JP5321301B2 - Optical element manufacturing method - Google Patents

Description

The present invention relates to the production how the optical element, in particular, relates to the production how the optical element to obtain an optical element by press molding the molten glass in the molding die.

  Optical elements made of glass have come to be used as lenses for digital cameras, optical pickup lenses such as DVDs, camera lenses for mobile phones, coupling lenses for optical communications, various mirrors, etc. It is. In recent years, as the downsizing and cost reduction of such devices have greatly progressed, glass optical elements used in such devices have been required to be smaller and less expensive, especially for mass production. There is a strong demand to increase productivity.

  Therefore, Patent Document 1 is a method in which a plurality of optical elements are integrally molded in a grid-arranged shape and separated into individual optical elements after molding to form a single optical element. A method has been proposed in which a mark for registering each optical element independently is molded on the molded body at the same time as the optical surface molding.

  Further, in Patent Document 2, as in Patent Document 1, a plurality of optical elements are integrally molded in a shape arranged in a grid, and after molding, the optical elements are separated into individual optical elements. Therefore, a method has been proposed in which a cut groove for separating each optical element is formed in an integrally molded body of a plurality of optical elements at the same time as the optical surface molding.

JP 2000-37787 A JP 2006-188388 A

  However, in both methods of Patent Document 1 and Patent Document 2, dicing for separating each optical element into a single optical element from an optical element array in which a plurality of optical elements are arranged in a lattice shape after molding is performed. A cutting process using an apparatus or the like is newly required. For this reason, the improvement in productivity was not sufficient.

The present invention has been made in view of the above problems, and an object thereof is to provide a manufacturing how very high optical element of productivity.

The above object is achieved by the invention described in any one of 1 to 6 below.

1. The molten glass supplied to the lower mold is pressure-molded by the lower mold and the upper mold, and a plurality of optical elements arranged in an integrated manner and the plurality of optical elements on the front surface and / or the back surface are used alone. A step of forming an optical element array formed with a groove for separating into,
A step of separating the plurality of optical elements independently by cooling the optical element array until the temperature of the molded optical element array decreases and reaches a predetermined temperature. Device manufacturing method.

2. The grooves are respectively formed at facing positions on the front surface and the back surface of the optical element array,
2. The method of manufacturing an optical element according to 1 above, wherein the depth of the groove satisfies the following conditional expression (1).

d1> d2 (1)
However,
d1: Depth of grooves on the back surface of the optical element array formed by the lower mold d2: Depth of grooves on the surface of the optical element array formed by the upper mold The groove is formed in a connection part of the plurality of optical elements arranged in an integrated manner,
3. The method of manufacturing an optical element according to 1 or 2, wherein the depth of the groove and the thickness of the connection portion satisfy the following conditional expression (2).

0.1 mm ≦ t− (d1 + d2) ≦ 0.5 mm (2)
However,
d1: Depth of grooves on the back surface of the optical element array formed by the lower mold d2: Depth of grooves on the surface of the optical element array formed by the upper mold t: Thickness of the connecting portion The groove is a back surface of the optical element array, and is formed in a connection portion of the plurality of optical elements arranged in an integrated manner.
2. The method of manufacturing an optical element according to 1 above, wherein the depth of the groove and the thickness of the connection portion satisfy the following conditional expression (3).

0.1 mm ≦ t−d1 ≦ 0.5 mm (3)
However,
d1: Depth of groove on the back surface of the optical element array formed by the lower mold t: Thickness of the connecting portion The groove is a surface of the optical element array, and is formed in a connection portion of the plurality of optical elements arranged in an integrated manner,
2. The method of manufacturing an optical element according to 1, wherein the depth of the groove and the thickness of the connection portion satisfy the following conditional expression (4).

