JP2930522B2 - Method for producing synthetic quartz glass molded article for optical use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an optical quartz glass molded article from a rod-shaped synthetic quartz glass.
Flat and cubic quartz glass compacts for optical members such as mirrors, windows and prisms can be efficiently and efficiently made of graphite or SiC from rod-shaped synthetic quartz glass.
The present invention relates to a method for producing a quartz glass molded article for optics, which can be produced by minimizing the decrease in light transmittance and the generation of fluorescence due to contamination from the mold in a molding step using a mold.

[0002]

2. Description of the Related Art Synthetic quartz glass has excellent light transmittance and is often used as optical components such as lenses, mirrors and windows. In particular, synthetic quartz glass is often used in optical components for ultraviolet light because of its high transmittance in the ultraviolet region that cannot be obtained with other glasses. Further, in particular, a synthetic quartz glass for optical use manufactured from a rod-shaped synthetic quartz glass can greatly improve the homogeneity of the refractive index by a special treatment, and, for example, has a very strong energy such as an excimer laser. In recent years, it has been used more frequently as an optical component for lithography necessary for manufacturing semiconductors because it is much more stable to ultraviolet light than other glasses.

[0003] Such an optical component made of synthetic quartz glass is manufactured by grinding and polishing a flat disk-shaped synthetic quartz glass molded body, for example, like a conventional quartz glass lens. A quartz glass window, mirror or prism is manufactured by grinding and polishing from a flat, prismatic or rectangular parallelepiped synthetic quartz glass molded body. These flat disk-shaped, prismatic or cubic shaped synthetic quartz glass molded bodies before grinding are particularly called quartz glass blanks, and usually are molded from a bar-shaped synthetic quartz glass molded body, such as a graphite mold. It is manufactured by molding into a flat, prismatic or rectangular parallelepiped shape at a high temperature.

[0004]

Here, in particular, in the molding step of a synthetic quartz glass molded body for producing an optical component for ultraviolet light made of synthetic quartz glass, the transmittance in the ultraviolet region is often caused by contamination from a mold. Is reduced or fluorescence is generated.

For example, in a molding step using a graphite mold, that is, a graphite mold, a starting quartz glass molded body usually has a rod-shaped synthetic quartz glass having a length of at least five times the outer diameter. It is. For example, from such an elongated rod-shaped synthetic quartz glass, when molded into a flat shape at once, for example, a disk shape, it takes a long time to form due to a large amount of deformation. When the molding temperature is increased or weight is applied to shorten the time, the synthetic quartz glass rod is often bent or non-uniformly deformed.

Further, the prolonged molding time leads to an increase in the contact time between the synthetic quartz glass and a mold such as a graphite mold. For this reason, the synthetic quartz glass molded article for optics, for example, The problem is that the contamination from the graphite type increases the amount of impurities and greatly reduces the optical characteristics. An object of the present invention is to solve problems related to contamination by a graphite mold or the like, and deformation of a synthetic quartz glass during a molding operation, for example, when molding into a flat shape from a rod-shaped synthetic quartz glass molded body. I have.

[0007]

Means for Solving the Problems The inventors of the present invention have made it possible to reduce the amount of impurities caused by contamination of a synthetic quartz glass molded article from a graphite mold or a SiC mold, and to uniformly mold the synthetic quartz glass molded article. As a result of intensive studies to find a molding method of a synthetic quartz glass molded article for optical members that enables
When the rod-shaped synthetic quartz glass is molded using, for example, a graphite mold, the length of the rod-shaped synthetic quartz glass is set to 1 to 4 times, preferably 2 to 3.5 times the outer diameter thereof. It has been found that the most uniform and efficient molding can be performed. In addition, the present inventors furthermore, when molding a synthetic quartz glass molded article into a flat shape using, for example, a graphite mold, before molding, beforehand 1 to 4 times the outer diameter, preferably Is formed by shaping a rod-shaped synthetic quartz glass having a length of 2 to 3.5 times with a lathe for quartz glass processing, thereby reducing contamination, having a high transmittance, and causing optically unfavorable results such as generation of fluorescence. Finding that synthetic quartz glass with the least characteristics can be obtained,
The present invention has been made.

