JPH0815504A - Optical device and production of optical device - Google Patents

Abstract

PURPOSE:To realize an optical device having desired surface shape. CONSTITUTION:This process for production of the optical device comprises forming a desired curved surface shape on the surface of a device material 1 by laminating a transfer material 3 transferred with a projecting spherical surface shape by using molds 2 formed with a recessed spherical surface shape meeting the prescribed projecting spherical surface shape on the surface of the device material l and subjecting the transfer material 3 and the device material l to physical etching with the surface shape of a reference surface which is the surface of the transfer material 3 as a starting shape. The surface of the device material 1 to be laminated with the transfer material is formed as the projecting spherical surface 4 having a prescribed radius of curvature. The selection ratio of the physical etching is varied from 1 or is continuously and/or stepwise changed with lapse of time according to the desired curved surface shape 4' to be formed on the device material 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device and an optical device manufacturing method.

[0002]

2. Description of the Related Art A special surface shape represented by an aspherical surface has come to be used for lenses and mirrors. It is not easy to create a special surface shape such as an aspherical surface by mechanical polishing, and it is often manufactured by a molding process using a mold.

For this reason, for example, most lenses having an aspherical refracting surface are manufactured as plastic molded products using a plastic material, and there is a problem that there is little room for material selection.

The "glass pressing method" is known as a technique for creating a desired surface shape on a glass surface by using a mold, but the mold used has a high temperature (6
(50 degrees or more) ・ It must withstand high pressure and must also be resistant to oxidation at high temperatures. Therefore, the mold material is limited to special metals and ceramics. Such a special material is very difficult to process the mold, and in addition, in order to add oxidation resistance, Si ₃ N ₄ , SiC, Au,
It is necessary to form a thin film of Pt or the like.

For this reason, the "mold" used in the glass pressing method is high in cost and used at high temperature and high pressure, so that the "life as a mold" is not so good even though the material is selected. Not long.

On the other hand, as a method of creating a refracting surface or a reflecting surface without using molding or polishing, a layer of photoresist is formed on the surface of an optical material, and this layer is patterned into, for example, a circle or an ellipse, Then, by heating the above layer, the surface of the photoresist is made into a curved surface shape by the thermal flow of the photoresist, and thereafter, the photoresist and the optical material are etched so that the curved surface shape of the photoresist surface is made optically. A method of engraving on a material has been proposed (for example, JP-A-5-173003: Claim 1).
6).

This method is suitable as a method for forming a refracting surface of a microlens, but it is not always easy to control the surface shape generated on the photoresist surface by heating, and it is possible to form a curved surface exactly as intended. Is difficult.

[0008]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a novel optical device having a desired surface shape accurately (claims 6 to 8). .

Another object of the present invention is to provide a novel optical device manufacturing method capable of easily and reliably manufacturing the above optical device (claims 1 to 5).

[0010]

The method for manufacturing an optical device of the present invention includes: "A transfer material having a convex spherical shape transferred using a molding die is laminated on the surface of a device material, and the transfer material surface is used as a reference surface; This is a method of forming a desired curved surface shape on the surface of the device material by physically etching the transfer material and the device material using the reference surface as a starting shape.

The "device material" is a material that should be the actual condition of the finally obtained optical device, and a transparent or opaque material is used, but if it is solid and capable of physical etching. Can be used without any particular restrictions.

The "molding die" has a concave spherical surface shape corresponding to a predetermined convex spherical surface shape, and the "predetermined convex spherical surface shape" obtained by inverting the concave spherical surface shape is transferred to the transfer material as its surface shape.

"Transfer material" on which a desired convex spherical shape is transferred
Is laminated on the surface of the device material, and the “surface on which the transfer material is laminated” in the device material is “a convex spherical surface having a predetermined radius of curvature”.

Further, the selection ratio of physical etching, that is, [etching rate of device material] / [etching rate of transfer material] can be made different from 1 according to a desired curved surface shape to be formed on the device material. Or, it is changed continuously and / or stepwise over time (claim 1).

As the above-mentioned "physical etching", dry etching such as RIE or ECR plasma etching is preferable.

