The following description will make this clear.

FIG. 2 is a flowchart showing each step in the manufacturing method of the present invention. The manufacturing process according to the present invention includes a process 201 of pressing a plate-shaped glass substrate using a pair of molds. As will be described later in detail, a pair of molds used in this press has one having a flat molding surface, and the other has an angle formed by the first reflection surface 12 and the surface 14 shown in FIG. It has a saw-tooth shaped molding surface with peaks formed at 90 degrees. By press molding using these molding dies, the plate-shaped glass substrate is rolled and, at the same time, one surface thereof is processed into a shape along the saw-tooth-shaped molding surface. The glass substrate formed by the press forming is hereinafter referred to as a prism array. A material suitable as a material for the microprism to be manufactured is adopted as a material for the glass substrate. For example, as a material of the glass substrate, glass of SiO 2 -alkali oxide-alkaline earth oxide used for glass for various substrates and other various optical glasses can be used.

FIG. 3 schematically shows how a glass substrate is pressed using the pair of molds. Figure (A)
As shown in FIG. 5, a plate-shaped glass substrate 3 that has been heated to a predetermined temperature and softened in advance on a molding die 31 having a flat molding surface 31a and heated to a predetermined temperature (for example, 700 degrees).
0 is placed. From above, the glass substrate 30
The mold 32 heated to a predetermined temperature and having the saw-toothed molding surface 32a is lowered, and the glass substrate 30 is pressed by the pair of molds 31 and 32. Mold 3
After lowering the temperature of 1 and 32 and maintaining this state until the glass substrate 30 reaches a predetermined temperature or lower, the forming die 32 is raised, and the pressed glass substrate 30 is naturally cooled, and then is carried out of the die. Through the pressing step 201, a prism array 40 as shown in FIG. 4 is obtained.
In a preferred embodiment, the size of the glass substrate is 20 ×
The size of the prism array formed by pressing is 27 × 1.28 mm, the total thickness H is 1.39 mm, the height h of the sawtooth portion is 0.45 mm, and the pitch P is 0.95 mm.
It is. Also, the material of the mold used is super hard,
The molding surface can be coated with a carbon-based release film.

In FIG. 2, the next manufacturing step according to the present invention is a step 202 of grinding and polishing the above-mentioned pressed prism array. In the micro prism finally manufactured, the light incident surface 11 must be processed to the required predetermined surface accuracy. In a preferred embodiment, when the wavelength of light incident on the microprism array to be manufactured is λ, the light incident surface 11 is λ / 2
Processed below. In the present invention, the surface on the prism array corresponding to the light incident surface 11 is a flat surface (surface 40a in FIG. 4) formed by a mold having the flat molding surface. In this step 202, the prism array is fixed on a base, the flat surface of the prism array is ground to a required size, and then polished to a predetermined surface accuracy.

One important factor in grinding and polishing the surface of the prism array is to uniformly grind and polish the entire area. The prism array has a thickness of 2 mm or less, and the other surface is processed in a saw-tooth shape. Therefore, in processing using a generally used flat base, in the case of the grinding and polishing, The surface may be slightly curved by a load applied to the prism array. The slight curvature reduces the uniformity of the grinding and polishing in this step, so that it must be avoided as much as possible.

FIGS. 5 and 6 show respective steps of grinding and polishing according to an embodiment of the present invention for avoiding the above-mentioned problem. The methods shown in these figures simultaneously use the two prism arrays manufactured in the pressing step 201. In this method, a pair of prism arrays are basically overlapped with their serrated surfaces facing each other and integrated with each other, and the outer flat surface is sequentially ground and polished in this state.
That is, as shown in the step 501 and FIG. 6A, the first prism array 40A is fixed on the base 60 such that the flat surface 40a faces down. Next, as shown in step 502 and FIG. 6B, the solid wax 61 as a bonding member is placed on the prism array 40A, and this is heated to about 100 degrees. As a result, the melted wax becomes the serrated surface 40 of the prism array 40A.
Spread all over b.

As shown in step 503 and FIG.
Another prism array 40B is superimposed on the prism array 40A on which the wax is arranged so that the saw-toothed surfaces 40b are engaged with each other. This step is performed before the melted wax is cooled and solidified. By solidifying the wax after a predetermined time, the prism array 40B is integrated with the fixed prism array 40A, so that the prism array 40B does not move in the subsequent grinding and polishing steps.