That is, the present invention relates to a method for producing a synthetic quartz glass article for optical use by molding a synthetic quartz glass rod into a synthetic quartz glass article for optical use by heating using a mold. Both ends of the rod-shaped synthetic quartz glass, which has a length exceeding
While rotating at the same rotational direction with a different number of rotations, pressurizing and deforming in the direction of the rotational axis to form a synthetic quartz glass preform having a length of 1 to 4 times the outer diameter, A method for producing a synthetic quartz glass molded article for optics, characterized by producing a synthetic quartz glass molded article for optics by molding a synthetic quartz glass preform using a mold under heating.

In the present invention, the deformation of the rod-shaped synthetic quartz glass having a length exceeding 5 times the outer diameter into a synthetic quartz glass preform is performed by using a quartz glass processing machine attached to both ends of the rod-shaped synthetic quartz glass. This is performed via a support member such as a support bar or a support block held by a lathe. In this case, while rotating the supporting members attached to both ends of the rod-shaped synthetic quartz glass, a part of the rod-shaped synthetic quartz glass is heated to form a melting zone, and one or both of the supporting members are placed on the rotating shaft. While moving in the direction in which the distance between the two support rods is reduced, and moving the heating means in the direction of movement of the support member, the molten zone formed in the rod-shaped synthetic quartz glass is deformed under pressure in the rotational axis direction. It is preferable to make the diameter of the rod-shaped synthetic quartz glass large by moving it to obtain a synthetic quartz glass preform.

In the present invention, the rod-shaped synthetic quartz glass is
The cross-section is formed into a circle or a square with rounded corners or an ellipse or a rectangle with rounded corners. However, the circular cross-section facilitates molding of optical members without impairing quality in manufacturing optical members. It is preferable because it is possible. In the present invention, the quartz glass molded body for optics is a disk, a rectangular plate, a rectangular parallelepiped,
Although it has a shape such as a cubic shape, a disk shape is preferable because the optical member can be easily molded without deteriorating the quality in manufacturing the optical member.

Since the quartz glass molded article for optical use is molded by using a graphite mold, a contaminated portion is generated from the mold, and the contaminated portion is removed by, for example, cutting. In the present invention, since there is little contamination by a mold such as a graphite mold of a synthetic quartz glass molded article for optics,
For example, the yield of an optical synthetic quartz glass molded article as a material for an optical member can be increased, which is efficient.

In the present invention, prior to forming an optical quartz glass molded body using a mold such as a graphite mold, a rod-shaped synthetic quartz glass as a raw material is stretched 1 to 4 times, preferably 2 to 4 times as long as the diameter. And formed into a synthetic quartz glass preform having a thickness. The molding of the synthetic quartz glass preform is performed without using a mold and without contact.

According to the present invention, in order to form a raw synthetic quartz glass rod into a synthetic quartz glass preform, the raw synthetic silica glass material is gripped at both ends by left and right chucks of a lathe for processing quartz glass. Attached to the supporting member. Then, a part of the rod-shaped synthetic quartz glass attached to the chuck of the lathe for quartz glass processing via the support member as described above is heated and softened to form a melting zone. By rotating the synthetic silica glass in the same direction at different rotation speeds, twisting the rod-shaped synthetic quartz glass, moving at least one of the chucks in a direction in which the distance between the two chucks is reduced, and deforming the molten zone under pressure. By moving a heating means such as a heating burner to deform the melting zone under pressure while moving it over the entire length of the rod-shaped synthetic quartz glass, the outer diameter of the rod-shaped synthetic quartz glass is increased, and the length with respect to the diameter is increased. Is 1 to 4 times, preferably 2 to 3.5 times.

In the present invention, the graphite type
Before forming the rod-shaped synthetic quartz glass, a preliminary forming step is provided, and the rod-shaped synthetic quartz glass has a length with respect to the outer diameter,
By molding into a synthetic quartz glass preform of 1 to 4 times, preferably 2 to 3.5 times, the optical quartz glass formed by a graphite mold can be formed such that buckling and quality are impaired. And minimize the effect of contamination from the graphite mold during molding,
Furthermore, a quartz glass molded article for optics with little decrease in transmittance in the ultraviolet region and little generation of fluorescence can be molded with a reduced molding time.

In the present invention, when producing a synthetic quartz glass preform, the difference in rotation between the two ends of the rod-shaped synthetic quartz glass is different from the number of revolutions on the high-speed rotation side.
It is preferable that the rotation speed on the low speed side is set to be lower by 4% to 36%. In particular, the rotation speed on the low speed side is reduced by 4% to 18% with respect to the rotation speed on the high speed side to set the rotation difference. Is preferred. Therefore, when the rotation speed on the high-speed side is 30 rotations / minute, the rotation speed on the low-speed side can be 28 to 19 rotations / minute, but is preferably 28 to 25 rotations / minute. In this case, it is preferable to reduce the number of revolutions on the side where the melting zone is first formed and on the side where external force is applied, since the work becomes easier.

