JP2005115148A - Optical element and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element and a method for manufacturing the same, in which the surface shape is precisely formed, without being influenced by the gas generated in the manufacture. <P>SOLUTION: The optical element, in which mold surfaces 10a and 11a of an upper mold 10 and a lower mold 11 are transferred, is formed by clamping a glass material 13 by the upper mold 10 and the lower mold 11. Groove parts 12a and 12b which communicate with the outside of the mold 11, from the mold surface 11a of the lower mold 11 via a flat part 11c and a guide part 11b of the lower mold 11, are formed. When the optical element is formed from the glass material 13, although the glass material 13 is heated and softens, here a gas is generated from the glass material 13. Although the gas is also released in the space between the mold surface 11a and the glass material 13, the gas is discharged to the outside from the groove parts 12a and 12b, with the progress of the clamping of the glass material 13 by the molds 10 and 11. Accordingly, there is no longer influence on the molding of the optical element by the press working of the glass material 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical element such as an optical lens used for optical communication and a method for manufacturing the same.

  In recent years, optical communication using optical fibers has become widespread. In such optical communication, a laser diode or the like has been used as a light source, and an optical lens is used to make light emitted from the light source incident on an optical fiber. This optical lens is for condensing the light from the light source on the incident surface of the optical fiber (see, for example, Non-Patent Document 1).

  According to the description, as shown in FIG. 3, an optical communication module 20 is formed by incorporating a laser diode 21, a tip portion of an optical fiber 22, and an optical lens 23. The optical lens 23 is connected to the laser diode 21 and the optical fiber. It is supported by a lens support portion 24 provided between the end portion of the fiber 22. Laser light diffused and emitted from the laser diode 21 is collected by the optical lens 23 at the entrance of the tip of the optical fiber 22.

  The optical lens 23 is an aspherical lens in order to increase the coupling efficiency between the laser diode 21 and the optical fiber 22, that is, in order to make the emitted light from the laser diode 21 efficiently enter the optical fiber 22. Is used.

  As an optical lens used for such optical communication, a glass lens is used. As an example of a manufacturing method thereof, a hot press working method is used. This is done by setting the optical lens material (glass blank) in the mold, pressing the mold in a state where the material is heated and softened, and clamping (pressing) the mold surface. The shape is transferred to a glass material. When the surface shape of the mold is transferred and the lens shape is completed, it is cooled and removed from the mold, and the press process is completed.

  By the way, as a manufacturing method by press working of an optical lens, various methods have been conventionally proposed (for example, see Patent Document 1).

  In the method described in Patent Document 1, as shown in FIG. 4A, an upper mold 30 having a mold surface 30a forming one surface shape of an optical lens and a mold surface 31a forming the other surface shape of the optical lens. A glass material 32 which is a lens material is disposed between the mold surfaces 30a and 31a, and an annular holder material 33 is disposed around the mold surface 31a of the lower mold 31.

  In this state, the glass material 32 is softened by heating, and then the upper die 30 is pressurized and pressed against the lower die 31 to obtain the state shown in FIG. In this state, the glass material 32 is pressed (clamped) by the mold surface 30 a of the upper mold 30, the mold surface 31 a of the lower mold 31, and the holder material 33, and the mold surfaces 30 a and 31 a become the glass material 32. The glass material 32 is transferred and adhered to the inner surface of the holder material 33.

  When the press working is thus completed, the glass material 32 and the like are cooled, and the upper mold 30 is raised, whereby the glass material 32 can be removed from the lower mold 31. In this case, the holder material 33 is fixed to the glass material 32. Therefore, as shown in FIG. 4C, the holder 36 made of the holder material 33 is attached to the lens portion 35 made of the glass material 32. An optical lens 34 with a metal holder is obtained. One side surface of the holder 36 can be used as a positioning reference surface in the optical axis direction when mounted on a semiconductor laser unit in optical communication.

  By the way, the optical lens 34 obtained by such a manufacturing method is unstable because the holder 36 may be detached from the lens portion 35 due to impact or vibration. Therefore, in order to further stabilize the coupling between the lens portion 35 and the holder 36, a configuration in which a convex portion is provided on the inner surface of the holder 36 has been proposed (for example, see Patent Document 2 and Patent Document 3).

However, in manufacturing such an optical lens, a convex portion must be formed on the inner surface of the holder material, which is very laborious. As one method for avoiding this, instead of providing the holder 36, as shown in FIG. 5, as the optical lens 37, a flange portion 39 made of the same material is provided on the outer periphery of the lens portion 38. As a method for manufacturing the optical lens 34 having such a configuration, for example, in the manufacturing method shown in FIG.
“Electronic Materials” Industrial Publishing, November 2001 pp.70-73 Japanese Patent No. 2793433 JP-A-3-167514 Japanese Patent No. 2907016

  FIG. 7 shows an example of an optical lens manufacturing process by press working.

