WO2005111668A1 - Optical member, imaging device using optical member, and method of producing optical member - Google Patents

Optical member, imaging device using optical member, and method of producing optical member Download PDF

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Publication number
WO2005111668A1
WO2005111668A1 PCT/JP2005/008868 JP2005008868W WO2005111668A1 WO 2005111668 A1 WO2005111668 A1 WO 2005111668A1 JP 2005008868 W JP2005008868 W JP 2005008868W WO 2005111668 A1 WO2005111668 A1 WO 2005111668A1
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WO
WIPO (PCT)
Prior art keywords
optical member
shape
optical
light
imaging device
Prior art date
Application number
PCT/JP2005/008868
Other languages
French (fr)
Japanese (ja)
Inventor
Yoshiharu Yamamoto
Motonobu Yoshikawa
Yasuhiro Tanaka
Katsuhiko Hayashi
Makoto Umetani
Original Assignee
Matsushita Electric Industrial Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co., Ltd. filed Critical Matsushita Electric Industrial Co., Ltd.
Publication of WO2005111668A1 publication Critical patent/WO2005111668A1/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
    • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
    • B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
    • B29C59/043—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts for profiled articles
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2011/00—Optical elements, e.g. lenses, prisms
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/0262—Constructional arrangements for removing stray light

Definitions

  • optical member imaging device using optical member, and method of manufacturing optical member
  • the present invention relates to an imaging device for capturing a wide angle of view, and more specifically, to an optical member and an optical member in an omnidirectional imaging device that captures an image reflected by a reflection mirror.
  • the present invention relates to an imaging device used and a method for manufacturing an optical member.
  • image input devices capable of inputting a wide range of visual information have been studied! These are expected to be applied to mobile robots, monitoring devices, and the like. Among them, image input devices capable of acquiring a large amount of visual information at a time are being studied.
  • FIG. 8 is a schematic diagram showing the configuration of the omnidirectional imaging device described in Patent Document 1.
  • the omnidirectional imaging device 20 includes a glass tubular body 23, a lens 24, and an image sensor 25.
  • the cylindrical body 23 is formed by integrally molding one end 21 having a quadratic curved surface shape and the other end 22 obtained by hollowing out a cylindrical partial force truncated cone.
  • the inner surfaces of the one end 21 and the other end 22 are each mirror-finished.
  • the cylindrical body 23 is configured such that the ceiling position of the hollowed portion of the other end 22 is equal to the focal position of the quadratic curved surface of the one end 21, and a lens 24 is installed at that position.
  • an image sensor 25 is provided further on the other end side than the lens 24.
  • the lens 24 focuses the incident light on the image sensor 25.
  • the imaging element 25 is a CCD (Charge Coupled Device), and converts an optical image formed by the lens 24 into an electric signal.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2002-244236
  • the omnidirectional imaging device 20 described in Patent Document 1 most of the light reflected on the inner surface of the other end portion 22 shaped like a truncated cone is converted into one end shaped like a quadratic surface. Light is incident in the direction of 21. In some cases, a part of the light reflected at the other end 22 may enter the inner peripheral surface of the side surface 26. Therefore, the light reflected on the side surface 26 of the cylindrical body 23 (hereinafter, referred to as the inner surface reflected light) is reflected on the one end 21 and then further enters the lens 24. Such internally reflected light enters the image sensor 25 as noise. As described above, the omnidirectional imaging device 20 described in Patent Document 1 may not be able to obtain high-quality imaging results.o
  • Another object of the present invention is to provide a method for manufacturing an optical member in which an antireflection structure is formed on a curved surface including a cylindrical shape.
  • optical member having the following configuration.
  • Imaging light that includes a condensing optical system that condenses incident light to form an optical image and an imaging device that converts an optical image formed by the condensing optical system into an electric image signal and outputs the same.
  • An anti-reflection structure that is periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among light incident on a structural unit having a predetermined shape is an inner peripheral surface of a side surface of an optical member. Prepare for.
  • the antireflection structure is formed on the inner peripheral surface of the cylindrical optical member.
  • the antireflection structure is formed on the inner peripheral surface of the cylindrical optical member.
  • the anti-reflection structure comprises:
  • the optical member is formed integrally on the inner peripheral surface with a sheet having a transparent material strength.
  • the antireflection structure is formed on the inner peripheral surface of the cylindrical optical member, it is possible to prevent the generation of reflected light on the inner surface and obtain a high-quality omnidirectional image. Further, by using the sheet, the antireflection structure can be easily formed on the optical member including the curved surface.
  • At least the side surface of the optical member also has a transparent material strength.
  • the optical member further includes a reflecting mirror having a curved reflecting surface at least at one end of the optical member having a cylindrical shape.
  • the condensing optical system receives the light reflected by the reflection mirror and forms an optical image.
  • the structural unit of the antireflection structure has a height of at least the pitch.
  • the structural unit of the antireflection structure has a substantially conical protruding shape and a Z or substantially conical depressed shape. It is.
  • the structural unit of the antireflection structure has a protruding shape selected from any of a substantially circular shape, a substantially rectangular shape, and a substantially regular hexagonal shape, and a Z or depression shape.