In the present invention, the synthetic quartz glass molded article for optical use is molded from a synthetic quartz glass preform using a mold such as a graphite mold. The synthetic quartz glass preform is compared with the synthetic quartz glass preform in order to avoid the occurrence of rejects due to the buckling and quality deterioration of the synthetic quartz glass preform during molding from the synthetic quartz glass preform. Therefore, it is necessary that the synthetic quartz glass preform has a length that is 1 to 4 times the outer diameter of the synthetic quartz glass preform in the present invention. Preferably, the length is in the range of 2 to 3.5 times the outer diameter.

That is, when a rod-shaped synthetic quartz glass having a length exceeding 5 with respect to the outer diameter is used as a starting material for molding with a graphite mold, for example, the shape after molding with the graphite mold generally has a shape with respect to the outer diameter. Since the height is often not more than one time, the amount of deformation is large, the molding time is long, the contamination from the graphite mold is large, and the yield is reduced. In addition, if the end face of the rod-shaped synthetic quartz glass is formed so as to slightly deviate from the right angle with respect to the side surface, at worst, the rod-shaped synthetic quartz glass placed upright in a graphite mold has a poor posture. As a result, the rod-shaped synthetic quartz glass falls or bends during the molding, so that stable molding cannot be performed. This is further promoted, for example, when a weight is placed on a rod-shaped synthetic quartz glass in order to shorten the molding time.

In the present invention, the rod-shaped synthetic quartz glass is
In the case of a highly homogeneous rod-shaped synthetic quartz glass subjected to a homogenization treatment, for example, a highly homogeneous disc-shaped synthetic quartz glass material for manufacturing a highly homogeneous synthetic quartz glass optical member for ultraviolet rays can be efficiently produced. It is preferable because it can be manufactured. According to the present invention, for example, a disk-shaped synthetic quartz glass molded body can be manufactured with high efficiency from a rod-shaped synthetic quartz glass. Therefore, in the present invention, the rod-shaped synthetic quartz glass can be a rod-shaped synthetic quartz glass as manufactured by a general direct method or a VAD method.

[0019]

According to the present invention, a part of the rod-shaped synthetic quartz glass is heated and softened to form a melting zone, both ends of the rod-shaped synthetic quartz glass are rotated at different rotation speeds, and the rod-shaped synthetic quartz glass is rotated in the direction of the rotation axis. By applying pressure to deform the melting zone under pressure, a rod-shaped synthetic quartz glass preform having a length to outer diameter ratio of 1 to 4 is formed, and then this rod-shaped synthetic quartz glass preform is made of graphite. Since the optical synthetic quartz glass molded material that is the raw material of the optical member is formed under heating using a mold, the optical synthetic quartz glass molded material from the rod-shaped synthetic quartz glass is affected by buckling and quality. It can be manufactured in a relatively short period of time by avoiding such forming, and can reduce the contamination of the rod-shaped synthetic quartz glass from the graphite mold. It can be prepared in high yield optical synthetic quartz glass molded body.

[0020]

EXAMPLES Hereinafter, examples of embodiments of the present invention will be described.
The present invention will be described with reference to comparative examples, but the present invention is not limited by the following description and examples. FIG. 1 shows the apparent transmittance (%) of ultraviolet rays (wavelength nm) measured with a transmittance meter for a 1 cm thick sample of the quartz glass molded body obtained in Example 1 and Comparative Example 1 of the present invention. FIG. 5 is a comparison diagram of an apparent transmittance measurement curve of ultraviolet light, which is indicated by a solid line for the sample of Example 1 and indicated by a dashed line for a sample of Comparative Example 1.