In the method for manufacturing an optical device according to claim 1, when the spherical shape of the molding die is transferred as the surface shape of the transfer material, the concave spherical surface of the molding die is subjected to "surface treatment for mold release". (Claim 2) As this surface treatment, plasma fluorine treatment or fluorine water repellent treatment with an organic substance (surface treatment with a triazinethiol fluorine derivative substance) is suitable.

The above-mentioned transfer material can be used without particular limitation as long as it is capable of physical etching and transfer of the surface shape, and is a "photo-curable material or thermosetting material".
Are particularly suitable (claim 3).

As the "photo-curable material", an epoxy resin, an acrylic resin, a urethane resin, a modified silicone resin, or a material composed of a mixture thereof can be used. In particular, a compound prepared by combining an epoxy resin and an acrylic resin is suitable as a transfer material. Of course, a commercially available ultraviolet curable resin or the like can be preferably used as the transfer material.

As the "thermosetting material", epoxy resin, phenol resin, urea resin, melamine resin and the like can be used. Since these are cured at a temperature of 200 ° C. or less, the heat treatment during curing causes less heat damage to the mold.

As described above, the device material is a transparent or opaque material, is solid, and can be physically etched, and the surface on which the transfer material is laminated is a spherical surface having a predetermined radius of curvature. However, as a preferable example, "transparent sphere" can be raised (claim 4).

As described above, when a transparent sphere is used as the device material, the optical device manufacturing method of the present invention can be preferably applied to a transparent sphere having a diameter of 10 mm or less, particularly a transparent sphere having a diameter of about 1 to 3 mm. (Claim 5).

The "optical device" of the present invention is an optical device manufactured by any one of the optical device manufacturing methods described in claims 1 to 5 (claim 6).

The "surface formed by physical etching" of this optical device may be an aspherical surface (claim 7).

Of course, using the above optical device manufacturing method,
A desired curved surface shape may be formed “two-sided” by forming “front and back” on the device material.

An optical device having a reflection film formed on the optical device according to claim 6 or 7 may be used as an "optical device" (claim 8). As described above, it goes without saying that the device material does not have to be transparent when the reflective film is formed into an optical device.

[0026]

As described above, in the optical device manufacturing method of the present invention, the transfer material laminated on the convex spherical surface of the device material is
It has a predetermined convex spherical shape as a “reference surface” and physically etches the device material and the transfer material, and at that time, makes the selection ratio different from 1 or continuously and / or with time. By changing the selection ratio stepwise, a desired curved surface shape is formed as the device material surface shape.

In FIG. 1A, reference numeral 1 is a transparent sphere which is a "device material", reference numeral 2 is a molding die, and reference numeral 3 is a transfer material. The transparent sphere 1 has a convex spherical surface 4 having a predetermined radius of curvature.

The transfer mold 2 has a "concave spherical surface shape corresponding to a predetermined convex spherical surface shape". The transfer material 3 is put in the concave spherical surface portion, and the transparent spherical body 1 is pressed from above to transfer the transfer material 3 therethrough.
When it is bonded to the surface of the transparent sphere 1 in a deformed state and die-cutting, as shown in FIG. 1B, a state in which the transfer material 3 is laminated on the surface of the transparent sphere 1 which is a device material is realized. To do.

The surface shape of the transfer material 3 laminated on the surface of the transparent sphere 1 is transferred by using the convex spherical shape, which is the inverted concave spherical shape of the molding die 2, as a "reference surface".

Physical transfer is performed on the transfer material 3 and the device material 1 using the reference surface as a starting shape, and a desired curved surface shape to be formed on the device material 1
By changing the selection ratio of the physical etching from 1 or changing it continuously and / or stepwise over time, as shown in FIG. 1 (c), the device material which was the transparent sphere 1 was changed. The desired surface shape 4'can be formed.

The desired surface shape 4'is a curved surface having a radius of curvature larger than the initial radius of curvature of the transparent sphere 1 when "the selection ratio is constant and different from 1", and the selection ratio is continuous and / Or if it is changed stepwise, it becomes an "aspherical shape".

The shape of the device material is not limited to a transparent sphere, and may be, for example, a lens shape having a convex spherical surface as at least one surface.