  • the difference between the refractive index of the sheet and the optical member with respect to the shortest wavelength is 0.2 or less.
  • the difference of the refractive index of the sheet and the optical member with respect to the shortest wavelength is 0.1 or less.
  • the object of the present invention is achieved by an imaging device having the following configuration.
  • An imaging device capable of outputting an optical image of a subject as an electric image signal, comprising: a reflecting mirror having a curved reflecting surface; A condensing optical system that receives the light reflected by the reflecting surface and forms an optical image, and an imaging device that converts the optical image formed by the condensing optical system into an electrical image signal and outputs the signal.
  • An anti-reflection structure that is periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among light incident on a structural unit having a predetermined shape is an inner peripheral surface of a side surface of an optical member. Prepare for.
  • the object of the present invention is achieved by the following production method.
  • Optical member having a cylindrical shape provided with antireflection structures periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among the light incident on the structural unit having a predetermined shape.
  • the optical member on which the reflection structure is formed can be manufactured at low cost and in large quantities.
  • the mold is
  • the anti-reflection structure is a cylindrical mold having an inverted shape on the outer peripheral surface, the first step is:
  • V Transfer the shape to the inner peripheral surface of the optical member.
  • the antireflection structure can be easily formed even on a member having a curved surface such as a cylindrical shape formed only by a planar optical member.
  • the transfer surface of the mold has a substantially cone-shaped protruding shape and a Z or substantially cone-shaped depressed shape in the structural unit.
  • the present invention it is possible to prevent the occurrence of light reflected on the inner surface of the optical member, and to improve the quality of It is possible to provide an optical member capable of obtaining a positional image and an imaging device provided with the optical member.
  • an optical member in which an antireflection structure is formed on a curved surface including a cylindrical shape.
  • FIG. 1 is a schematic cross-sectional view illustrating a configuration of an imaging device according to a first embodiment of the present invention.
  • FIG. 2 is a schematic perspective view showing a configuration of an imaging device according to the first embodiment of the present invention.
  • FIG. 3 is a schematic perspective view showing, on an enlarged scale, an anti-reflection structure constituting an optical member used in the imaging device according to the first embodiment of the present invention.
  • FIG. 4 is a schematic perspective view showing a method for manufacturing an optical member used for the imaging device according to the first embodiment of the present invention.
  • FIG. 5A is a schematic perspective view showing, in an enlarged manner, another example of an anti-reflection structure constituting an optical member used in the imaging device according to the first embodiment of the present invention.
  • FIG. 5B is a schematic perspective view showing, in an enlarged manner, another example of the antireflection structure constituting the optical member used in the imaging device according to the first embodiment of the present invention.
  • FIG. 5C is a schematic perspective view showing, in an enlarged manner, another example of an anti-reflection structure constituting an optical member used in the imaging device according to the first embodiment of the present invention.
  • FIG. 5D is a schematic perspective view showing another example of the antireflection structure constituting the optical member used in the imaging device according to the first embodiment of the present invention in an enlarged manner.
  • FIG. 5E is an enlarged schematic perspective view showing another example of the antireflection structure constituting the optical member used in the imaging device according to the first embodiment of the present invention.
  • FIG. 6 is a schematic sectional view showing an imaging device according to a second embodiment of the present invention.
  • FIG. 7 is a schematic view showing a sheet manufacturing method according to a second embodiment of the present invention.
  • FIG. 8 is a schematic cross-sectional view showing a configuration of an omnidirectional imaging device according to a conventional technique. Explanation of reference numerals [0028] 1, 11 imaging device
  • FIG. 1 is a schematic cross-sectional view showing an imaging device according to a first embodiment of the present invention
  • FIG. 2 is a schematic perspective view of the imaging device
  • FIG. 3 is used for the imaging device according to the first embodiment of the present invention.
  • FIG. 3 is an enlarged perspective view showing an anti-reflection structure constituting an optical member.
  • the imaging apparatus 1 according to the present embodiment is mainly configured by an imaging optical unit 4 and an optical member 5.
  • the imaging optical unit 4 includes the light-collecting optical system 2 and the imaging device 3.
  • the focusing optical system 2 includes a lens and forms an optical image of a subject on the image sensor 3.
  • the image pickup device 3 is a CCD (Charge Coupled Device), and converts an optical image formed by the condensing optical system 2 into an electric signal.
  • the image sensor 3 may be a CMOS (Complementary Metal-Oxide Semiconductor) sensor or a MOS image sensor!
  • the optical member 5 is a cylindrical member having a transparent material strength. At one end of the optical member 5, an imaging optical unit 4 is provided, and a second mirror 7 that surrounds the imaging optical unit 4 and has a convex mirror power is provided. The other end of the optical member 5 is provided with a first mirror 16 having a concave mirror power. The second mirror 7 is transmitted through the side surface of the optical member 5 and incident from the outside. Light is reflected in the direction of the first mirror 6. On the other hand, the first mirror 6 causes the light reflected from the second mirror 7 to enter the condensing optical system 2.
  • the optical member 5 has a length along the central axis of 30 mm, an inner diameter of 20 mm, and a wall thickness of 2 mm. It is made of a transparent material such as terephthalate resin.
