JPH04187527A - Production of material for forming optical element and formed lens - Google Patents

Abstract

PURPOSE:To obtain a material useful in mainly reheating and pressing. an optical element with a high accuracy by dropping and cooling molten glass onto a pan and polishing the dropped surface of the molten glass in contact with the aforementioned pan. CONSTITUTION:Molten glass is dropped onto a pan and cooled. The dropped surface of the molten glass in contact with the above-mentioned pan is then polished to afford a material for forming an optical element. The resultant material can be used for forming a lens to afford the objective excellent lens by forming. The lens having <=0.1s Rmax surface roughness of the whole surface can be readily prepared at a low cost according to the aforementioned method for producing the material. The lens obtained by forming the aforementioned material is excellent in optical properties and appearance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a material for molding an optical element and a method of manufacturing a molded lens, which are mainly used when reheat pressing a high-precision optical glass element.

2. Description of the Related Art Recently, a method of forming an optical lens by one-shot molding without a polishing process is being realized.

In this case, the most efficient force is to pour the glass material from a molten state into a mold. A method of pre-processing a glass material into a certain shape, supplying it between a pair of molds, heating it, and suppressing the molding (reheat press method)?
This is disclosed in Publication No. 4.

When producing a precise lens in one molding process using this method, it is necessary to smooth the surface of the glass material to obtain a smooth lens, as disclosed in Japanese Patent Application Laid-open No. 9716. Is it something that should be done or is it necessary? Various methods are being considered for the preliminary processing of glass materials, and among them, a method using a cylindrical material that is relatively easy to process and is cost effective is being considered. Many have been done.

Hereinafter, the above-mentioned conventional molding method will be explained with reference to the drawings.

Figure 3 is an explanatory diagram of the conventional method. Figure (a) shows the appearance of the cylindrical glass material, Figure (b) is a cross-sectional view of the state during molding, and Figure (C) shows the appearance of the molded lens. In Figure 3(a), the polished surfaces 20 at both ends of the glass material 18 have been polished to a very clean mirror surface. In addition, the cylindrical surface 21 on the side surface (which is probably formed by centerless processing) has a surface roughness of about 3.23 in Rmax, and a large amount of surface roughness remains due to the crushed layer on the surface of the glass material.

Furthermore, the polished surface 20 and the cylindrical surface 214L are finished at right angles by centerless processing to form a four-way joint portion 19.

FIG. 3(b) is a sectional view of a molded lens using this glass material.

After the glass material 28 is supplied between a pair of upper molds 31 and lower molds 32 attached to a press stage 35 with a built-in heater (not shown) and a press head 34, it is heated to a temperature near the softening point of the glass and pressed. It is pressed by the head 34 and the press stage 35 and deformed under pressure.

After the deformation is completed, the lens is slowly cooled to a temperature at which the molded lens can be taken out, and then the molds 31 and 32 are opened and the lens is taken out.

FIGS. 4(a) and 4(b) are a plan view and a front view of the lens thus obtained after molding.

When the material as shown in Fig. 3(a) is molded, the optical surface 27 has a circular ridgeline 29 force caused by the edge portion 19 (furthermore, a part of the rough cylindrical surface 21 turns to the molded surface). Rough areas 30 will appear.

Problems to be Solved by the Invention As described above, the conventional example has the problem that not only the appearance quality is significantly lowered, but also the transmittance, which is important for optical performance, is also significantly lowered.

In addition, a method of cylindrical polishing to increase the surface roughness of the cylindrical surface is also considered (a significant increase in cost is expected, and
There is a problem in that the edge portion also needs to be improved separately.

Means for Solving the Problems A platform for solving the above problems In the method for producing a material for molding optical elements of the present invention, molten glass is dropped onto a receiving plate and the receiving plate and the surface facing it are polished by double-sided polishing. form a surface.

In addition, in the method for manufacturing a molded lens of the present invention, a lens is molded using the material for molding an optical element thus obtained.

Effect: According to the above-mentioned means, the obtained optical element molding material (
The cylindrical surface becomes an extremely smooth mirror surface due to the surface tension of the dropped glass when it melts. Further, the contact surface with the tray can be polished to a mirror surface.

By using this material for lens molding, an extremely good lens can be obtained by molding.Example 1 (a) 4;L, Outline of the method for manufacturing the material for molding optical elements of the present invention FIG.

