JP6091365B2 - Optical element manufacturing method and optical element manufacturing apparatus - Google Patents

Description

  The present invention relates to an optical element manufacturing method and manufacturing apparatus for manufacturing an optical element.

  Conventionally, a method of forming the outer peripheral surface of a lens into a rough surface by outer diameter centering by grinding has been performed. Thereby, when a part of the light incident on the lens becomes stray light and hits the outer peripheral surface, ghost and flare are prevented by irregular reflection on the rough surface.

FIG. 6A is a cross-sectional view showing a lens 200 whose outer peripheral surface is a ground surface 200a.
FIG. 6B is a cross-sectional view showing a lens 300 whose outer peripheral surface is a mirror surface 300a.

  As shown to FIG. 6A, when the outer peripheral surface of the lens 200 is the grinding surface 200a, the stray light L10 is scattered by irregular reflection in the grinding surface 200a (scattered light L11, L12, L13). Therefore, ghost and flare can be prevented.

  On the other hand, as shown in FIG. 6B, when the outer peripheral surface of the lens 300 is a mirror surface 300a, the stray light L20 is reflected on the ground surface 200a (reflected light L21). Therefore, the reflected light L21 causes ghost and flare.

  Therefore, from the viewpoint of preventing ghost and flare, it is desirable that the outer peripheral surface of the lens is a rough surface such as a ground surface 200a shown in FIG. 6A. However, recently, improvement in the accuracy of the lens outer diameter is required, and if a highly accurate outer diameter is formed by grinding, there is a problem that the cost becomes very high.

  In this respect, forming a highly accurate outer diameter by heating and softening the molding material to mold the optical element can be mass-produced at low cost because the accuracy of the outer diameter regulating member is transferred as it is. Moreover, it is also possible to shape | mold the optical element which has an uneven | corrugated outer peripheral surface by giving an unevenness | corrugation to this outer diameter control member (for example, refer patent document 1).

In addition, a method is known in which a stray light suppression region colored in gray is formed by irradiating ultraviolet rays outside the effective diameter of the optical element (see, for example, Patent Document 2).
In addition, although it is the marking method which marks a light transmissive material, the method of marking inside a light transmissive material with a laser beam is known (for example, refer patent document 3).

JP 2000-203852 A JP 2007-163551 A Japanese Patent No. 3208730

  As described above, the method of forming the concavo-convex outer peripheral surface on the optical element by the outer diameter regulating member forms the concavo-convex outer peripheral surface including the free surface by molding, so that the stray light cannot be sufficiently scattered, The harmful effects of stray light such as flare cannot be reliably prevented. In addition, if the outer diameter cannot be formed with high accuracy due to the irregularities on the outer peripheral surface, or if irregularities greater than the linear expansion difference between the optical element and the outer diameter regulating member are provided, the molded optical element will come off the outer circumference regulating member. The problem of disappearing occurs.

  Moreover, the method of forming the stray light suppression region colored in gray as described above may take a long time to form the stray light suppression region, or it may be difficult to sufficiently color depending on the material of the optical element. . Furthermore, since stray light cannot be scattered, it is not possible to reliably prevent harmful effects caused by stray light.

  Note that the outer diameter can be formed with high accuracy and low cost by leaving the outer peripheral surface as a mirror surface after molding without performing processing such as grinding on the outer peripheral surface of the optical element. However, in order to prevent harmful effects due to stray light, it is necessary to take measures such as applying a paint containing an additive to the outer peripheral surface. For example, the accuracy of the outer diameter deteriorates due to variations in the film thickness of the paint. .

  Note that the above-mentioned problems of the prior art occur not only in lenses but also in other optical elements such as prisms. Although the accuracy of the outer diameter has been described, the accuracy is similarly required for other external dimensions such as the length and width of one side when the optical element has a polygonal cylindrical shape.

  An object of the present invention is to provide an optical element manufacturing method and an optical element that can easily and reliably prevent harmful effects caused by stray light while forming the outer dimensions with high accuracy.