0.1 mm ≦ t−d2 ≦ 0.5 mm (4)
However,
d2: depth of groove on the surface of the optical element array formed by the upper mold t: thickness of the connecting portion 6. The method of manufacturing an optical element according to any one of 1 to 5, wherein a cross-sectional shape of the groove is V-shaped.

  According to the present invention, an optical element array in which a plurality of optical elements arranged in an integrated manner and a groove for independently separating the plurality of optical elements on the front surface and / or the back surface thereof is molded. Thereafter, by cooling the optical element array until the temperature of the molded optical element array decreases and reaches a predetermined temperature, the plurality of optical elements are separated individually.

  An optical element array in which molten glass is molded using, for example, a droplet method has a high temperature immediately after molding. If the optical element array is cooled before the temperature of the high-temperature optical element array is lowered by natural cooling and reaches a predetermined temperature, a stress is generated inside the optical element array due to a rapid temperature change. This stress is greatest at the site where the cross-section is narrowed by the grooves formed at the same time as the optical element array is molded. Thereby, a crack (crack) enters along the groove, and a plurality of optical elements arranged in an integrated manner can be separated independently. That is, it can be easily separated into individual optical elements by the cooling step without providing a cutting step for separating each optical element into a single optical element. As a result, extremely high productivity can be obtained.

It is a cross-sectional schematic diagram which shows schematic structure of the manufacturing apparatus of the optical element concerning embodiment of this invention. It is the plane which shows an example of the glass lens array concerning embodiment of this invention, and a cross-sectional schematic diagram. It is a cross-sectional schematic diagram which shows an example of the glass lens concerning embodiment of this invention. It is a cross-sectional schematic diagram which shows an example of the manufacturing process of the shaping die concerning embodiment of this invention. It is a cross-sectional schematic diagram which shows another example of the manufacturing process of the shaping die concerning embodiment of this invention.

  An optical element manufacturing method and an optical element according to an embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiment.

  First, a schematic configuration of an optical element manufacturing apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an optical element manufacturing apparatus 1. In FIG. 1, the left figure shows the state in the molten glass supply process, the middle figure shows the state in the pressurizing process, and the right figure shows the state in the cooling process.

  The optical element manufacturing apparatus 1 includes a melting tank 70, an upper mold 10, a lower mold 20, a molding apparatus 2 having a pressure unit 50, a cooling stage 3, and the like.

  The molding apparatus 2 press-molds the molten glass 80 supplied to the lower mold 20 with the upper mold 10, and has a plurality of optical elements (glass lenses) 100 arranged in a lattice shape and the front and back surfaces or An optical element array (glass lens array) 100A in which a lattice-like groove 110 for separating the plurality of optical elements 100 independently is formed on either one of them.

  The lower mold 20 is between a position P1 for receiving the molten glass 80 below the nozzle 71 by a driving means (not shown) and a position P2 for pressing the molten glass 80 opposite to the upper mold 10. It is configured to be movable.

  The melting tank 70 melts the glass material charged therein to generate a molten glass 80. A nozzle 71 is provided below the melting tank 70, and the molten glass 80 is supplied from the nozzle 71 to the molding surface (receiving surface) 20 a of the lower mold 20. Further, a stirring blade (not shown) is provided inside the melting tank 70, and the stirring blade is rotated to stir and homogenize the molten glass 80.

  As a material for the melting tank 70, the nozzle 71, and the stirring blade, for example, platinum can be used. Further, a refractory reinforcing member (not shown) may be provided outside the melting tank 70 in order to support the entire tank. Further, around the melting tank 70 and the nozzle 71, there are provided a heater and a temperature sensor (not shown) for controlling heating to a predetermined temperature.

  The molding die is composed of an upper mold 10, a lower mold 20, and the like. On the upper mold 10 and the lower mold 20, a plurality of concave aspherical molding surfaces 10 a and molding surfaces 20 a for forming the optical surfaces 100 a and 100 b of the plurality of glass lenses 100 are respectively formed in a lattice shape. ing. In the present embodiment, the molding surface 10a of the upper mold 10 and the molding surface 20a of the lower mold 20 are both formed as a concave aspherical surface, but may be a convex aspherical surface or a spherical surface. Further, either the molding surface 10a or the molding surface 20a may be a flat surface.

