JPH02133326A - Production of optical element - Google Patents

Abstract

PURPOSE:To easily produce a lens having an arbitrary shape at a low cost by pressing the end of a hollow cylindrical molding cylinder to the stock in a softened state and reducing the pressure in the hollow hole or pressurizing the inside of the hole at the time of producing the flat plate optical element having the convex or concave lens. CONSTITUTION:The optical element stock 5 is formed to a flat plate and is fitted into the recess 2 of a holding mold 1 where the flat plat is heated and softened by a heater 6. The end part of the molding cylinder 4 having the hollow hole 3 is then pressed to the optical element stock 5 and the pressure in the hole 3 is reduced down to the pressure lower than the pressure on the outside of the molding cylinder 4. The optical element stock 5 is sucked into the hollow hole 3 of the molding cylinder 4 in this way and the convex lens of a spherical shape formed without contact at the point of the time when the pressure balances with the surface tension. On the other hand, the concave lens having a spherical shape is formed when the pressure in the hollow hole 3 of the molding cylinder 4 is regulated higher than the external pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a flat optical element having a convex lens or a concave lens.

[Conventional technology]

Generally, in a method for manufacturing a flat optical element, a convex lens array is formed by creating a refractive index distribution based on the ion concentration distribution in the flat plate surface. However,
This method has the disadvantage that the period required for ion exchange is extremely long. Furthermore, in the molding method for optical elements that has recently been put into practical use, although the molding itself is simple, it has the disadvantage that it is difficult to select the material for the mold and to create the shape.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 59-196226, a spherical pushing member (molding mold) is pressed into a heat-softened optical element material to form a flat optical element having a continuous concave lens surface. There is a way to get it.

Furthermore, as disclosed in Japanese Patent Application Laid-Open No. 61266322, a convex lens can be formed by pressing a heat-softened optical element material against a flat mold having a molding hole and extruding the optical element material from the molding hole. A method of obtaining a flat optical element having the following has been carried out.

[Problem to be solved by the invention]

However, in the prior art disclosed in Japanese Unexamined Patent Publication No. 59-196226, the lens surface is formed in contact with the optical element material by pushing a spherical pushing member into the material.

Therefore, sophisticated techniques are required to maintain and manage the surface condition of the push-in member, resulting in an increase in the cost of the molded lens and the problem that only concave lenses can be formed.

Furthermore, although the conventional technique disclosed in JP-A-61-266322 has the advantage of being able to form lenses in a non-contact manner without requiring a high-precision mold as in the molding method, only a plano-convex lens shape can be obtained. Therefore, there was a problem in that it was not possible to obtain a lens with an arbitrary shape.

The present invention has been made in view of these conventional problems, and allows lenses of arbitrary shapes to be produced without contact at low cost without requiring advanced technology for the creation of molds or the maintenance and management of their surface conditions. It is an object of the present invention to provide a method for manufacturing an optical element that can be easily obtained.

[Means for Solving the Problems] In order to achieve the above object, the present invention, when manufacturing a flat optical element, presses the end of a molding cylinder having a hollow hole into a softened optical element material. The lens is formed by deforming the optical element material by reducing or increasing the pressure inside the hollow hole of the molding cylinder compared to the pressure outside the molding cylinder.

[Effect]

According to the method for manufacturing an optical element having the above configuration, by reducing the pressure inside the hollow hole of the molding cylinder to be lower than the pressure outside the molding cylinder, the optical element material is sucked into the hollow hole of the molding cylinder and balances the surface tension. At this point, a spherical convex lens is formed in a non-contact manner. On the other hand, by increasing the pressure inside the hollow hole of the molding cylinder more than the pressure outside the molding cylinder, a concave part is formed in the optical element material in the part facing the hollow hole, and when the surface tension is balanced, it becomes a spherical concave lens. is formed without contact.

In addition, plano-convex and plano-concave lenses can be formed by arranging two molding cylinders coaxially and facing each other, pressing the ends of each molding cylinder against the optical element material, and reducing or increasing the pressure in the hollow hole as appropriate. Lenses of various shapes can be formed without being limited to.

〔Example〕

(First example) In this example, one plano-convex lens was formed.

FIG. 1a shows the optical element manufacturing apparatus used in this example, in which a cylindrical recess 2 is formed on the upper surface of a holding mold 1, and the bottom surface 2a of this recess 2 is flat. It is formed. The bottom surface 2a of the recess 2 functions as a mold for molding the flat side of the lens, and is therefore mirror-finished.

Above the concave portion 2 of the holding mold l, a cylindrical molding cylinder 4 having a cylindrical hollow hole 3 is provided so as to be able to move toward and away from the holding mold l. That is, the molding cylinder 4 is connected to a pressure device (not shown) and is provided so as to be able to press the optical element material 5 housed in the recess 2 of the holding mold l. Further, the hollow hole 3 of the forming cylinder 4 is connected to a pressure regulating device (not shown), which is provided so that the pressure inside the hollow hole 3 can be adjusted to be lower or higher than the pressure outside the forming cylinder 4. There is. Furthermore, a heater 6 is arranged around the holding mold 1 and the molding cylinder 4.