The method for manufacturing an optical element of the present invention is to heat and soften a molding material and mold the optical element, and maintain the outer dimensions of the optical element formed by molding so as not to fluctuate exceeding 5 μm. A scattering region creation step for creating a scattering region outside the effective diameter of the optical element, and in the molding step, a pair of molding dies and a cylindrical body positioned around the pair of molding dies The optical element is molded by a mold, and in the scattering region forming step, the scattering region is created on a free surface that is a non-contact portion between the pair of molding dies and the body mold.
According to another aspect of the present invention, there is provided a method for manufacturing an optical element, in which a molding material is heated and softened to mold the optical element, and an outer dimension of the optical element formed by the molding does not vary more than 5 μm. while maintaining, anda scattering region creation process for creation of the scattering region in the effective diameter of the optical element, wherein the scattering region creation step, irradiating the laser to the inside from the outer peripheral side of the optical element Then, by forming a crack or altered layer in the interior, creating the scattering region in the interior, by changing the depth of the position to form the scattering region in the thickness direction of the optical element, The scattering region is created discontinuously.

  According to the present invention, it is possible to easily and reliably prevent the harmful effects caused by stray light while forming the outer dimensions with high accuracy.

It is sectional drawing which shows the molding state of the optical element in 1st Embodiment of this invention. It is a front view for demonstrating creation of the scattering area | region in 1st Embodiment of this invention. It is a right view for demonstrating creation of the scattering area | region in 1st Embodiment of this invention. It is a front view for demonstrating creation of the scattering area | region in 2nd Embodiment of this invention. It is a right view for demonstrating creation of the scattering area | region in 2nd Embodiment of this invention. It is a front view for demonstrating creation of the scattering area | region in 3rd Embodiment of this invention. It is a right view for demonstrating creation of the scattering area | region in 3rd Embodiment of this invention. It is a front view for demonstrating creation of the scattering area | region in 4th Embodiment of this invention. It is a right view for demonstrating creation of the scattering area | region in 4th Embodiment of this invention. It is sectional drawing which shows the lens whose outer peripheral surface is a grinding surface. It is sectional drawing which shows the lens whose outer peripheral surface is a mirror surface.

<First Embodiment>
FIG. 1 is a cross-sectional view showing a molded state of the optical element 100 in the first embodiment of the present invention.
A mold set 10 shown in FIG. 1 includes an upper mold 11, a lower mold 12, and a trunk mold 13.

The upper mold 11 has a substantially cylindrical shape, and a convex molding surface 11a is formed on the bottom surface.
The lower mold 12 has a substantially cylindrical shape, and a planar molding surface 12a is formed on the upper surface.
The upper mold 11 and the lower mold 12 are an example of a pair of molds, and the above shape is merely an example.

The trunk mold 13 has a cylindrical shape and is located around the upper mold 11 and the lower mold 12. An inner peripheral molding surface 13 a is formed on the inner periphery of the trunk mold 13.
The upper mold 11 is pressed downward by a pressing means (not shown), and slides in the body mold 13 to pressurize the optical element 100.

  The optical element 100 is obtained by pressing and molding through the mold set 10 (for example, the upper mold 11) in a state where the molding material is heated and softened by heat conduction from the mold set 10, for example (molding process). The optical element 100 is a lens, for example. The molding material is preferably glass.

  The outer diameter E formed by molding the optical element 100 shown in FIGS. 2A and 2B is substantially maintained even after a scattering region creation process described later. Therefore, the outer diameter E of the optical element 100 may be formed to a desired dimension in the molding process.

  Note that the optical element 100 is cooled to a temperature equal to or lower than the glass transition point, for example, before the scattering region creation process described later. Therefore, the molding process includes a heating process for heating the molding material, a pressurizing process for pressurizing the heated molding material, and a cooling process for cooling the pressurized molding material.

  The optical element 100 has its upper molding surface 100b, lower molding surface 100c, and outer peripheral molding surface 100d formed by transferring shapes from the upper mold 11, the lower mold 12, and the body mold 13. Since the shape is transferred from the convex molding surface 11a to the upper molding surface 100b, a concave portion 100b-1 is formed at the center. The shape of the optical element 100 is, for example, a disk shape or a cylindrical shape, but may be other shapes such as a polygonal prism shape.

