JPS6121925A - Forming of pressed lens - Google Patents

Abstract

PURPOSE:To form a pressed lens eliminating an abrasive and a polishing stage by forming the surface of a lens which has been ground by CO2 laser beam to a shape close to a desired final lens prior to press-forming, and then press-forming by heating and softening. CONSTITUTION:A ground product 1 having a shape close to the shape of a final lens is held in an annular holder 2 with a step held at above the glass transition temp. Then, the ground product 1 in this stage is transferred to a position for irradiation with CO2 laser light in an electric furnace together with the holder 2, and irrdiated and heated with laser beam 4 emitted from an output end 3 of the laser beam. By this process, a preform formed to mirror surface not so much deforming but softened on the surface is obtd., which is then transferred to the inside of a cylindrical sleeve 7 for guiding a male die 5 and a female die 6, and press-formed at a specified temp. The intensity of defocussed laser beam 4 is adjusted preferably to 2-30W/cm<2>, and irradiation of the ground product is preferred to be done for >=30sec with said adjusted laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application] The present invention relates to a glass press-molding method, and in particular, the present invention relates to a method for press-molding glass, and in particular, to form a lens close to the final desired shape using carbon dioxide scraping light.
This relates to method I, in which the removed surface is made into a mirror surface, and this is finally pressed into a lens having a desired optical mirror surface and surface precision.

[Problems with conventional technology] Conventionally, the method for manufacturing glass lenses involves melting or softening glass and putting it into a mold, press-molding it into the approximate shape of the lens, and then grinding and polishing it. However, recent patent publications use a special mold material and mold it into the desired lens shape. It is disclosed that by processing and finishing the mold surface to an optical mirror surface and press-molding the glass in a non-oxidizing atmosphere, it is possible to obtain an optical mirror surface that does not require grinding or polishing and a lens that has good surface accuracy. For example, in Japanese Patent Application Laid-Open No. 47-11277, ganic carbon is used as a mold material, glass is placed on the mold, and the mold is heated to soften the glass. There is a description of a person who starts pressing and continues pressing until the glass becomes below the glass transition point to obtain a lens.When manufacturing lenses by this method, grinding and polishing are not required, so Although a considerable J-strikedown is expected, the cycle time of press molding becomes significantly longer, and the glass is constantly in contact with the mold, so the chemical reaction between the glass and the mold material causes the surface of the mold to become rough. This is more likely to occur, resulting in the problem of adversely affecting the life of the mold (U-L life).

[Objective of the Invention J] The present invention has been made with attention to such problems, and therefore, the polishing T culm is omitted, the grinding step is simplified, time and effort are saved, and the mold is improved. The object of the present invention is to provide a high-precision glass press-forming method that can improve the service life of glass and shorten the press-forming cycle time.

1. Solving Problems 4.Ic: Mechanism J In the present invention, prior to press molding, a ground product close to the final lens shape is placed on a holder, and the glass shape is almost deformed by irradiating it with carbon dioxide Lade light. It is characterized in that after the surface of the ground surface is made into a mirror surface, the resulting preform is heated and softened, and then press-molded using a mold to finally form the desired lens.

A ground product close to the final lens shape is adjusted by spherical grinding, and there is no need to perform [1 grinding with a die Xy' end pellet. Place this ground product in a holder and
Preheat. Next, a defocused carbon dioxide gas laser beam is irradiated onto the surface of this ground product to heat and soften it to obtain a mirror surface. In this case, a carbon dioxide gas laser beam formed into a sulfuric acid gas may be scanned to soften the carbon dioxide by heating, or a defocused carbon dioxide gas laser beam itself may be scanned.

The wavelength of the carbon dioxide laser beam is as long as 10.6 μm, and it is absorbed by the extremely shallow surface layer of the glass surface, ranging from several μm to several μm, and is heated and softened, smoothing out the unevenness of the ground surface and forming a mirror surface. Therefore, a surface with fairly good surface precision can be obtained with only a small amount of deformation of the glass. Therefore, the desired optical lens can be obtained by applying a very small amount of deformation to the Blino A~m during press molding using a mold. .

