JP2007022847A - Molding apparatus of quartz glass and method of molding quartz glass using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for molding quartz glass in which large diameter quartz glass having rotationally-symmetric refractive index is efficiently and surely molded by uniformly extending qaurtz glass gob from the center axis of the quartz glass lump toward the outer peripheral direction and a method of molding the quartz glass using the same. <P>SOLUTION: The apparatus for molding quartz glass is provided with a mold 15 having a hollow part 21 capable of housing the quartz glass gob, a pressure plate 23 mounted inside the hollow part 21 to be movable, a heating means for heating the quartz glass gob 25 housed in the hollow part 21 and a molding means for pressing the pressure plate in the pressing direction and the quartz glass gob 25 is pressed by the pressure plate 23 into a prescribed shape while being heated by the heating means. In the apparatus for molding the quartz glass, a conical shaped projecting part having an apex in the pressing direction is formed on the contact surface of the pressure plate 23 with the quartz glass gob 25 and the the center axis of the pressure plate is included on the bottom surface of the projecting part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a quartz glass molding apparatus and a quartz glass molding method using the same, and more specifically, quartz glass that contains quartz glass in a mold and is heated and pressurized to mold the quartz glass into a predetermined shape. The present invention relates to a glass molding apparatus and a method for molding quartz glass using the same.

  Quartz glass is often used as the material for the illumination optical system of the projection exposure apparatus using a light source having a wavelength shorter than the i-line or the optical member such as a lens, mirror, and reticle of the projection optical system. Such quartz glass is synthesized by a method such as a direct method for producing transparent quartz glass by flame hydrolysis. In the direct method, first, a combustion-supporting gas (oxygen-containing gas such as oxygen gas) and a combustible gas (hydrogen-containing gas such as hydrogen gas or natural gas) are mixed and burned in a quartz glass burner, A high-purity silicon compound (for example, silicon tetrachloride gas) is diluted as a source gas from the center of the burner with a carrier gas (usually oxygen gas) and ejected. Then, the raw material gas is reacted (hydrolysis reaction) by combustion of the surrounding oxygen gas and hydrogen gas to generate quartz glass fine particles, and the quartz glass fine particles are rotated, oscillated and disposed below the burner. A quartz glass ingot is obtained by depositing on a target made of an opaque quartz glass plate that performs a lowering movement and simultaneously melting and vitrifying it by the combustion heat of the oxygen gas and hydrogen gas. A quartz glass ingot obtained by adopting such a direct method is particularly suitable for a lens material because the refractive index distribution has a rotational symmetry.

  In recent years, in order to obtain an optical member having a large area such as a large lens or reticle, or a large liquid crystal display, a quartz glass lump such as a quartz glass ingot formed in advance is heated and pressed to be flattened. A molding method is used in which the shape is enlarged to increase the area. In such a molding method, quartz glass having a large area is molded by pressing with a pressure plate in a state where the quartz glass block is accommodated in a mold and heated.

  For example, in Japanese Patent Application Laid-Open No. 61-83638 (Patent Document 1), a graphite mold having a structure for relieving stress caused by a difference in thermal expansion coefficient between quartz glass and a mold mold material is used. A method of pressure-molding quartz glass at 1700 ° C. has been proposed. In Japanese Patent Laid-Open Publication No. 56-129621 (Patent Document 2) and Japanese Patent Laid-Open Publication No. 57-67031 (Patent Document 3), a molding apparatus in which a graphite mold has a vertical structure with two or more divisions is used. There has been proposed a method of pressure-forming quartz glass by heating to a high temperature of 1700 ° C. or higher. Furthermore, Japanese Patent Application Laid-Open No. 2002-220240 (Patent Document 4) discloses a method of pressure forming quartz glass by providing a coating layer made of quartz powder on the inner surface of a graphite mold. And in the manufacturing apparatus of quartz glass used for the method of press-molding such quartz glass described in Patent Documents 1 to 4, a pressing plate having a flat pressing surface (planar shape) is used. Further, in Japanese Patent Application Laid-Open No. 2003-246631 (Patent Document 5), a glass ingot is placed in an outer mold having a square cross section of an ingot housing recess, and the shape of the pressure surface is a regular quadrangular pyramid while heating the glass ingot. A method is disclosed in which quartz glass is pressure-molded into a predetermined shape by pressing with a pressing die that is shaped.

However, in the above conventional quartz glass molding method and the quartz glass molding apparatus used therefor, the symmetry of the refractive index distribution of the quartz glass block is lost during molding, and the symmetry of the refractive index distribution is good. There was a problem that it was difficult to obtain a large-diameter quartz glass.
JP-A-61-83638 JP-A-56-129621 JP 57-67031 A JP 2002-220240 A JP 2003-246631 A

  The present invention has been made in view of the above-described problems of the prior art. The quartz glass block is uniformly enlarged from the central axis of the quartz glass block toward the outer periphery, and the refractive index distribution has a large rotational symmetry. It is an object of the present invention to provide a quartz glass molding apparatus capable of efficiently and reliably molding a quartz glass having a diameter, and a quartz glass molding method using the quartz glass molding apparatus.

  As a result of intensive studies to achieve the above object, the present inventors have found that it is difficult to uniformly expand the quartz glass block for the following reasons in the conventional method and apparatus for forming quartz glass. I found. That is, in a conventional quartz glass molding method and molding apparatus, generally, a pressure plate having a flat surface (pressure surface) in contact with the quartz glass block is used, and the pressure plate is perpendicular to the deformation direction of the quartz glass. Forming by applying pressure in the direction. For this reason, in the conventional quartz glass molding method and molding apparatus, theoretically, the pressure load is made uniform, and the viscosity inside the quartz glass is made uniform, so that the glass components inside the quartz glass are evenly moved in the outer circumferential direction. Thus, it should be possible to uniformly expand the quartz glass block from the central axis in the outer peripheral direction.

  However, in order to uniformly apply a pressure load during such molding, the surface of the pressing surface of the pressing plate, the surface of the bottom plate of the mold, the surface of the pressed surface of quartz glass that contacts the pressing plate, and It was necessary to control as much as possible the surface accuracy and parallelism of the surface of the quartz glass contacted surface that is in contact with the bottom plate. In addition, in order to control the parallelism of the pressure plate as much as possible, it is necessary to suppress warping of the pressure plate, so the material and structure of the pressure plate, the method for applying pressure to the pressure plate, etc. It was necessary to devise. Furthermore, in order to make the viscosity inside the quartz glass uniform, it is necessary to make the temperature distribution inside the quartz glass as uniform as possible, and the arrangement of the heater and the shape and material of the mold present between the heater and the glass It was also necessary to devise thickness.