A case where a plano-convex lens is formed using a manufacturing apparatus having such a configuration will be described.

Heavy flint glass SF7 was used as the optical element material 5. First, the optical element material 5 was made to have a diameter of 12 mm.

It was formed into a flat plate with a thickness of 3 mm. Then, this optical element material 5 was fitted into the recess 2 of the holding mold 1 and heated to 610'C by the heater 6.

The diameter of the forming cylinder 4 was set to 8InI1), and the inner diameter of the hollow hole 3 was set to 3 values. After heating and softening the optical element material 5, the end of the molding cylinder 4 is pushed into the optical element material 5 at a pressure of 10 kg/c+a, and the pressure inside the hollow hole 3 is increased by IX
The pressure was reduced to 10-'' Torr, and a part of the optical element material 5 in a softened state was sucked into the hollow hole 3. At this time, the pressure outside the molding cylinder 4 was atmospheric pressure. 5 stopped deforming when the suction force due to the reduced pressure and the surface tension of the optical element material 5 were balanced, and became a spherical lens.The lens thus molded was cooled and molded into the holding mold 1. When taken out, a plano-convex lens 7 as shown in Fig. 1 was obtained.The shape of the convex surface of this plano-convex lens 7 has a radius of curvature of 1.82 mm up to an effective shape of 2.9M.
Met.

Note that the radius of curvature can be easily controlled by changing the heating temperature of the optical element material 5 to a temperature higher than its softening point or by adjusting the pressure inside the hollow hole 3.

As described above, in this embodiment, the plano-convex lens 7 is formed by reducing the pressure in the hollow hole 3 provided in the molding tube 4 and sucking the optical element material 5. There is no need for an expensive spherical mold, it is sufficient to simply use a cylindrical molding tube 4, and a convex surface can be formed in a non-contact manner, making it easy to manufacture and maintain the molding tube 4, resulting in a clean surface. lenses can be manufactured at extremely low cost.

Incidentally, when a large number of plano-convex lenses 7 according to this embodiment are arranged side by side, it can be used as a lens array for a copying machine.

(Second example) In this example, one plano-concave lens was formed.

FIG. 2a shows the optical element manufacturing apparatus used in this example, and this apparatus has the same configuration as the apparatus of the first example.

As the optical element material 5, SF7 similar to that in the first embodiment was used. First, the optical element material 5 is melted and an appropriate amount is placed in the holding mold l.
Since the viscosity of the optical element material 5 in this state poured into the recess 2 was as low as 10 to 103 poise, the heater 6 was used to control the viscosity to 106°5 poise.

After the optical element material 5 has softened to the above viscosity, the molding tube 4 is
It was pushed into the optical element material 5 with a pressure of kg/cj, and at the same time, the pressure inside the hollow hole 3 was reduced to 2 kg/c4, and a part of the optical element material 5 in a softened state was pushed and spread below the hollow hole 3. At this time, the pressure outside the molding cylinder 4 was atmospheric pressure. As a result, the optical element material 5 stopped deforming in a state where the pressing force due to the pressure increase and the surface tension of the optical element material 5 were balanced, and became a spherical lens. When the lens thus molded was cooled and taken out from the holding mold 1, a plano-convex lens 8 as shown in FIG. 1 could be obtained. The shape of the convex surface of this plano-convex lens 8 had a radius of curvature of 3.25 mm up to an effective shape of 2.7 mm.

Note that the radius of curvature can be changed by changing the viscosity of the optical element material 5 using the heater 6 or by adjusting the pressure inside the hollow hole 3, as in the first embodiment.

In this embodiment, the plano-convex lens 8 is formed by increasing the pressure in the hollow hole 3 provided in the molding tube 4 and pushing and expanding the optical element material 5, so an expensive spherical mold for molding the spherical surface is not required. This is not necessary, and the same effects as in the first embodiment can be obtained.

(Third example) In this example, a flat plate-shaped double-convex lens was formed.

FIG. 3a shows the optical element manufacturing apparatus used in this example, in which a rectangular recess 10 is formed on the upper surface of the holding mold 9, and the bottom surface 10a of this recess 10 is shaped like a flat plate. It is formed. The holding mold 9 also has a bottom surface 1 of the recess 10.
Four through holes 1) are drilled through Oa. The center position of each through hole 1) is 4 of a square with − sides of 10 ai.
They are located at each corner.

On the other hand, a lower molding cylinder 4a is slidably fitted into each through hole 1). A hollow hole 3a is formed in the lower molding cylinder 4a, similar to the molding cylinder 4a shown in FIG.

Moreover, a lower molding cylinder 4b is disposed above each lower molding cylinder 4a, coaxially with and facing the lower molding cylinder 4a. Lower molding cylinder 4b
A hollow hole 3b is formed in the lower molding cylinder 4a.

