JP4471751B2 - Manufacturing method of glass optical element - Google Patents

Description

  The present invention relates to an improvement in a method for producing a glass optical element. More specifically, the present invention relates to a method for efficiently producing a glass optical element having a high optical performance, with internal distortion removed, a good appearance, and high optical performance by a precision mold press.

  There is known a method of molding a glass optical element by a precision mold press using a mold that has been subjected to shape processing based on the optical element shape to be obtained. Since this method does not require post-processing such as polishing, there is an advantage that an optical element having a shape such as an aspherical surface can be obtained with high productivity. In general, a molded body press-molded by applying a load in a mold is cooled to a predetermined temperature near a transition point, and then released from the mold and taken out. At this time, if it is rapidly cooled, strain remains in the glass molded body, which may impair the optical performance. However, if the molded body in the mold is gradually cooled over time, the molding cycle time becomes long, and the productivity is significantly inhibited.

  As a method of manufacturing an optical element from which internal strain has been removed, for example, after heating and softening the optical element material to a deformable temperature and applying pressure by a pair of molds, the surface shape of the mold is transferred to the optical element material. Along with the method of releasing the mold by thermally deforming the optical element, a method of annealing treatment to remove the internal strain of the optical element after the mold release (see, for example, Patent Document 1), and molding the optical element molded between the molds after molding A method of producing an optical element free from internal strain by taking out from the mold and annealing at least one of the optical elements together is known (for example, see Patent Document 2).

  On the other hand, the need for an optical material having a high refractive index is increasing with the increase in the number of pixels and the reduction in size and size of small imaging devices such as cameras, videos, and portable terminals. Conventionally, high-refractive index glass materials have been mainly high-dispersion glass. However, small-sized imaging devices such as those described above need to have high refraction and low dispersion. Moreover, in order to be able to manufacture an aspherical lens with high productivity, there has been a demand for a glass material that is applicable to a precision mold press.

  As the glass material for precision molding, it is preferable that the glass transition point (Tg) is lower in consideration of the durability of the mold used and the release film. However, in order to satisfy the required optical constant and to obtain stability as glass, it is inevitable that Tg is increased.

  The present inventors have previously proposed a glass material for precision molding having a high refractive index and an intermediate dispersion region. For example, the refractive index nd is 1.70 to 1.90 and the Abbe number νd is 35 to 65. This glass material is mainly an optical glass having a Tg of 530 ° C. or higher in order to select a composition that satisfies the optical constant and prevents the tendency to be easily crystallized (see Patent Documents 3 to 5).

  Using a glass material that has been pre-molded into a predetermined volume and shape of such optical glass, the lens is molded by precision mold pressing, and annealed after mold release. There has occurred.

Japanese Patent Laid-Open No. 10-7423 JP 2003-183039 A JP 2003-267748 A JP 2002-249337 A JP 2003-201143 A

  The annealing treatment after the release is intended to remove the strain and / or adjust the refractive index, but is performed in an appropriate temperature range near Tg or less than Tg. If the glass material has a relatively high Tg, the annealing temperature is also set higher. For example, (Tg−50 ° C.) to (Tg + 20 ° C.). As a temperature range, it becomes the vicinity of 500-600 degreeC, for example. The present inventors examined the cause of spider or contamination on the surface of the glass molded body by such annealing.

As a glass material, there is a case where a carbon-containing film provided on the surface is used mainly for the purpose of preventing fusion to a mold during press molding. Usually, this carbon-containing film is used for an optical element after press molding. The carbon-containing film is removed because it impairs the performance of the optical element or hinders the film formation of the functional film attached to the optical element. For example, when the annealing treatment of the optical element is performed in an atmosphere having an oxidizing ability, the carbon-containing film disappears mainly as CO ₂ . However, when the annealing temperature is high, the reaction between the film component and the glass component proceeds simultaneously with the reaction of disappearing the carbon-containing film, and attaching the reactants to the glass surface may cause spider or contamination. Was found by the present inventors.

  For example, lithium contained in the glass component reacts with the components of the carbon-containing film at a high temperature to generate lithium carbonate and adhere to the glass surface. If heat treatment is performed at a higher temperature in order to thermally decompose this deposit, the glass will exceed the appropriate annealing temperature range, and the glass shape will be impaired.