  Therefore, when pressure molding is performed by a conventional molding method or the like, in reality, the pressure load cannot be made uniform and the viscosity inside the quartz glass cannot be made uniform. The balance of the distribution of the glass and the viscosity inside the quartz glass is slightly broken, and the quartz glass is deformed preferentially in the direction of the balance being lost. It moved across the central axis of the lump. In the conventional molding method using a pressure plate with a flat pressure surface, the quartz glass lump is uniformly expanded because the internal glass component moves in the direction where the pressure distribution and viscosity balance is lost. Furthermore, since the glass component moves across the central axis of the quartz glass block, it is found that the rotational symmetry of the refractive index distribution of the quartz glass block cannot be maintained during molding. It was. In addition, even in the conventional method for forming quartz glass in which the shape of the pressure surface of the pressure plate is a quadrangular pyramid, the balance of pressure toward the outer peripheral direction of the quartz glass is lost during the molding, It has also been found that it cannot be uniformly enlarged from the central axis toward the outer peripheral direction.

  Therefore, as a result of further diligent research, the present inventors first formed a convex portion on the pressing surface of the pressing plate and / or the contact surface with the quartz glass block of the bottom receiving plate of the mold. The outer peripheral direction applied to the quartz glass lump by positively applying a pressure toward the outer peripheral direction from the central axis to the glass, and further making the shape of the convex part a substantially conical shape without a helicopter (edge) Since the pressure distribution toward the surface becomes uniform and the movement of the glass component in the outer circumferential direction can be caused uniformly, the quartz glass lump is moved from the central axis to the outer circumferential direction without being affected by the minute viscosity difference inside the quartz glass. It has been found that it is possible to enlarge uniformly toward. And by expanding the quartz glass lump uniformly from the central axis to the outside in this way, it is possible to prevent the glass component inside the quartz glass from moving to the opposite side across the central axis of the quartz glass, It can be molded without losing the rotational symmetry of the refractive index distribution of the quartz glass block obtained by the direct method, and a large-diameter quartz glass having a rotational symmetry of the refractive index distribution can be obtained efficiently and reliably. As a result, the present invention has been completed.

That is, the first quartz glass molding apparatus of the present invention includes a mold having a hollow part capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow part, and the hollow part. Heating means for heating the quartz glass block accommodated in the container and molding means for pressing the pressure plate in the pressing direction, and the quartz glass block is pressurized by the pressure plate while being heated by the heating unit. A quartz glass molding apparatus for molding into a shape,
A substantially conical convex portion having an apex in the pressing direction is formed on a contact surface of the pressure plate with the quartz glass block, and a central axis of the pressure plate is included on the bottom surface of the convex portion. That
It is characterized by.

Further, the second quartz glass molding apparatus of the present invention includes a mold having a hollow portion capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow portion, and the hollow portion. Heating means for heating the quartz glass block accommodated in the container and molding means for pressing the pressure plate in the pressing direction, and the quartz glass block is pressurized by the pressure plate while being heated by the heating unit. A quartz glass molding apparatus for molding into a shape,
On the contact surface of the bottom receiving plate of the mold with the quartz glass block, a substantially conical convex portion having a vertex in the direction opposite to the pressing direction is formed, and on the bottom surface of the convex portion The center axis of the bottom plate is included,
It is characterized by.

Further, the third quartz glass molding apparatus of the present invention includes a mold having a hollow part capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow part, and the hollow part. Heating means for heating the quartz glass block accommodated in the container and molding means for pressing the pressure plate in the pressing direction, and the quartz glass block is pressurized by the pressure plate while being heated by the heating unit. A quartz glass molding apparatus for molding into a shape,
A substantially conical convex portion having an apex in the pressing direction is formed on a contact surface of the pressure plate with the quartz glass block, and a central axis of the pressure plate is included on the bottom surface of the convex portion. A convex portion having a substantially conical shape having a vertex in a direction opposite to the pressing direction is formed on the contact surface of the bottom receiving plate of the mold with the quartz glass block, and The bottom surface of the convex part includes the central axis of the bottom receiving plate;
It is characterized by.

  In the quartz glass molding apparatus of the present invention, the bottom surface of the convex portion formed on the pressure plate has an area of 50% or more of the area of the pressed surface of the quartz glass block before molding. It is preferable.

  In the quartz glass molding apparatus of the present invention, the bottom surface of the convex portion formed on the bottom receiving plate has an area of 50% or more of the area of the contacted surface of the quartz glass block before molding. Preferably it is.

  In the quartz glass molding apparatus of the present invention, it is preferable that the bottom surface of the convex portion has an area of 25% or more of the area of the surface that can come into contact with the quartz glass after molding.

  In the quartz glass molding apparatus of the present invention, it is preferable that the height of the convex portion is in the range of 3 to 10% of the diameter of the bottom surface of the convex portion.

  In the quartz glass molding apparatus of the present invention, it is preferable that the central axis of the convex portion is on the same line as the central axes of the pressure plate and the bottom receiving plate.

  Furthermore, the quartz glass molding method of the present invention uses the first to third quartz glass molding devices of the present invention to house a quartz glass lump in a hollow portion of a mold provided in the molding device, and heating means The quartz glass lump is pressed and molded between the pressure plate and the bottom receiving plate of the mold by a pressure plate provided in the molding apparatus while heating the quartz glass lump. is there.

  Further, in the method for molding quartz glass of the present invention, the quartz glass lump is formed on the surface to be pressed of the quartz glass lump and / or the surface to be contacted with the bottom receiving plate of the quartz glass lump. It is preferable that a concave portion into which the tip of the convex portion formed on the bottom receiving plate is to be introduced is formed.

  According to the present invention, a quartz glass lump is uniformly expanded from the central axis of the quartz glass lump toward the outer peripheral direction, and a large-diameter quartz glass having a refractive index distribution having rotational symmetry is efficiently and reliably formed. It is possible to provide a quartz glass molding apparatus that enables the above, and a quartz glass molding method using the quartz glass molding apparatus.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

  First, a pressure plate included in the first quartz glass molding device of the present invention, a bottom receiving plate included in the second quartz glass molding device of the present invention, and a third quartz glass molding device of the present invention are provided. The convex parts formed on the pressure plate and the bottom receiving plate will be described.

  In the present invention, the convex portion formed on the pressure plate and / or the bottom receiving plate has a substantially conical shape. 1 to 4 show schematic longitudinal sectional views of convex portions each having a suitable shape. Here, the substantially conical shape means a three-dimensional shape having a circular bottom surface 1, a vertex 3 on a central axis 2 perpendicular to the bottom surface 1, and rotational symmetry with respect to the central axis 2. As such a substantially conical shape, the inclined surface 4 as shown in FIG. 1 is a conical shape with a straight line, and the inclined surface 4 as shown in FIG. 2 is directed in a direction opposite to the direction from the center of the bottom surface 1 toward the vertex 3. A curved shape, a shape in which the slope 4 as shown in FIG. 3 is curved in the direction from the center of the bottom surface 1 toward the vertex 3, and the like can be given. Moreover, as such a convex part, in order to prevent the shift | offset | difference of a center axis | shaft more reliably at the time of making glass flow (at the time of shaping | molding), as shown in FIG. It is preferable to make the shape into a more acute angle.