The method of press forming the preform using a mold is as described above (preheating the obtained preform to a predetermined temperature,
Similarly, pressing is carried out using a preheated mold to obtain the final lens shape. Zonobriform goes to 1o.
Since press forming is completed in a high viscosity region of 10"poise, press forming can be carried out in a short time while maintaining the temperature of the brifform and the mold at a relatively low temperature corresponding to its viscosity.

This makes it difficult for the surface of the mold to become rough, making it possible to shorten and lengthen press molding time.

Illuminates the grinding surface with defocused carbon dioxide laser light.
When performing PJ, in order to obtain a surface with good surface accuracy, it is desirable to heat the shallow part of the surface to a temperature of 1 J in as short a time as possible. However, if the surface temperature is too high, a foaming phenomenon will occur due to the volatilization of the glass, so the temperature cannot be raised too high. Further, when the ground surface is irradiated with defocused L] carbon dioxide gas Radhe light to make it a mirror surface, fine bubbles are generated due to the fine cracks generated during grinding. This kind of foam is generated when the foam part softens first and closes the crack, trapping air inside the foam.The width of the rack is approximately 1 to 2μ.
m, and the depth is approximately several μrn to 20 μm. Therefore, the size of the bubbles that erupt is extremely small, with a diameter of several micrometers, and can hardly be observed with the naked eye, but it can be seen with an optical microscope.

Mirrors are observed, and if their number is very large, naked eyes are also observed. To solve these bubbling phenomena, the intensity of the diff A-customized carbon dioxide laser beam should be reduced to 2-30W.
It is desirable to irradiate the glass surface at a weak level of /ci.
If the glass surface is irradiated with carbon dioxide laser light at an intensity lower than 2 W/cd, the glass will not be heated or softened much due to the heat balance between the glass and the surrounding atmosphere, and a mirror surface will not be obtained.

When the glass surface is irradiated with carbon dioxide sheet light at an intensity higher than 30 W/ci, the above-mentioned minute bubbles can be clearly seen with the naked eye.

In addition, the same illumination f with an intensity higher than 100w/car
) When the mixture is heated to J, volatilization begins instantly and a foaming phenomenon occurs.

Therefore, it is desirable to irradiate the glass surface with carbon dioxide gas 1j light with an intensity of 2.about.30 W/ci, including -f ion. At this time, the irradiation time must be at least 30 seconds or more. In addition, in order to prevent the generation of fine bubbles, the grinding surface was immersed in hydrofluoric acid or a mixed acid such as hydrofluoric acid and sulfuric acid to remove fine cracks, then dip A.
Irradiation with a powerful carbon dioxide laser beam is desirable. This pretreatment is applied to the surface by sanding with loose abrasive grains.
Ru. Usually, free abrasive grains remain on the sanded surface after ultrasonic cleaning (
), carbon dioxide gas sea 11 light softens the surface of the glass, and free abrasive grains become stains on the glass surface. This is because since it is removed from the surface, no stains are generated even when irradiated with carbon dioxide laser light.

In addition, in order to prevent the generation of fine bubbles, the grinding product should be directly
It is also desirable to irradiate the grinding surface with carbon dioxide laser light in a vacuum chamber. The upper part of the crack softens first, and even if the crack is closed, there is no air inside the crack, so the glass inside is allowed to flow naturally.The crack closes and softens, so bubbles are generated and a mirror surface is obtained. Under these conditions], the intensity of the defocused carbon dioxide laser light may be set to 30 W/cd and 100 W/cd. Since the carbon dioxide gas laser beam is γ-focused, it may be a single mode laser beam. The oscillation mode 1 of the laser beam is continuous (・b pulse (-'t> better).

The holder for holding the ground product may be a flat tray, a curved tray, or a donut-shaped ring made of SUS stainless steel.1. Use the donut-shaped ring as a holder! In this case, it may be difficult to irradiate the carbon dioxide laser beam from both sides of the grinding surface. In addition, defocused carbon dioxide
Even if the preform is adjusted by irradiating the ground surface with light and then press-molded continuously, the preform adjustment and press-forming are performed separately. The surface m1& of the lens is 21-tons (although it is several pieces), a press lens with a surface precision of 1 to 2 Newtons after press molding can be obtained.