  A rail-like shape for forming grooves 110 for separating the plurality of glass lenses 100 independently between the plurality of molding surfaces 10a and 20a formed on the upper mold 10 and the lower mold 20, respectively. The convex portions 20p are formed in a lattice shape. In addition, in this embodiment, although the convex part 20p is formed in both the upper mold | type 10 and the lower mold | type 20, any one may be sufficient as it.

  Here, FIG. 4 shows an example of the manufacturing process of the molding die. 4A to 4C are schematic cross-sectional views illustrating an example of the manufacturing process of the lower mold 20.

  In the present embodiment, the convex portion 20p is formed directly on the surface (cavity surface) of the lower mold 20.

  First, the mold base material 20A (FIG. 4A) is processed to form a rail-shaped convex portion 20p on the cavity surface (FIG. 4B). Next, a concave aspherical molding surface 20a is formed across the convex portion 20p (FIG. 4C). In this way, the lower mold 20 having a plurality of molding surfaces 20a on the cavity surface and projections 20p formed in a lattice shape between the molding surfaces 20a is completed.

  FIG. 5 shows another example of the manufacturing process of the molding die. FIG. 5A to FIG. 5D are schematic cross-sectional views showing other examples of the manufacturing process of the lower mold 20.

  In the present embodiment, the convex portion 20q is configured to be nested in the surface (cavity surface) of the lower mold 20.

  First, the mold base 20A (FIG. 5A) is processed to form a concave aspherical molding surface 20a on the cavity surface (FIG. 5B). Next, a groove 20m is formed between the molding surfaces 20a (FIG. 5C). Subsequently, a rail-shaped groove forming member 20q is loaded into the groove 20m (FIG. 5D). In this way, the lower mold 20 having a plurality of molding surfaces 20a on the cavity surface and a groove forming member 20q formed in a lattice shape between the molding surfaces 20a is completed.

  Returning to FIG. 1, the upper mold 10 and the lower mold 20 are provided with a heater and a temperature sensor (not shown) for controlling the heating to a predetermined temperature.

  The heater and the temperature sensor may be configured such that the temperature of each member can be adjusted independently, or the entire molding die may be heated together by one or a plurality of heaters. As a heater, it can select suitably from well-known various heaters, and can use it. For example, a cartridge heater that is used by being embedded inside the member, a sheet-like heater that is used while being in contact with the outside of the member, an infrared heating device, a high-frequency induction heating device, or the like can be used. Moreover, as a temperature sensor, well-known sensors, such as a platinum resistance thermometer and various thermistors other than various thermocouples, can be used.

  The heating temperature of the upper mold 10 and the lower mold 20 needs to be set within a temperature range in which the shape of the molding surface 10a and the molding surface 20a can be satisfactorily transferred to the molten glass 80. Usually, Tg (glass transition) of the glass to be molded is used. Point) It is preferable that the temperature range is about -100 ° C to Tg + 100 ° C. If the heating temperature is too low, it becomes difficult to transfer the shape of the molding surface 10a and the molding surface 20a to the molten glass 80 satisfactorily. On the other hand, it is not preferable to raise the temperature more than necessary from the viewpoint of preventing fusion between the molten glass 80 and the molding die and the life of the molding die. In practice, the appropriate temperature is determined taking into account various conditions such as the glass material to be molded, the shape and size of the glass lens, the mold material, the type of protective film, and the position of the heater and temperature sensor. To do.

