JP2986583B2 - Optical element molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an optical element by heat-softening a glass material and press-molding the glass material with a molding die.

[0002]

2. Description of the Related Art Recently, as a method of manufacturing a glass optical element such as a lens or a prism, a method of heat-softening a glass material and press-molding it with a molding die has been developed and implemented.

[0003] Such a method has attracted attention as a method for producing a large amount of aspherical optical elements which have conventionally been expensive at low cost.

The following inventions are disclosed as the above-mentioned conventional methods.

For example, in the invention described in Japanese Patent Application Laid-Open No. 62-96329, the step of press molding at a molding speed set according to the viscosity of a glass material is divided into two steps of preforming and main molding. Have been proposed.

In the invention described in Japanese Patent Application Laid-Open No. Sho 59-141435, the upper mold for molding the functional surface of the optical element is pressed against the upper edge of the lower mold for molding the other functional surface of the optical element. Has been proposed.

[0007]

In recent years, the use of the pressure molding technique in optical elements has been increasingly expanded. In terms of the glass material to be molded, not only optical elements made of a single glass material but also different types of glass are used. The range of application is expanding to applications to optical elements made of materials.

As a specific example, there is an application to a single fiber optical element as shown in FIGS. FIG. 9 shows a single fiber 81 before molding, and FIG. 10 shows a single fiber 82 after molding.

The single fiber 81 has a core 83 and a clad 8
4 and both form an interface 85. Core 8
The refractive index of the glass material used for 3 is selected to be as large as possible, and the refractive index of the glass material used for the cladding 84 is selected to be smaller than the refractive index of the core 83 and large.

As a result, light incident from one end face of the formed single fiber 82 is emitted from another end face while being reflected at the interface 85 with little loss. In addition, the other end face has a curved surface 8 to have power as a lens.
6 are formed.

The single fiber lens described above has an extremely large effect in, for example, an illumination optical system that covers a wide angle range with a small number of lenses.

However, in order to exert the above-described optical effect, the interface 8 of the formed single fiber 82 is required.
5 must be in proper condition. That is, it is necessary to prevent the interface 85 from undulating at the time of molding.

However, in the invention described in Japanese Patent Application Laid-Open No. 62-96329, the outer peripheral portion of the glass material is greatly deformed as shown in the specification,
The interface is no longer in an appropriate state.

Further, in the invention described in Japanese Patent Application Laid-Open No. S59-141435, although the eccentricity of the optical element can be eliminated as shown in the specification, a desired thickness dimension is required. In order to obtain, the remaining portion of the glass material is caused to flow into the gap provided in the upper portion of the lower mold. Therefore, there is a disadvantage that a residual portion remains on the outer peripheral portion of the optical element, and the interface is not in an appropriate state.

Accordingly, the present invention has been developed in view of the above-mentioned drawbacks in the prior art, and is an optical element capable of performing pressure molding while maintaining the interface of a single fiber consisting of a core and a clad in an appropriate state. An object of the present invention is to provide a molding method.

[0016]

SUMMARY OF THE INVENTION According to the present invention, a cylindrical second optical material having an outer diameter smaller than the inner diameter of the first optical material is heated and softened inside the first cylindrical optical material. This is a method of forming the first and second optical elements into a single optical element by press-fitting and pressing the axial end face of the second optical material.

FIGS. 1 to 3 are conceptual views of a method for molding an optical element according to the present invention.

Reference numeral 1 denotes a single fiber.
Is composed of a clad 2 and a core 3.

The clad 2 is cylindrical and has the same shape and dimensions as the final shape because it is not deformed. The core 3 is formed in a cylindrical shape having an outer diameter smaller than the inner diameter of the clad 2, and has a volume substantially equal to that of the core 3 of the formed single fiber 1.

In molding, first, only the core 3 is heated to the softening point or higher, and then the core 3 is inserted into the clad 2.
Next, pressure molding is started by being sandwiched between a pair of dies (not shown) arranged opposite to each other.

The core 3 expands in the radial direction because it is pressurized in the clad 2. The outer peripheral surface of the core 3 is in close contact with the inner peripheral surface of the clad 2 to form an interface 4. At the same time, the molding surface 5 is molded into a desired shape by the pair of molds (not shown).