  The present invention has been made under such circumstances, using a glass optical element having a Tg of 530 ° C. or higher, having internal distortion removed, having a good appearance, and high optical performance. It aims at providing the method of manufacturing efficiently by precision mold press molding.

  As a result of intensive studies to achieve the above object, the inventors of the present invention pressed a preform made of optical glass having a carbon-containing film on the surface and having a Tg of 530 ° C. or higher with a mold in a softened state. After molding, the molded body is taken out, heat-treated to remove the carbon-containing film on the surface, and then annealed at a temperature higher than the above heat-treatment temperature, so that the object can be achieved. Based on this finding, the present invention has been completed.

That is, the present invention
(1) (A) A step of press-molding a preform formed of optical glass having a carbon-containing film on the surface and having a glass transition point (Tg) of 530 ° C. or higher with a molding die in a softened state by heating, (B ) After press molding, cool and take out the molded body from the mold, heat treatment to remove the carbon-containing film on the surface, and (C) the molded body from which the carbon-containing film has been removed. An annealing process at a temperature higher than the heat treatment temperature in the process, and a method for producing a glass optical element,
(2) (B) The manufacturing method of the glass optical element as described in said (1) description whose heat processing temperature in a carbon containing film removal process is 200-500 degreeC,
(3) (C) The method for producing a glass optical element according to (1) or (2) above, wherein the annealing temperature in the annealing step is in the range of Tg-50 ° C. to Tg + 20 ° C. of the optical glass,
(4) The glass optical element according to any one of (1) to (3) above, wherein the (C) annealing treatment step is performed in the same heating furnace in succession to the (B) carbon-containing film removal step. Manufacturing method,
(5) The method for producing a glass optical element according to any one of (1) to (4) above, wherein the optical glass contains an alkali metal as a glass component,
(6) The method for producing a glass optical element according to (5) above, wherein the optical glass contains 0.5 to 25 mol% of lithium as a glass component,
(7) The glass optics according to any one of (1) to (6) above, wherein the optical glass has a refractive index (nd) of 1.6 to 1.9 and an Abbe number (νd) of 35 to 65. Device manufacturing method,
(8) optical glass, as represented by mol% _{B 2 O 3: 20~60%,} SiO 2: 0~25%, ZnO: 2~35%, Li 2 O: 0.5~15%, CaO: 0 _{~10%, La 2 O 3:} 5~20%, Gd 2 O 3: 0~15%, ZrO 2: 0~10%, Ta 2 O 5: 0~10%, Nb 2 O 5: 0~5 _{%, WO 3: 0~15%,} Y 2 O 3: 0~8%, Yb 2 O 3: comprises 0-8%, and containing more than 92 mol% of these components in total, (6) Or the manufacturing method of the glass optical element as described in (7) term,
(9) an optical glass, as represented by mol% _{B 2 O 3: 25~55%,} SiO 2: 0~25%, ZnO: 4~35%, Li 2 O: 1~15%, CaO: 0~10 %, La ₂ O ₃ : 4 to 20%, Gd ₂ O ₃ : 0 to 15%, ZrO ₂ : 0 to 10%, TiO ₂ : 0 to 15%, Nb ₂ O ₅ : 1 to 10%, WO ₃ : The method for producing a glass optical element according to the above (6) or (7), which contains 0 to 14% and contains more than 95 mol% of these components, and (10) % indicated by _{B 2 O 3: 30~60%,} SiO 2: 0~20%, ZnO: 0~20%, Li 2 O: 0.5~25%, CaO: 2~30%, MgO: 0~ _{12%, SrO: 0~12%,} BaO: 0~10%, La 2 O 3: 2~18%, Gd 2 O 3: _{~10%, Y 2 O 3:} 0~10%, ZrO 2: 0~8%, Ta 2 O 5: 0~8%, Nb 2 O 5: 0~3%, WO 3: the 0-5% A method for producing a glass optical element according to the above (6) or (7),
I will provide a.

  ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing efficiently the glass optical element from which an internal distortion is removed by a precision mold press, an external appearance is favorable, and high optical performance can be provided.

  The method for producing a glass optical element of the present invention is a method for producing a glass optical element by molding a preform formed of optical glass having a carbon-containing film on the surface thereof by a precision mold press.