In this state, as shown in step 504 and FIG. 6D, the smooth surface 40a of the upper prism array 40B is ground to a predetermined size. Grinding is
A method such as sanding may be used. Subsequent to the grinding of the surface 40a, a step of polishing this surface to the required surface accuracy is performed. Although not shown in the figure, the polishing of the surface can be performed by using a solution such as cerium oxide CeO2 as an abrasive and sliding a polishing plate against the surface. Thus, grinding and polishing for one prism array 40B are completed. In a preferred embodiment, the total thickness is 1.39.
The total thickness of the 0.2 mm prism array after grinding and polishing is 0.
It was 59 mm. The plane accuracy (PRt) when measured by scanning with a length of 15 mm in the length direction using a surface profiler (Talysurf) was 0.3 μm or less. On the other hand, when the two prism arrays are not overlapped as in the present embodiment, and one of the prism arrays is fixed to the base with the serrated surface facing down, and the grinding and polishing are performed, the PRt value is as follows. Under the same conditions.

Next, the other prism array 40A
In order to process the surface 40a, in step 505, the prism array pair is turned upside down, and the prism array 40A is fixed on the base so that the prism array 40A is on the upper side. Then, in step 506, grinding and polishing steps are performed on the surface 40a of the prism array 40A, as described above in step 504 and FIG. 6D. Thus, the grinding and polishing steps for the two prism arrays 40A and 40B are completed.

In the present invention, however, instead of performing the grinding and polishing steps using the two prism arrays, a base having a surface shape corresponding to the saw-tooth surface shape of the prism array is prepared. Grinding and polishing can also be performed above.

In FIG. 2, the next manufacturing step according to the present invention is a step 203 of separating the ground and polished prism array into individual microprisms. This step is achieved by cutting and separating the prism array in a direction along the serrated valley and in a direction intersecting the valley, that is, in a matrix. In this embodiment, a dicing saw is used to cut and separate the prism array.

FIG. 7 shows a dicing saw 7 rotated at a high speed.
An embodiment in which the prism array 40 is cut and separated using 0 is shown. The dicing saw 70 is formed such that the tip end 70a of the blade surface has a mountain shape with a predetermined angle. In cutting the prism array 40 in the direction along the serrated valley, the tip 70a is used, thereby forming the microprism surfaces 13 and 15 shown in FIG. 1 together with the separation of the prism array. In FIG. 8, a part of the prism array is enlarged, and a region to be cut by the dicing saw 70 is indicated by oblique lines. In the embodiment shown in the drawings, the opening angle of the tip 70a of the dicing saw 70 is 90 degrees. Subsequently, using a dicing saw 70, the prism array 40 is separated at predetermined intervals in a direction intersecting the sawtooth-shaped valleys. The interval is the required micro prism 1
Match the width dimension of 0. As described above, a large number of microprisms of the same type are simultaneously manufactured from one prism array 40.

The embodiment of the present invention has been described with reference to the drawings. However, it is apparent that the present invention is not limited to the matters described in the above embodiments, and that changes, improvements, and the like can be made based on the description in the claims. In the present invention, step 2 of grinding and polishing the prism array
Prior to 02, a step of heat-treating the prism array for a predetermined time may be performed. This heat treatment step removes the array residual stress and improves the flatness after polishing. As a result of holding for 2 hours at the transition temperature of the glass used (500 ° C. in the example), the PRt value of the surface after grinding and polishing according to FIGS. 5 and 6 was 25% of that without the heat treatment.
To about the value.

Further, the manufacturing method of the present invention is not limited to the above-described method of manufacturing a microprism, and can be employed in the manufacture of various microlenses and diffraction gratings. That is, as shown in FIG. 9A, the lens array 90 is press-molded using a mold along a spherical surface of a desired lens, and is subjected to a polishing process (the polishing process is unnecessary in the production of a specific lens). This is cut and separated to obtain individual microlenses 91. Further, as shown in FIG. 2B, the diffraction grating array 92 is press-molded using a molding tool along the desired irregularities of the diffraction grating, and this is cut and separated to obtain individual diffraction gratings 93. .

[0040]

As described above, according to the present invention, a large number of glass optical elements such as microprisms can be manufactured at the same time, and the productivity can be significantly improved.

The quality of the microprism produced from one glass body by the present production method is constant, and as a result, a glass optical element of stable quality can be produced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a microprism manufactured by a manufacturing method of the present invention.

FIG. 2 is a flowchart showing each step in the manufacturing method of the present invention.

FIG. 3 is a diagram schematically showing a state in which a glass substrate is pressed according to a pressing step in the present invention.

FIG. 4 is a perspective view of a prism array formed by press fixing according to the present invention.