Example 1 Next, the content of the present invention will be explained from C1 based on Example 3. Figure 1: 1 Grinded product 1 close to the final lens shape is placed on ring-shaped holder 2 , Figure 2 shows the ground product in the holder numbered 10 being irradiated with defocused carbon dioxide laser light, Figure 3 shows the obtained preform being pressed, and Figure 4 shows the ground product being vacuumed. Cross-sectional view T:i1\C shows the state in which the medium laser beam is irradiated. First, a ground product 1 having a shape close to the final lens shape is placed on a ring-shaped holder 2 with steps. At this time, the holder 2 is maintained at a temperature above the glass transition temperature.The ground product 1, while remaining on the holder 2, is moved to the carbon dioxide laser beam irradiation position 1a in an electric furnace, where it is kept at a temperature above the glass transition temperature. It is irradiated and heated by the laser beam 4 emitted from the laser beam output end 3, and the surface softens and becomes a mirror surface without much deformation. It is transferred into a cylindrical sleeve that guides the mold 6, etc., and press-molded by the upper mold 5 and lower mold 6 at a predetermined temperature C. Moreover, FIG. 4 shows a state in which the ωI cut product 8 is placed in a vacuum chamber 9 and the laser beam 4 emitted from the laser beam output end 3 is irradiated through a window 10 made of a carbon dioxide laser beam-transmitting material and is heated and softened. . Grinding product 8
is placed on a plate-shaped holder 11, and both are placed on an X-Y table 12 to determine the irradiation position. The vacuum chamber 5) is evacuated by a vacuum pump 14 through a vacuum valve 13, and a stable vacuum state of 10'torr is obtained. The following table lists the carbon dioxide laser light irradiation conditions and pretreatment conditions for each example. (The following is a blank space) As is clear from the table, the present invention can be applied regardless of the type and shape of the glass. There are optimum conditions for irradiation of carbon dioxide laser light depending on the type of glass. Softening temperature 1jlt (S
With glass materials having a low p), a mirror surface can be obtained in a relatively short time with a strength of 2 to 10W10+f. For glass materials with high softening strength (Sp), a mirror surface can be obtained by irradiation at an intensity of 15 to 30 W/cn for a relatively long time. In addition, irradiation after hydrofluoric acid treatment,
13 and the vacuum chamber, it is possible to shorten the irradiation time.

[Effect of the invention 1 According to the present invention, the grinding process is omitted, the grinding process is simplified, time and labor are saved, and the molding life of the mold is improved to shorten the recycle time of press molding. Every thing (・monkey 1゜

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a ring-shaped holder (double 111.) where a ground product close to the shape of the final lens is held; Figure 2 is a cross-sectional view of the laser irradiation; Figure 3 is a press forming ] Showing the culm - t l!li side view, Fig. 4 t, l vacuum chamber 11' C cross-sectional view C without showing the process of turning a ground product into a mirror finish 9゜ 1...Grinded product, 2 ...Ring-shaped holder, 3...
Carbon dioxide laser light output intensity 1.4...γisno4-cush laser light, 5...1≧(su, 6...pa1 type, 7
... Cylindrical sleeve, 8... (u (removed, 9...
Vacuum chamber 17, 10... Carbon dioxide gas lede light transmitting material window, 11... Plate-shaped holder, 12... X-
Y7-Pull, 13...Vacuum valve, 14...Vacuum pump

Claims (1)

[Claims] 1. Before press molding, the ground product close to the final lens shape is laser polished with defocused carbon dioxide laser light to make the ground surface a mirror surface, and then this is heated and softened as a preform. A method for forming a press lens, which is characterized in that it is then press-molded. 2 Adjust the intensity of the defocused carbon dioxide laser light to 2~
The method for molding a pressed lens according to claim 1, wherein the ground product close to the final lens shape is irradiated with irradiation at 30 W/cm^2 for 30 seconds or more to make the ground surface mirror-like. 3. The press lens molding method according to claim 1, wherein a ground product close to the final lens shape is polished with hydrofluoric acid and irradiated with defocused carbon dioxide laser light to make the ground surface a mirror surface. 4. The press lens forming method according to claim 1, wherein the ground product having a shape close to the final lens shape is irradiated with defocused carbon dioxide laser light in a vacuum to make the ground surface a mirror surface.