  • An anti-reflection structure is a structure in which structural units having a predetermined shape are periodically arrayed at a pitch smaller than the lower limit of the wavelength of light that contributes to imaging of incident light, that is, at a pitch smaller than the shortest wavelength of imaging light. They are arranged in a shape.
  • the anti-reflection structure formed on the inner peripheral surface of the optical member means a member having a fine structure formed on the surface in order to prevent reflection of light whose reflection is to be reduced. This includes not only an embodiment in which the light to be reduced is not completely reflected but also an embodiment having an effect of preventing reflection of light whose reflection at a predetermined wavelength should be reduced.
  • a conical protrusion having a height H is used as a structural unit, and these conical protrusions are periodically arranged at a pitch P. Structures that are typically arranged in an array.
  • the anti-reflection structure 8 in the present embodiment has a conical shape with a pitch P of 0.15 m ⁇ a height H of 0.15 / z m.
  • the pitch P means the pitch in the densest arrangement direction when the antireflection structure is composed of a two-dimensional arrangement of a large number of microstructure units.
  • the pitch P of the structural units is substantially substantially constant in one array direction in the antireflection structure, and may be smaller than the shortest wavelength of light that contributes to imaging among incident light.
  • the strong pitch P is preferably 1Z2 or less, more preferably 1Z3 or less, which is the shortest wavelength of the imaging light.
  • the height H of the structural unit is not particularly limited. Although the height H is not necessarily constant, the higher the force H, the better the antireflection function against incident light. Accordingly, the height H is at least the pitch P or more (the minimum structural unit height is the pitch or more), and is at least three times or more the pitch P (the minimum structural unit height is three or more times the pitch). U, which is preferred. In consideration of the manufacturability of the anti-reflection structure as described later, it is desirable that the height H is not larger than a certain level. The maximum height of the structural unit is preferably about 5 times or less the pitch).
  • the anti-reflection film 9 for preventing reflection of incident light is formed on the outer peripheral surface of the cylindrical optical member 5.
  • the anti-reflection film 9 is a dielectric multilayer film made of a dielectric material such as magnesium fluoride and aluminum oxide. As a result, sufficient imaging light can be taken into the optical member 5.
  • the imaging device 1 As shown in FIG. 1, light at 360 ° around the imaging device 1 passes through the side surface of the optical member 5 and enters the inside. The light that has entered the inside of the optical member 5 is reflected by the second mirror 7. In the second mirror 7, most of the reflected light is directed toward the first mirror 6 due to its curved surface shape. The light reflected by the first mirror 6 is incident on the condenser optical system 2 of the imaging optical unit 4 and is focused on the imaging device 3. Thus, an image of 360 ° around the image pickup device 1 can be obtained by the image pickup device 3.
  • the light from the circumferential direction of the imaging device 1 includes an ultraviolet band wavelength (150 ⁇ !
  • a visible band wavelength 400 ⁇ ! To 700 nm
  • a near-infrared band wavelength 700 ⁇ ! To 2 ⁇ m
  • the peripheral light incident on the imaging device 1 with a force other than the effective angle of view is reflected by the second mirror 7, does not directly enter the first mirror 6, but remains inside the optical member 5. It may be incident on the peripheral surface.
  • the light incident on the inner peripheral surface of the cylindrical shape as described above enters the condensing optical system as internally reflected light, and generates noise that causes flare and ghost. I was letting it. Therefore, in the imaging device 1 according to the present embodiment, by forming the anti-reflection structure 8 on the inner peripheral surface of the optical member 5, it is possible to prevent the generation of reflected light on the inner surface. Therefore, the imaging device 1 according to the present embodiment has an anti-reflection structure.
  • the body 8 can reduce noise components and obtain high-quality omnidirectional images.
  • the optical member 5 included in the imaging device 1 according to the present embodiment can be manufactured, for example, as follows. That is, as shown in FIG. 4, the optical member 5 can be obtained by a method of transferring a cylindrical mold having a shape inverted from the anti-reflection structure 8 to the optical member 5.
  • the cylindrical mold 10 is nickel-coated on its surface, and also has a special steel force for a mold having a smaller diameter than the optical member 5.
  • a shape having a structure in which conical depressions are periodically arranged in an array at a pitch P is formed on the outer peripheral surface of the cylindrical mold 10 (first step).
  • the cylindrical mold 10 is installed such that the outer peripheral surface having a shape inverted from the anti-reflection structure 8 is in contact with the inner peripheral surface of the optical member 5. Then, by pressing the cylindrical mold 10 against the inner surface of the optical member 5, the antireflection structure 8 is transferred to the inner peripheral surface of the optical member 5. Furthermore, the antireflection structure 8 can be transferred onto the entire inner peripheral surface of the optical member 5 by simultaneously rotating the cylindrical mold 10 while heating and pressing (second step).
  • the inner peripheral surface of the optical member 5 made of acrylic resin with a length along the central axis of 30 mm, an inner diameter of 2 Omm, and a wall thickness of 2 mm is used to prevent reflection.
  • the heating temperature be 100 ° C to 130 ° C and the pressing force be about 980N.