The molten glass 2 in the melting furnace 1 heated to a temperature higher than the glass melting temperature by a heating device (not shown) is heated to a nozzle heater 3.
The set temperature of the nozzle part 4 and the receiving time of the glass tray 5 are controlled to form an appropriate amount of dripping gob 6 on the glass tray 6. In this embodiment, the nozzle 4 and the glass tray 5 are made of ceramic (any material with high heat resistance and reaction resistance can be used).

At this time, shrinkage wrinkles 7 (so-called orange marks) appear on the surface where the dripping gob 6 and the glass tray 5 are in contact.

Also, the side surface of this drip gob (cylindrical surface 21 in the conventional example)
) becomes an extremely smooth mirror surface due to surface tension.

This dripping gob 6 is mirror-polished using a double-sided polisher (not shown). At this time, the polishing method for mirror polishing was set to 0.3 m.
The shrinkage wrinkles 7 cannot be removed by removing m or more. Figure 1 (b) shows the glass material 8 after polishing in this way.
In the external view, the polished surface 10 and the side edge portion 9 can easily form a mirror surface, and the surface roughness can be sufficiently grooved to RmaxO81s or less.

In this example, the side surface of the dripping gob does not require polishing, and the glass material can be manufactured in large quantities with a simple device, making it possible to significantly reduce costs. ) (Yo) FIG. 1 is a cross-sectional view showing the state of molding of a lens using the glass material formed in FIG. 1.

After supplying the above-mentioned glass material 8 between the pair of upper and lower molds 11 and 12 attached to the press stage 15 and the press head 14, which have a built-in heater (not shown), the glass material 8 is heated to a temperature close to the softening point of the glass. The press head 14 and press stage 15 press and deform it.

After the deformation is completed, the molded lens is slowly cooled to a temperature at which the lens can be taken out, and then the mold is opened and the lens is taken out.

FIG. 2(b) is a schematic diagram of the appearance of the molded lens thus obtained. On the surface of the optical surface 17, there are no circular ridge lines or rough areas as shown in FIG. 4 of the conventional example, and there is no decrease in the transmittance of the lens, which is obtained in this way. The surface of the lens sufficiently satisfies RmaxO,ls or less.

Effects of the Invention As is clear from the above explanation, depending on the method of manufacturing the material for molding optical elements of the present invention, the surface roughness of the entire surface <,
It can be easily and inexpensively produced with RmaxO,is or less, and lenses molded from this material can be provided with extremely good optical performance, so the industrial value of the present invention is truly great.

[Brief explanation of the drawing]

Figure 1 (a) i;! , Fig. 1(b) is an illustration of an embodiment of the method for manufacturing a material for molding an optical element of the present invention. Fig. 2(a) is an illustration of the appearance of the material for molding an optical element obtained in the same example.
Figure 3 (b) iL External view of the molded lens obtained in the same example Figure 3 (a) (Cylindrical optics in the main conventional example) The appearance of the element molding material Fig. 3 (b) It Explanation of the conventional molding method for molded lenses @ Fig. 4 (a) (b)
) Ii is an external view of a molded lens obtained in a conventional example. ■...Glass melting drink 2...Fused glass 7,. 3...
・Nozzle heater, 4... Nozzle height 5... Glass receiver calm 6... Dripping goss 7... Shrinkage wrinkle orange mark), 18, 28... Glass material, 9... Glass top 1IO120.・・Ken Nto 11, 31...
Upper sales 12.32...Lower mold 13, 33...Junsei 14
, 34... Press head mi 15, 35... Press stage, 16.26... Lens after pressing, 17
, 27... Optical surface 19... Edge lying 21... Cylinder blood 29... Ridge line 30... None near rough ground. Name of agent: Patent attorney Akira Okaji and 2 other names 1
Figure 1 (L) ゝ-1 lθ material 7! Figure 2 (α) Figure 3 Figure 4 Figure 1m 27 Hikari Shrine

Claims (2)

[Claims] (1) A method for producing a material for molding an optical element, in which a material for molding an optical element is obtained by cooling molten glass by dropping it onto a saucer and polishing the dropping surface of the molten glass that comes into contact with the saucer. (2) Cooling the molten glass by dropping it onto a saucer, polishing the dripping surface of the molten glass that comes into contact with the saucer to obtain a material for molding an optical element, and molding the material for molding an optical element to obtain a molded lens. manufacturing method.