  The materials of the upper mold 10 and the lower mold 20 are known as molding dies for pressure-molding the glass lens array 100A, such as a super hard material mainly composed of tungsten carbide, silicon carbide, silicon nitride, aluminum nitride, carbon, or the like. These materials can be appropriately selected and used. Moreover, what formed protective films, such as various metals, ceramics, and carbon, on the surface of these materials can also be used. The upper mold 10 and the lower mold 20 may be made of the same material, or may be made of different materials.

  As a mechanism of the pressurizing unit 50, a known pressurizing mechanism such as an air cylinder, a hydraulic cylinder, and an electric cylinder using a servo motor can be used. The pressing unit 50 press-molds the molten glass 80 by driving the upper mold 10. In the present embodiment, the pressing unit 50 is configured to drive the upper mold 10, but is not limited thereto, and drives the lower mold 20 or both the upper mold 10 and the lower mold 20. It is good also as a structure.

  The glass material is not particularly limited, and well-known glass used for optical applications can be selected and used according to the application. For example, silica glass, phosphate glass, lanthanum glass, and the like can be given.

  The cooling stage 3 is a water-cooled or air-cooled cooling device that cools the glass lens array 100A molded by the molding device 2, and the surface temperature thereof is set to about 10 ° C.

  Next, the outline of the manufacturing method of the glass lens 100 using the optical element manufacturing apparatus 1 having such a configuration will be described with reference to FIG.

  First, the molten glass 80 is applied to the molding surface (receiving surface) 20a of the lower mold 20 of the molding die heated to a predetermined temperature lower than the temperature of the molten glass 80 from the nozzle 71 provided in the lower part of the melting tank 70. Supply (molten glass supply step). At this time, the melting tank 70 and the nozzle 71 are each heated to a predetermined temperature by a heater (not shown). The lower mold 20 to which the molten glass 80 is supplied moves to below the upper mold 10, and the lower mold 20 and the upper mold 10 press-mold the molten glass 80 (pressure process). The molding surface (molding surface 10a, molding surface 20a) is transferred by pressure molding, and a plurality of glass lenses 100 arranged in a lattice shape and a rail-like convex portion 20p are transferred to a plurality of glass lenses 100. A glass lens array 100A in which a lattice-like groove 110 for separating each of the two is formed is obtained (molding process: molten glass supplying process + pressurizing process).

  A glass lens array 100A obtained in the molding step is shown in FIG. FIG. 2A is a schematic plan view showing an example of the glass lens array 100A, and FIG. 2B is a schematic cross-sectional view taken along the line AA ′ in FIG.

  As shown in FIG. 2A, a glass lens array 100A includes a plurality of glass lenses 100 that are integrated and arranged in a lattice shape, and a lattice-shaped groove 110 that separates the plurality of glass lenses 100 independently. , Is formed.

  As shown in FIG. 2B, a convex aspherical transfer surface 100a (optical surface) by the molding surface 10a of the upper mold 10 and a groove 110a are formed on the surface of the glass lens array 100A. A convex aspherical transfer surface 100b (optical surface) by the molding surface 20a of the lower mold 20 and a groove 110b are formed on the back surface of 100A. The cross-sectional shapes of the groove 110a and the groove 110b include a V shape, a trapezoid, an arc, and the like. In order to maximize the stress generated in the glass lens array 100A in the groove 110 in the cooling process described later. Is preferably V-shaped.

  Returning to FIG. 1, next, the glass lens array 100A obtained in the molding process is moved onto the cooling stage 3, and the temperature of the glass lens array 100A is lowered by natural cooling to reach a predetermined temperature. The plurality of glass lenses 100 are separated independently by cooling the optical element array 100A (cooling step).