  • the imaging device since the imaging device according to the present embodiment includes the antireflection structure on the inner peripheral surface of the cylindrical optical member, it prevents incident light from being reflected on the inner peripheral surface. Therefore, a high-quality omnidirectional image with reduced noise components can be obtained.
  • a transfer method using a cylindrical mold having a shape inverted from that of the anti-reflection structure allows only a planar optical member to be used.
  • An antireflection structure can be easily formed on an optical member having a curved surface such as a cylindrical shape.
  • a force using a conical structure as the antireflection structure is not necessarily limited to the structure having such a shape.
  • the structural unit may be a pyramid-shaped structure such as a regular hexagonal pyramid or a quadrangular pyramid.
  • the shape of the strong structural unit is not necessarily limited to a cone. However, even if it is a bell shape with a rounded tip as shown in Figs. 5B and 5C, it may have a frustum shape such as a truncated cone shape as shown in Fig. 5D or a truncated pyramid shape as shown in Fig. 5E. May be.
  • each structural unit does not need to have a strict geometric shape, and may be substantially a cone, a bell, a truncated cone, or the like.
  • the antireflection structure should be at least a pitch smaller than the shortest wavelength in the wavelength region where the image sensor has sensitivity.
  • the antireflection structure is formed on the entire inner peripheral surface of the optical member, but is not limited to this.
  • the anti-reflection structure may be formed only in a half area on the imaging device side of the inner peripheral surface of the optical member.
  • the first and second mirrors and the force formed as a member separate from the cylindrical optical member are not necessarily limited to this configuration.
  • an optical member in which an optical member and a first or second mirror are formed in a body may be used.
  • the imaging device includes an antireflection film made of a dielectric material on the outer peripheral surface of the optical member, but is not limited to this. If sufficient imaging light can be taken into the optical member, it is not always necessary to form an antireflection film.
  • the method for manufacturing an optical member according to the present embodiment has been used for manufacturing an optical member made of a transparent material, the present invention is not limited to this.
  • the above-described manufacturing method can also be used for members having a material strength other than transparent, such as a black material.
  • the mold has a depressed shape having an inverted shape of the antireflection structure, but may have a protruded shape.
  • FIG. 6 is a schematic cross-sectional view illustrating a configuration of an imaging device according to the second embodiment of the present invention.
  • the imaging device according to the second embodiment has substantially the same configuration as the imaging device according to the first embodiment, but differs in the following points. That is, the imaging device 11 according to the present embodiment includes the sheet 12 on the inner peripheral surface of the cylindrical optical member 5.
  • the same reference numerals as those in the first embodiment denote the same components. Hereinafter, differences from the first embodiment will be described. Will be described.
  • the sheet 12 formed on the inner peripheral surface of the optical member 5 is made of a transparent material such as acrylic resin, polyester resin, polycarbonate resin, cycloolefin resin, polyethylene terephthalate resin, and the like.
  • An anti-reflection structure 8 is formed.
  • the antireflection structure 8 has a cone shape with a pitch of 0.15 / ⁇ and a height of 0.15 m, and apparently has a continuous refractive index with respect to incident light.
  • the thickness of the sheet 12 including the antireflection structure 8 is 0.05 mm.
  • the sheet 12 on which the antireflection structure 8 is formed is attached to the inner peripheral surface of the cylindrical optical member 5.
  • the optical member 5 and the sheet 12 can be bonded by heat or photo-curing resin. Accordingly, the peripheral light incident on the imaging device 11 from other than the effective angle of view is reflected by the second mirror 7 and then does not directly enter the first mirror 6 but enters the inner peripheral surface of the optical member 5. Even in such a case, it is possible to prevent the generation of the internally reflected light.
  • the difference between the refractive indices of the sheet 12 and the optical member 5 is desirably 0.2 or less.
  • the difference in the refractive index is desirably 0.2 or less.
  • the difference in the refractive index between the sheet 12 and the optical member 5 be 0.1 or less. This makes it possible to further reduce the reflection occurring at the interface between the sheet 12 and the optical member 5, and to efficiently suppress the generation of stray light.
  • an acrylic resin having a refractive index of 1.491 is used for the optical member 5
  • a polyester resin having a refractive index of 1.607 is used for the sheet 12
  • OKP4 trade name, manufactured by Osaka Gas Chemical Co., Ltd.
  • the difference between the refractive indices of both can be 0.116.
  • the difference in the refractive index between the optical member 5 and the sheet 12 can be set to 0.2 or less.
  • acrylic resin for the optical member 5 and using polycarbonate resin having a refractive index of 1.586 for the sheet 12 the difference in the refractive index between the optical member 5 and the sheet 12 is set to 0.095.
  • the difference in the refractive index can be set to 0.1 or less, so that the reflection generated at the interface between the optical member 5 and the sheet 12 can be further reduced.
  • an acrylic resin is used for the optical member 5 and a cycloolefin resin having a refractive index of 1.525 (for example, trade name: Zeo) is used for the sheet 12.
  • Zeo trade name
  • the difference in the refractive index between the optical member 5 and the sheet 12 can be set to 0.034, so that the reflection at the interface can be further reduced.
  • acrylic resin for the optical member 5 and the sheet 12 it is possible to eliminate the difference in refractive index between the two and to prevent the occurrence of reflection at the interface.