  The optical glass used in the present invention has a glass transition point (Tg) of 530 ° C. or higher, preferably 550 ° C. or higher, particularly preferably 580 ° C. or higher. The effect of the present invention is remarkably exhibited with respect to the optical glass having such Tg.

  The optical glass preferably contains an alkali metal as a glass component, and the effect of the present invention is remarkably recognized particularly when lithium is contained. The lithium content is preferably about 0.5 to 25 mol%, more preferably 0.5 to 15 mol%.

  The optical glass preferably has a refractive index (nd) of 1.6 to 1.9, more preferably 1.67 to 1.87, and an Abbe number (νd) of preferably 35 to 65, more preferably. Is preferably 38-52 optical glass.

Specific examples include optical glasses A to C having the glass composition shown below.
Optical glass A:
_B 2 _O 3 by _{mol%: 20~60%, SiO 2: 0~25} %, ZnO: 2~35%, Li 2 O: 0.5~15%, CaO: 0~10%, La 2 O ₃ : 5-20%, Gd ₂ O ₃ : 0-15%, ZrO ₂ : 0-10%, Ta ₂ O ₅ : 0-10%, Nb ₂ O ₅ : 0-5%, WO ₃ : 0 15%, Y ₂ O ₃ : 0 to 8%, Yb ₂ O ₃ : 0 to 8%, and a total of more than 92 mol% of these components, the refractive index (nd) being 1 An optical glass having an optical constant of .75 to 1.87 and an Abbe number (νd) in the range of 38 to 52.

Optical glass B:
Mol% in _{B 2 O 3: 25~55%,} SiO 2: 0~25%, ZnO: 4~35%, Li 2 O: 1~15%, CaO: 0~10%, La 2 O 3: _{4~20%, Gd 2 O 3:} 0~15%, ZrO 2: 0~10%, TiO 2: 0~15%, Nb 2 O 5: 1~10%, WO 3: comprises 0-14% And an optical constant having a total refractive index of more than 95 mol%, a refractive index (nd) of 1.75 to 1.87, and an Abbe number (νd) of 28 to 45. Is an optical glass.

Optical glass C:
Mol% in _{B 2 O 3: 30~60%,} SiO 2: 0~20%, ZnO: 0~20%, Li 2 O: 0.5~25%, CaO: 2~30%, MgO: 0 _{~12%, SrO: 0~12%,} BaO: 0~10%, La 2 O 3: 2~18%, Gd 2 O 3: 0~10%, Y 2 O 3: 0~10%, ZrO 2 _{: 0~8%, Ta 2 O 5} : 0~8%, Nb 2 O 5: 0~3%, WO 3: comprises 0-5%, and a refractive index (nd) of 1.67 to 1.80 And an optical glass having an optical constant having an Abbe number (νd) in the range of 45-60.

  The preform used in the present invention was obtained by subjecting the optical glass to a process such as cutting and polishing in a cold state, or by dripping or flowing down to a receiving mold in a molten state and forming it hot. Is. Preferably, when a spherical shape, a biconvex curved surface shape, or the like is formed by hot forming, a defect-free surface can be obtained efficiently.

  In the present invention, a carbon-containing film formed on the surface of this preform is used. This carbon-containing film prevents the fusion between the preform surface and the mold during press molding, and improves the slipperiness of the preform surface, thereby positioning the preform on the molding surface. To make it easier.

  The carbon-containing film is preferably a film containing carbon as a main component, and may contain other components such as a hydrocarbon film. As a film forming method, a known film forming method such as vacuum vapor deposition using a carbon raw material, sputtering, ion plating method, plasma treatment, ion gun treatment or the like can be used. Alternatively, the film may be formed by thermal decomposition of a carbon-containing material such as a hydrocarbon, and further, a method of forming a self-assembled film by bringing a preform into contact with a raw material solution or gas. .

  The thickness of the carbon-containing film is usually about 1 to 20 nm, preferably 1 to 10 nm, and more preferably 2 to 5 nm.

  In the present invention, the preformed body made of optical glass having a carbon-containing film on the surface thus obtained is press-molded with a molding die in a state of being softened by heating [step (A)]. There is no restriction | limiting in particular in this press molding method, A conventionally well-known method is employable.