  The effective diameter 100a of the optical element 100 is a portion (optical functional surface) that exhibits optical characteristics, and is, for example, a portion that is narrower in plan view than the concave portion 100b-1 of the upper molding surface 100b. Although details will be described later, in the present embodiment, as an example of the outside of the effective diameter 100a, a scattering region 100f is created in a region outside the recess 100b-1.

  The optical element 100 is not in contact with the upper mold 11, the lower mold 12, and the body mold 13, that is, between the upper molding surface 100b and the outer peripheral molding surface 100d and between the lower molding surface 100c and the outer peripheral molding surface 100d. Is the free surface 100e. This free surface 100e becomes a mirror surface, for example.

  Next, a scattering region creation process for creating the scattering region 100f outside the effective diameter 100a of the optical element 100 while substantially maintaining the outer diameter E of the optical element 100 formed by molding will be described. The outer diameter E is an example of outer dimensions, and other outer dimensions include dimensions such as the length and width of one side when the optical element 100 has a polygonal cylindrical shape.

2A and 2B are a front view and a right side view for explaining the creation of the scattering region 100f in the first embodiment.
As shown in FIGS. 2A and 2B, the optical element 100 is rotated by the rotation holding units 21 and 22 being rotated by the pair of rotation holding units 21 and 22 (arrow D2).

The laser irradiation unit 23 irradiates the optical element 100 with the laser L via the condenser lens 23a. The laser irradiation unit 23 is movable in the thickness direction of the optical element 100 (arrow D1).
In this embodiment, the laser irradiation part 23 irradiates the laser L to the outer peripheral molding surface 100d that is the outer peripheral surface of the optical element 100 and the free surface 100e as an example of a portion outside the effective diameter 100a.

  Thereby, a scattering region 100f which is a crack or a deteriorated layer is created by laser marking on the outer peripheral molding surface 100d and the free surface 100e of the optical element 100. Note that the scattering region 100f may be created only on one of the outer peripheral molding surface 100d and the free surface 100e. Moreover, you may create the scattering area | region 100f only in a part in the outer periphery molded surface 100d and the free surface 100e.

  The scattering region 100f is created while substantially maintaining the outer diameter E of the optical element 100 formed by the molding process. The case where the outer diameter E of the optical element 100 is substantially maintained is a case where the outer diameter E of the optical element 100 does not fluctuate, for example, exceeding 5 μm even after the scattering region creation step.

  In the case where a rough surface is formed on the outer peripheral surface of the optical element 100 by grinding as in the prior art, it is difficult to perform processing so as not to fluctuate beyond 5 μm, which is a cause of cost increase in normal processing.

  The laser irradiation unit 23 creates a scattering region 100f for one circumference of the optical element 100 and then moves in the thickness direction (arrow D1) to create the scattering region 100f for one circumference of the optical element 100 again. It is good to repeat the operation of live. However, the scattering region 100f may be created while finely moving the laser irradiation unit 23 in the thickness direction (arrow D1) and rotating the optical element 100. Further, the laser irradiation unit 23 may be rotated around the optical element 100 without rotating the optical element 100.

  When the laser L is an ultrashort pulse laser such as a femtosecond laser, a cracked layer does not occur in the scattering region 100f because a deteriorated layer is formed in a short time before heat is transmitted. However, since the scattering region 100f is created outside the effective diameter 100a, even if it is a crack, if the size is small, there is often no problem.

  In the first embodiment described above, the manufacturing method of the optical element 100 includes a molding process in which the molding material is heated and softened to mold the optical element 100, and the outer diameter E (outside dimension of the optical element 100 formed by molding). A scattering region creation step of creating a scattering region 100f outside the effective diameter 100a of the optical element 100 while substantially maintaining one example).

  Therefore, the scattering region 100f can be created without deteriorating the accuracy of the outer diameter E as in the case of forming a rough surface during grinding or molding. In addition, by creating the scattering region 100f, the scattering region 100f can prevent harmful effects caused by stray light such as ghosts and flares without taking as much time as in the case where a colored portion is formed inside the optical element 100 as in the prior art. Can be prevented.

  Therefore, according to the present embodiment, it is possible to easily and reliably prevent the harmful effects caused by stray light while forming the outer diameter E with high accuracy.