  • the optical member 5 of the present embodiment can be manufactured, for example, as follows. First, a master mold having a pressed surface precisely machined into a shape inverted from the structure of the antireflection structure 8 is manufactured. Then, the heat-softened glass is press-molded using the produced master mold to obtain a mold for molding an anti-reflection structure. Furthermore, using the anti-reflection structure molding die, a 0.05 mm thick acrylic resin, polyester resin, polycarbonate resin, cycloolefin resin, or polyethylene terephthalate resin is press-formed. By shaping, the sheet 12 provided with the antireflection structure is produced. The sheet 12 manufactured in this manner is bonded to the inner peripheral surface of the optical member 5 using the above-described ultraviolet curable resin or the like.
  • the sheet 12 to be bonded to the optical member 5 can also be obtained by a method of transferring the same shape as the antireflection structure.
  • one of the roller surfaces 13 of the pair of rollers has a shape inverted from the structure of the antireflection structure.
  • a sheet of acrylic resin or the like is guided by a pair of rotatable rollers, and the same shape as that of the antireflection structure is transferred. Thereby, it is possible to obtain a sheet on which the antireflection structure is continuously formed.
  • the shape formed on the mold is not limited to the depressed shape inverted from the antireflection structure, but may be a protruding shape.
  • the sheet provided with the anti-reflection structure for preventing the reflection of the incident light is formed on the inner peripheral surface of the optical member. Generation of reflected light can be prevented. Therefore, a high-quality omnidirectional image with reduced noise components can be obtained.
  • the antireflection structure can be easily formed not only on a planar optical member but also on an optical member having a curved surface such as a cylindrical shape.
  • the sheet on which the antireflection structure is formed is not limited to the force bonded to the entire inner peripheral surface of the optical member.
  • the sheet may be bonded only to a half area on the imaging device side of the inner peripheral surface of the optical member.
  • the sheet can be attached to a partial area of the optical member by, for example, using a vacuum suction machine to adsorb a portion of the sheet on which the antireflection structure is not provided and perform the attaching operation. it can.
  • an imaging device having the antireflection structure at low cost is provided. be able to.
  • the optical member may be a force glass using resin.
  • the imaging device of the present invention is suitable for a monitoring device, a visual sensor of a mobile robot, an in-vehicle imaging device, and the like where a high-quality captured image is demanded.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Studio Devices (AREA)

Abstract

An optical member used for an imaging device capable of obtaining high-quality images of all directions. An optical member (5) with a hollow-circular shape, capable of being connected to an imaging optical unit (4) that includes a light collecting optical system (2) collecting incident light to form an optical image and includes an imaging element (3) for converting the optical image formed by the light collecting optical system into an image signal and outputting the signal. The inner peripheral surface of a side of the optical member (5) has a reflection preventive structure body (8) where structure units having a predetermined shape are periodically arranged in an array form at intervals smaller than the shortest wavelength of light, out of incident light, contributing to imaging.

Description

光学部材および光学部材を用いた撮像装置、ならびに光学部材の製造 方法  Optical member, imaging device using optical member, and method of manufacturing optical member
技術分野  Technical field
[0001] 本発明は、広角の画角を撮影するための撮像装置に関し、より特定的には、反射ミ ラーにより反射された画像の撮影を行う全方位撮像装置における光学部材および光 学部材を用いた撮像装置ならびに光学部材の製造方法に関する。  The present invention relates to an imaging device for capturing a wide angle of view, and more specifically, to an optical member and an optical member in an omnidirectional imaging device that captures an image reflected by a reflection mirror. The present invention relates to an imaging device used and a method for manufacturing an optical member.
背景技術  Background art
[0002] 近年、広 、範囲の視覚情報を入力することのできる画像入力装置が研究されて!ヽ る。これらは、移動型ロボットや監視装置などへの応用が期待されており、その中でも 特に、視覚情報を一度に多く取得することができる画像入力装置が研究されている。  [0002] In recent years, image input devices capable of inputting a wide range of visual information have been studied! These are expected to be applied to mobile robots, monitoring devices, and the like. Among them, image input devices capable of acquiring a large amount of visual information at a time are being studied.
[0003] このような画像入力装置として、装置の周囲 360° の方向の画像情報（以下、全方 位画像と ヽぅ）を一度に取得することができる全方位撮像装置が提案されて ヽる (特 許文献 1)。図 8は、特許文献 1に記載された全方位撮像装置の構成を示す概略図 である。全方位撮像装置 20は、ガラス製の筒状体 23とレンズ 24と撮像素子 25とを中 心に構成される。  [0003] As such an image input device, an omnidirectional imaging device capable of acquiring image information in a 360-degree direction around the device (hereinafter, an omnidirectional image and 画像) at one time has been proposed. (Patent Document 1). FIG. 8 is a schematic diagram showing the configuration of the omnidirectional imaging device described in Patent Document 1. The omnidirectional imaging device 20 includes a glass tubular body 23, a lens 24, and an image sensor 25.
