JPH02224962A - Manufacture of optical element - Google Patents

Abstract

PURPOSE:To obtain a lens of a high eccentric accuracy by fixing a glass material to a forming die without releasing from the forming die after forming, using the forming die as a sticking jig for polishing and executing polishing, in manufacturing the optical element of a lens, etc. CONSTITUTION:A forming die 5 is installed inside a forming chamber 4 and a glass material 7 is placed on a forming ace 5a. The glass material 7 is of a parallel plate and only the face 7a brought into contact with the forming face 5a of the forming die 5 is subjected to polishing and an opposite face 7b is just as a cutting face. After a heater 6 on the circumference of the die 5 is installed, the forming chamber 4 is subjected to pressure reducing by a vacuum pump and an inert gas is filled up. When the material 7 is held for specific time at its softening temperature by the heater 6, the material 7 is deformed. When it is subjected to natural cooling thereafter, an optical functional face is formed on the face 7a. When a pitch is coated on the outer periphery of the forming face 5a at about 100 deg.C of the temperature of the die 5, the material 7 and die 5 are sticked strongly. Grinding and polishing are executed on the face 7b of the material 7 thus sticked with the die 5 as the reference.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing an optical element, in which a glass material is heated and softened, molded, and then one surface is polished.

[Conventional technology]

Generally, a method is known in which an optical element is obtained by heating and softening a glass material and press-molding it between a pair of molds (for example, Japanese Patent Publication No. 6,132,263). Among them,
For example, as proposed in Japanese Patent Application No. 62306509,
There is a method of press-forming a glass material and then finishing one side by polishing. This is because one mold is divided into multiple parts, and molding is performed by setting independent molding pressure and molding temperature for each divided mold, so there is a step on one surface of the resulting optical element. Since this occurs, the step is polished to make it smooth.

In this way, in the method of manufacturing glass lenses etc. by forming an optically functional surface on only one surface by molding and polishing the other surface, conventionally, the glass material after pressure molding is placed in a mold for molding. He took it out, stuck it on a polishing jig, and polished it.

[Problem to be solved by the invention]

However, in the conventional optical element manufacturing method described above, although it is possible to easily obtain a lens with a desired shape without being constrained by the lens shape, when attaching the glass material after molding to the polishing attachment jig, the core This makes it difficult to produce lenses with high eccentricity accuracy.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a method for manufacturing an optical element that can obtain an optical element with particularly high eccentricity accuracy.

(Means for Solving the Problems) In order to achieve the above object, the present invention heats and softens a glass material to form it to make one surface an optically functional surface, and then finishes the other surface by polishing. In the method for manufacturing an optical element, as shown in FIG. 1, after the molding, the glass material 1 is fixed to the mold 2 with an adhesive 3 or the like without being released from the mold 2, and then was used as a polishing attachment jig to polish the other surface.

[For production]

According to the manufacturing method of the present invention, the optical functional surface obtained by molding and the polishing attachment jig are bonded without any eccentricity, so even if the other surface is finished by polishing, An optical element with extremely high eccentricity accuracy can be obtained.

〔Example〕

(First Example) FIG. 2 shows the molding apparatus used in this example. Inside the molding chamber 4, there is a mold 5 that also serves as a polishing attachment jig (polishing attachment plate). It is located.

The mold 5 is molded from stainless steel or ceramics, and its molding surface 5a is formed into an aspherical shape and has a surface roughness of 0.06 μm (R, -
X) The following is mirror-finished and covered with a film of chromium nitride or titanium nitride. Furthermore, a cylindrical heater 6 is arranged around the mold 5 so as to surround the mold 5. The heater 6 is for heating the mold 5 and the glass material 7 placed on the mold 5.

Using the molding apparatus configured as described above, an optical element was manufactured in the following manner.

First, the mold 5 for molding is installed in the molding chamber 4, and its molding surface 5
A glass material 7 was placed on top a. This glass material 7 is
A surface 7 that is a parallel flat plate and is in contact with the molding surface 5a of the mold 5
Only the surface a is polished, and the opposite surface 7b remains as a cut surface. Then, after installing a heater 6 so as to cover the mold 5 on which the glass material 7 is placed, the molding chamber 4 is sealed, and a vacuum pump (not shown) is used to heat the mold with an I.times.10
The pressure was reduced to about -' Torr, and then it was filled with inert gas. The gas pressure at this time is 5 x 10-'Tor
It is about r. Next, the glass material 7 was maintained at a temperature for a predetermined period of time using a heater 6 to soften it. As a result, the glass material 7 was deformed due to its own weight. After that, it was naturally cooled,
In this cooling process, after the temperature of the glass material 7 becomes sufficiently lower than the transition point, the molding chamber 4 is opened, and
Heater 6 was removed.

In the process up to this point, an optically functional surface that is an inversion of the molding surface 5a of the mold 5 was formed on one surface 7a of the glass material 7.

Thereafter, when the temperature of the mold 5 reached around 100°C, Pitch 8 was applied to the outer periphery of the molding surface 5a of the mold 5 as shown in FIG. Here, in the cooling process,
Since the glass material 7 and the molding die 5 have different coefficients of linear expansion, there is a slight gap between them. The pitch 8 applied to the outer periphery of the molding surface 5a of the mold 5 penetrates into the gap and firmly adheres the glass material 7 and the mold 5. The surface 7b of the bonded glass material 7 on which the optically functional surface is not formed was subjected to grinding and polishing using the mold 5 as a reference.