  Thus, the shape of the convex portion is a substantially conical shape, is a three-dimensional shape having rotational symmetry with respect to the central axis 2, and has no helicopter (edge). Therefore, by providing the molding apparatus with the pressure plate on which the convex portions are formed and / or the bottom receiving plate on which the convex portions are formed, the pressure from the central axis of the convex portions toward the outer circumference is increased. Pressure can be applied uniformly, and the quartz glass lump can be uniformly expanded in the outer peripheral direction without being affected by a minute viscosity difference inside the quartz glass.

  Moreover, as said convex part, it is necessary to include the center axis | shaft of the said pressurization board or bottom receiving plate in which the convex part was formed in the bottom face 1 of the said convex part. If the bottom surface 1 of the convex portion does not include the central axis of the pressure plate or the bottom receiving plate on which the convex portion is formed, the pressing portion that presses the pressure plate is usually near the central axis of the pressure plate. Therefore, during pressure molding, a higher pressure is applied near the center axis of the pressure plate or bottom receiving plate, and the pressure at the portion where the convex portion is formed becomes lower, so the outer peripheral direction applied by the convex portion As a result, the quartz glass lump cannot be uniformly expanded in the outer circumferential direction.

  Moreover, it is preferable that the bottom face 1 of the convex part has an area of 50% or more of the area of the pressed surface of the quartz glass block to be molded. When the area of the bottom surface 1 of such a convex part is less than 50% of the area of the pressed surface of the quartz glass block, the pressure applied by the convex part toward the outer circumferential direction is reduced, and the viscosity inside the quartz glass is reduced. There is a tendency that the quartz glass block cannot be uniformly expanded due to the influence of the difference. Further, from the viewpoint of more uniformly expanding the quartz glass lump toward the outer peripheral direction, the area of the bottom surface 1 of the convex portion is more preferably 64% or more of the area of the surface to be pressed of the quartz glass lump. 80% or more is particularly preferable. Furthermore, the upper limit in particular of the area of the bottom face 1 of such a convex part is not restrict | limited, The whole pressurization surface may be a convex part. In addition, also from the same viewpoint also in the convex part formed in a bottom receiving plate, the bottom face of the said convex part is 50% or more (more preferably) of the area of the contact surface with the said bottom receiving plate of the quartz glass block to shape | mold. 64% or more, particularly preferably 80% or more), and the upper limit of the area is not particularly limited, and the entire contact surface with the quartz glass block of the bottom plate is a convex portion. May be. In addition, the diameter L of the bottom surface 1 of the convex portion is preferably not less than a diameter such that the area of the bottom surface 1 of the convex portion is 50% or more of the area of the pressed surface of the quartz glass block to be formed, More preferably, it is 80% or more of the diameter of the pressed surface of the quartz glass block.

  Moreover, it is preferable that the bottom surface 1 of the convex part has an area of 25% or more of the area of the surface that can come into contact with the quartz glass after molding. When the area of the bottom surface 1 of such a convex part is less than 25% of the area of the surface that can come into contact with the quartz glass after molding, the pressure in the outer peripheral direction given by the convex part becomes low, and the quartz glass inside There is a tendency that the quartz glass lump cannot be expanded uniformly due to the effect of the viscosity difference. Further, from the viewpoint of expanding the quartz glass lump more uniformly toward the outer peripheral direction, the area of the bottom surface 1 of the convex portion is set to 50% or more of the area of the surface that can come into contact with the quartz glass after molding. More preferred.

  Moreover, as the height h of such a convex part, the pressure component which goes to an outer peripheral direction increases at the time of shaping | molding by making the height higher, and it is less susceptible to the viscosity difference inside quartz glass. Therefore, the quartz glass block can be expanded more uniformly. Therefore, although the upper limit of the height h of the convex portion is not essentially limited from the viewpoint of more uniformly expanding, the height h of the convex portion is the diameter of the bottom surface 1 of the convex portion. It is preferable that it is 3 to 10% of L. When the height h of the convex portion is less than 3% of the diameter L, the pressure toward the outer periphery of the quartz glass lump is reduced during molding, and therefore the quartz glass lump is affected by the viscosity difference inside the quartz glass. On the other hand, if it exceeds 10% of the diameter L, the columnar region of the resulting quartz glass tends to be small and the productivity tends to decrease.

  Moreover, as a convex part formed in such a pressurization board, it is preferable that the central axis 2 of a convex part exists on the same line as the central axis of the said pressurization board. Thus, when the quartz glass lump is pressed by arranging the projections so that the center axis 2 of the projections and the center axis 2 of the pressure plate are collinear, the center axis of the pressure plate Since the pressure in the outer peripheral direction can be applied uniformly by the quartz glass block, the quartz glass tends to be expanded more uniformly. Moreover, also in the convex part formed in the bottom receiving plate, it is preferable from the same viewpoint that the central axis of the convex part and the central axis of the bottom receiving plate are on the same line.

  Next, preferred embodiments of the first to third quartz glass forming apparatuses of the present invention will be described in detail.

[First quartz glass forming device]
First, the 1st quartz glass shaping | molding apparatus of this invention is demonstrated. That is, the first quartz glass molding apparatus of the present invention includes a mold having a hollow part capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow part, and the hollow part. Heating means for heating the quartz glass block accommodated in the container and molding means for pressing the pressure plate in the pressing direction, and the quartz glass block is pressurized by the pressure plate while being heated by the heating unit. A quartz glass molding device for molding into a shape,
A substantially conical convex portion having an apex in the pressing direction is formed on a contact surface of the pressure plate with the quartz glass block, and a central axis of the pressure plate is included on the bottom surface of the convex portion. That
It is characterized by.

  FIG. 5 shows a schematic longitudinal sectional view of a preferred embodiment of the first quartz glass molding apparatus of the present invention. In such a forming apparatus 10 shown in FIG. 5, the heat insulating material 12 provided over the entire surface of the inner wall of the metal vacuum chamber 11 and the heating means provided in the vertical wall of the heat insulating material 12 are used. A carbon heater 13 is provided, and a mold 15 is accommodated in a substantially central portion inside the vacuum chamber 11.

  The mold 15 includes a bottom portion 18 having a bottom plate 16 and a bottom receiving plate 17, and a side wall portion 20 formed in a cylindrical shape on the top of the bottom portion 18, and the cylindrical side wall portion 20 and the bottom portion 18 A hollow portion 21 is formed. Further, a pressure plate 23 having an outer shape corresponding to the shape of the hollow portion 21 is disposed in the hollow portion 21.

  In FIG. 6, the schematic longitudinal cross-sectional view of the pressurization plate 23 with which such a shaping | molding apparatus 10 is provided is shown. A convex portion 31 is formed on the pressure plate 23, and the shape thereof is a conical shape having a vertex on the central axis 32 of the pressure plate 23. In the present embodiment, the area of the bottom surface of the convex portion 31 formed on the pressure plate 23 is the same as the area of the pressure surface when the pressure surface 23a of the pressure plate is flat (planar shape). The entire pressure surface 23 a of 23 is a convex portion 31. Therefore, in the present embodiment, the area of the bottom surface of the convex portion formed on the pressure plate 23 is an area of 50% or more of the area of the pressed surface of the quartz glass lump 25, and the molded quartz glass and It is an area of 25% or more of the area of the surface that can be contacted. Further, in the present embodiment, a pressure plate in which the height h of the convex portion 31 is 6.7% of the diameter L of the bottom surface of the convex portion 31 is used.