Example 1 A synthetic quartz glass rod having a diameter of 60 mm and a length of 1000 mm is gripped at both ends by chucks of a lathe for processing quartz glass, and a support rod made of synthetic quartz glass having the same diameter as the synthetic quartz glass rod is attached. It is gripped by a chuck of a lathe for processing quartz glass via a support rod. When the synthetic quartz glass rod was attached to both chucks of a lathe for processing quartz glass, both chucks were rotated synchronously. In this example, this rotation was 30 rotations / minute. After the left end of the synthetic quartz glass rod was heated and softened to form a melting zone, both chucks were rotated at different rotation speeds. In this example, the left chuck was rotated 30 times and the right chuck was rotated 25 times. The melting zone is pressurized and deformed by slowly pressing the left chuck of the quartz glass lathe in the direction of the rotation axis to apply pressure to the melting zone. Due to the pressure deformation of the melting zone, the burner is moved from left to right in accordance with the movement of the chuck on the left while increasing the diameter of the synthetic quartz glass rod, and the entire synthetic quartz glass rod is kept at an outer diameter of 100 mm. Molded. A portion having a uniform outer diameter of the preformed synthetic quartz glass rod was cut off from the support rod, and the outer diameter was 100 mm and the length was 340 m.
m of the synthetic quartz glass preform was obtained. In this case, the yield of the synthetic quartz glass preform was 95%.

This synthetic quartz glass preform was prepared by
Placed in a graphite mold having a height of 00 mm and a height of 400 mm, placed in an electric furnace as it is, evacuated the furnace, filled with nitrogen, and heated to 1800 ° C. at a heating rate of 20 ° C./min. And stops energizing as soon as the maximum temperature is reached,
Naturally cooled. After cooling, outer diameter 200mm, height 85mm
Was obtained. It was again heated to 1150 ° C. in the atmosphere in an electric furnace and gradually cooled to remove strain. When this synthetic quartz glass for optical use was irradiated with ultraviolet rays having a wavelength of 254 nm to observe fluorescence, green fluorescence due to contamination from graphite was observed within a range of 5 mm from the surface portion.
The outer peripheral surface portion and both end surface portions where this fluorescence was observed were ground and removed. In this example, the yield of the non-fluorescent portion was 75%.

Also, from the central portion, a vertical length of 10 mm and a horizontal width of 1 mm
A sample for transmittance measurement having a height of 0 mm and a height of 50 mm was cut out, and the side face was polished to measure the transmittance.
The transmittance measured by a transmittance meter, so-called apparent transmittance, was 90.81% for ultraviolet rays of m, and the internal transmittance for ultraviolet rays of 200 nm was 99.9% or more.
Here, the internal transmittance (%) is given by apparent transmittance (%) / theoretical transmittance (%). The apparent transmittance measured by a transmittance meter for a 1 cm thick sample of the quartz glass molded body in this example is shown by a solid line in FIG. With respect to the synthetic quartz glass molded article for optical use in the present example, for example, if the optical path length of a precise optical system is set to 40 cm for convenience of calculation, and the transmittance is calculated, the reflection due to the entire reflection of the synthetic quartz glass molded article for optical use in this example will be described. The transmittance excluding the loss is 96.1%.
It is.

Example 2 A synthetic quartz glass rod having a diameter of 60 mm and a length of 1000 mm was gripped at both ends by a chuck of a lathe for quartz glass processing, and made of synthetic quartz glass having the same diameter as the synthetic quartz glass rod as in Example 1. Is mounted on the chuck of the lathe for processing quartz glass via the support bar. When the synthetic quartz glass rod was attached to both chucks of the lathe for processing quartz glass via support rods, both chucks were rotated synchronously. In this example, this rotation was 30 rotations / minute. After the left end of the synthetic quartz glass rod was heated and softened to form a melting zone, both chucks were rotated at different rotation speeds. In this example, the left chuck was rotated 30 times and the right chuck was rotated 25 times. By slowly pressing the left chuck of the lathe for quartz glass processing in the direction of the rotation axis to apply pressure to the melting zone, and deforming the melting zone by pressing, the diameter of the synthetic quartz glass rod is increased while increasing the diameter. The burner was moved from left to right in accordance with the movement of the chuck, and the entire synthetic quartz glass rod was preformed to an outer diameter of 120 mm.

A portion of the preformed synthetic quartz glass rod having a uniform outer diameter is cut off from the supporting rod, and the outer diameter is 120 m.
m and a quartz glass preform having a length of 200 mm were obtained. The yield of this quartz glass preform was 80%. This quartz glass preform is 200 mm in inner diameter and 400 m in height.
m in a graphite mold, placed in an electric furnace as it is, evacuated the furnace, and filled with nitrogen.
The temperature was raised to 800 ° C. at a heating rate of 20 ° C./min. When the temperature reached the maximum temperature, energization was stopped, and the product was naturally cooled. After cooling, a quartz glass molded body having an outer diameter of 200 mm and a height of 72 mm was obtained. It was again heated to 1150 ° C. in the atmosphere in an electric furnace and gradually cooled to remove strain.