In FIG. 2A, reference numeral 5 denotes a device material formed by forming a desired lens surface 7 on a part of a transparent sphere by the method of FIG. 1 or another method.

On the convex spherical surface 6 having a predetermined radius of curvature of the device material 5, the transfer material 3 whose convex spherical shape has been transferred by the molding die 2 is laminated, and the surface thereof is used as a reference surface (see FIG. 2).
(B)) Physically etching the transfer material 3 and the device material 5 using the reference surface as a starting shape, and selecting physical etching according to a desired curved surface shape to be formed on the device material 5. By varying the ratio from 1 or changing it continuously and / or stepwise over time, a desired surface profile 6 ′ can be formed on the device material 5 as shown in FIG. 2 (c).

The surface shape 6'in FIG. 2 (c) is an aspherical shape, which is realized by the change of the selection ratio with time.

The relationship between the selection ratio and the surface shape of the etching result will be modeled as follows.

For example, when physical etching is performed using the reference surface in the case of FIG. 1B as a starting shape, the transfer material 3 is laminated on the surface of the transparent sphere 1, so that it is related to the selection ratio for a while. However, the engraving progresses only on the transfer material 3.

After a while, the transfer material 3 is engraved and the surface of the transparent sphere 1 is exposed.

FIG. 3 (a) schematically shows the state where the top of the transparent sphere 1 is exposed for the first time from the state of FIG. 1 (b) to the physical etching (the vertical relationship of FIG. 1 (b)). It is the opposite of the one).

For easy understanding of the explanation, the spherical shapes of the surface of the transparent sphere 1 and the surface of the transfer material 3 are shown as "stepwise". The step of the "stairs representing the surface shape" corresponds to the curvature of the surface shape.

That is, the step difference of “stairs” representing the continuous inclination of the surface shape of the transfer material 3 is smaller than the step difference of “stairs” indicating the continuous inclination of the surface of the transparent sphere 1 of the transfer material 3. It shows that the curvature of the surface is smaller than the curvature of the surface of the transparent sphere 1.

FIG. 3 shows the progress of etching when anisotropic physical etching is performed with a selectivity of 0.5, and shows the progress of etching as time progresses. The time stamp progresses sequentially from (a) to (d) of FIG.

The reference numeral 20 in FIG. 3 indicates a jig for supporting the device material when the physical etching is performed.

Since the selection ratio is 0.5, the transfer material 3 is eroded at twice the speed of the transparent sphere 1, so that the top of the transparent sphere 1 and the surface of the transfer material 3 at the right end of the figure. The "height difference" of was initially: ΔH (Fig. 3 (a)), but gradually increased with time, and in the state of Fig. 3 (d),
It has expanded to 1.3 times the original size.

This means that the curvature of the curved surface formed on the transparent sphere 1 becomes larger than the curvature of the surface of the transfer material 3 which initially covered the surface of the transparent sphere 1.

That is, the "selection ratio smaller than 1" acts to make the curvature of the curved surface formed on the transparent sphere 1 larger than the "curvature of the reference surface".

FIG. 4 shows the progress of erosion with time when anisotropic etching is carried out from the same starting state as in FIG. 3 (a) with a selection ratio of 1.5. As time goes by, the etching state due to etching sequentially progresses from (a) to (d) of FIG.

Since the transparent sphere 1 is engraved at a speed 1.5 times that of the transfer material 3, the "height difference" between the top of the transparent sphere 10 and the surface of the transfer material 30 at the right end of the figure. Initially: Δ
What was H was gradually reduced with time, and as shown in FIG.
In this state, it has been reduced to 0.7 times the original size.

This means that the radius of curvature of the curved surface formed on the transparent sphere 1 is smaller than the curvature of the surface of the solidified viscous surface 3 which initially covered the surface of the transparent sphere 1.

That is, the "selection ratio larger than 1" acts to make the curvature of the curved surface formed on the transparent sphere 1 smaller than the "curvature of the reference surface".

The case where the radius of curvature of the reference surface is larger than the radius of curvature of the convex spherical surface of the device material has been described above.
The same applies when the radius of curvature is opposite.