  Further, in the molding apparatus 10 shown in FIG. 5, a cylinder of a hydraulic cylinder (not shown) as a pressing apparatus in which the pressing surface 23 b (upper surface) of the pressing plate 23 shown in FIG. 6 is installed outside the vacuum chamber 11. By pressing with the rod 26, it can move to the bottom 18 side of the mold 15.

  The hydraulic cylinder provided with the cylinder rod 26 is configured to move under pressure by adjusting the hydraulic pressure supplied from the outside, but detailed illustration is omitted.

  The mold 15 and the pressure plate 23 are made of a material that has heat resistance and strength against the temperature and pressure at the time of forming the quartz glass lump 25 and that is difficult to mix impurities even if it contacts the quartz glass lump 25 at the time of forming. It is preferable to use graphite as such a material.

  Further, the quartz glass block 25 is not particularly limited, and is an ingot of synthetic quartz glass manufactured using a silicon compound such as silicon tetrachloride, silane, or organic silicon, or a part thereof, or Ge, Ti, B, F. Examples thereof include a quartz glass lump such as an ingot of synthetic quartz glass to which a component for changing the refractive index such as Al is added, or a part thereof.

  Next, a preferred method for forming quartz glass using such a forming apparatus 10 will be described.

  When molding quartz glass using such a molding apparatus 10, first, the mold 15 is formed by combining the bottom plate 16, the bottom receiving plate 17, and the side wall portion 20 in the vacuum chamber 11. Then, the quartz glass block 25 is disposed in the hollow portion 21 of the mold 15.

  Such a quartz glass block 25 can be arranged in the mold such that the central axis of the quartz glass perpendicular to the surface to be pressed and the central axis of the convex portion formed on the pressing plate are on the same line. preferable. In this way, by making the central axis of the quartz glass block 25 and the central axis of the convex portion collinear, the quartz glass block 25 is expanded more uniformly from the central axis toward the outer peripheral direction. Therefore, it becomes possible to obtain quartz glass having a higher rotational symmetry of the refractive index distribution.

  Moreover, as the quartz glass lump 25 used in such a method for forming quartz glass, the bottom surface of the convex portion 31 formed on the pressure plate 23 is 50% or more of the area of the pressed surface of the quartz glass lump 25 before forming. It is preferable to use a quartz glass lump 25 having a surface to be pressed that has an area of (more preferably 64% or more, particularly preferably 80% or more).

  Further, the quartz glass block 25 used in the method for forming such quartz glass is not particularly limited, but the convex portion 31 formed on the pressure plate 23 is formed on the pressed surface of the quartz glass block 25. It is preferable that a recess into which the tip is to be introduced is formed. In that case, it is more preferable that the shape of the concave portion is the same as or similar to the shape of the convex portion, and it is particularly preferable that the central axis of the concave portion is collinear with the central axis of the quartz glass block. By using such a quartz glass lump 25, it becomes possible to install the quartz glass lump 25 by aligning the position of the convex part and the position of the concave part. For example, on the central axis of the quartz glass lump 25 and the concave part When the central axis of the quartz glass is on the same line, the quartz glass lump 25 can be more efficiently and uniformly expanded from the central axis toward the outer peripheral direction. In this embodiment, the quartz glass block 25 in which the apex of the recess is formed on the central axis of the quartz glass block 25 is used.

  Next, the pressure plate 23 is disposed on the quartz glass block 25 accommodated in the hollow portion 21, and the pressing portion of the cylinder rod 26 of the hydraulic cylinder is set in contact with the pressing surface 23 b of the pressure plate 23. .

Then, after reducing the pressure in the vacuum chamber 11 using a vacuum pump, the inside of the vacuum chamber 11 is replaced with an inert gas. The pressure conditions and the like in this case are not particularly limited, but after the pressure in the vacuum chamber 11 is reduced to about 0.2 Pa to 10 Pa (preferably 1 to 10 Pa) using a vacuum pump, the inside of the vacuum chamber 11 is inactive. It is preferable to replace with gas (for example, pure nitrogen gas) so that the pressure in the vacuum chamber 11 is, for example, 1 × 10 ⁴ Pa to 1 × 10 ⁵ Pa.

  Next, the quartz glass lump 25 accommodated in the mold 15 and the hollow portion 21 is heated by the carbon heater 13. The holding temperature of the quartz glass lump 25 when heated in this way is not particularly limited as long as it is not less than the crystallization temperature of the quartz glass and not more than the softening point, but it is 1500 ° C. to 1700 ° C. (more preferably 1570 ° C. to 1670 ° C.). Further, the rate of temperature increase during such heating is not particularly limited, but the carbon heater 13 is caused to generate heat so that the temperature is increased from the heating temperature to about 200 ° C./hr to 800 ° C./hr. After raising the temperature to a predetermined temperature within the holding temperature, it is preferable to hold the holding temperature at the holding temperature for about 15 to 45 minutes, for example, until the inside of the massive quartz glass 25 is sufficiently heated.

Next, with the quartz glass block 25 heated as described above, the hydraulic pressure to the hydraulic cylinder is controlled and adjusted, so that the cylinder rod 26 is moved downward, and the pressure plate 23 is pressed at the pressing portion of the cylinder rod 26. The surface 23b is pressed. As a result, the pressure plate 23 moves in the pressure direction on the bottom 18 side of the mold 15, and the massive quartz glass 25 is pressed between the pressure surface 23 a of the pressure plate 23 and the bottom 18. In such a pressing step, it is preferable to take an initial load of 2000kg ^{/ m 2} ~3000kg ^/ m 2 degree, it is preferable that the press speed and 0.1 to 0.3 mm / sec.

  Then, when the quartz glass 25 is formed into a plate-shaped body having a predetermined shape, pressurization by the pressure plate 23 is finished. Thereafter, the quartz glass 25 molded into a plate shape is cooled while being placed in the mold 15, and the molding is completed by removing the molded body from the vacuum chamber 11.

  In such molding, the quartz glass to be molded has an area of convex portions formed on the pressure plate 23 that is 25% or more of the area of the contact surface of the quartz glass with the pressure plate 23 after molding (more preferably It is preferable to use quartz glass having a contact surface with an area of 50% or more.

  As described above, when quartz glass is molded, the pressure applied from the cylinder rod 26 in the pressurizing direction (vertically downward) is the vertically downward component on the surface of the pressurizing plate 23a and the central axis of the quartz glass block 25. The components can be divided into components that go from the outer periphery toward the outer periphery, and this makes it possible to uniformly expand the inner glass component in the outer periphery without being affected by the minute viscosity difference inside the quartz glass block. Therefore, when the quartz glass ingot obtained by the direct method is used for the quartz glass block 25, the quartz glass can be molded while maintaining the rotational symmetry of the refractive index distribution.