  The glass lens array 100A immediately after molding is at a high temperature. When the glass array 100A is cooled (for example, at a cooling temperature of 10 ° C.) until the temperature of the high-temperature glass lens array 100A is lowered by natural cooling and reaches a predetermined temperature (for example, 100 ° C.), due to a rapid temperature change, Stress is generated inside the glass lens array 100A. This stress is greatest at the portion where the cross section is narrowed by the groove 110 formed at the same time when the glass lens array 100A is formed. Thereby, a crack (crack) enters along the groove 110, and a plurality of glass lenses 100 arranged in an integrated manner can be separated independently. When the glass lens array 100A is cooled by the cooling stage 3 and the surface of the glass lens array 100A is loaded with a biasing member (not shown) or the like to distort the glass lens array 100A, a plurality of glasses are more accurately obtained. The lens 100 can be separated independently.

  The glass lens 100 obtained by being separated in the cooling step is shown in FIG. FIG. 3 is a schematic cross-sectional view showing an example of the glass lens 100.

  As shown in FIG. 3A, a convex aspherical transfer surface 100a (optical surface) is formed on the surface of the glass lens 100 by the molding surface 10a of the upper mold 10, and on the back surface of the glass lens 100, A convex aspheric transfer surface 100b (optical surface) is formed by the lower mold 20 molding surface 20a. In addition, on the front and back surfaces of the four end surfaces of the connection portion 120, a partial surface 100c having a cross-sectional shape in which a groove 110a is formed on the front surface side, and a partial surface having a cross-sectional shape in which a groove 110b is formed on the back surface side 100d forms a chamfered surface. With this chamfered surface, the glass lens 100 can be prevented from being damaged (chipping) when the glass lens 100 is incorporated into various devices, and the glass lens 100 that is easy to handle can be obtained.

  Here, referring back to FIG. 2, it is preferable that the depths of the grooves 110a and 110b satisfy the following conditional expression (1).

d1> d2 (1)
However,
d1: Depth of the groove 110b on the back surface of the glass lens array 100A formed by the lower mold 20 d2: Depth of the groove 110a on the surface of the glass lens array 100A formed by the upper mold 10 Since the transfer property of the lower mold 20 in contact with the molten glass 80 is superior to that of the upper mold 10, a desired shape can be transferred with higher accuracy. For this reason, the depth of the groove 110b on the back surface of the glass lens array 100A formed by the lower mold 20 is set to be the upper mold 10 so that the plurality of glass lenses 100 can be separated properly in the cooling process described above. It is preferable to make it deeper than the depth of the groove 110a on the surface to be formed.

  Moreover, it is preferable that the depth of the groove 110a and the groove 110b and the thickness of the connection part (flange part) 120 of the plurality of glass lenses 100 arranged in a lattice shape satisfy the following conditional expression (2).

0.1 mm ≦ t− (d1 + d2) ≦ 0.5 mm (2)
However,
d1: Depth of the groove 110b on the back surface of the glass lens array 100A formed by the lower mold 20 d2: Depth of the groove 110a on the surface of the glass lens array 100A formed by the upper mold 10 t: Thickness of the connecting portion 120 Expression (2) defines the thickness td (td = t− (d1 + d2)) of the portion of the connecting portion 120 where the grooves 110a and 110b are formed. When the depths d2 and d1 of the grooves 110a and 110b become too deep, and the thickness td becomes less than the lower limit value of the conditional expression (2), the glass lens array 100A after molding is moved to the cooling stage 3. It becomes separated due to the load caused by handling until it is done, making handling difficult. On the other hand, when the depth d2 and the depth d1 of the groove 110a and the groove 110b become too shallow and the thickness td exceeds the upper limit value of the conditional expression (2), the groove 110a and the groove of the connecting portion 120 are formed in the cooling step. The aforementioned stress at the site where 110b is formed is reduced, making separation difficult. Therefore, by satisfying conditional expression (1), it is possible to accurately separate in the cooling process.

  In the above-described embodiment, the grooves 110 are formed on the front surface and the back surface of the glass lens array 100A (grooves 110a and 110b), as shown in FIGS. 2C and 2D. Alternatively, it may be formed only on the back surface or the front surface (groove 110g, groove 110h). Also in this case, by satisfying the following conditional expressions (3) and (4), the same effects as those in the case of FIG. 2B can be obtained.