Further, each of the upper and lower molding cylinders 4a, 4b is connected to a pressure device (not shown), similar to the molding cylinder 4 shown in FIG. 5
It is provided so that it can be pressed. Each of the hollow holes 3a and 3b of the upper and lower moldings 14a and 4b is connected to a pressure adjusting device (not shown), so that the pressure inside the hollow holes 3a and 3b can be freely adjusted.

The other configuration is similar to that of the manufacturing apparatus shown in FIG.

A case where a flat plate-shaped biconvex lens is formed using a manufacturing apparatus having such a configuration will be described.

Heavy crown glass SK20 was used as the optical element material 5. First, the optical element material 5 is sized 22 x 22 x 3M.
It was formed into a flat plate. Then, insert this into the recess 10 of the holding mold 9.
and heated to 660'C using heater 6.

The diameter of the upper and lower molding cylinders 4a, 4b is 8 mm, and the hollow holes 3a, 3
The inner diameter of b was set to 31nI1). After heating and softening the optical element material 5, each -E molding cylinder 4b weighs 15 kg.
/c4 pressure into the optical element material 5, and each opposing lower molding cylinder 4a is also pressed 15k through the through hole 1).
g/c- into the optical element material 5, and the pressures in the hollow hole 3b of the lower molding m4b and the hollow hole 3a of the lower molding cylinder 4a are reduced to 1 x 10-'' Torr, respectively, to a softened state. A part of a certain optical element material 5 was sucked into the hollow holes 3a and 3b.

Further, at this time, the pressure outside the upper and lower forming cylinders 4a and 4b was atmospheric pressure. As a result, the optical element material 5 stopped deforming in a state where the suction force due to the reduced pressure and the surface tension of the optical element material 5 were balanced, and became a spherical lens. When the lens thus molded was cooled and taken out from the holding mold 9, a flat lens 12 having four biconvex lenses as shown in FIG. 3 was obtained. The shape of the convex surface is
The radius of curvature was 1.74M up to the effective shape 2.80.

Note that the change in the radius of curvature is the same as in the first embodiment.

In this embodiment, four opposing upper and lower forming cylinders 4a,
Since the flat biconvex lens 12 is formed by increasing the pressure in the hollow holes 3a and 3b provided in the hollow holes 3a and 3b provided in the optical element material 5 and sucking the optical element material 5, the same effect as in the first embodiment can be obtained. Ta.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be applied by arbitrarily setting the combination of residual pressure or pressure increase in the hollow hole of the molding cylinder, for example, as shown in FIG. 4a.
As shown in FIGS. and b, a convex-concave lens 13 and a biconcave lens 14 can also be formed. Further, the shape of the hollow hole of the molding cylinder is not limited to a circular shape, but can be made into any shape. For example, in the case of a rectangular hollow hole, a cylindrical lens 15 as shown in FIG. 4C can be formed. On the other hand, the optical element material is not limited to glass, and the present invention can of course be applied to thermoplastic resin materials and the like.

〔Effect of the invention〕

As described above, according to the method for manufacturing an optical element of the present invention,
The end of a molding cylinder having a hollow hole is pressed against the softened optical element material, and the pressure inside the hollow hole of the molding cylinder is reduced or increased compared to the pressure outside the molding cylinder, thereby deforming the optical element material. Since we decided to form a lens,
It is possible to manufacture convex lenses and concave lenses of any shape in a non-contact manner, and there is no need for an expensive LF surface mold for molding spherical surfaces, just a molding cylinder with a hollow hole is required, and molding is possible. The production and maintenance of tubes has become extremely easy,
A planar optical element with a defect-free and clean lens surface can be manufactured at extremely low cost.

[Brief explanation of the drawing]

Fig. 1a is a longitudinal sectional front view showing the optical element manufacturing apparatus used in the first embodiment of the present invention, Fig. 1 is a front view of the lens obtained in the first embodiment, and Fig. 2a is the main A longitudinal sectional front view showing the optical element manufacturing apparatus used in the second embodiment of the invention, FIG. 2 is a front view of the lens obtained in the second embodiment, and FIG. 3a is a third embodiment of the invention FIG. 3 is a front view of the lens obtained in the third embodiment, and FIGS. 4a, b, and C are respectively other embodiments of the present invention. FIG. 3 is a front view and a perspective view of the obtained lens. 1.9... Holding mold 3.3a, 3b... Hollow holes 44a, 4b... Molding tube 5... Heater 6... Optical element material 7 8.12.13.14 15... Lens

Claims (1)

[Claims] (1) The end of a molding cylinder having a hollow hole is pressed against the softened optical element material, and the pressure inside the hollow hole of the molding cylinder is reduced or increased compared to the pressure outside the molding cylinder, thereby molding the optical element material. A method for manufacturing an optical element, which comprises deforming it to form a lens.