JP2008162182A - Manufacturing method of optical element, insert member and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical element which enables a mold to be formed at a low cost and suppresses the leakage of a resin material, and to provide an insert member and the optical element. <P>SOLUTION: In the mold in which the plate-like insert member 30 is inserted/extracted between/from the cavities 11, 21 of the upper die 10 and the bottom die 20, a liquid resin is injected through the flow passages (33, 34, 35) formed in the insert member 30 and this unnecessitates forming flow passages for the resin such as runner gates, air vents, etc. , on the parting faces of the upper and bottom dies 10, 20 to result in the cost reduction in manufacturing the mold. Further, if the formed optical element OE is released from the mold as one body with the insert member 30, it becomes unnecessary to provide ejector pins and the like for the mold, which accordingly unnecessitates providing a sliding part and saves time and labor since cleaning it is not necessary. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for molding an optical element, and particularly relates to a manufacturing method for molding an optical element using a thermosetting resin, an insert member used therefor, and an optical element manufactured thereby.

  As an optical element molding method of an optical device in a laser printer having an optical scanning system, a digital copying machine, a facsimile machine, an optical disk apparatus having an optical signal pickup system, a digital still camera having an imaging system, a portable terminal with a camera, etc. In the case of using a raw material, there are an injection molding method, an injection compression molding method, a resin press method, and the like.

For example, in the injection molding method and the injection compression molding method, the molten resin is injected and filled into a fixed volume cavity of the mold while the mold temperature is lower than the softening temperature of the molding resin, and the holding pressure is controlled. In this method, the mold is opened after slow cooling while the mold is opened (see Patent Document 1).
JP 2001-124902 A

  By the way, in a mold used for an injection molding method or the like, in addition to a molding cavity, a runner and a gate for supplying resin to the molding cavity, and when the molding cavity is filled with resin, extruded air flows. It is common practice to provide air vent cavities for the purpose. They are usually formed by electrical discharge machining or cutting, but in order to ensure resin flow, releasability, and dimensional accuracy, precise processing and surface treatment are required, and a great deal of cost and time are required. Yes. Furthermore, if the shape of runners, gates, vent cavities, etc. need to be changed due to changes in molding materials and molding conditions, high cost and long time are required for additional machining or remanufacturing of molds. . In addition, when resin clogging occurs in the runner, gate, vent cavity, etc. due to defective mold release, it is necessary to stop the apparatus for a long time and perform the cleaning operation, which causes a problem that molding efficiency is lowered.

  Also, as a means of filling the optical element material into the molding cavity, there is a method of applying pressure to the melted resin and pushing it into the molding cavity. Especially when a resin material having a low viscosity at the time of filling is used, The resin material leaks from the gap, which causes burrs and mold release defects. Such a problem can be improved to some extent by accurately finishing the flatness of the butt surface of the mold, but it can be said that it is difficult to completely eliminate the leakage of the resin material only by improving the flatness.

  The present invention has been made in view of the problems of the prior art, and can be used to form a mold at a low cost, or a method for manufacturing an optical element capable of suppressing leakage of a resin material, an insert member used therefor, and thereby An object is to provide a manufactured optical element.

The method for producing an optical element according to claim 1 comprises:
A step of interposing a plate-like insert member between an upper mold and a lower mold that are relatively moved to transfer and mold an optical element;
A step of pressing the upper member and the lower die with a predetermined pressing pressure while compressing the insert member; and
Injecting and curing a liquid resin into the cavities of the upper mold and the lower mold through a flow path formed in the insert member;
A step of relatively moving the upper mold and the lower mold away from each other after curing the resin,
A cutout is formed in the insert member for allowing the air pushed out by pouring liquid resin into the cavity of the upper mold and the lower mold to flow out of the cavity.