  As shown in FIG. 2C, when the grooves 110g are formed on the back surface of the glass lens array 100A, the connection portions (flange portions) of the plurality of glass lenses 100 arranged in a lattice shape with the depth of the grooves 110g. The thickness of 120 preferably satisfies the following conditional expression (3).

0.1 mm ≦ t−d1 ≦ 0.5 mm (3)
However,
d1: Depth of the groove 110g on the back surface of the glass lens array 100A formed by the lower mold 20 t: Thickness of the connecting portion 120 Further, as shown in FIG. 2 (d), a groove 110h is formed on the surface of the glass lens array 100A. When formed, it is preferable that the depth of the groove 110h and the thickness of the connection portions (flange portions) 120 of the plurality of glass lenses 100 arranged in a lattice shape satisfy the following conditional expression (4).

0.1 mm ≦ t−d2 ≦ 0.5 mm (4)
However,
d2: Depth of the groove 110h on the surface of the glass lens array 100A formed by the upper mold 10 t: Thickness of the connecting portion 120 As described above, in the manufacturing method of the glass lens 100 in the embodiment of the present invention, the glass lens array Without providing a cutting step for separating each glass lens 100 from 100A into a single glass lens 100, it can be easily separated into a single glass lens 100 by a cooling step, thereby obtaining extremely high productivity. be able to.

  An example of the manufacturing method of the glass lens 100 according to the embodiment of the present invention will be described with reference to FIGS.

  In the molded glass lens array, the outer diameter of one glass lens 100 is 2 mm, the optical effective diameter is 1.5 mm, the design value of the lens center thickness (axial thickness) is 1.0 mm, and the flange thickness is 0.1 mm. A glass lens array 100A in which 16 7-mm biconvex aspherical lenses are arranged in a lattice pattern is used.

  As the glass material, silica-based glass having a glass transition point Tg of 480 ° C., a refractive index nd of about 1.6, and a thermal expansion coefficient of 12 × 10 ^ -6 / ° C. was used.

  As a material of the molding die, a super hard material having a thermal expansion coefficient of 5.0 × 10 ^ −6 / ° C. mainly composed of tungsten carbide was used.

  Further, as the lower mold, the lower mold 20 in which the convex portion 20p having a height of 0.6 mm and a width of 0.1 mm was formed at a position corresponding to the outer diameter □ 2 mm of the glass lens 100 of the lower mold (see FIG. 4 (c)).

  First, the lower mold 20 is moved to a position P1 for receiving the molten glass 80 below the nozzle 71 by a driving means (not shown), and heated to a temperature (about 450 ° C.) lower than the temperature of the molten glass 80. Molten glass 80 was supplied to the molding surface (receiving surface) 20a of the mold 20 from a nozzle 71 provided at the lower portion of the melting tank 70 (left figure in FIG. 1: molten glass supplying step).

  Next, the lower mold | type 20 to which the molten glass 80 was supplied was moved to the position P2 for pressure-molding the molten glass 80 facing the upper mold | type 10. FIG. After 5 seconds have passed since the lower mold 20 has reached the position P2, the upper mold 10 is moved downward, and the molten glass 80 is pressure-molded with the lower mold 20 and the upper mold 10 (the figure in FIG. 1: pressure process). . At this time, the moving speed of the upper mold 10 was 20 mm / second, the press pressure was 980 N, and the press pressure maintenance time was 10 seconds.

  In this way, a convex aspherical transfer surface 100a (optical surface) by the molding surface 10a of the upper mold 10 is formed on the front surface, and a convex aspherical transfer surface 100b (optical) by the molding surface 20a of the lower mold 20 is formed on the rear surface. Glass lens array 100A (surface) formed with a plurality of glass lenses 100 that are integrated and arranged in a lattice shape, and a lattice-shaped groove 110g formed by convex portions 20p of the lower mold 20 on the back surface. 2 (a) and FIG. 2 (c)) were obtained (molding step: molten glass supply step + pressure step).