  Further, in the present embodiment, the outer peripheral molding surface 100d which is the outer peripheral surface of the optical element 100 is irradiated with the laser L, and a crack or an altered layer is formed on the outer peripheral molding surface 100d, whereby the scattering region 100f is formed on the outer peripheral molding surface 100d. Created.

  Therefore, since the scattering region 100f can be created by irradiating the outer peripheral molding surface 100d with the laser L, adverse effects due to stray light can be easily prevented.

  In the present embodiment, the scattering surface 100f is created on the free surface 100e by irradiating the free surface 100e of the optical element 100 with the laser L and forming a crack or an altered layer on the free surface 100e.

  By the way, it has been found that in the optical element 100 obtained only by molding without centering, for example, internal reflection on the free surface 100e which is a mirror surface is a major cause of adverse effects such as ghosts and flares. Therefore, by creating the scattering region 100f on the free surface 100e, it is possible to easily and reliably prevent harmful effects caused by stray light.

Second Embodiment
This embodiment is different from the first embodiment in that the position of the scattering region 100g is located inside the optical element 100, and the others are the same. Therefore, detailed description is omitted.

3A and 3B are a front view and a right side view for explaining creation of the scattering region 100g in the second embodiment.
Also in this embodiment, as shown in FIGS. 3A and 3B, the optical element 100 is rotated by rotating these rotation holding portions 21 and 22 while being held by the pair of rotation holding portions 21 and 22. (Arrow D2). Also in the present embodiment, the laser irradiation unit 23 is movable in the thickness direction of the optical element 100 (arrow D1).

  In the present embodiment, the laser irradiation unit 23 irradiates the laser L inside the effective diameter 100 a of the optical element 100. As a result, a scattering region 100g which is a crack or an altered layer is created inside the optical element 100.

Since the scattering region 100g is created inside the optical element 100, the outer diameter E is maintained (substantially maintained) unchanged from that formed by the molding process.
Also in the present embodiment, the laser irradiation unit 23 creates the scattering region 100f on the outer circumference of the optical element 100, moves in the thickness direction (arrow D1), and then again on the outer circumference of the optical element 100. The operation of creating the scattering region 100f may be repeated. Thereby, the scattering region 100g is created in a cylindrical shape inside the optical element 100.

  If a scattering region 100g that is a crack is created across the upper molding surface 100b and the lower molding surface 100c of the optical element 100, the optical element 100 may be missing or missing. Therefore, it is preferable that both ends of the scattering region 100g are positioned with a space between the upper molding surface 100b and the lower molding surface 100c so as not to be exposed to the outside.

Also, the internal scattering region 100g is preferably created between the light incident side to the optical element 100 and the free surface 100e so that stray light does not easily reach the free surface 100e.
Further, the laser irradiation unit 23 may irradiate the laser L in the thickness direction (arrow D1) from the upper molding surface 100b side or the lower molding surface 100c side of the optical element 100, but in that case, the thickness direction (arrow D1) If the scattering region 100g is not created from the back to the front, the previously created scattering region 100g inhibits the creation of the scattering region 100g.

  Also in the second embodiment described above, the method of manufacturing the optical element 100 includes a molding step of heating and softening a molding material to mold the optical element 100, and an outer diameter E (outer dimension) of the optical element 100 formed by molding. 1) is substantially maintained, and a scattering region creation step for creating a scattering region 100g outside the effective diameter 100a of the optical element 100 is included. Therefore, stray light is formed while forming the outer diameter E with high accuracy. It is possible to easily and reliably prevent the harmful effects caused by.

In this embodiment, the scattering region 100g is created inside by irradiating the inside of the optical element 100 with the laser L and forming a crack or an altered layer inside.
Therefore, compared to the case where the scattering region 100f is created on the outer peripheral surface like the outer peripheral molding surface 100d and the free surface 100e of the first embodiment, the creation of the scattering region 100g does not affect the outer diameter. Stray light can be reliably scattered, for example, by forming large cracks or altered layers.