"Controlling the selection ratio" so as to obtain a desired curved surface shape using the reference surface as a starting shape can be realized by computer control.

That is, for example, the surface shape (reference surface) of the transfer material 3 in FIG.
Assuming that the surface shape 6 ′ of the lens material 1 shown in 1 is the “target shape”, the procedure proceeds as follows as an example.

First, a parameter for controlling the selection ratio is determined, and "computer simulation" is performed on how to control the above parameters in order to obtain the target shape from the starting shape.

That is, it is investigated by simulation how the surface shape of the device material changes according to various temporal changes of the above parameters, and the surface shape change from the starting shape to the target shape is traced by the simulation. While
Find out what kind of selection ratio control is most suitable.

Next, an experiment is carried out while actually realizing the change of the selection ratio obtained in this way by the change of the parameter, the control state is corrected, and the target shape can be actually obtained from the starting shape. Determine such control conditions.

It is only necessary to program the control conditions thus determined and program-control the "selection ratio control" in the actual etching apparatus.

Physical etching is easier to control than chemical etching, and moreover, if control of the selection ratio is the same for the same reference surface shape (starting shape) of the same device material, it is always the same. The result (same target shape) is obtained. That is, it has excellent reproducibility.

In some cases, the transfer material may remain on the surface of the device material when the desired curved surface shape is obtained on the device material. In this case, the residual transfer material may be removed by a means such as cleaning, or if a light-shielding material is selected and used as the transfer material in advance, the residual transfer material itself is
It can also be used as an aperture for an optical device.

In some cases, the shape of the convex curved surface transferred to the transfer material may not exactly correspond to the concave spherical surface of the molding die. For example, there is a case where the radius of curvature of the convex spherical surface to be accurately transferred is r, but the radius of curvature of the actually transferred surface is r '.

Even in such a case, if the radius of curvature of the surface transferred to the transfer material has good reproducibility and is always r ', the selection ratio control in physical etching is performed in the reference surface shape. By setting the radius of curvature of r to r ′, it is possible to form a desired curved surface shape on the surface of the device material.

For example, if the transfer material contracts when the spherical shape, which is the transfer surface shape of the mold, is transferred to the transfer material, the transferred shape does not correspond exactly to the spherical shape of the mold.

When the physical etching is carried out at a selection ratio of 1, the transfer surface shape is corrected in consideration of the contraction of the transfer material,
As a result of shrinkage accompanying transfer, it is necessary to be able to form a desired shape on the transfer material.

However, in the present invention, if the shape transferred to the transfer material has reproducibility, the target shape can be created by changing the etching conditions. Therefore, the transfer surface shape itself of the molding die is corrected. No need.

The present invention can be applied to cases where the curvature of the transfer material is larger or smaller than that of the transparent sphere.

That is, in an optical device in which the curvature of the target shape is large in the vicinity of the optical axis and decreases with distance from the optical axis, it has a concave spherical surface shape with a large curvature on the surface of the transparent material having the curvature that minimizes the amount of processing. A convex curved surface shape having a large curvature is transferred using a molding die, and then the etching condition is changed to have a different selection ratio from 1 or is changed continuously and / or stepwise over time to obtain a transparent material It is possible to create a convex spherical surface or a convex aspherical shape having a curvature larger than the curvature.

Although it is possible to process an aspherical surface die to create a large-diameter aspherical shape, in the case of creating an aspherical surface shape having a small diameter, it may be difficult or impossible to process the die. When creating an aspherical shape with a small aperture in this way, that is, when the diameter of the transparent sphere as the device material is 10
The present invention is extremely effective when the diameter is less than or equal to mm, especially when the diameter is about 1 to 3 mm (Claim 5).

[0068]

EXAMPLE As an optical device, a lens having a spherical first surface and a second aspheric surface was designed as an "optical communication coupler".

“Effective diameter of light beam” is φ:
0.48 mm, φ: 1.1 mm with respect to the second surface, and coupling efficiency: 58%. Based on the design result, the above lens as an optical device was manufactured as follows.

Material: SF60 (wavelength: 1.3 μm infrared light refractive index: 1.76817), diameter:
A 2.0 mm transparent sphere was prepared as a "device material".