  After completion of molding, the upper mold 10 was retracted upward, and the glass lens array 100A remaining on the lower mold 20 was sucked and collected by a robot arm (not shown).

  Subsequently, the collected high-temperature glass lens array 100A is quickly moved onto the cooling stage 3, and the glass glass array 100A is lowered by natural cooling until the temperature reaches about 100 ° C. The array 100A was cooled (cooling step: right diagram in FIG. 1). The surface temperature of the cooling stage 3 was set to 10 ° C.

  At this time, cracks (cracks) are formed along the lattice-shaped grooves 110g due to stress in the above-described inside caused by a rapid temperature change caused by rapidly cooling the glass lens array 100A immediately after molding. It was confirmed that the plurality of glass lenses 100 arranged in a separated manner were separated.

DESCRIPTION OF SYMBOLS 1 Optical element manufacturing apparatus 2 Molding apparatus 3 Cooling stage 10 Upper mold | type 10a Molding surface 20A Mold base material 20 Lower mold | type 20a Molding surface (receiving surface)
20m groove 20p convex part 20q groove forming member 50 pressure part 70 melting tank 71 nozzle 80 molten glass 100A glass lens array (optical element array)
100 Glass lens (optical element)
100a, 100b Transfer surface (optical surface)
100c, 100d Chamfered surfaces 110, 110a, 110b, 110g, 110h Groove 120 Connection portion (flange portion)

Claims (6)

The molten glass supplied to the lower mold is pressure-molded by the lower mold and the upper mold, and a plurality of optical elements arranged in an integrated manner and the plurality of optical elements on the front surface and / or the back surface are used alone. A step of forming an optical element array formed with a groove for separating into,
A step of separating the plurality of optical elements independently by cooling the optical element array until the temperature of the molded optical element array decreases and reaches a predetermined temperature. Device manufacturing method. The grooves are respectively formed at facing positions on the front surface and the back surface of the optical element array,
The method for manufacturing an optical element according to claim 1, wherein the depth of the groove satisfies the following conditional expression (1).
d1> d2 (1)
However,
d1: Depth of grooves on the back surface of the optical element array formed by the lower mold d2: Depth of grooves on the surface of the optical element array formed by the upper mold The groove is formed in a connection part of the plurality of optical elements arranged in an integrated manner,
The optical element manufacturing method according to claim 1, wherein the depth of the groove and the thickness of the connection portion satisfy the following conditional expression (2).
0.1 mm ≦ t− (d1 + d2) ≦ 0.5 mm (2)
However,
d1: Depth of grooves on the back surface of the optical element array formed by the lower mold d2: Depth of grooves on the surface of the optical element array formed by the upper mold t: Thickness of the connection portion The groove is a back surface of the optical element array, and is formed in a connection portion of the plurality of optical elements arranged in an integrated manner.
2. The method of manufacturing an optical element according to claim 1, wherein the depth of the groove and the thickness of the connection portion satisfy the following conditional expression (3).
0.1 mm ≦ t−d1 ≦ 0.5 mm (3)
However,
d1: Depth of groove on the back surface of the optical element array formed by the lower mold t: Thickness of the connecting portion The groove is a surface of the optical element array, and is formed in a connection portion of the plurality of optical elements arranged in an integrated manner,
2. The method of manufacturing an optical element according to claim 1, wherein the depth of the groove and the thickness of the connection portion satisfy the following conditional expression (4).
0.1 mm ≦ t−d2 ≦ 0.5 mm (4)
However,
d2: depth of groove on the surface of the optical element array formed by the upper mold t: thickness of the connecting portion   The method for manufacturing an optical element according to claim 1, wherein a cross-sectional shape of the groove is V-shaped.

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