<Third Embodiment>
In the present embodiment, the laser L is irradiated to the inside of the optical element 100 from the outer peripheral side (the outer peripheral molding surface 100d side or the free surface 100e side) of the optical element 100. In addition, the scattering regions 100h-1, 100h-2, 100h-3 are changed in the thickness direction (arrow D1) of the optical element 100 to change the scattering regions 100h-1, 100h-2, 100h-3. -3 is created discontinuously. In the present embodiment, these are different from the first embodiment and the second embodiment, and the others are the same. Therefore, detailed description is omitted.

4A and 4B are a front view and a right side view for explaining creation of the scattering regions 100h-1, 100h-2, and 100h-3 in the third embodiment.
Also in the present embodiment, as shown in FIGS. 4A and 4B, the optical element 100 is rotated by rotating the rotation holding units 21 and 22 while being held by the pair of rotation holding units 21 and 22. (Arrow D2). Also in the present embodiment, the laser irradiation unit 23 is movable in the thickness direction of the optical element 100 (arrow D1).

  In the present embodiment, the laser irradiation unit 23 irradiates the inside of the optical element 100 with the laser L from the outer peripheral side (the outer peripheral molding surface 100d or the free surface 100e) of the optical element 100. Moreover, the laser irradiation part 23 changes the focus position of the laser L, and changes the depth of the position which forms scattering region 100h-1,100h-2,100h-3 to the thickness direction (arrow D1) of the optical element 100. Change in. Thereby, inside the optical element 100, a plurality of scattering regions 100h-1, 100h-2, 100h-3, which are cracks or altered layers, are created discontinuously.

  As in the second embodiment, since the scattering regions 100h-1, 100h-2, and 100h-3 are created inside the optical element 100, the outer diameter E is not changed from that formed by the molding process. Maintained (substantially maintained).

  Also in the present embodiment, the laser irradiation unit 23 creates the scattering region 100f on the outer circumference of the optical element 100, moves in the thickness direction (arrow D1), and then again on the outer circumference of the optical element 100. The operation of creating the scattering region 100f may be repeated. Further, by changing the focal position of the laser L by the laser irradiation unit 23 at least once, the depth of the position where the scattering regions 100h-1, 100h-2, and 100h-3 are formed as described above is changed to the optical element 100. It is good to change in the thickness direction (arrow D1).

  Also in the third embodiment described above, the manufacturing method of the optical element 100 includes a molding process in which the molding material is heated and softened to mold the optical element 100, and the outer diameter E (outer dimension) of the optical element 100 formed by molding. 1) is substantially maintained, and the scattering region creation step of creating the scattering regions 100h-1, 100h-2, 100h-3 outside the effective diameter 100a of the optical element 100 is provided. While forming E with high accuracy, it is possible to easily and reliably prevent harmful effects caused by stray light.

  In the present embodiment, the laser element L is irradiated into the optical element 100 from the outer peripheral side (the outer peripheral molding surface 100d side or the free surface 100e side) of the optical element 100, and the scattering regions 100h-1, 100h-2, 100h- 3 is changed in the thickness direction (arrow D1) of the optical element 100, the scattering area optical elements 100h-1, 100h-2, 100h-3 are created discontinuously. .

  Therefore, as in the second embodiment, the creation of the scattering region 100g does not affect the outer diameter, and therefore, stray light can be reliably scattered by forming large cracks or altered layers. Furthermore, it is possible to prevent the optical element 100 from being missing or missing due to the continuous scattering regions 100h-1, 100h-2, and 100h-3 inside the optical element 100.

<Fourth embodiment>
This embodiment is different from the first embodiment in creating the scattering region 100i by etching, and the others are the same. Therefore, detailed description is omitted.

5A and 5B are a front view and a right side view for explaining creation of the scattering region 100i in the fourth embodiment.
Also in the present embodiment, as shown in FIGS. 4A and 4B, the optical element 100 is rotated by rotating the rotation holding units 21 and 22 while being held by the pair of rotation holding units 21 and 22. (Arrow D2).

  In the present embodiment, as an example, the scattering region 100 i is created on the free surface 100 e by applying fluoride using the etching pen 24. Since the scattering region 100i only needs to be created outside the effective diameter 100a, the scattering region 100i may be created also on the outer peripheral molding surface 100d, or the scattering region 100i is created only on the outer peripheral molding surface 100d. Also good. Further, the etching pen 24 may be operated by a human hand or moved automatically.