[0022]

Embodiment 1 FIG. 4 is a longitudinal sectional view of a molding apparatus used in this embodiment.

Reference numeral 11 denotes a molding device. A slide device 13 is provided on a base 12 of the molding device 11, and a transfer arm 14 is provided on the slide device 13 so as to be slidable left and right. At the tip of the transfer arm 14, a transfer plate holding portion 15 with a notch is formed.

A transport rail 16 is provided on the base 12, and a push-up bar 18 is provided below the transport rail 16 via a cylinder 17 installed on the base 12 so as to be vertically movable.

Further, a core material heating furnace 20 in which a heater 19 is provided is provided on the base 12.

The core material heating furnace 2 is placed on the base 12.
A molded portion 21 is provided in parallel with 0. Molding part 21
Is composed of an upper die base 23 and a lower die base 24 held by the upper ends of the columns 22 erected on the base 12.

An upper die 26 is attached to the lower surface of the upper die base 23 by an upper die pressing ring 25, and an upper heater 27 for heating the upper die 26 is provided on the outer periphery of the upper die 26.

The lower mold base 24 is held by a lower shaft cylinder 28 fixed to the base 12 via a lower shaft 29 so as to be vertically movable. A lower die 31 is attached to the upper surface of the lower die base 24 by a lower die holding ring 30 so as to be coaxial with the upper die 26, and a lower die heater 32 for heating the lower die 31 is provided around the lower periphery of the lower die 31. Is provided. A push-up ring 33 is slidably fitted on the upper periphery of the lower mold 31, and the push-up ring 33 is constantly urged upward by a spring 34 wound on the lower mold 31.

Further, a transfer rail 35 is provided between the upper die 26 and the lower die 31 inside the molding part 21.

The method of molding an optical element using the molding apparatus having the above-described structure is performed by the transfer plate 3 on which the core material 36 is placed.
7 is mounted on the transport rail 16. Then, the transfer plate 37
Is transported on the transport rail 16 and stops right above the push-up bar 18.

On the other hand, a clad material transfer plate 39 on which the clad material 38 is placed is mounted on the transfer rail 35. The clad transport plate 39 is transported on the transport rail 35, and the upper die 2
6 and stops at a position coaxial with the lower mold 31 and waits.

Next, the push-up rod 1 is moved by the cylinder 17.
8 rises and lifts the transport tray 37. In this state, the transfer arm 14 moves forward by the slide device 13, and the transfer plate holding unit 15 formed at the tip of the transfer arm 14 stops below the transfer plate 37.

When the push-up bar 18 is lowered to the original position, the transfer plate 37 is placed on the transfer plate holder 15 of the transfer arm 14.

Next, the transfer arm 14 is further advanced, and the transfer plate holder 15 is stopped at the central position in the heating furnace 20.
The core material 36 is heated above the softening point.

After the heating of the core material 36 is completed, the transfer arm 1
4 further moves forward, and the transport tray holding unit 15 stops at a position above the lower mold 31 and below the transport rail 35.

Then, the lower die 31 is raised by the lower shaft cylinder 28, the push-up ring 33 lifts the transfer plate 37 from the transfer plate holder 15, and inserts the core material 36 into the clad material 38.

Further, the lower die 31 moves up and lifts the clad material transfer plate 39 from the transfer rail 35 via the transfer plate 37.

The lower mold 31 is further raised, and the clad material 3 is raised.
8 or the core material 36 contacts the upper mold 26. Then
The spring 34 is compressed and contracts. Due to this reduction, the tip of the lower mold 31 comes into contact with the core material 36, and the core material 36 is pressed.

The core material 36 expands in the outer peripheral direction by the pressure at the time of pressing, and the inner peripheral surface of the clad material 38 and the core material 3
6 is completely adhered to the outer peripheral surface (see FIG. 5).

The formed single fiber 40 is used for the upper and lower molds 2.
After being released from the molds 6, 31 and returning to the transport rail 35 together with the clad material transport plate 39, they are transported on the transport rail 35 and taken out.

In this embodiment, crystal light having a diameter of 3.5 mm, an inner diameter of 3.2 mm and a height of 2 mm is used as the cladding material 38 (softening point 690 ° C.), and the outer diameter φ3.1 is used as the core material 36.
SFL6 (softening point: 677 ° C.) having a height of 1.8 mm and a height of 1.8 mm was used.