The quartz glass molded body was irradiated with ultraviolet light having a wavelength of 254 nm and observed for fluorescence.
Green fluorescence due to contamination from graphite was observed in the range of m. The outer peripheral surface portion and both end portions where the fluorescence was observed were ground and removed. In this example, the yield of the portion that does not emit fluorescence was 62%. A sample for transmittance measurement having a length of 10 mm, a width of 10 mm, and a height of 50 mm was cut out from the center portion, and both sides were polished to measure the transmittance.
0.81%, and the internal transmittance with respect to 200 nm ultraviolet rays was 99.9% or more.

Comparative Example 1 A synthetic synthetic quartz glass rod having a diameter of 60 mm and a length of 1000 mm was placed in a graphite mold having an inner diameter of 200 mm and a height of 1000 mm, placed in an electric furnace as it was, and the furnace was evacuated. Fill nitrogen and 10 ℃ up to 1800 ℃
The temperature was raised at a heating rate of / min., Maintained at the maximum temperature for 5 hours, then turned off, and allowed to cool naturally. After cooling, a quartz glass molded body having an outer diameter of 200 mm and a height of 90 mm was obtained. It was again heated to 1150 ° C. in the atmosphere in an electric furnace and gradually cooled to remove strain.

The quartz glass molded body was irradiated with ultraviolet light having a wavelength of 254 nm and observed for fluorescence.
In addition to observing strong green fluorescence due to contamination from graphite in the range of mm, pale green fluorescence was observed as a whole. In this example, the yield of the portion that does not emit fluorescence is 0%.
Met. In addition, 10 mm in length and 10 mm in width from this central part.
mm, cut out a sample for transmittance measurement with a height of 50 mm,
Both sides were polished and the transmittance was measured.
Has an apparent transmittance of 89.54% with respect to ultraviolet rays,
The internal transmittance for 200 nm ultraviolet light was 98.5%. For the quartz glass molded body in this example, for example, when the transmittance is calculated by setting the optical path length of the precise optical system to 40 cm for convenience of calculation, the transmittance excluding the loss due to the entire reflection of the quartz glass molded body in this example is calculated. Is 54.6
%. Thickness 1 of quartz glass compact in this comparative example
The apparent transmittance measured by a transmittance meter for a sample of cm is shown by a dashed line in FIG.

Comparative Example 2 A synthetic quartz glass rod having a diameter of 60 mm and a length of 1000 mm was placed in a graphite mold having an inner diameter of 200 mm and a height of 1100 mm.
m of graphite weight. The weight is provided so as to be able to slide up and down as the quartz glass is deformed. The graphite mold was placed in an electric furnace as it was, and the furnace was evacuated.
The temperature was raised to 00 ° C. at a heating rate of 20 ° C./min, and after maintaining at the maximum temperature for 1 hour, the energization was stopped and the product was naturally cooled. After cooling, when the quartz glass molded body was taken out, it was bent in the middle and the intended quartz glass molded body could not be obtained.

Comparative Example 3 A synthetic quartz glass rod having the same diameter was provided on both ends of a synthetic quartz glass rod having a diameter of 60 mm and a length of 1000 mm, and this support rod was gripped by a chuck of a lathe for processing quartz glass. Was rotated synchronously. In this example, this rotation was 30 rotations / minute. After heating and softening the left end of the synthetic quartz glass rod to form a melting zone, both chucks were rotated to generate a rotation difference. In this example, this rotation was 28 rotations for the left chuck and 25 rotations for the right chuck. Slowly push the chuck on the left side of the lathe for quartz glass processing in the direction of the rotation axis to apply pressure to the melting zone, increase the diameter of that part, move the burner to the right according to the movement of the chuck, and synthesize Quartz glass rod with outer diameter 80
mm.

A portion of the preformed synthetic quartz glass rod having a uniform outer diameter is cut off from the supporting rod, and the outer diameter is 80 mm.
A 560 mm long quartz glass preform was obtained. This quartz glass preform is 200 mm in inner diameter and 400 mm in height.
Placed in a graphite mold, placed in an electric furnace as it is, evacuated from the furnace, and then filled with nitrogen.
The temperature was raised to 0 ° C. at a heating rate of 20 ° C./min. When the temperature reached the maximum temperature, energization was stopped, and the product was naturally cooled. Although cooled, the molding was not completed, and a disk-shaped quartz glass molded body was not obtained.