  The preferred embodiment of the first quartz glass molding apparatus and the quartz glass molding method using the molding apparatus of the present invention has been described above, but the first quartz glass molding apparatus and the molding thereof of the present invention have been described. The method for forming quartz glass using the apparatus is not limited to the above embodiment. For example, in the above-described embodiment, the pressure plate as shown in FIG. 6 is used. However, such a pressure plate is not particularly limited as long as the pressure plate has a convex portion that satisfies the above-described requirements for the convex portion. For example, a pressure plate having a higher height h, or a convex portion having a shape in which the inclined surface 4 as shown in FIG. 2 is curved in a direction opposite to the direction from the center of the bottom surface 1 toward the vertex 3. 3, a pressure plate having a convex portion having a shape in which the inclined surface 4 as shown in FIG. 3 is curved from the center of the bottom surface 1 toward the vertex 3, and a pressure surface as shown in FIG. It is also possible to use the pressure plate 23 in which the convex part 31 is formed in a part of 23a.

[Second quartz glass manufacturing equipment]
Next, the 2nd quartz glass shaping | molding apparatus of this invention is demonstrated. That is, the second quartz glass molding apparatus of the present invention includes a mold having a hollow portion capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow portion, and the hollow portion. Heating means for heating the quartz glass block accommodated in the container and molding means for pressing the pressure plate in the pressing direction, and the quartz glass block is pressurized by the pressure plate while being heated by the heating unit. A quartz glass molding apparatus for molding into a shape,
On the contact surface of the bottom receiving plate of the mold with the quartz glass block, a substantially conical convex portion having a vertex in the direction opposite to the pressing direction is formed, and on the bottom surface of the convex portion The center axis of the bottom plate is included,
It is characterized by.

  FIG. 8 shows a schematic cross-sectional view of a preferred embodiment of such a second quartz glass molding apparatus. The configuration of the molding apparatus 10 shown in FIG. 8 is that the bottom receiving plate 17 formed with a conical convex portion having a vertex in the direction opposite to the pressing direction is used, and the pressing plate 23 is flat. The configuration is the same as that of the first quartz glass molding device described above except that a pressure plate having a pressing surface is used.

  FIG. 9 shows a schematic cross-sectional view of the bottom receiving plate provided in the molding apparatus 10 shown in FIG. As shown in FIG. 9, in the bottom receiving plate 17, a convex portion 31 is formed on the contact surface 17 a side with the quartz glass block 25, and its shape has a vertex on the central axis 32 of the bottom receiving plate 17. It has a conical shape. Further, in the present embodiment, the area of the bottom surface of the convex portion 31 formed on the bottom receiving plate 17 is the same as the area of the pressing surface when the pressing surface 23a of the bottom receiving plate is flat (planar shape), The entire contact surface 17 a with the quartz glass block of the bottom receiving plate 17 is a convex portion 31. Therefore, in the present embodiment, the area of the bottom surface of the convex portion formed on the bottom receiving plate 17 is 50% or more of the area of the contacted surface of the quartz glass lump 25, and the quartz glass after molding. It is an area of 25% or more of the area of the surface that can come into contact with. Further, in the present embodiment, the bottom receiving plate 17 is used in which the height h of the convex portion 31 is 6.7% of the diameter L of the bottom surface of the convex portion 31.

  Next, a preferred method for forming quartz glass using such a forming apparatus 10 will be described. The method for molding quartz glass using such a molding apparatus 10 is the same as that of the first quartz glass described above except that the molding apparatus 10 shown in FIG. 8 which is the second quartz glass molding apparatus of the present invention is used. This is the same method as the method for forming quartz glass using a forming apparatus.

  Further, the quartz glass lump 25 used in a suitable method for forming quartz glass using such a molding apparatus 10 is not particularly limited, but the quartz glass lump 25 is covered with the bottom receiving plate 17. It is preferable that a concave portion into which the tip of the convex portion 31 formed on the bottom receiving plate 17 is to be introduced is formed on the contact surface. In that case, it is more preferable that the shape of the concave portion is the same as or similar to the shape of the convex portion, and it is particularly preferable that the central axis of the concave portion is collinear with the central axis of the quartz glass block. By using such a quartz glass lump 25, it is possible to install the quartz glass lump 25 by aligning the position of the convex part and the position of the concave part. For example, the concave part on the central axis of the quartz glass lump 25 is provided. Is formed, the quartz glass lump 25 can be uniformly enlarged from the central axis of the quartz glass lump 25 toward the outer periphery.

  Further, as the quartz glass block 25 used in such a method for forming quartz glass, the bottom surface of the convex portion 31 formed on the bottom receiving plate 17 is 50% of the area of the contacted surface of the quartz glass block 25 before forming. It is preferable to use the quartz glass block 25 having a contacted surface with an area of the above (more preferably 64% or more, particularly preferably 80% or more).

  The preferred embodiment of the second quartz glass molding apparatus and the quartz glass molding method using the molding apparatus of the present invention has been described above. However, the second quartz glass molding apparatus of the present invention and the molding thereof have been described. The method for forming quartz glass using the apparatus is not limited to the above embodiment. For example, the bottom receiving plate 17 as shown in FIG. 8 is used in the above embodiment, but the bottom receiving plate is not particularly limited as long as the bottom receiving plate is formed with a convex portion that satisfies the above-described requirements. For example, a bottom receiving plate having a higher height h, or a shape in which the slope 4 as shown in FIG. 2 is curved in a direction opposite to the direction from the center of the bottom surface 1 to the vertex 3. FIG. 10 shows a bottom receiving plate in which convex portions are formed, and a convex portion having a shape in which the inclined surface 4 as shown in FIG. 3 is curved in a direction from the center of the bottom surface 1 toward the vertex 3. It is also possible to use the bottom receiving plate 17 in which the convex portion 31 is formed on a part of the contact surface 17a.

[Third quartz glass manufacturing equipment]
Next, the 3rd quartz glass shaping | molding apparatus of this invention is demonstrated. That is, the third quartz glass molding apparatus of the present invention includes a mold having a hollow portion capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow portion, and the hollow portion. Heating means for heating the quartz glass block accommodated in the container and molding means for pressing the pressure plate in the pressing direction, and the quartz glass block is pressurized by the pressure plate while being heated by the heating unit. A quartz glass molding apparatus for molding into a shape,
A substantially conical convex portion having an apex in the pressing direction is formed on a contact surface of the pressure plate with the quartz glass block, and a central axis of the pressure plate is included on the bottom surface of the convex portion. A convex portion having a substantially conical shape having a vertex in a direction opposite to the pressing direction is formed on the contact surface of the bottom receiving plate of the mold with the quartz glass block, and The bottom surface of the convex part includes the central axis of the bottom receiving plate;
It is characterized by.