The "transparent sphere" itself can be used as a ball lens, and the coupling efficiency when it is used as a ball lens as a coupler for optical communication is "15%" under the optimum use condition.

Reference numeral 10 in FIG. 5A is SF60.
2 shows a device material made of transparent spheres having a diameter of 2.0 mm according to FIG.

A diameter larger than the effective light beam diameter (1.1 mm) on the second surface side of the device material 10: a portion outside 1.2 mm is polished with a diamond wheel, and then, as shown in FIG.
As shown in (b), both ends in the vertical direction have “curvature radius:
The "cylindrical shape", which is a "1.0 mm spherical surface", is adopted.

The device material 10 in the shape of a cylinder is fitted and held "closely" to the support jig 50 (see FIG. 5).
(C)), in this state, the second
The surface side (the lower spherical surface in the figure) was treated with a primer.

Radius of curvature: concave spherical shape 20 with 1.11 mm
The surface of the concave spherical surface 200A of the molding die 200 on which 0A was formed was subjected to plasma fluorine treatment (plasma treatment using Ar and CF ₄ introduced and used) to improve releasability.

The molding die 200 was formed as follows. That is, a convex spherical surface having a curvature radius of 1.11 mm was produced by ultra-precision machining, and the convex spherical surface was electroformed to obtain a molding die 200.

As described above, the concave spherical surface shape 200A of the molding die 200 which has been subjected to the surface treatment for enhancing the releasability is used as the transfer material 30 such as "UV curing type in which acrylic resin and epoxy resin are mixed at a ratio of 9: 1. Anaerobic resin ",
As shown in FIG. 5C, the spherical surface on the second surface side of the device material 10 was pressed.

Next, the whole (device material 10, molding die 200, transfer material 30, support jig 50) is fixed, and ultraviolet light of 2500 mJ / cm ² or more is irradiated from the device material 10 side to cure the transfer material 30. Let

After the transfer material 30 is cured, the molding die 200 is formed.
And the transfer material 30 is peeled off. This peeling could be easily performed by the surface treatment effect of the transfer surface shape portion of the molding die.
At the time of peeling, if a heat shock or the like is applied, the peeling can be performed more easily.

In this way, the second
The solidified transfer material 30 was laminated on the surface side (FIG. 5).
(D)). The surface shape of the transfer material 30 has a curvature radius of 1.11.
The concave spherical surface shape 200A of the molding die 200 is transferred and inverted with a convex spherical surface of mm, which is a "reference surface".

The shape of the "aspherical surface" to be formed on the second surface side of the device material 10 is the well-known aspherical surface formula: Z = (1 / R) h ² / [1 + √ {1- (K + 1) ) (1 /
R) ² h ² }] + Ah ⁴ + Bh ⁶ + Ch ⁸ R: Curvature on the optical axis K: Conical constant A, B, C: Aspherical constant (A is 4th order, B is 6th order, C is 8th)
(Next term) Z: At distance from lens vertex, R = -1.0, K = -0.1071166 × 10 ¹ , A = 0.481868 × 10 ~ ² , B = -0.3087594 × 10 ~ ¹ , C = 0.3821575, and so that this shape can be realized as the final shape in the device material 10 by computer simulation and experiment, the time control condition of the physical etching (condition for controlling the selection ratio). Was set.

The material and size (diameter) of the device material 10 and the shape (curvature radius) of the reference surface are preliminarily experimentally and / or theoretically set so that the above physical etching can be realized easily. The optimum value is calculated and determined.

Since the aspherical shape has a conical constant: K smaller than −1, it is basically “hyperboloidal”, and the shape type is “large curvature (small radius of curvature) near the optical axis, optical axis The shape is such that the curvature becomes smaller (the radius of curvature becomes larger) with increasing distance.

Subsequently, the device material 10 (FIG. 5D) on which the transfer material 30 is laminated is set in the ECR plasma etching apparatus while being held by the supporting jig 50, and Ar,
CHF ₃ and O ₂ gas were introduced, and anisotropic etching was performed under the conditions of 2 to 4 × 10 to ⁴ Toor while changing the etching conditions with time.