A quartz glass preform was again formed under the same conditions, set in a mold in the same manner, heated in a vacuum furnace, kept at the maximum temperature for 2 hours, cooled, then cooled to an outer diameter of 200 mm and a height of 87.5 m.
m was obtained. Again in the atmosphere in an electric furnace 11
The strain was removed by heating to 50 ° C and gradually cooling. The quartz glass molded body was irradiated with ultraviolet light having a wavelength of 254 nm and observed for fluorescence. As a result, green fluorescence due to contamination from graphite was observed within a range of 15 mm from the surface portion. The outer peripheral surface portion and both end portions where the fluorescence was observed were ground and removed. In this example, the yield of the portion that did not emit fluorescence was 46%.

Further, a sample for measuring transmittance having a diameter of 60 mm and a thickness of 10 mm was cut out from the central portion, and both sides were polished and the transmittance was measured. The apparent transmittance with respect to ultraviolet rays of 200 nm was 89.72%. Yes, 200nm
Had an internal transmittance of 98.7% with respect to ultraviolet rays. With respect to the quartz glass molded body in this example, for example, when the optical path length of the precise optical system is set to 40 cm for convenience of calculation and the transmittance is calculated, the overall transmittance of the quartz glass molded body in this example is 59.2%. .

[0034]

According to the present invention, a rod-shaped synthetic quartz glass is heated and softened to form a melting zone, and both ends of the rod-shaped synthetic quartz glass are rotated at different rotational speeds, and the rod-shaped synthetic quartz glass is rotated in the rotation axis direction. The glass is pressurized to deform the melting zone under pressure to form a rod-shaped synthetic quartz glass preform having a length to outer diameter ratio of 1 to 4; Since the optical synthetic quartz glass molded body which is a raw material of the optical member is formed under heating using a mold made of glass, it is compared with a conventional method of manufacturing an optical synthetic quartz glass molded body using a graphite mold. An optical synthetic quartz glass molded body can be manufactured in a short time.

Further, according to the present invention, as compared with the conventional method for producing a quartz glass molded body which is a raw material of an optical member using a graphite mold, contamination due to contact with the graphite mold can be reduced, and the optical member can be reduced. It is possible to produce a quartz glass molded body which does not emit fluorescence and has good transparency to ultraviolet rays, which is a raw material for the above, with a high yield.

[Brief description of the drawings]

FIG. 1 shows the apparent transmittance of ultraviolet light measured by a transmittance meter for a 1 cm thick sample of the quartz glass molded body obtained in Example 1 of the present invention and Comparative Example 1, and the solid line for the sample of Example 1. FIG. 7 is a comparison diagram of an apparent transmittance measurement curve of ultraviolet light indicated by a dashed line for the sample of Comparative Example 1.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiko Sugama 88, Kawakubo, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Prefecture Inside the Koriyama Plant, Shinetsu Quartz Co., Ltd. Quartz Co., Ltd. Takefu Factory (72) Inventor Wolfgang English 65779 Keelkh im Heldarinstraße 54 (56) References JP-A-62-41727 (JP, A) JP-A-54-111889 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) C03B 23/13 C03B 11/00 C03B 20/00

Claims (2)

(57) [Claims] 1. A method for producing a synthetic quartz glass article for optical use by molding a synthetic quartz glass rod into a synthetic quartz glass article for optical use by heating it using a mold, wherein the length exceeds 5 times the outer diameter. While rotating both ends of a rod-shaped synthetic quartz glass partly heated to form a melting zone, while rotating at the same rotational direction at different rotational speeds, pressurizing and deforming in the direction of the rotational axis, A synthetic quartz glass preform having a length of 1 to 4 times the diameter is formed, and then the synthetic quartz glass preform is molded using a mold under heating to form an optical synthetic quartz glass molded article. A method for producing a synthetic quartz glass molded article for optics, comprising: 2. The synthetic quartz glass preform is formed by applying an external force to one or both ends of a rod-shaped synthetic quartz glass partly formed with a molten zone, and forming a rod-shaped synthetic quartz glass on a rotating shaft. The method according to claim 1, wherein the length of the quartz glass is reduced, and the melting zone is moved in a direction in which the length of the rod-shaped synthetic quartz glass is reduced, so that the diameter of the rod-shaped synthetic quartz glass is changed to be large. A method for producing the synthetic quartz glass molded article for optics according to the above.