In the figure, after supplying the preform (glass material), before heating, the system is evacuated (first time) and N ₂ substitution is performed. This is to prevent oxidation of the mold during heating. Next, after heating and soaking, vacuuming is again performed (second time), and then pressing is performed. After pressing, the decree and rapid cooling complete the optical lens.

  By the way, various shapes of lenses are used as optical lenses in accordance with applications and purposes. For example, when a lens is installed in the V-groove of the optical bench, a very thick lens may be required for the purpose of improving the sitting of the lens in the V-groove. In the manufacturing method by press working, the following problems occur when producing such a thick optical lens.

That is, when producing such a thick optical lens, the amount of glass material required is naturally increased. For this reason, when such an optical lens is manufactured by the method shown in FIG. 4, when the glass material 32 is placed on the lower mold 31 as shown in FIG. The inside of the mold 31, that is, the mold surface 31a is blocked. In this state, as shown in FIG. 6B, when the glass material 32 is pressed by the upper mold 30, the gas (N ₂ ), the mold surface 31a of the lower mold 31 cannot be transferred to the glass material 32 with high accuracy.

  As a method for solving this problem, for example, a multi-stage press method can be used. That is, in this method, the mold is transferred while the gas inside the lower mold 31 is removed by repeating the pressurization and depressurization in the pressing process and gradually pressing in multiple stages.

  However, the above method is not a useful method because the time per one molding cycle becomes very long, resulting in high cost.

  An object of the present invention is to solve such problems and provide an optical element having a surface shape formed with high accuracy and a method for manufacturing the same.

  In order to achieve the above object, the present invention provides an optical element comprising a surface having a desired shape and a land portion around the surface, and the land portion has a land portion extending from an inner diameter side end to an outer diameter side end. One or more strip-shaped convex portions are provided.

  The present invention is also a method of manufacturing an optical element in which the optical element is molded by clamping an element material with two molds, a lower mold and an upper mold, and communicates from the mold surface of the lower mold to the outside. The groove part releases the gas in the mold to the outside when the mold is clamped.

  According to the optical element of the present invention, a highly accurate surface shape can be obtained, and the convex portion formed on the land portion can be used as a mark of the mounting direction at the time of mounting on the device. Simplify the installation work.

  Further, according to the method for manufacturing an optical element according to the present invention, it is possible to release the gas generated when the material is clamped by the mold to the outside. Molding is possible, and an optical element having a highly accurate surface shape can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a view showing an embodiment of an optical element according to the present invention, in which FIG. 1 (a) is a perspective view thereof, and FIG. 1 (b) is a side view of FIG. Yes, 1 is an optical element of this embodiment (here, an optical lens), 2 is a lens portion, 3 is an edge portion, 4 is a land portion which is an end surface of the edge portion 3, and 5a and 5b are convex portions. .

  In FIGS. 2A and 2B, an optical element, that is, an optical lens 1 is composed of a lens portion 2 and an edge portion 3 formed integrally with the lens portion 2 around the lens portion 2. Band-shaped convex portions 5a and 5b are formed on at least one of the land portions 4 which are end surfaces of the portion 3 so as to cross the entire land portion 4 from the inner diameter side to the outer diameter side which is the lens portion 2 side. Yes. Here, these convex portions 5a and 5b are directed to the central axis of the lens portion 2, and are therefore on the same straight line that crosses the central axis. The number may be one as long as it crosses the entire four, or two or more may be provided at appropriate positions on the land portion 4.

  Thus, by providing the convex portions 5 a and 5 b on one land portion 4 of the edge portion 3, the convex portions 5 a and 5 b can be used as marks for the orientation of the lens surface of the optical lens 1. For example, as the lens 23 used in the module 20 for optical communication as shown in FIG. 3, the cross-sectional shape (spot shape) of the laser beam emitted from the laser diode 21 is an elliptical shape. Needs to be converted into a laser beam having a circular cross section and supplied to the optical fiber 22, and therefore, the respective curvatures are different in the x and y axes in the radial direction of the lens surface, or the respective curvature directions are also different. Different toric lenses are used. When such a non-axisymmetric lens is installed in the module 20, it is necessary to correctly set the direction of the lens surface of the lens 23. When the optical lens 1 shown in FIG. 1 is used as the lens 23 of the module 20, the convex portions 5a and 5b can be used as marks for determining the orientation of the lens surface. The operation of attaching the optical lens to a device that needs to consider the orientation of the lens surface of the optical lens becomes easier.

  2A and 2B are views for explaining an embodiment of the method of manufacturing an optical element according to the present invention. FIG. 2A is a cross-sectional view of the main part of the manufacturing apparatus, and FIG. 10 is an upper mold, 10a is its mold surface, 11 is a lower mold, 11a is its mold surface, 11b is a guide part, 11c is a flat part, 12a and 12b are groove parts, Is a glass material.

  In FIGS. 4A and 4B, a cylindrical guide portion 11b is provided on the outer diameter portion of the upper surface of the lower mold 11, and the heated glass material 13 is pressed (clamped). In some cases, the upper die 10 is pressurized and is guided by the guide portion 11b to move to the lower die 11 side. As a result, the glass material 13 is clamped by the upper mold 10 and the lower mold 11, the mold surface 10 a of the upper mold 10 and the flat surface around it are transferred to one side of the glass material 13, and the glass material 13 The mold surface 11a of the lower mold 11 and the surface of the surrounding flat portion 11c are transferred to the other side.