  According to the present invention, since the liquid resin is injected into the cavity of the upper mold and the lower mold through the flow path formed in the insert member, the dividing surface of the upper mold and the lower mold is injected. There is no need to form resin flow paths such as runners and gates, and the cost of manufacturing the mold is reduced. On the other hand, since the insert member is plate-shaped, the resin flow path can be easily and accurately formed by pressing or the like. Furthermore, since the insert member is inexpensive, it can also be used by replacing it for each molding, and when the molding material and molding conditions change, it is necessary to change the shape of the runner gate, etc. Since it is sufficient to replace the insert member with a different shape, the molding efficiency is improved. If the molded optical element is released from the insert member integrally, there is no need to provide an extrusion pin or the like in the mold, and therefore there is no need to provide a sliding portion. There is also an advantage that it does not need to be done and takes time and effort. In addition, even if molding failure occurs in the runner / gate, etc., it is possible to perform molding using the same mold with a new insert member in the next molding cycle. Disappear. The press pressure applied to the upper mold and the lower mold, the extrusion pressure applied to the resin, and the amount of the press need not be constant, and bubbles are generated by increasing or decreasing the pressure during curing. Can be suppressed, and moldability can also be improved.

  Further, according to the present invention, the insert member is formed with a notch for allowing the air pushed out by injecting liquid resin into the cavity of the upper mold and the lower mold to flow out of the cavity. Therefore, it is not necessary to form an air vent or the like on the dividing surface of the upper mold and the lower mold, and the cost for manufacturing the mold is reduced. On the other hand, since the insert member has a plate shape, the notch can be easily and accurately formed by a press or the like. The “notch” formed in the insert member means that a shape for forming a space in which air pushed out by the injection of resin can be retained is provided, and such a space is formed. However, it is not intended how the shape is formed. Furthermore, since the insert member is inexpensive, it can also be used after being molded, and when the molding material or molding conditions are changed, it is necessary to change the position or capacity of the air vent, etc. Since it is sufficient to replace the insert member with a different shape, the molding efficiency is improved. If the molded optical element is released from the insert member integrally, there is no need to provide an extrusion pin or the like in the mold, and therefore there is no need to provide a sliding portion. There is also an advantage that it does not need to be done and takes time and effort. Also, even if a molding failure occurs due to a notch in the insert member, molding can be performed with the same mold in the next molding cycle using a new insert member. Disappear.

  According to a second aspect of the present invention, there is provided an optical element manufacturing method according to the first aspect of the invention, wherein the resin is a thermosetting resin. Thermosetting resins have a significantly lower viscosity when heated to a liquid state than acrylic and polycarbonate used as materials for conventional optical elements. However, it is possible to suppress the leakage by interposing the insert member between the upper mold and the lower mold as in the present invention.

  Here, examples of the “thermosetting resin” include silicon resin, allyl ester, acrylic resin, epoxy resin, polyimide, and urethane resin. Examples of the “optical element” include lenses, prisms, diffraction grating optical elements (diffraction lenses, diffraction prisms, diffraction plates), optical filters (spatial low-pass filters, wavelength band-pass filters, wavelength low-pass filters, wavelength high-pass filters, etc.). , A polarizing filter (analyzer, optical rotator, polarization separation prism, etc.) and a phase filter (phase plate, hologram, etc.), but are not limited thereto.

  According to a third aspect of the present invention, there is provided the method for manufacturing an optical element according to the first or second aspect of the invention, wherein the divided surfaces of the upper mold and the lower mold are flat surfaces other than a surface forming a cavity. To do. Thereby, the upper mold and the lower mold can be processed easily with high accuracy.

The optical element manufacturing method according to claim 4 is the invention according to any one of claims 1 to 3, wherein the longitudinal elastic modulus of the insert member is E, and the insert member contacts the upper die or the lower die. S is the area to be used, t is the thickness of the insert member in the initial state, F is the press pressure applied to the upper mold and the lower mold, and the surface roughness Ra of the contact surface of the upper mold with the insert member is Ra (1), Ra (2) the surface roughness Ra of the contact surface with the insert member in the lower mold, Ra (3) the surface roughness Ra of the contact surface with the upper mold in the insert member, When the surface roughness Ra of the contact surface with the lower mold in the insert member is represented by Ra (4),
F (1) = E × S × (Ra (1) + Ra (3)) / t (1)
F (2) = E × S × (Ra (2) + Ra (4)) / t (2)
F ≧ max (F (1), F (2)) (3)
It satisfies the following conditions.
However, max (F (1), F (2)): The larger value of F (1) and F (2)

  It is possible to prevent the molten resin from leaking out of the cavity by compressing and deforming the insert member by a pressing pressure during molding and bringing the upper die and the lower die into close contact with the insert member. As a result, burrs and mold-clamping defects are less likely to occur, and molding defects and cleaning operations are reduced by stopping the molding equipment, increasing the equipment availability and reducing the cost of efficient and product-quality molded products. Can be produced.