  The third quartz glass molding apparatus includes a pressure plate having the convex portions as described above and a bottom receiving plate having the convex portions as described above. In the third quartz glass molding apparatus, since the convex portions as described above are provided on both the pressure plate and the bottom receiving plate, the effect of applying a pressure component from the central axis of the convex portion toward the outer peripheral direction is achieved. Since it can be obtained from both the pressed surface and the contacted surface of the quartz glass lump to be molded, pressure toward the outer peripheral direction can be more reliably applied to the entire inside of the quartz glass lump, which is higher. It becomes possible to uniformly expand the quartz glass in the outer peripheral direction with accuracy. As described above, since the pressure toward the outer circumferential direction can be reliably applied to the entire inside of the quartz glass block, the third quartz glass forming apparatus is preferably used for forming a quartz glass block having a particularly large thickness. be able to.

  Further, in the third quartz glass molding apparatus of the present invention, the central axis of the convex portion formed on the pressure plate and the central axis of the convex portion formed on the bottom receiving plate are on the same line. It is preferable to have it. In this way, the central axis of the convex portion formed on the pressure plate and the central axis of the convex portion formed on the bottom receiving plate are on the same line, so that the direction from the central axis toward the outer circumferential direction. Since pressure can be uniformly applied to the quartz glass, the rotational symmetry of the refractive index of the quartz glass obtained by molding the quartz glass block obtained by the direct method tends to be higher.

  FIG. 11 shows a schematic cross-sectional view of a preferred embodiment of such a third quartz glass molding apparatus. The configuration of the molding apparatus 10 shown in FIG. 11 is the first quartz glass described above except that the bottom receiving plate 17 having a conical convex portion having an apex in the direction opposite to the pressing direction is used. The configuration of this molding apparatus is basically the same. That is, the molding apparatus 10 shown in FIG. 11 includes a pressure plate 23 as shown in FIG. 6 and a bottom receiving plate 17 as shown in FIG.

  Next, a preferred method for forming quartz glass using such a forming apparatus 10 will be described. A suitable method for molding quartz glass using such a molding apparatus 10 is the same as the method for molding quartz glass using the first quartz glass molding apparatus described above, except that such a molding apparatus 10 is used. Is the method.

  Further, the quartz glass lump 25 used in the method for forming such quartz glass is not particularly limited, but the surface to be pressed of the quartz glass lump and the contact surface of the quartz glass lump with the bottom receiving plate are not limited. It is preferable that a concave portion into which the tip of the convex portion 31 formed on the pressure plate and the bottom receiving plate is to be introduced is formed on the surface. In that case, it is more preferable that the shape of the concave portion is the same as or similar to the shape of the convex portion, and it is particularly preferable that the central axis of the concave portion is on the same line as the central axis of the quartz glass block. By using such a quartz glass lump 25, it is possible to install the quartz glass lump 25 by aligning the position of the convex part and the position of the concave part. For example, the concave part on the central axis of the quartz glass lump 25 is provided. Is formed, it is possible to apply pressure uniformly from the central axis of the quartz glass lump 25 toward the outer periphery, and to enlarge the quartz glass lump 25 more efficiently and uniformly. .

  The preferred embodiment of the third quartz glass molding apparatus and the quartz glass molding method using the molding apparatus of the present invention has been described above, but the third quartz glass molding apparatus and the molding of the third quartz glass of the present invention have been described. The method for forming quartz glass using the apparatus is not limited to the above embodiment. For example, in the embodiment, the bottom receiving plate 17 and the pressure plate 23 as shown in FIG. 11 are used. However, the bottom receiving plate and the pressure plate have bottom portions on which convex portions that satisfy the above-described requirements are formed. Any plate and pressure plate can be used without particular limitation.

  The quartz glass molded by the first to third quartz glass molding apparatus and the quartz glass molding method using the molding apparatus of the present invention is used as various optical members, preferably, It is used as a material used for manufacturing a lens, a mirror, a reticle substrate and the like irradiated with a laser having a wavelength of 250 nm or less, and more preferably a reticle (such as a large liquid crystal mask, a semiconductor mask). It is used as a plate-like body having a wide surface used for a photomask) substrate, a large lens material for an imaging optical system, and other large glass blocks. In addition, the quartz glass molded as described above is obtained by enlarging the quartz glass block obtained by the direct method while maintaining the rotational symmetry of the refractive index distribution. Suitable for lens materials.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
As the pressure plate 23, the quartz glass molding apparatus 10 shown in FIG. 5 provided with the pressure plate 23 having a conical convex portion having a diameter L of 300 mm and a height h of 20 mm shown in FIG. As the quartz glass block 25, a concave portion into which the tip of the convex portion formed on the pressure plate 23 is to be introduced is formed on a cylindrical bottom surface having a circular bottom surface with a diameter of 200 mm and a height of 145 mm, and the shape of the concave portion is A quartz glass lump 25 having a shape similar to the shape of the protrusion and having a height of 10 mm and a vertex of the recess on the central axis of the columnar quartz glass lump 25 is used to form quartz. A glass lump 25 is formed, and a cylindrical top surface having a bottom surface with a diameter of 300 mm and a height (thickness) of 70 mm is recessed into a conical shape with a height of 20 mm which is the same shape as the convex portion. Glass was obtained.

That is, first, the quartz glass block 25 was disposed in the hollow portion 21 of the mold 15 so that the bottom surface of the quartz glass block 25 was in contact with the bottom receiving plate 17 at the bottom of the mold 15. Next, the pressure plate 23 is disposed on the quartz glass block 25 accommodated in the hollow portion 21, and the pressing portion of the cylinder rod 26 of the hydraulic cylinder is set in contact with the pressing surface 23 b of the pressure plate 23. . Then, after reducing the pressure in the vacuum chamber 11 to 0.67 Pa with a vacuum pump, pure nitrogen gas was filled until the pressure reached 10 kPa. And it controlled so that the inside of the hollow part 21 of the mold 15 might become 1640 degreeC holding temperature, and after heating up with the temperature increase rate of 400 degreeC / hr, it hold | maintained for 40 minutes at the said holding temperature. At this time, the temperature in the hollow part 21 of the mold 15 was measured with a two-color thermometer. Thereafter, quartz glass was pressure-molded by pressing the pressure plate 23 with the cylinder rod 26 under the conditions of an initial load of 2000 kg / m ² and a press speed of 1 mm / sec. Then, when the thickness of the formed quartz glass reaches 70 mm, the pressurization is terminated and cooled to form a cylindrical shape having a bottom surface with a diameter of 300 mm and a height (thickness) of 70 mm. And the quartz glass of the shape dented in the cone shape of height 20mm whose upper surface is the same shape as the said convex part was obtained.

  When the roundness (difference between the radius of the maximum inscribed circle and the radius of the minimum circumscribed circle) of the quartz glass thus obtained was measured, the roundness was 1.1 mm. From such a result, it was confirmed that the quartz glass can be uniformly expanded in the outer circumferential direction by using a quartz glass molding apparatus including a pressure plate on which the convex portions are formed.