[0004] 筒状体 23は、 2次曲面状をなす一端部 21と、円柱部分力 円錐台をくり抜いた他 端部 22とを一体成形して構成される。一端部 21および他端部 22の内面は、それぞ れ鏡面に仕上げられている。また、筒状体 23は、他端部 22のくり抜かれた部分の天 井位置と、一端部 21の 2次曲面の焦点位置とが等しくなるよう構成され、その位置に はレンズ 24が設置される。さらに、レンズ 24よりもさらに他端部側には、撮像素子 25 が設けられている。レンズ 24は、入射した光を撮像素子 25に集束する。撮像素子 25 は、 CCD (Charge Coupled Device)であり、レンズ 24により形成される光学的な 像を電気的な信号に変換する。  [0004] The cylindrical body 23 is formed by integrally molding one end 21 having a quadratic curved surface shape and the other end 22 obtained by hollowing out a cylindrical partial force truncated cone. The inner surfaces of the one end 21 and the other end 22 are each mirror-finished. Further, the cylindrical body 23 is configured such that the ceiling position of the hollowed portion of the other end 22 is equal to the focal position of the quadratic curved surface of the one end 21, and a lens 24 is installed at that position. You. Further, an image sensor 25 is provided further on the other end side than the lens 24. The lens 24 focuses the incident light on the image sensor 25. The imaging element 25 is a CCD (Charge Coupled Device), and converts an optical image formed by the lens 24 into an electric signal.
[0005] 全方位撮像装置 20の周方向からの光は、筒状体 23の側面 26から筒状体 23の内 部に入射する。筒状体 23の内部に入射した光は、鏡面からなる他端部 22の内面で 反射された後、さらに鏡面力もなる一端部 21の内面で反射される。そして、一端部 2 1で反射された光は、レンズ 24に入射し、レンズ 24により撮像素子（CCD) 25に集束 される。その結果、全方位撮像装置 20は、撮像素子 (CCD) 25において、周囲 360 ° の全方位画像を得ることができる。 [0005] Light from the circumferential direction of the omnidirectional imaging device 20 enters the inside of the cylindrical body 23 from the side surface 26 of the cylindrical body 23. The light that has entered the inside of the cylindrical body 23 is reflected by the inner surface of the other end portion 22 having a mirror surface, and then reflected by the inner surface of the one end portion 21 having a mirror surface force. And one end 2 The light reflected by 1 enters the lens 24 and is focused on the image sensor (CCD) 25 by the lens 24. As a result, the omnidirectional imaging device 20 can obtain an omnidirectional image of 360 ° around the imaging device (CCD) 25.
特許文献 1：特開 2002— 244236号公報  Patent Document 1: Japanese Patent Application Laid-Open No. 2002-244236
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0006] 特許文献 1に記載された全方位撮像装置 20において、円錐台状に成形された他 端部 22の内面で反射された光の大部分は、 2次曲面状に成形された一端部 21の方 向へ入射する。し力しながら、他端部 22で反射された光の一部は、側面 26の内周面 に入射する場合がある。そのため、筒状体 23の側面 26で反射された光（以下、内面 反射光という）は、一端部 21で反射された後、さらにレンズ 24に入射する。このような 内面反射光は、ノイズとして撮像素子 25に入射する。このように、特許文献 1に記載 された全方位撮像装置 20では高品質の撮像結果を得ることができないおそれがあ つた o [0006] In the omnidirectional imaging device 20 described in Patent Document 1, most of the light reflected on the inner surface of the other end portion 22 shaped like a truncated cone is converted into one end shaped like a quadratic surface. Light is incident in the direction of 21. In some cases, a part of the light reflected at the other end 22 may enter the inner peripheral surface of the side surface 26. Therefore, the light reflected on the side surface 26 of the cylindrical body 23 (hereinafter, referred to as the inner surface reflected light) is reflected on the one end 21 and then further enters the lens 24. Such internally reflected light enters the image sensor 25 as noise. As described above, the omnidirectional imaging device 20 described in Patent Document 1 may not be able to obtain high-quality imaging results.o
[0007] そこで本発明の目的は、光学部材における内面反射光の発生を防止して、高品質 の全方位画像を得ることのできる光学部材および光学部材を備えた撮像装置を提供 することを目的とする。  [0007] It is therefore an object of the present invention to provide an optical member capable of obtaining high-quality omnidirectional images by preventing the generation of internally reflected light in the optical member, and an image pickup apparatus provided with the optical member. And
[0008] また本発明の目的は、円筒形状を含む曲面に反射防止構造体が形成された光学 部材の製造方法を提供することを目的とする。  Another object of the present invention is to provide a method for manufacturing an optical member in which an antireflection structure is formed on a curved surface including a cylindrical shape.
課題を解決するための手段  Means for solving the problem
[0009] 本発明の目的は、以下の構成を備えた光学部材によって達成される。 [0009] The object of the present invention is achieved by an optical member having the following configuration.
入射した光を集光し光学的な像を形成する集光光学系と集光光学系により形成さ れる光学的な像を電気的な画像信号に変換して出力する撮像素子とを含む撮像光 学ユニットに接続可能な円筒形状を有する光学部材であって、  Imaging light that includes a condensing optical system that condenses incident light to form an optical image and an imaging device that converts an optical image formed by the condensing optical system into an electric image signal and outputs the same. An optical member having a cylindrical shape connectable to the optical unit,
所定の形状を有する構造単位が入射する光のうち撮像に寄与する光の最短波長よ りも小さいピッチで周期的にアレイ状に配列された反射防止構造体を光学部材の側 面の内周面に備える。  An anti-reflection structure that is periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among light incident on a structural unit having a predetermined shape is an inner peripheral surface of a side surface of an optical member. Prepare for.