Here, the pressing pressure is F, the longitudinal elastic modulus of the plate-like insert member is E, the area where the insert member is clamped by the upper die or the lower die is S, and the thickness of the insert member in the initial state (free state) is t. In this case, the stress σ generated in the insert member, the strain ε of the insert member, and the deformation amount Δt of the insert member can be expressed by the following equations.
ε = Δt / t, σ = F / S, σ = E × ε = E × Δt / t (4)
F = S × E × Δt / t (5)

Furthermore, the surface roughness Ra of the contact surface with the upper insert member is Ra (1), the surface roughness Ra of the contact surface with the lower insert member is Ra (2), and the contact with the upper mold of the insert member When the surface roughness Ra of the surface is represented by Ra (3) and the surface roughness Ra of the contact surface with the lower mold of the insert member is represented by Ra (4), the gap x (1) between the upper mold and the insert member, The gap x (2) between the insert members can be expressed by the following equation.
x (1) = Ra (1) + Ra (3) (6)
x (2) = Ra (2) + Ra (4) (7)

Here, if the larger value of x (1) and x (2) is x, the condition of x ≦ Δt may be satisfied.
F ≧ S × E × x / t (8)
If this condition is satisfied, the upper die, the insert member, and the lower die are in close contact with each other.

  According to a fifth aspect of the present invention, there is provided the optical element manufacturing method according to any one of the first to fourth aspects, wherein the insert member is compressed by bringing a part of the upper die and the lower die into contact with each other. The thickness of time is regulated. Thus, the thickness of the insert member when compressed can be kept constant regardless of the press pressure. Accordingly, the molding conditions are constant, the on-axis thickness of the optical element is constant, and stable and reliable molding can be realized, so that a molded product can be obtained with high quality and high efficiency.

  A part of the molds may be in contact with a block in which at least one of the upper mold and the lower mold abuts against the other, or a molding apparatus that drives opening and closing of the upper mold and the lower mold. An obstacle that abuts on the stroke may be provided, or an intangible system that servo-controls the coordinates of the stroke position may be used. The gist of the present invention is to perform the position control of the mold at the time of molding without depending on the insert member.

  The insert member according to claim 6 is used in the method for manufacturing an optical element according to any one of claims 1 to 5.

  An optical element according to a seventh aspect is manufactured by the method for manufacturing an optical element according to any one of the first to fifth aspects.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical element which can form a metal mold | die at low cost, or can suppress the leakage of a resin material, the insert member used therefor, and the optical element manufactured by it can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a mold and an insert member of the optical element according to the first embodiment. FIG. 2 is a cross-sectional view of the mold of the optical element and the insert member in the molded state. 1 and 2, a plate-shaped insert member 30 is arranged between the block-shaped upper mold 10 and the lower mold 20, but the cavity is shown as a single for easy understanding. Yes.

  On the lower surface (divided surface) of the upper mold 10, circular concave upper cavities 11 are arranged side by side in two rows, and two pin holes 12 (only one is shown in FIG. 1) apart from each other on a diagonal line. Is formed. On the other hand, a circular concave lower cavity 21 is formed in two rows corresponding to the upper cavity 11 on the upper surface (divided surface) of the lower mold 20, and an alignment pin 22 corresponding to the pin hole 2. It has been planted. The dividing surfaces of the upper mold 10 and the lower mold 20 are flat except for the cavity.

  The insert member 30 is a copper plate, and circular openings 31 are formed in two rows corresponding to the cavities 11 and 21, and alignment holes 32 are formed corresponding to the alignment pins 22. The thermal conductivity of the insert member 30 is preferably the same as or higher than the thermal conductivity of the molds 10 and 20. The insert member 30 may be made of other metal such as phosphor copper or aluminum, glass, or resin material such as Teflon or PC.

  Furthermore, the insert member 30 forms an elongated notch 33 extending from the end portion between the rows of the openings 31 arranged in two rows corresponding to the cavities 11 and 21, and each opening from the notch 33. A taper-shaped notch 34 is formed toward 31. Between the cutout portion 34 and the opening 31, gate portions 35 each having a small cross-sectional area (narrow width) are formed. A notch 36 is formed at the edge of the opening 31 on the side opposite to the gate portion 35. The cutout portions 33 and 34 constitute a runner, the cutout portions 33 and 34 and the gate portion 35 constitute a resin flow path, and the cutout 36 constitutes an air vent.