For example, as a mold, a heat-resistant and strong material such as cemented carbide or ceramics (Si ₃ N ₄ , SiC, etc.) is precisely processed based on the shape of the optical element to be obtained. Prepare. For the purpose of preventing fusion and facilitating mold release, it is preferable to provide a release film (any of those containing a noble metal as a main component or carbon as a main component) on the molding surface.

  The preform is supplied to the pair of molds prepared as described above and softened by heating, or the preform that has been softened by heating is supplied to the mold and subjected to a predetermined load, thereby forming the mold. The surface shape is transferred. At this time, the atmosphere is preferably non-oxidizing so that the carbon-containing film provided on the surface of the preform does not disappear. For example, an inert gas (such as nitrogen or argon) or a reducing gas (such as hydrogen) may be mixed therein.

In the present invention, after forming the preform in this manner, the glass molded body is cooled to a temperature near Tg while being held in the mold, taken out from the mold, and subjected to heat treatment to obtain carbon on the surface. The contained film is removed [step (B)]. The mold release temperature is preferably in the range of 10 ¹³ to 10 ¹⁴ dPa · s in terms of glass viscosity.
From the viewpoint of not unnecessarily lengthening the molding cycle time, the cooling can be performed at 50 to 300 ° C./min (with an average value from the molding temperature to the mold release temperature).

  The atmosphere in the heat treatment of the glass molded body preferably contains oxygen at least in the process of removing the carbon-containing film, and the oxygen concentration is preferably 0.01 to 100 vol%. If it is less than 0.01 vol%, the effect of removing the carbon-containing film is insufficient. The higher the oxygen concentration, the shorter the time required for carbon removal. However, in order to avoid other reactions such as oxidation of the metal constituting the furnace body and lens contamination resulting from it, preferably 0.01 to 10 vol% It is.

In the heat treatment, the temperature inside the furnace into which the compact has been introduced is increased, and the rate of temperature increase may be selected in a range that does not unnecessarily increase the cycle time, for example, 60 to 300 ° C./hr, more preferably 100 to The temperature is raised at 300 ° C./hr to a predetermined temperature (film removal temperature). The predetermined temperature is within a temperature range in which the carbon-containing film on the surface of the molded body is oxidized and disappears in the atmosphere. For example, when the temperature is 200 to 500 ° C., the carbon-containing film disappears with generation of CO ₂ . More preferably, it is 300-500 degreeC. It is preferable to hold at such a temperature for 1 hour or longer. If the holding temperature is too long, the effect is not improved, and the production efficiency is lowered, more preferably 2 to 4 hours.

In the present invention, the molded body from which the carbon-containing film has been removed is annealed [step (C)].
In the case of annealing a molded body having a carbon-containing film on the surface without performing the step (B), the annealing treatment effect is difficult to be exhibited because it is too low in the above temperature range, Then, the carbon-containing film disappears due to oxidation, and the reaction between the components of the carbon-containing film and the glass component proceeds simultaneously, and the product adheres to the glass surface, thus generating spiders and surface contamination. For example, CO ₂ produced during oxidation of the carbon-containing film reacts with an alkali component such as lithium in the glass to precipitate a carbonate, thereby inhibiting the light transmittance of the optical element.

  Therefore, in the present invention, after the carbon-containing film is removed in the step (B), the molded body is further heated and annealed in the step (C). The annealing treatment may be carried out in the same heating furnace continuously from the step (B), or alternatively, the molded body after the step (B) is taken out from the heating furnace and once lowered to room temperature. Then, the annealing treatment may be performed by re-introducing the furnace and raising the temperature directly to a predetermined annealing temperature. If the steps (B) and (C) are performed continuously as in the former case, energy loss is small, and no setup change is required, thereby improving production efficiency. When the steps (B) and (C) are performed discontinuously as in the latter case, an appropriate annealing temperature can be set individually for molded articles having different annealing temperatures in accordance with the glass type. This makes it possible to carry out annealing with higher accuracy.

  In the present invention, the annealing treatment is a step of reducing the residual strain inside the glass by heat treatment and subsequent cooling, or adjusting the refractive index with it, and the temperature range (annealing temperature) is (Tg-50). ° C.) to (Tg + 20 ° C.). More preferably, they are (Tg-50 degreeC)-(Tg-10 degreeC), More preferably, they are (Tg-50 degreeC)-(Tg-20 degreeC). Thereby, the shape accuracy of a molded object is maintained favorable. The temperature increase from the carbon-containing film removal temperature to the annealing temperature is preferably 1 hour or more, and the temperature increase rate at this time is about 60 to 300 ° C./hr. The holding at the annealing temperature is preferably 2 to 4 hours.