That is, from the start of etching to the end of etching,
While gradually reducing the amount of "O ₂ gas" introduced in the introduced gas with time, the selection ratio was initially small in the range of 0.05 to 2.0 (the curved surface formed on the device material was thereby formed). Has a large curvature near the optical axis (see FIG. 3),
While gradually increasing with time (the curvature of the curved surface formed in the device material decreases as the optical axis moves away, see FIG. 4), etching is performed for 420 minutes to obtain the desired aspherical surface 100A. Formed (Fig. 5
(E)).

FIG. 6 shows a state in which the lens 10B which is the optical device thus obtained is used as a coupler for optical communication. Reference numeral 40 on the left side of the figure is L which is a light source
Reference numeral 60 on the right side of D and the lens 10B indicates an optical fiber.

Full angle at half maximum of LD: 32 °, distance between LD and lens first surface: 0.385 mm, distance between optical axis of lens first surface and lens second surface: 1.983 mm, lens second
Under the condition that the distance between the surface and the optical fiber was 5.927 mm, the coupling efficiency was 57%, which was a value as designed.

[0088]

As described above, according to the present invention, it is possible to provide a novel optical device and a method for manufacturing the same.

According to the optical device manufacturing method of the first to fifth aspects, a molding die having a concave spherical surface shape that can be formed with high surface accuracy is used, and an accurate reference surface is transferred onto a transfer material to form a convex spherical surface of the device material. Since the physical etching is performed with good reproducibility under the conditions according to the target shape to be formed on the device material, it is possible to easily and surely manufacture an optical device having a desired surface shape.

The optical devices described in claims 6 to 8 are manufactured by the methods described in claims 1 to 5, so that they are easy to manufacture, low in cost, good in mass productivity, and substantially as designed. You can realize things. Further, since the device material may be any material that can be physically etched, the degree of freedom in selecting a material is wide and the degree of freedom in optical design is large.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an optical device manufacturing method according to the present invention.

FIG. 2 is a diagram for explaining the optical device manufacturing method of the present invention.

FIG. 3 is a diagram for explaining an action of etching when physical etching is performed with a selection ratio smaller than 1 with a reference surface as a starting shape.

FIG. 4 is a diagram for explaining the action of etching when physical etching is performed with a selection ratio larger than 1 using the reference surface as a starting shape.

FIG. 5 is a diagram for explaining an example.

FIG. 6 is a diagram showing an optical coupling state of an optical communication coupler formed in an example.

[Explanation of symbols]

 1 device material (transparent sphere) 2 molding die 3 transfer material 4'desired surface shape formed as a lens surface

Claims (8)

[Claims] 1. A transfer material having the convex spherical surface shape transferred thereto is stacked on a device material surface by using a molding die having a concave spherical surface shape corresponding to a predetermined convex spherical surface shape, and the transfer material surface is In the optical device manufacturing method in which the reference surface is used as a starting shape, physical etching is performed on the transfer material and the device material to form a desired curved surface shape on the surface of the device material, the transfer of the device material is performed. The surface on which the material is laminated is a convex spherical surface having a predetermined radius of curvature, and the selection ratio of the physical etching is different from 1 according to the desired curved surface shape to be formed on the device material, And a step of continuously and / or stepwise changing the optical device manufacturing method. 2. The optical device manufacturing method according to claim 1, wherein when the spherical shape of the molding die is transferred as the surface shape of the transfer material, the concave spherical shape of the molding die is subjected to surface treatment for releasing. Characteristic optical device manufacturing method. 3. The optical device manufacturing method according to claim 1, wherein a photo-curable material or a thermosetting material is used as the transfer material. 4. The optical device manufacturing method according to claim 1, 2 or 3, wherein the device material is a transparent sphere. 5. The method for manufacturing an optical device according to claim 4, wherein the transparent sphere which is a device material has a diameter of 10 mm or less. 6. An optical device manufactured by the method for manufacturing an optical device according to claim 1, 2, 3 or 4 or 5. 7. The optical device according to claim 6, wherein the surface formed by physical etching is an aspherical surface. 8. An optical device obtained by forming a reflective film on the optical device according to claim 6.