Here, the longitudinal elastic modulus of the insert member 30 is E, the area where the insert member 30 contacts the upper die 10 and the lower portion 20 is S, the thickness of the insert member 30 is t, the pressing pressure is F, and the insert member 30 in the upper die 10 is. The surface roughness Ra of the contact surface with Ra (1), the surface roughness Ra of the contact surface with the insert member 30 in the lower mold 20 Ra (2), the surface of the contact surface with the upper mold 10 in the insert member 30 When the roughness Ra is represented by Ra (3) and the surface roughness Ra of the contact surface with the lower mold 20 in the insert member 30 is represented by Ra (4),
F (1) = E × S × (Ra (1) + Ra (3)) / t (1)
F (2) = E × S × (Ra (2) + Ra (4)) / t (2)
F ≧ max (F (1), F (2)) (3)
To meet the conditions.

  FIG. 3 is a schematic view showing a process of molding an optical element using the mold and insert member of the present embodiment, but shows a single cavity for easy understanding. First, as shown to Fig.3 (a), the insert member 30 is mounted on the lower mold | type 20 installed on the surface plate, and the upper mold | type 10 is set above it. At this time, since the alignment pin 22 of the lower mold 20 shown in FIG. 1 is fitted into the alignment hole 32 of the insert member 30 and the pin hole 12 of the upper mold 10, the molds 10, 20 and the insert member 30 are It will be accurately aligned in the direction.

  Here, referring to FIG. 3 (b), the upper mold 10 is pressurized by a hydraulic cylinder 40. The hydraulic cylinder 40 is provided with a pressure sensor 41 so that the press pressure can be detected. The press pressure detected by the pressure sensor 41 is input to the control device 42. The control device 42 can control the pressure of the hydraulic cylinder 40 in accordance with the detected press pressure.

  In FIG. 3B, the upper mold 10 pressed by the hydraulic cylinder 40 applies a compressive force to the insert member 30. As a result, the insert member 30 comes into close contact between the upper mold 10 and the lower mold 20 with a predetermined surface pressure. Furthermore, since the distance between the upper mold 10 and the lower mold 20 changes by adjusting the press pressure within the elastic deformation region of the insert member 30, the axial thickness of the optical element after molding is thereby changed. Can be adjusted.

  In FIG. 3C, the molds 10 and 20 and the insert member 30 are heated by the heater 50 while maintaining the pressing pressure, and the heated thermosetting resin having a low viscosity is cut out from the outside of the insert member 30. It inject | pours inside through 33 (FIG. 1). Since the insert member 30 is in close contact with the dividing surface of the upper die 10 and the lower die 20, the resin flow path formed by the notches 33, 34 and the gate portion 35 is shielded and sealed by the insert member 30 itself. Therefore, the leakage of the thermosetting resin having a low heated viscosity does not occur. The resin injected from the outside passes through the notches 33 and 34 and the gate portion 35 and reaches the cavities 11 and 21. At this time, the air pushed out by the resin flowing into the cavities 11 and 12 is stored in the notch 36. Thereby, the highly accurate shape of the optical element to be molded can be ensured.

  When the upper mold 10 is moved upward after cooling for a certain period, the optical element OE molded so that the flange portion is in close contact with the insert member 30 is exposed. Therefore, as shown in FIG. 3D, all the optical elements OE attached to the insert member 30 can be removed at once by removing the insert member 30 from the lower mold 20. Thereafter, another insert member 30 can be arranged between the upper mold 10 and the lower mold 20 to prepare for molding again (see FIG. 3A). In parallel with this, the optical element OE can be separated from the removed insert member 30. Thereby, the molding cycle time can be shortened. The intermediate member 30 from which the optical element OE has been removed can be reused.