  The atmosphere in the annealing treatment step is not particularly limited, but preferably by setting the oxygen concentration to 0 to 5 vol%, oxidation of the constituent materials of the furnace and contamination of the lens resulting therefrom can be avoided.

  The temperature lowering rate from the annealing temperature is preferably selected so that the residual strain of the obtained optical element is 10 nm or less due to birefringence. More preferably, it is performed to be 1 nm or less. For example, it is 60 degrees C / hr or less, More preferably, it is 20-60 degrees C / hr.

  When the glass temperature is sufficiently cooled, for example, reaches about Tg-180 ° C., the glass may be rapidly cooled within a range where the glass is not broken. For example, cooling of 100 ° C./hr or more can be performed. In this way, when the temperature reaches room temperature or about 100 ° C. or less, it can be removed from the furnace.

The method of the present invention is particularly effective for a mold press lens using optical glass having a relatively high Tg (that is, a relatively high annealing temperature) as described above. In the present invention, when press molding is performed using a preform with a carbon-containing film formed on the surface, the generated CO ₂ reacts with the glass component on the partially exposed glass surface, and the product is glass. Prevent sticking to the surface. That is, in the present invention, the oxidation and disappearance of the carbon-containing film and the reaction with the glass component are prevented from proceeding in parallel, and the disappearance and vaporization of the carbon-containing film are advanced first, and then the optical glass molded body Annealing treatment is performed.

Next, the present invention will be described in more detail with reference to experimental examples, but the present invention is not limited to these experimental examples.
Experimental Example A press-molding preform was produced using optical glasses having the compositions shown in Tables 1 to 3 and the optical constants and glass transition points (Tg) shown in Tables 4 to 6. That is, each optical glass was dropped from a molten state onto a receiving mold, and a preform was formed by preforming into a biconvex curved surface shape in a floating state in a receiving mold for injecting gas.

  Next, a carbon-containing film was formed on the surface of the preform. Film formation was carried out as follows using a carbon-based film formed by thermal decomposition of acetylene.

Specifically, the inside of the reaction vessel (Bergger) containing the pre-formed object to be processed was evacuated to 67 Pa or less, and then heated and maintained at 480 ° C. By evacuating with a vacuum pump while flowing nitrogen gas from the gas pipe, it was kept at 21 kPa and purged for 30 minutes. Thereafter, the introduction of gas was stopped, and the exhaust was performed to 67 Pa. Thereafter, acetylene was continuously introduced for 100 minutes at a flow rate of 65 cm ³ / min until the pressure reached 16 kPa. After reaching a predetermined pressure, the heating was stopped, the introduction of acetylene was stopped, and vacuuming was performed. After the temperature dropped, the preform was taken out.

  The preformed body having the carbon-containing film thus obtained was press-molded into a convex meniscus lens shape having a diameter of 15 mm. That is, the preform is preheated to 650 to 750 ° C. outside the mold, and is transported onto the lower mold surface using a floating jig in a softened state, and the preform is divided by dividing the floating dish. Then, it was dropped and supplied onto the lower mold surface. Immediately, the preform was pressed between the upper and lower molding surfaces with a load of 2.9 kN, and cooled at a cooling rate of 100 ° C./min when fully pressed. When the temperature became equal to or lower than the glass Tg, the mold was released and the molded body was taken out. Preheating of the preform and press molding were performed in a nitrogen atmosphere.

  The plurality of molded bodies taken out were collectively introduced into a heating furnace at room temperature, and then the heating furnace was heated and heat-treated. The atmosphere in the heating furnace was a nitrogen atmosphere having an oxygen concentration of 1 vol%.