[0010] この構成により、円筒形状の光学部材の内周面に反射防止構造体が形成されるの で、内面反射光の発生を防止することができ、高品質の全方位画像を得ることができ る。 [0010] With this configuration, the antireflection structure is formed on the inner peripheral surface of the cylindrical optical member. Thus, it is possible to prevent the generation of internally reflected light, and to obtain a high-quality omnidirectional image.
[0011] 好ましくは、反射防止構造体は、  [0011] Preferably, the anti-reflection structure comprises:
光学部材の内周面に透明材料力もなるシートと一体して形成されている。  The optical member is formed integrally on the inner peripheral surface with a sheet having a transparent material strength.
[0012] この構成により、円筒形状の光学部材の内周面に反射防止構造体が形成されるの で、内面反射光の発生を防止し、高品質の全方位画像を得ることができる。また、シ ートを用いることにより、曲面を含む光学部材に反射防止構造体を容易に形成するこ とがでさる。  [0012] With this configuration, since the antireflection structure is formed on the inner peripheral surface of the cylindrical optical member, it is possible to prevent the generation of reflected light on the inner surface and obtain a high-quality omnidirectional image. Further, by using the sheet, the antireflection structure can be easily formed on the optical member including the curved surface.
[0013] 好ましくは、光学部材は、少なくとも側面が透明材料力もなる。  [0013] Preferably, at least the side surface of the optical member also has a transparent material strength.
好ましくは、円筒形状を有する光学部材の少なくとも一端部に曲面形状の反射面を 有する反射ミラーをさらに備え、  Preferably, the optical member further includes a reflecting mirror having a curved reflecting surface at least at one end of the optical member having a cylindrical shape.
集光光学系は、反射ミラーにより反射された光を受光して光学的な像を形成する。  The condensing optical system receives the light reflected by the reflection mirror and forms an optical image.
[0014] 好ましくは、反射防止構造体の構造単位が、少なくともピッチ以上の高さを有する 好ましくは、反射防止構造体の構造単位が、略錐状の突出形状及び Z又は略錐 状の陥没形状である。 [0014] Preferably, the structural unit of the antireflection structure has a height of at least the pitch. Preferably, the structural unit of the antireflection structure has a substantially conical protruding shape and a Z or substantially conical depressed shape. It is.
好ましくは、反射防止構造体の構造単位が、略円形状、略矩形状、略正六角形状 のいずれかが選択される突出形状及び Z又は陥没形状を有する。  Preferably, the structural unit of the antireflection structure has a protruding shape selected from any of a substantially circular shape, a substantially rectangular shape, and a substantially regular hexagonal shape, and a Z or depression shape.
[0015] この構成により、光学部材の内周面に入射する光の反射を良好に抑制することが できる。 [0015] With this configuration, it is possible to satisfactorily suppress the reflection of light incident on the inner peripheral surface of the optical member.
[0016] 好ましくは、シートと光学部材との最短波長に対する屈折率の差は 0. 2以下である 好ましくは、シートと光学部材との最短波長に対する屈折率の差は 0. 1以下である  Preferably, the difference between the refractive index of the sheet and the optical member with respect to the shortest wavelength is 0.2 or less. Preferably, the difference of the refractive index of the sheet and the optical member with respect to the shortest wavelength is 0.1 or less.
[0017] この構成により、シートと光学部材との界面で発生する反射を良好に抑制すること ができる。 [0017] With this configuration, it is possible to satisfactorily suppress reflection occurring at the interface between the sheet and the optical member.
[0018] 本発明の目的は、以下の構成を備えた撮像装置によって達成される。  [0018] The object of the present invention is achieved by an imaging device having the following configuration.
被写体の光学的な像を電気的な画像信号として出力可能な撮像装置であって、 曲面形状の反射面を有する反射ミラーと、 反射面によって反射された光を受光して光学的な像を形成する集光光学系と、 集光光学系により形成された光学的な像を電気的な画像信号に変換して出力する 撮像素子と、 An imaging device capable of outputting an optical image of a subject as an electric image signal, comprising: a reflecting mirror having a curved reflecting surface; A condensing optical system that receives the light reflected by the reflecting surface and forms an optical image, and an imaging device that converts the optical image formed by the condensing optical system into an electrical image signal and outputs the signal. When,
所定の形状を有する構造単位が入射する光のうち撮像に寄与する光の最短波長よ りも小さいピッチで周期的にアレイ状に配列された反射防止構造体を光学部材の側 面の内周面に備える。  An anti-reflection structure that is periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among light incident on a structural unit having a predetermined shape is an inner peripheral surface of a side surface of an optical member. Prepare for.