  The scattering region 100i is created while substantially maintaining the outer diameter E of the optical element 100 formed by the molding process. As described in the first embodiment, the case where the outer diameter E of the optical element 100 is substantially maintained means that the outer diameter E of the optical element 100 does not fluctuate, for example, exceeding 5 μm even after the scattering region creation step. Is the case.

  In the present embodiment, after the scattering region 100i is created on the outer circumference of the optical element 100, the etching pen 24 is moved in the thickness direction (arrow D1), and the scattering area is again placed on the outer circumference of the optical element 100. The operation of creating 100i may be repeated.

  In order to create the scattering region 100i, instead of chemical wet etching using fluoride, other etching using a plasma ion beam or the like may be used. Alternatively, if the outer diameter E of the optical element 100 is substantially maintained, the scattering region 100i can be created without using the laser L of the first to third embodiments described above or the etching of the present embodiment. Good.

  Also in the fourth embodiment described above, the manufacturing method of the optical element 100 includes the molding step of heating and softening the molding material to mold the optical element 100, and the outer diameter E (outer dimension) of the optical element 100 formed by molding. 1) is substantially maintained, and a scattering region creation step for creating the scattering region 100i outside the effective diameter 100a of the optical element 100 is included. Therefore, stray light is formed while forming the outer diameter E with high accuracy. It is possible to easily and reliably prevent the harmful effects caused by.

  In the present embodiment, since the scattering region 100i is created by etching, it is possible to easily prevent the harmful effects caused by stray light. Furthermore, by creating the scattering region 100i by other methods such as etching other than the laser L, the creation method of the scattering region 100i can be determined according to the material of the optical element 100, the manufacturing equipment, and the like.

  In addition, according to the above-described first to fourth embodiments, the outer dimension (outer diameter E) can be formed with high accuracy, but it is 1 to form the scattering region while substantially maintaining the outer diameter. For example, the effects of the first to fourth embodiments can be obtained without forming a mirror surface having no fine irregularities on the outer peripheral surface at the molding stage. For this reason, the outer diameter in the molding process is preferably as high as possible, but is not particularly limited as long as it is appropriately determined with necessary precision.

10 Mold Set 11 Upper Mold 11a Convex Molded Surface 12 Lower Mold 12a Planar Molded Surface 13 Body Mold 13a Inner Peripheral Molded Surface 21 Rotation Holding Unit 22 Rotation Holding Unit 23 Laser Irradiation Unit 23a Condensing Lens 24 Etching Pen 100 Optical Element (Molding material)
100a Effective diameter 100b Upper molding surface 100b-1 Recessed portion 100c Lower molding surface 100d Outer peripheral molding surface 100e Free surface 100f Scattering region 100g Scattering region 100h-1 Scattering region 100h-2 Scattering region 100h-3 Scattering region 100i Scattering region

Claims (3)

A molding process for heating and softening the molding material and molding the optical element;
A scattering region creation step of creating a scattering region outside the effective diameter of the optical element, while maintaining the outer dimensions of the optical element formed by molding so as not to fluctuate more than 5 μm ,
In the molding step, the optical element is molded with a pair of molding dies and a cylindrical body mold positioned around the pair of molding dies,
In the scattering region forming step, the scattering region is created on a free surface that is a non-contact portion between the pair of molding dies and the body die among the optical elements.   2. The scattering region creation step creates the scattering region on the outer peripheral surface by irradiating the outer peripheral surface of the optical element with a laser and forming a crack or a deteriorated layer on the outer peripheral surface. Of manufacturing the optical element. A molding process for heating and softening the molding material and molding the optical element;
A scattering region creation step of creating a scattering region outside the effective diameter of the optical element, while maintaining the outer dimensions of the optical element formed by molding so as not to fluctuate more than 5 μm ,
In the scattering region creation step, a laser is irradiated from the outer peripheral side of the optical element to the inside, and a crack or an altered layer is formed in the inside, thereby creating the scattering region in the inside, and A method for manufacturing an optical element, wherein the scattering region is created discontinuously by changing a depth of a position to be formed in a thickness direction of the optical element.

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