Only the core material 36 is heated to 700 ° C. (the clad material 38 is not heated), and the mold temperature is 460 ° C.
・ Pressing was performed at a pressure of 5 kg / mm ² for 15 seconds to press-mold a single fiber lens having a concave aspheric surface on one side. At this time,
The surface accuracy on the aspherical surface is compared to the mold surface accuracy p-V1μm.
The target surface accuracy of approximately 1.3 μm was obtained.

According to this embodiment, since only the core material is heated and integrated with the clad material during pressing, the clad material is not softened or deformed. Therefore, the interface between the core material and the clad material, which had been undulating because of their close softening points, was also straightened, and a highly accurate interface was obtained.

Further, since there are few restrictions on the temperature of the clad material, various kinds of materials can be used as the clad material.

[0045]

Embodiment 2 FIG. 6 is a longitudinal sectional view of a molding apparatus used in this embodiment.

The molding apparatus 41 used in this embodiment is different from the first embodiment in that the conveying rail 35 provided inside the molding section 21 of the molding apparatus 11 in the first embodiment is eliminated, and the other components are the same. The same components are denoted by the same reference numerals and the description thereof will be omitted.

The molding method using the molding apparatus having the above-described configuration is different from the conveying plate 37 in the first embodiment in that
The molding is performed using the transfer tray 42 having a stepped structure. This transfer plate 42
A clad material 38 is placed on the upper part, and a core material 36 is placed on the lower part.

At this time, the glass transition point of the clad material 38 must be higher than the softening point of the core material 36.
The outer diameter of the core material 36 is smaller than the inner diameter of the clad material 38.

The process is the same as in the first embodiment until the core material 36 is heated to a temperature higher than the softening point. After the heating of the core material 36 is completed, the transfer arm 14 advances further, and the transfer plate holding unit 1
5 stops between the upper mold 26 and the lower mold 31.

Then, the lower die 31 is raised by the lower shaft cylinder 28, and the push-up ring 33 lifts the transport tray 42 from the transport tray holder 15. When the upper end of the clad material 38 and the upper end of the transfer plate 42 abut on the upper die 26, pressure is applied and the spring 34 contracts. Due to this reduction, the tip of the lower mold 31 comes out, and the core material 36 is lifted. The core material 36 is inserted into the inside of the clad material 38, and its upper end abuts on the upper die 26, and the core material 36 is pressed.

The core material 36 expands in the outer peripheral direction due to the pressure at the time of pressing, and the outer peripheral surface of the core material 36 and the inner peripheral surface of the clad material 38 are completely adhered.

The formed single fiber 40 is used for the upper and lower molds 2.
6 and 31 and the transfer arm 14 with the transfer plate 42
Is again mounted on the transfer dish holding unit 15 of the first embodiment. Transfer arm 14
Returns until the transfer tray holding unit 15 is at a position above the push-up bar 18. At that position, the push-up bar 18 is lifted by the cylinder 17 and lifts the transport tray 42 from the transport tray holder 15.

In this state, the transfer arm 14 further returns, and then the push-up bar 18 descends, and the transfer plate 42 returns on the transfer rail 16. Then, the transport plate 42 is transported on the transport rail 16 and taken out.

According to this embodiment, although there is a restriction that the glass transition point of the clad material must be higher than the softening point of the core material, the clad material is heated to a temperature higher than the softening point of the core material. The adhesion between the material and the clad material is increased.

Further, the equipment for the transfer tray and the transfer system dedicated to the clad material in the first embodiment can be eliminated.

[0056]

Embodiment 3 FIG. 7 is a longitudinal sectional view of a molding apparatus used in this embodiment.

The molding apparatus used in this embodiment is the same as the molding apparatus of the first embodiment, and the same reference numerals are given and the description of the configuration is omitted.

The molding method using the molding apparatus 11 having the above-described configuration is performed by using a clad material conveying plate 51 surrounding the entire outer peripheral surface of the clad material 38 instead of the clad material conveying plate 39 of the first embodiment. I do. The clad material transfer tray 51 is formed such that the outer diameter of a desired single fiber is within an allowable value.