  A sample was prepared from the obtained quartz glass and the refractive index distribution was measured. That is, the outer periphery of the obtained quartz glass was processed to prepare a cylindrical sample having a diameter of 290 mm and a height of 45 mm, and the refractive index distribution was measured using an interferometer. From the obtained refractive index distribution data, it was found that the refractive index contour distribution of the quartz glass obtained as described above was clean and concentric, and the center coincided with one point. From these facts, it was confirmed that the quartz glass obtained as described above has high refractive index homogeneity. Further, from the refractive index distribution data obtained in this way, the non-rotationally symmetric component of the refractive index distribution was determined, and the quartz glass obtained as described above has high rotational symmetry of the refractive index distribution, It was confirmed that the lens material can sufficiently withstand use.

(Example 2)
The pressure plate 23 of the quartz glass molding apparatus 10 shown in FIG. 11 is provided with a pressure plate formed with a cone-shaped convex portion having a diameter L of 300 mm and a height h of 20 mm as shown in FIG. A quartz glass molding apparatus 10 as shown in FIG. 11 provided with a bottom receiving plate on which a conical convex portion having a diameter L shown in FIG. 9 of 300 mm and a height h of 20 mm is formed on the receiving plate 17. As the quartz glass lump 25, the tips of the convex portions formed on the bottom receiving plate 17 and the pressure plate 23 are respectively introduced into the upper and lower surfaces of a cylindrical shape having a circular bottom surface with a diameter of 200 mm and a height of 250 mm. A power concave portion is formed, the shape of the concave portion is similar to the shape of the convex portion, and the height is 10 mm, and the apex of the concave portion is on the central axis of the cylindrical quartz glass lump 25, respectively. Use quartz glass lump 25 of a certain shape Then, the quartz glass block 25 is molded, and the cylindrical upper surface and lower surface having a bottom surface with a diameter of 300 mm and a height (thickness) of 122 mm have a conical shape with a height of 20 mm, which is the same shape as the convex portion. A hollow quartz glass was obtained. The quartz glass was molded in the same manner as in Example 1.

  When the roundness (difference between the radius of the maximum inscribed circle and the radius of the minimum circumscribed circle) of the quartz glass thus obtained was measured, the roundness was 0.8 mm. From such a result, it was confirmed that the quartz glass can be uniformly expanded in the outer peripheral direction by using a quartz glass molding apparatus including the pressure plate and the bottom receiving plate on which the convex portions are formed.

  A sample was prepared from the obtained quartz glass and the refractive index distribution was measured. That is, the outer periphery of the obtained quartz glass was processed to prepare a cylindrical sample having a bottom of 290 mm in diameter and a height of 75 mm, and the refractive index distribution was measured using an interferometer. From the obtained refractive index distribution data, it was found that the refractive index contour distribution of the quartz glass obtained as described above was clean and concentric, and the center coincided with one point. From these results, it was confirmed that the quartz glass obtained as described above has high refractive index homogeneity. Further, when the non-rotationally symmetric component of the refractive index distribution was determined from the refractive index data thus obtained, the quartz glass obtained as described above has a high rotational symmetry of the refractive index distribution, and the lens. It was confirmed that the material can sufficiently withstand use.

(Example 3)
FIG. 9 is a view in which a bottom receiving plate 17 of the quartz glass forming apparatus 10 shown in FIG. 5 is provided with a bottom receiving plate on which conical convex portions having a diameter L of 300 mm and a height h of 20 mm shown in FIG. 9 are formed. 11 using a molding apparatus 10 of quartz glass as shown in FIG. 11, a projection formed on a bottom receiving plate 17 on a cylindrical bottom surface (bottom surface) having a circular bottom surface of 200 mm in diameter and a height of 145 mm as a quartz glass lump 25. A concave portion into which the tip of the portion is to be introduced is formed, and the shape of the concave portion is similar to the shape of the convex portion, and the height is 10 mm, and the apex of the concave portion is the columnar quartz glass block. A quartz glass lump 25 is formed using a quartz glass lump 25 having a shape on the central axis of 25, and a cylindrical lower surface having a bottom diameter of 300 mm and a height (thickness) of 70 mm is formed on the convex surface. 20mm high cone with the same shape as the part To obtain the quartz glass of the concave shape to Jo. The quartz glass was molded in the same manner as in Example 1.

  When the roundness (difference between the radius of the maximum inscribed circle and the radius of the minimum circumscribed circle) of the quartz glass thus obtained was measured, the roundness was 1.0 mm. From such a result, it was confirmed that the quartz glass can be uniformly expanded in the outer circumferential direction by using a quartz glass molding apparatus including a pressure plate on which the convex portions are formed.

  A sample was prepared from the obtained quartz glass and the refractive index distribution was measured. That is, the outer periphery of the obtained quartz glass was processed to prepare a cylindrical sample having a height of 45 mm on the bottom surface having a diameter of 290 mm, and the refractive index distribution was measured using an interferometer. From the obtained refractive index distribution data, it was found that the refractive index contour distribution of the quartz glass obtained as described above was clean and concentric, and the center coincided with one point. From these results, it was confirmed that the quartz glass obtained as described above has high refractive index homogeneity. Further, from the refractive index distribution data obtained in this way, the non-rotationally symmetric component of the refractive index distribution was determined, and the quartz glass obtained as described above has high rotational symmetry of the refractive index distribution, It was confirmed that the lens material can sufficiently withstand use.

(Comparative Example 1)
The conventional quartz glass as shown in FIG. 12 is provided with a pressure plate and a bottom receiving plate having a flat shape (planar shape) in which the contact surface of the pressure plate 23 with the quartz glass and the contact surface with the quartz glass of the bottom receiving plate are flat. Using a molding apparatus, a quartz glass lump 25 is molded using a cylindrical quartz glass lump 25 having a diameter of 200 mm and a height of 120 mm, and a cylindrical quartz glass having a diameter of 300 mm and a cylindrical bottom having a height of 53 mm. 25 was obtained. The quartz glass was molded in the same manner as in Example 1.

  When the roundness (difference between the radius of the maximum inscribed circle and the radius of the minimum circumscribed circle) of the quartz glass thus obtained was measured, the roundness was 9.2 mm. Thus, in the conventional quartz glass molding apparatus, the quartz glass could not be uniformly expanded in the outer peripheral direction.

  A sample was prepared from the obtained quartz glass and the refractive index distribution was measured. That is, the outer periphery of the obtained quartz glass was processed to prepare a cylindrical sample having a height of 45 mm on the bottom surface having a diameter of 290 mm, and the refractive index distribution was measured using an interferometer. From the obtained refractive index distribution data, the refractive index contour distribution of quartz glass obtained as described above is not concentric but distorted in an elliptical shape, and its center is also biased in one direction. It turns out that. From these results, it was confirmed that the quartz glass obtained as described above has low refractive index homogeneity. Further, from the refractive index distribution data obtained in this way, the non-rotationally symmetric component of the refractive index distribution was determined, and the quartz glass obtained as described above has a low rotational symmetry of the refractive index distribution, It was confirmed that the lens material cannot be used.