The heat treatment was performed according to the following schedule 1 (comparative example) and schedule 2 (example).
<Schedule 1>
(1) Schedule 1-1 (Tg-35)
FIG. 1 is an explanatory diagram of the heat treatment conditions of schedule 1-1. As shown in FIG. 1, first, the heating furnace was heated from room temperature to Tg-35 ° C. (annealing temperature) in 3 hours. The temperature was maintained at this temperature for 3 hours, and then the temperature was lowered to a temperature (ie, Tg-185 ° C.) of (the above holding temperature −150 ° C.) at −50 ° C./hr. After this, it was rapidly cooled to room temperature at −100 ° C./hr.
(2) Schedule 1-2 (Tg-45)
FIG. 2 is an explanatory diagram of the heat treatment conditions of schedule 1-2. As shown in FIG. 2, first, the heating furnace was heated from room temperature to Tg-45 ° C. (annealing temperature) in 3 hours. The temperature was maintained at this temperature for 3 hours, and then the temperature was decreased to a temperature (that is, Tg-195 ° C.) of (the above holding temperature −150 ° C.) at −50 ° C./hr. After this, it was rapidly cooled to room temperature at −100 ° C./hr.
<Schedule 2>
(1) Schedule 2-1 (450 / Tg-35)
FIG. 3 is an explanatory diagram of the heat treatment conditions of the schedule 2-1. As shown in FIG. 3, first, the heating furnace was heated from room temperature to 450 ° C. (film removal temperature) in 2 hours and held at this temperature for 3 hours. This corresponds to the carbon-containing film removal step of the present invention. Further, the temperature was raised and heated to Tg-35 ° C. (annealing temperature) in 2 hours at a temperature raising rate of about 150 ° C./hr. After being held at this annealing temperature for 3 hours, it was cooled to a temperature (ie, Tg-185 ° C.) at a temperature decrease rate of −50 ° C./hr (the holding temperature−150 ° C.). After this, it was rapidly cooled to room temperature at −100 ° C./hr.
(2) Schedule 2-2 (325 / Tg-45)
FIG. 4 is an explanatory diagram of the heat treatment conditions of schedule 2-2. As shown in FIG. 4, first, the heating furnace was heated from room temperature to 325 ° C. (film removal temperature) in 2 hours and held at this temperature for 3 hours. This corresponds to the carbon-containing film removal step of the present invention. Further, the temperature was raised and heated to Tg-45 ° C. (annealing temperature) in 2 hours at a temperature raising rate of about 150 ° C./hr. After being held at this annealing temperature for 3 hours, it was cooled to a temperature (ie, Tg-195 ° C.) at a temperature decrease rate of −50 ° C./hr (the holding temperature−150 ° C.). After this, it was rapidly cooled to room temperature at −100 ° C./hr.

After the heat treatment, the optical element was taken out of the furnace and the appearance was confirmed. The results are shown in Tables 4-6.
In the table, the standard of appearance was x when either scratch-like dirt or spider was visually observed, and ◯ when none was recognized.

  Here, the flawed dirt is a flawed dirt having a width of 30 μm or more with respect to the lens diameter D and a length exceeding D / 10, or a width of 30 μm or more with respect to the lens diameter D, and D / 20 to D. / 10 Indicates that there are two or more scratch-like stains of length.

  In addition, the spider indicates that the spider is visually confirmed by holding the lens in the state of being 10 cm away from the eye in front of the 60 W light bulb.

なお、光学ガラスＡ−１２、およびその中に含有するＬｉ_２ＯをＺｎＯに置換した以外は、光学ガラスＡ−１２と同じガラスを用意し、それぞれを容器に入れ、ＣＯ_２雰囲気下で４５０℃に加熱し、３時間保持した。この結果、ガラスにはいずれも変化がなかった。一方、加熱温度を５８０℃として、３時間保持したところ、Ｌｉ_２Ｏを含有するガラスには表面に顕著なクモリが生じたが、Ｌｉ_２Ｏを含有しない方のガラスには、変化が見られなかった。

The optical glass A-12, and except for substituting Li ₂ O containing therein ZnO, prepared the same glass as the optical glass A-12, placed respectively on the vessel, 450 ° C. under a CO ₂ atmosphere And held for 3 hours. As a result, there was no change in any glass. On the other hand, when the heating temperature was set to 580 ° C. and held for 3 hours, the glass containing Li ₂ O had noticeable spider on the surface, but the glass not containing Li ₂ O showed a change. There wasn't.