  According to the present embodiment, the liquid resin is injected into the cavities 11 and 21 of the upper mold 10 and the lower mold 20 through the flow paths (33, 34, 35) formed in the insert member 30. In addition, it is not necessary to form a resin flow path such as a runner / gate, an air vent, or the like on the dividing surface of the upper mold 10 and the lower mold 20, and the cost for manufacturing the mold is reduced. On the other hand, since the insert member 30 is plate-shaped, a resin flow path and an air vent can be easily and accurately formed by pressing or the like. Furthermore, since the insert member 30 is inexpensive, it can be used after being molded, and when the shape of the runner / gate, air vent, etc. needs to be changed due to changes in the molding material and molding conditions. However, since it is sufficient to replace the insert member 30 with another shape, the molding efficiency is improved. If the molded optical element OE is released from the insert member 30 integrally, there is no need to provide an extruding pin or the like in the mold, and therefore there is no need to provide a sliding portion. There is also an advantage that it does not need to be done and takes time and effort. In addition, even if molding defects occur due to runners, gates, air vents, etc., the molding can be performed using the new insert member 30 with the same mold in the next molding cycle. There is no need to do it.

  FIG. 4 is a perspective view of a mold and an insert member of the optical element according to the second embodiment. FIG. 5 is a cross-sectional view of the mold of the optical element and the insert member in the molded state. In the present embodiment, the insert member 30 ′ only has notches 37 and 38 formed on both sides of each opening 31. On the other hand, on the lower surface of the upper mold 10 ′, large grooves 13 extending from the ends of the upper mold 10 ′ are formed between the rows of the upper cavities 11, and are further communicated from the large grooves 13 toward the upper cavities 11. A not-formed taper groove 14 is formed. The large groove 13 and the tapered groove 14 constitute a runner. Further, a clearance groove 15 is formed on the lower surface of the upper mold 10 on the opposite side of the large groove 13 across the upper cavities 11 of each row, and at the end opposite to the end where the large groove 13 opens. It is open.

  As shown in FIG. 5, when the insert member 30 ′ is overlapped between the upper mold 10 ′ and the lower mold 20 ′, the notch 37 of the insert member 30 ′ communicates with the tapered groove 14, and the notch 38 is the escape groove. 15 will be communicated. By adjusting the overlapping area of the notch 37 and the tapered groove 14, it can function as a gate portion.

  Further, in FIG. 5, the lower mold 20 ′ has two projecting portions 26 formed on its dividing surface with the lower cavity 21 interposed therebetween. In the free state, the upper surface of the insert member 30 ′ is located higher than the upper end of the protrusion 26.

  Referring to FIG. 3, when the upper mold 10 ′ is pressed from above during molding, the protrusion 26 of the lower mold 20 ′ comes into contact with the dividing surface of the upper mold 10 ′ and prevents further compression. Become. Here, if the compressed insert member 30 is in the elastic deformation region with the protruding portion 26 ′ of the lower mold 20 ′ in contact with the dividing surface of the upper mold 10 ′, the resin leaks from the flow path due to the sealing function. It can be suppressed from coming out. Further, since the protrusion 26 of the lower mold 20 ′ abuts against the dividing surface of the upper mold 10 ′, the distance between the upper mold 10 ′ and the lower mold 20 ′ is determined. Therefore, it is not necessary to control the press pressure as in the above-described embodiment, and the cost of the molding apparatus can be reduced.

  According to the present embodiment, the melted resin passes from the outside through the large groove 13, the tapered groove 14, and the notch 37 and reaches the cavities 11 and 21. At this time, the air pushed out by the resin flowing into the cavities 11 and 12 flows out from the notch 38 through the escape groove 15.

  FIG. 6 is a perspective view of a mold and an insert member of an optical element according to a modification of the present embodiment. In the insert member 30 of this modification, the air vent cutouts 36 connected to the openings 31 arranged in two rows are respectively connected to the slits 39 extending along the arrangement of the openings 31. The inside of the air vent notch 36 and the slit 39 is a sealed space by being sandwiched between the upper mold 10 and the lower mold 20. Thus, by making the air vent notch 36 communicate with the slit 39, it is possible to suppress fluctuations and variations in the injection pressure applied to each cavity from the start to the end of resin filling.

  FIG. 7 is a perspective view of a mold and an insert member of an optical element according to another modification of the present embodiment. In the insert member 30 of the present modification, a notch 34 as a sub-channel connected to each opening 31 is introduced into the notch 33 as a main channel extending between the openings 31 arranged in two rows. The angle is formed on the side away from the mouth. According to this modification, the filling can be completed more quickly by reducing the resistance when the resin flows from the main flow path to the sub flow path and increasing the flow velocity. The cutouts 34 as the sub flow paths do not need to be parallel to each other, and optimal filling can be performed by gradually changing the angle, the width (including the gate), and the like as proceeding to the back side of the main flow path. The air vent notch 36 has a circular shape close to the inner diameter of the opening 31.