FIG. 5 is a flowchart according to an embodiment of the grinding / polishing step of the present invention.

FIG. 6 is a view along one embodiment of a grinding / polishing step in the present invention.

FIG. 7 is a diagram schematically showing a state in which a prism array is cut and separated according to a separation step in the present invention.

FIG. 8 is an enlarged view of a part of the prism array in FIG. 7;

FIG. 9 is a diagram of a microlens and a diffraction grating manufactured according to the manufacturing method of the present invention.

[Explanation of symbols]

 Reference Signs List 10 Microprism 11 Light entrance surface 12 First reflection surface 13 Second reflection surface 14, 15 surface 16 Photodiode 30 Plate-like glass substrate 31, 32 Mold 31a, 32a Mold surface 40 Prism array 60 Base 61 Solid wax 62 Grinding Whetstone 70 Dicing saw 90 Lens array 91 Micro lens 92 Diffraction grating array 93 Diffraction grating

Claims (18)

[Claims] A glass material is press-molded with a mold including at least an upper mold and a lower mold to form a first and a second mold having a desired shape and surface accuracy formed by the upper mold and the lower mold. Obtaining a glass body in which a plurality of irregularities of a predetermined shape are formed on at least the first surface, including at least one irregularity of the predetermined shape on the first surface;
And a step of obtaining a plurality of glass optical elements by cutting and separating the glass body into a plurality of pieces so as to include a part of the second surface. Method. 2. Before the step of cutting and separating the glass body into a plurality of pieces, a step of polishing the second surface so that a glass optical element to be obtained has a desired optical function. The method for manufacturing a glass optical element according to claim 1, wherein: 3. A step of preparing a glass body having a first surface and a second surface opposite to the first surface, wherein a plurality of irregularities having a predetermined shape are formed on at least the first surface. Polishing the second surface so that the glass optical element to be obtained has a desired optical function, including at least one irregularity having a predetermined shape on the first surface;
And a step of obtaining a plurality of glass optical elements by cutting and separating the glass body into a plurality of pieces so as to include a part of the polished second surface. Device manufacturing method. 4. The method for manufacturing a glass optical element according to claim 1, wherein the glass material to be pressed is obtained by heating and softening a glass plate formed in a predetermined shape in advance. 5. In the polishing step, one or both of the glass bodies are prepared in a state where two glass bodies are prepared, and the two glass bodies are overlapped with the first surface on which the irregularities of the predetermined shape are formed inside. The method for manufacturing a glass optical element according to claim 2, wherein the second surface is flatly polished. 6. The superimposed state according to claim 5, wherein the superposed portions of the predetermined shape of the one glass body are overlapped with the concave portions of the predetermined shape of the other glass body. A method for producing a glass optical element. 7. The method for manufacturing a glass optical element according to claim 1, wherein at least a part of the irregularities having the predetermined shape has an optical function. 8. The unevenness having the predetermined shape includes a first plane,
The method for manufacturing a glass optical element according to claim 1, further comprising a second plane having a predetermined angle with respect to the first plane. 9. The method for manufacturing a glass optical element according to claim 1, wherein the glass body has a thickness of 2 mm or less at a convex portion of the irregularities of the predetermined shape. 10. The method of manufacturing a glass optical element according to claim 9, wherein the glass body after the polishing step has a thickness of 0.7 mm or less at a convex portion of the irregularities having the predetermined shape. 11. The glass body has a thickness of 1 mm or less at a concave portion of the irregularities of the predetermined shape.
The method for producing a glass optical element according to any one of the above. 12. The polishing step, wherein the surface accuracy of a flat surface, which is a functional surface of the optical element, is λ / 2 or less (where λ is the wavelength of light incident on the glass optical element to be manufactured). The method for producing a glass optical element according to claim 2, wherein the polishing is performed. 13. The method of manufacturing a glass optical element according to claim 2, further comprising a heat treatment step of heat-treating the press-molded glass body for a predetermined time before the polishing step. 14. The heat treatment step is performed at a temperature near a transition point of glass constituting the glass body.
3. The method for producing a glass optical element according to item 3. 15. The method according to claim 1, wherein the glass optical element is a micro prism. 16. The method according to claim 1, wherein the glass optical element is a microlens. 17. The method for manufacturing a glass optical element according to claim 1, wherein the glass optical element is a diffraction grating. 18. After a glass optical element is manufactured by the method according to any one of claims 1 to 18, the glass optical element and a signal obtained by reflection and / or refraction of light by the glass optical element are further processed. An optical device manufacturing method including a step of combining a light receiving element to be read.