This seems to have caused Li to react with CO _{2 in the} atmosphere to produce carbonate. An alkali metal such as Li has a high decomposition temperature of carbonate and does not decompose at the annealing temperature of the optical glass, and thus deposits on the surface of the glass as a spider.

  As apparent from Tables 4 to 6, when Schedule 2 was applied, the optical element (lens) after the heat treatment did not show any appearance defects and was good. On the other hand, in Schedule 1, in all cases, appearance defects were recognized based on a certain standard.

  The glass optical element manufacturing method of the present invention uses a glass having a Tg of 530 ° C. or higher, and produces a glass optical element having high optical performance with good internal appearance, internal distortion removed by a precision mold press. Can do.

It is explanatory drawing of the heat processing conditions of the schedule 1-1 in an experiment example. It is explanatory drawing of the heat processing conditions of the schedule 1-2 in an experiment example. It is explanatory drawing of the heat processing conditions of the schedule 2-1 in an experiment example. It is explanatory drawing of the heat processing conditions of the schedule 2-2 in an experiment example.

Claims (10)

  (A) A step of press-molding a preformed body made of optical glass having a carbon-containing film on the surface and having a glass transition point (Tg) of 530 ° C. or higher with a molding die in a softened state by heating, (B) press-molding After cooling, the molded body is taken out from the mold, subjected to heat treatment to remove the carbon-containing film on the surface, and (C) the molded body from which the carbon-containing film has been removed is heated in the step (B). And a step of annealing at a temperature higher than the processing temperature.   (B) The manufacturing method of the glass optical element of Claim 1 whose heat processing temperature in a carbon containing film removal process is 200-500 degreeC.   (C) The manufacturing method of the glass optical element of Claim 1 or 2 whose annealing process temperature in an annealing process is the range of Tg-50 degreeC thru | or Tg + 20 degreeC of optical glass.   The manufacturing method of the glass optical element of any one of Claim 1 thru | or 3 which performs (C) annealing treatment process in the same heating furnace continuously from the (B) carbon containing film removal process.   The manufacturing method of the glass optical element of any one of Claim 1 thru | or 4 with which optical glass contains an alkali metal as a glass component.   The manufacturing method of the glass optical element of Claim 5 in which optical glass contains 0.5-25 mol% of lithium as a glass component.   The method for producing a glass optical element according to any one of claims 1 to 6, wherein the optical glass has a refractive index (nd) of 1.6 to 1.9 and an Abbe number (νd) of 35 to 65. Optical glass, _B 2 _O 3 by _{mol%: 20~60%, SiO 2: 0~25} %, ZnO: 2~35%, Li 2 O: 0.5~15%, CaO: 0~10% , La ₂ O ₃ : 5 to 20%, Gd ₂ O ₃ : 0 to 15%, ZrO ₂ : 0 to 10%, Ta ₂ O ₅ : 0 to 10%, Nb ₂ O ₅ : 0 to 5%, WO _{3: 0~15%, Y 2 O} 3: 0~8%, Yb 2 O 3: comprises 0-8%, and containing more than 92 mol% of these components in total, according to claim 6 or 7 Manufacturing method of the glass optical element. Optical glass, as represented by mol% _{B 2 O 3: 25~55%,} SiO 2: 0~25%, ZnO: 4~35%, Li 2 O: 1~15%, CaO: 0~10%, La ₂ O ₃ : 4 to 20%, Gd ₂ O ₃ : 0 to 15%, ZrO ₂ : 0 to 10%, TiO ₂ : 0 to 15%, Nb ₂ O ₅ : 1 to 10%, WO ₃ : 0 to 0 The manufacturing method of the glass optical element of Claim 6 or 7 which contains 14% and contains more than 95 mol% of these components in total. Optical glass, _B 2 _O 3 by _{mol%: 30~60%, SiO 2: 0~20} %, ZnO: 0~20%, Li 2 O: 0.5~25%, CaO: 2~30% _{, MgO: 0~12%, SrO:} 0~12%, BaO: 0~10%, La 2 O 3: 2~18%, Gd 2 O 3: 0~10%, Y 2 O 3: 0~10 %, ZrO ₂ : 0 to 8%, Ta ₂ O ₅ : 0 to 8%, Nb ₂ O ₅ : 0 to 3%, WO ₃ : 0 to 5%, glass optics according to claim 6 or 7 Device manufacturing method.

Images