(Comparative Example 2)
As the pressure plate 23, a pressure plate 23 in which a convex surface having a quadrangular pyramid shape with a bottom surface having an apex in the pressure direction of 300 mm in length and 300 mm in width and 20 mm in height is formed on the contact surface of the pressure plate 23 with quartz glass. 5 is used, and a quartz glass lump 25 having a diameter of 200 mm and a height of 145 mm is used as the quartz glass lump 25 using the same quartz glass forming apparatus as the quartz glass forming apparatus shown in FIG. A quartz glass having a shape in which the upper surface was recessed in a square shape with a height of 20 mm and the same shape as the convex portion was obtained. The quartz glass thus obtained did not have a cylindrical shape. Further, the quartz glass was molded in the same manner as in Example 1.

  A sample was prepared from the obtained quartz glass and the refractive index distribution was measured. That is, the outer periphery of the obtained quartz glass was processed to prepare a cylindrical sample having a height of 45 mm on the bottom surface having a diameter of 290 mm, and the refractive index distribution was measured using an interferometer. From the obtained refractive index distribution data, the refractive index contour distribution of the quartz glass obtained as described above is not concentric, and the portion corresponding to the quadrangular pyramid edge of the convex portion of the pressure plate is large. It turned out to be distorted. From these results, it was confirmed that the quartz glass obtained as described above has low refractive index homogeneity. Further, from the refractive index distribution data obtained in this way, the non-rotationally symmetric component of the refractive index distribution was determined, and the quartz glass obtained as described above has a low rotational symmetry of the refractive index distribution, It was confirmed that the lens material cannot be used.

  As described above, according to the present invention, the quartz glass block is uniformly expanded from the central axis of the quartz glass block toward the outer peripheral direction, and the large-diameter quartz glass having a refractive index distribution having rotational symmetry is efficiently obtained. In addition, it is possible to provide a quartz glass molding apparatus that can be reliably molded, and a quartz glass molding method using the quartz glass molding apparatus.

  Therefore, the quartz glass molding apparatus of the present invention can enlarge a quartz glass lump having a rotational symmetry of the refractive index distribution obtained by the direct method while maintaining the rotational symmetry. It is useful as an apparatus for molding a quartz glass molded body having a wide surface such as a lens material.

It is a schematic longitudinal cross-sectional view of the convex part which has a suitable shape. It is a schematic longitudinal cross-sectional view of the convex part which has a suitable shape. It is a schematic longitudinal cross-sectional view of the convex part which has a suitable shape. It is a schematic longitudinal cross-sectional view of the convex part by which protrusion was provided in the vertex. It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of the shaping | molding apparatus of the 1st quartz glass of this invention. It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of a pressurization board. It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of a pressurization board. It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of the shaping | molding apparatus of the 2nd quartz glass of this invention. It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of a base plate. It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of a base plate. It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of the shaping | molding apparatus of the 3rd quartz glass of this invention. It is a schematic longitudinal cross-sectional view which shows one Embodiment of the shaping | molding apparatus of the conventional quartz glass.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bottom surface, 2 ... Center axis, 3 ... Vertex, 4 ... Slope, 5 ... Protrusion, 10 ... Molding device, 11 ... Vacuum chamber, 12 ... Heat insulating material, 13 ... Carbon heater, 15 ... Mold, 16 ... Bottom plate of mold , 17 ... bottom receiving plate, 18 ... bottom part, 20 ... side wall part, 21 ... hollow part, 23 ... pressure plate, 25 ... quartz glass block, 26 ... cylinder rod, 31 ... convex part, L ... diameter of the bottom surface of the convex part , H: height of the convex portion.

Claims (10)

A mold having a hollow part capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow part, a heating means for heating the quartz glass lump accommodated in the hollow part, and A quartz glass molding apparatus comprising: a molding unit that presses a pressure plate in a pressing direction; and the quartz glass lump is pressed by the pressure plate while being heated by the heating unit, and is molded into a predetermined shape.
A substantially conical convex portion having an apex in the pressing direction is formed on a contact surface of the pressure plate with the quartz glass block, and a central axis of the pressure plate is included on the bottom surface of the convex portion. That
A quartz glass molding device characterized by A mold having a hollow part capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow part, a heating means for heating the quartz glass lump accommodated in the hollow part, and A quartz glass molding apparatus comprising: a molding unit that presses a pressure plate in a pressing direction; and the quartz glass lump is pressed by the pressure plate while being heated by the heating unit, and is molded into a predetermined shape.
On the contact surface of the bottom receiving plate of the mold with the quartz glass block, a substantially conical convex portion having a vertex in the direction opposite to the pressing direction is formed, and on the bottom surface of the convex portion The central axis of the bottom plate is included,
A quartz glass molding device characterized by A mold having a hollow part capable of accommodating a quartz glass lump, a pressure plate installed so as to be movable inside the hollow part, a heating means for heating the quartz glass lump accommodated in the hollow part, and A quartz glass molding apparatus comprising: a molding unit that presses a pressure plate in a pressing direction; and the quartz glass lump is pressed by the pressure plate while being heated by the heating unit, and is molded into a predetermined shape.
A substantially conical convex portion having an apex in the pressing direction is formed on a contact surface of the pressure plate with the quartz glass block, and a central axis of the pressure plate is included on the bottom surface of the convex portion. A convex portion having a substantially conical shape having a vertex in a direction opposite to the pressing direction is formed on the contact surface of the bottom receiving plate of the mold with the quartz glass block, and The bottom surface of the convex part includes the central axis of the bottom receiving plate;
A quartz glass molding device characterized by   The bottom surface of the convex portion formed on the pressure plate has an area of 50% or more of the area of the surface to be pressed of the quartz glass lump before molding. Quartz glass molding equipment.   The bottom surface of the convex part formed in the bottom receiving plate has an area of 50% or more of the area of the contacted surface of the quartz glass block before forming. The quartz glass molding apparatus as described.   The quartz glass molding apparatus according to claim 1, wherein a bottom surface of the convex portion has an area of 25% or more of an area of a surface that can come into contact with the quartz glass after molding.   The quartz glass molding apparatus according to claim 1, wherein a height of the convex portion is in a range of 3 to 10% of a diameter of a bottom surface of the convex portion.   The quartz glass molding apparatus according to claim 1, wherein a central axis of the convex portion is collinear with a central axis of the pressure plate and the bottom receiving plate.   Using the quartz glass molding apparatus according to any one of claims 1 to 8, the quartz glass lump is accommodated in a hollow portion of a mold provided in the molding apparatus, and the quartz glass lump is heated by a heating unit. A method for forming quartz glass, wherein the quartz glass lump is pressed and formed between the pressure plate and a bottom receiving plate of the mold while being heated by a pressure plate provided in the molding apparatus.   The quartz glass lump is a convex portion formed on the pressure plate and / or the bottom receiving plate on the pressed surface of the quartz glass lump and / or the contact surface of the quartz glass lump with the bottom receiving plate. The method for forming quartz glass according to claim 9, wherein a recess into which the tip of the glass is to be introduced is formed.

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