Here, the lower mold 11 is formed with two strip-shaped grooves 12a and 12b that pass from the edge of the mold surface 11a through the flat portion 11c, pass through the guide portion 11b, and communicate with the side surface of the lower mold 11. Even when the glass material 13 is placed on the upper surface of the mold 11 and the upper mold 10 is clamped, the mold surface 11a communicates with the outside of the lower mold 11 through these groove portions 12a and 12b. Thus, after the second evacuation step, when a gas (N ₂ or the like) is left in the space formed by the glass material 13 and the mold surface 11a, the grooves 12a and 12b are formed. This is a gas passage.

  Therefore, when the press working of the glass material 13 by the upper mold 10 is started, the glass material 13 is pushed toward the mold surface 11a side of the lower mold 11, so that it exists in the space between the glass material 13 and the mold surface 11a. The gas is discharged to the outside through the grooves 12a and 12b. As a result, the glass material 13 is clamped with high accuracy, and an optical lens having the mold surfaces 10a and 11a transferred with high accuracy is obtained.

  The optical lens 1 shown in FIG. 1 is formed as described above, and the lens surface of the lens portion 2 is formed by transferring the mold surface 10a of the upper mold 10 and the mold surface 11a of the lower mold 11. The edge portion 3 is formed by a flat portion around the mold surface 10a of the upper mold 10 and a flat surface portion 11c and a guide portion 11b of the lower mold 11, and both ends of the edge portion 3 are formed. The land portion 4 is a portion where the flat portion of the upper mold 10 and the flat portion 11c of the lower mold 11 are transferred.

  At the end of mold clamping (pressing) of the glass material 13, the glass material 13 also enters the grooves 12 a and 12 b of the lower mold 11, so that one land portion at the edge portion 3 of the optical lens 1 is thereby obtained. 4, the convex portions 5a and 5b are formed.

  Thus, in this embodiment of the manufacturing method, since the gas can be discharged to the outside by the grooves 12a and 12b provided in the lower mold 11, the optical lens 1 can be molded without being affected by the gas. Therefore, an optical lens having a highly accurate surface shape can be obtained.

  Since the lens surface of the lens portion 2 of the molded optical lens 1 (FIG. 1) is obtained by transferring the shape of the mold surface 10a of the upper mold 10 and the mold surface 11a of the lower mold 11, these mold surfaces. By appropriately setting the shapes of 10a and 11a, the optical lens 1 can be an axially symmetric lens or a non-axisymmetric lens, and the lens surfaces on both sides can have the same shape. Can be different or different.

  Here, in the embodiment of the manufacturing method, the optical lens 1 shown in FIG. 1 is described as being manufactured. However, depending on how the convex portions as described above are formed in the land portion 4 of the optical lens, Needless to say, one or two or more groove portions in the mold 11 are also provided.

  Further, the guide part 11b for guiding the upper mold 10 is provided in the lower mold 11, but instead of the guide part 11b, other means such as a cylindrical guide part provided outside the lower mold 11 and the upper mold 10 are provided. Thus, the upper mold that moves may be guided (if the lower mold 11 moves, the lower mold 11 or, if both molds 10, 11 move, these).

  In the above embodiment, the optical element is an optical lens. However, the present invention is not limited to this, and can be applied to other optical elements that require a highly accurate surface shape. Needless to say.

  Further, it goes without saying that the present invention is applicable not only to optical elements for optical communication but also to optical elements of other devices such as an objective lens of an optical recording / reproducing apparatus.

It is a figure which shows one Embodiment of the optical element by this invention. It is a figure for description of one Embodiment of the manufacturing method of the optical element by this invention. It is a block diagram which shows one prior art example of the module for optical communications. It is process drawing which shows one prior art example of the manufacturing method by press work of an optical lens. It is a figure which shows the other example of the optical lens by the manufacturing method shown in FIG. It is a figure explaining the problem of the manufacturing method shown in FIG. It is a figure which shows an example of the optical lens manufacturing process by press work.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical element 2 Lens part 3 Edge part 4 Land part 5a, 5b Convex part 10 Upper mold | type 10a Mold surface 11 Lower mold | type 11a Mold surface 11b Guide part 11c Plane part 12a, 12b Groove part 13 Glass material

Claims (2)

In an optical element composed of a surface of a desired shape and a land portion around it,
An optical element, wherein the land portion is provided with one or more belt-like convex portions that cross from the inner diameter side end to the outer diameter side end of the land portion. In the method of manufacturing an optical element according to claim 1, the element material is clamped by two molds, a lower mold and an upper mold.
A method of manufacturing an optical element, characterized in that a gas in the mold is released to the outside when the mold is clamped by a groove portion communicating from the mold surface of the lower mold to the outside.

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