The operation is the same as that of the first embodiment. However, when the clad material 38 tries to spread due to the thermal stress of the core material 36 at the time of press molding, the spread is caused by the inner peripheral surface of the clad material transfer plate 51. Is constrained and molded.

According to this embodiment, the same effects as those of the first embodiment can be obtained, and the cladding does not spread under any conditions, and a single fiber having a desired outer diameter can be obtained.

[0061]

Embodiment 4 FIG. 8 is a vertical sectional view of a molding apparatus used in this embodiment.

The molding apparatus 61 of this embodiment is similar to that of the first embodiment.
The transfer rail 35 provided inside the forming section 21 of the forming apparatus 11 is abolished, and a transfer heating system for the clad material 38 having the same structure as the transfer heating system for the core material 36 is provided on the right side of the forming section 21 instead. The difference is that the other components have the same configuration, and the same components are denoted by the same reference numerals and description thereof is omitted.

The heating system for transporting the clad material 38 is provided with a transport arm 64 slidable left and right via a slide device 63 installed on a molding machine base 62.
At the tip of the transfer arm 64, a transfer plate holding portion 65 having a notch is formed. The transfer plate holder 65 of the transfer arm 14 on the opposite side (left side in the drawing) is
Transporting the core material 36 and the upper and lower dies 26, 31
The height is set so as not to interfere on the axis.

A transfer rail 66 is provided on the molding machine base 62, and below the molding rail 62.
A push-up bar 68 is provided slidably up and down via a cylinder 67 installed at the bottom. A clad material carrying plate 39 is mounted on the carrying rail 66, and a clad material 38 is placed on the clad material carrying plate 39.

Further, on the molding machine base 62, a clad material heating furnace 70 in which a heater 69 is provided is installed next to the molding section 21.

In the molding method using the molding apparatus having the above configuration, the core material 36 is heated by the same operation as in the first embodiment.

The clad material 38 is the clad material transfer plate 3
The transfer arm 64 is pushed up by the push-up bar 68 while being placed on the transfer plate holding portion 65 of the transfer arm 64. Then, the transfer arm 64 moves forward, and the clad material heating furnace 70
Inside, the clad material 38 is heated.

After the heating is completed, the transfer arm 64 moves forward and stops at a position where the clad material 38 comes between the upper and lower dies 26 and 31. At this time, the core material 36 heated and softened almost simultaneously
Stops at a position just below the cladding material 38 where there is no interference.

Then, as in the first embodiment, the lower mold 31
Is lifted by the lower cylinder 28 to lift the core material 36 and the clad material 38 to perform press molding.

After pressing, the formed single fiber returns to the transfer arm 64 together with the clad material transfer plate 39 and is taken out. The transfer plate 37 returns to the transfer arm 14 and is taken out.

According to the present embodiment, it is possible to heat the clad material to a certain temperature at which the clad material is not deformed. Does not occur, and a more accurate single fiber can be obtained.

[0072]

As described above, according to the method for molding an optical element according to the present invention, a single fiber having a good interface quality can be obtained without deforming the interface between the core and the clad.

Further, since the core and the clad are separate bodies, it is not necessary to prepare a single fiber molding material in advance, which is advantageous in cost.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the present invention.

FIG. 2 is a conceptual diagram of the present invention.

FIG. 3 is a conceptual diagram of the present invention.

FIG. 4 is a longitudinal sectional view showing the first embodiment.

FIG. 5 is a sectional view of a main part of the first embodiment.

FIG. 6 is a longitudinal sectional view showing a second embodiment.

FIG. 7 is a longitudinal sectional view showing a third embodiment.

FIG. 8 is a longitudinal sectional view showing a fourth embodiment.

FIG. 9 is a sectional view showing a conventional example.

FIG. 10 is a sectional view showing a conventional example.

[Description of Signs] 1 Single fiber 2 Clad 3 Core 4 Interface 5 Molding surface

──────────────────────────────────────────────────の Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 3/00-3/14 G03B 37/00-37/16 G02B 6/00, 6/02 G02B 6 / 16-6/22 G02B 6/44

Claims (1)

(57) [Claims] 1. A cylindrical second optical material having an outer diameter smaller than the inner diameter of the first optical material is inserted into the cylindrical first optical material by heating and softening the second optical material. A method for forming an optical element, wherein the first and second optical elements are formed into a single optical element by pressing an axial end face.