  FIG. 8 is a perspective view of a mold and an insert member of an optical element according to another modification of the present embodiment. In this modification, two notches 33 as flow paths are formed so as to communicate with the openings 31 arranged in each row from the end of the insert member 30. The air vent notch 36 has a circular shape exceeding the inner diameter of the opening 31 and is formed at the end of the notch 33. According to this modification, since the resin introduced into the notch 33 proceeds only in one direction, the resistance at the time of filling decreases, and the filling can be completed earlier. In addition, since it is not necessary to provide a sub-channel and the notch for the air vent can be efficiently arranged at the end of the notch 33, the molding cavity can be arranged at a higher density, and a large number of optical elements can be provided without increasing the area of the dividing surface. A mold that can be molded at once can be applied.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate.

It is a perspective view of the metal mold | die and insert member of the optical element by 1st Embodiment. It is sectional drawing of the metal mold | die and insert member of an optical element in a shaping | molding state. It is the schematic which shows the process of shape | molding an optical element using the metal mold | die and insert member of this Embodiment. It is a perspective view of the metal mold | die and insert member of the optical element by 1st Embodiment. It is sectional drawing of the metal mold | die and insert member of an optical element in a shaping | molding state. It is a perspective view of the metal mold | die and insert member of the optical element concerning the modification of this Embodiment. It is a perspective view of the metal mold | die and insert member of the optical element concerning another modification of this Embodiment. It is a perspective view of the metal mold | die and insert member of the optical element concerning another modification of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Upper mold | type 11 Upper cavity 12 Pin hole 20 Lower mold | type 21 Lower cavity 22 Alignment pin 13 Large groove 14 Taper groove 15 Escape groove 26 Projection part 30 Insert member 33 Notch 34 Notch 35 Gate part 40 Hydraulic cylinder 41 Pressure sensor 42 Control apparatus 50 Heater OE optical element

Claims (7)

A step of interposing a plate-like insert member between an upper mold and a lower mold that are relatively moved to transfer and mold an optical element;
A step of pressing the upper member and the lower die with a predetermined pressing pressure while compressing the insert member; and
Injecting and curing a liquid resin into the cavities of the upper mold and the lower mold through a flow path formed in the insert member;
A step of relatively moving the upper mold and the lower mold away from each other after curing the resin,
An optical element formed by forming a notch in the insert member for allowing air pushed out by injecting liquid resin into the cavity of the upper mold and the lower mold to flow out of the cavity. Manufacturing method.   The method for manufacturing an optical element according to claim 1, wherein the resin is a thermosetting resin.   3. The method of manufacturing an optical element according to claim 1, wherein the divided surface of the upper mold and the lower mold is a plane other than a plane forming a cavity. The longitudinal elastic modulus of the insert member is E, the area where the insert member is in contact with the upper die or the lower die is S, the thickness of the insert member in the initial state is t, and the upper die and the lower die are given. Pressing pressure F, Ra (1) the surface roughness Ra of the contact surface with the insert member in the upper mold, Ra (2) the surface roughness Ra of the contact surface with the insert member in the lower mold, When the surface roughness Ra of the contact surface with the upper mold in the insert member is represented by Ra (3), and the surface roughness Ra of the contact surface with the lower mold of the insert member is represented by Ra (4),
F (1) = E × S × (Ra (1) + Ra (3)) / t (1)
F (2) = E × S × (Ra (2) + Ra (4)) / t (2)
F ≧ max (F (1), F (2)) (3)
The method for manufacturing an optical element according to claim 1, wherein the following condition is satisfied.
However, max (F (1), F (2)): The larger value of F (1) and F (2)   The optical element manufacturing method according to any one of claims 1 to 4, wherein a thickness of the insert member during compression is regulated by bringing a part of the upper mold and the lower mold into contact with each other. Method.   An insert member used in the method for manufacturing an optical element according to claim 1. An optical element manufactured by the method for manufacturing an optical element according to claim 1.

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