The thing to be most careful about in this step is eccentricity accuracy, which is the main objective of the present invention. FIG. 4 shows a method of fixing the mold 5 to the work shaft of the CG machine during CG processing (rough grinding). That is, the shank portion 5b and flange portion 5C of the molding die 5, which also serves as a polishing attachment jig, are
The position was determined by bringing it into contact with the work shaft 9 of the G machine. The shank portion 5b corrects deviations in the shift direction, and the flange portion 5C corrects deviations in the tilt direction. In this state, CG
By suctioning the mold 5 with air from the suction hole 10 of the work shaft 9 of the machine, the mold 5 is fixed to the work shaft 9 of the 00 machine, so processing can be performed with extremely high eccentricity accuracy. .

In the fine grinding and polishing process after CG processing, the shank portion 5b and flange portion 5c of the molding die 5 are brought into contact and fixed in the same manner as described above, and processed with extremely high eccentricity accuracy. I was able to process it with

In this example, since eccentricity during molding is not a problem at all, compared to a processing method in which both sides are finished by one molding, it is very advantageous in terms of the eccentricity accuracy of the molding machine, etc. .

Furthermore, since a low-cost parallel flat plate is used as the glass material 7, it is advantageous in terms of cost.

(Second Embodiment) FIG. 5 shows the molding apparatus used in this example, in which a pair of upper and lower molding molds 12 and 13 are installed in the molding chamber 11, an upper mold mount 14 and a lower mold mount, respectively. It is attached to a mounting base 15. The upper mold 12 is similar to the mold 5 used in the first embodiment, and the lower mold 13 is
The difference is that it does not have an optical functional surface and functions only as a pressing mold. Although not shown, the molding chamber 1
1 is equipped with a drive mechanism that moves the upper mold 12 up and down and a mechanism that heats each mold 12 and 13.

Using the molding apparatus having such a configuration, an optical element was manufactured in the following manner.

First, the glass material 7 was placed on the lower mold 13 for molding.

This glass material 7 is the same as that used in the first embodiment. Thereafter, the remolding molds 12 and 13 were heated to a temperature at which the glass material 7 softened, and then the upper molding mold 12 was lowered to pressurize the glass material 7. After maintaining this state for a predetermined time, the temperature of the remolding molds 12 and 13 was lowered. Through the operations up to this point, the shape of the upper mold 12 was transferred to the upper surface of the glass material 7.

After the remolding molds 12 and 13 were sufficiently cooled, an instant adhesive was applied to the outer periphery of the molding surface 12a of the molding upper mold 12 while pressing the glass material 7 with the molding upper mold 12. after that,
After the glass material 7 and the upper mold 12 were sufficiently bonded, the pressing force of the upper mold 12 was removed.

Grinding and polishing was performed on the surface of the glass material 7 bonded in this manner, on which the optically functional surface was not formed, using the upper mold 12 as a reference. In this case, since the upper mold 12 did not have a flange as in the first embodiment, the method of fixing it was as shown in FIG. That is, the cylindrical portion 12b and bottom portion 2c of the upper mold 12 were brought into contact with the work shaft 16 of the 00 machine for positioning. The columnar portion 2b corrects deviations in the shift direction, and the bottom portion 12c corrects deviations in the tilt direction. A magnet 17 is attached to the work shaft 16, and the upper mold 12 for molding is fixed by this magnet 17. Rough grinding, fine grinding, and polishing were performed under these conditions, and we were able to perform processing with extremely high eccentricity accuracy.

In this example, during molding, the re-molding mold 12.13
Since the glass material 7 is pressed by the glass material 7, the shape of the molding upper die 12 is extremely easily transferred to the upper surface of the glass material 7.

Moreover, when bonding the glass material 7 and the upper mold 12,
Since the glass material 7 is pressed by the re-molding die 1213, the glass material 7 and the upper mold 12 do not become misaligned. Further, since the upper mold 12 has no flange and has a simple shape, it has the advantage that the cost of the mold can be kept low.

Note that in the above embodiment, fitting and magnets are used as a method of fixing the mold to the work shaft during grinding, but instead, a collet chuck, which is normally used in metal processing, is used. You may do so.

(Effects of the Invention) As described above, according to the method for manufacturing an optical element of the present invention,
After molding, the glass material is fixed to the mold without being released from the mold, and then the mold is used as a polishing jig for polishing, making it possible to create an optical element with extremely high eccentricity accuracy. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a state in which a glass material is fixed to a mold in the method for manufacturing an optical element of the present invention, and FIGS. 2 to 4 show a first embodiment of the present invention. Second
The figure is a longitudinal cross-sectional view showing the molding device, Fig. 3 is a front view showing the state in which the glass material is fixed to the mold, and Fig. 4 is the longitudinal cross-section showing the state in which the mold is attached to the work shaft of CC@. figure,
Figures 5 and 6 show a second embodiment of the present invention, with Figure 5 being a longitudinal sectional view showing the molding device, and Figure 6 showing the upper mold for molding attached to the work shaft of the CG machine. FIG. 1.7... Glass material 2.5.12.13... Molding mold

Claims (1)

[Claims] (1) In a method for manufacturing an optical element in which a glass material is heated and softened and molded to make one surface an optically functional surface, and the other surface is finished by polishing, the glass material is separated from the mold after the molding. A method for manufacturing an optical element, characterized in that the optical element is fixed to a mold without being molded, and then the other surface is polished using the mold as a polishing attachment jig.