[0019] この構成により、光学部材の内周面に入射した光の反射を良好に抑制することがで き、高品質の全方位画像を取得可能な撮像装置を実現することができる。  With this configuration, it is possible to favorably suppress the reflection of light that has entered the inner peripheral surface of the optical member, and it is possible to realize an imaging device capable of acquiring a high-quality omnidirectional image.
[0020] 本発明の目的は、以下の製造方法によって達成される。 [0020] The object of the present invention is achieved by the following production method.
所定の形状を有する構造単位が入射する光のうち撮像に寄与する光の最短波長よ りも小さいピッチで周期的にアレイ状に配列された反射防止構造体を備えた円筒形 状を有する光学部材の製造方法であって、  Optical member having a cylindrical shape provided with antireflection structures periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among the light incident on the structural unit having a predetermined shape. The method of manufacturing
反射防止構造体とは反転した形状を転写面に有する金型を用意する第 1工程と、 用意された金型を熱プレスして反射防止構造体と等しい形状を光学部材の内周面 に転写する第 2工程とを備える。  The first step of preparing a mold having an inverted shape of the anti-reflection structure on the transfer surface, and hot pressing the prepared mold to transfer the same shape as the anti-reflection structure to the inner peripheral surface of the optical member And a second step of performing.
[0021] この構成により、反射構造体が形成された光学部材を安価でかつ大量に製造する ことができる。 [0021] With this configuration, the optical member on which the reflection structure is formed can be manufactured at low cost and in large quantities.
[0022] 好ましくは、金型は、 [0022] Preferably, the mold is
反射防止構造体とは反転した形状を外周面に有する円筒状金型であり、 第 1工程は、  The anti-reflection structure is a cylindrical mold having an inverted shape on the outer peripheral surface, the first step is:
円筒状金型を加熱加圧しながら、かつ同時に回転させて、反射防止構造体と等し Rotate the cylindrical mold while heating and pressurizing it and rotate it at the same time,
V、形状を光学部材の内周面に転写する。 V. Transfer the shape to the inner peripheral surface of the optical member.
[0023] この構成により、平面状の光学部材だけでなぐ円筒形状等の曲面を有する部材に も反射防止構造体を容易に形成することができる。 According to this configuration, the antireflection structure can be easily formed even on a member having a curved surface such as a cylindrical shape formed only by a planar optical member.
[0024] 好ましくは、金型の転写面は、構造単位が略錐状の突出形状及び Z又は略錐状の 陥没形状を有する。 [0024] Preferably, the transfer surface of the mold has a substantially cone-shaped protruding shape and a Z or substantially cone-shaped depressed shape in the structural unit.
発明の効果  The invention's effect
[0025] 本発明によれば、光学部材における内面反射光の発生を防止して、高品質の全方 位画像を得ることのできる光学部材および光学部材を備えた撮像装置を提供するこ とがでさる。 According to the present invention, it is possible to prevent the occurrence of light reflected on the inner surface of the optical member, and to improve the quality of It is possible to provide an optical member capable of obtaining a positional image and an imaging device provided with the optical member.
[0026] また本発明によれば、円筒形状を含む曲面に反射防止構造体が形成された光学 部材の製造方法を提供することができる。  Further, according to the present invention, it is possible to provide a method for manufacturing an optical member in which an antireflection structure is formed on a curved surface including a cylindrical shape.
図面の簡単な説明  Brief Description of Drawings
[0027] [図 1]図 1は、本発明の第 1の実施形態における撮像装置の構成を示す概略断面図 である。  FIG. 1 is a schematic cross-sectional view illustrating a configuration of an imaging device according to a first embodiment of the present invention.
[図 2]図 2は、本発明の第 1の実施形態における撮像装置の構成を示す概観斜視図 である。  FIG. 2 is a schematic perspective view showing a configuration of an imaging device according to the first embodiment of the present invention.
[図 3]図 3は、本発明の第 1の実施形態における撮像装置に用いられる光学部材を構 成する反射防止構造体を拡大して示した概略斜視図である。  FIG. 3 is a schematic perspective view showing, on an enlarged scale, an anti-reflection structure constituting an optical member used in the imaging device according to the first embodiment of the present invention.
[図 4]図 4は、本発明の第 1の実施形態における撮像装置に用いられる光学部材の 製造方法を示す概略斜視図である。  FIG. 4 is a schematic perspective view showing a method for manufacturing an optical member used for the imaging device according to the first embodiment of the present invention.
[図 5A]図 5Aは、本発明の第 1の実施形態における撮像装置に用いられる光学部材 を構成する反射防止構造体の他の例を拡大して示した概略斜視図である。  FIG. 5A is a schematic perspective view showing, in an enlarged manner, another example of an anti-reflection structure constituting an optical member used in the imaging device according to the first embodiment of the present invention.
[図 5B]図 5Bは、本発明の第 1の実施形態における撮像装置に用いられる光学部材 を構成する反射防止構造体の他の例を拡大して示した概略斜視図である。  FIG. 5B is a schematic perspective view showing, in an enlarged manner, another example of the antireflection structure constituting the optical member used in the imaging device according to the first embodiment of the present invention.
[図 5C]図 5Cは、本発明の第 1の実施形態における撮像装置に用いられる光学部材 を構成する反射防止構造体の他の例を拡大して示した概略斜視図である。  FIG. 5C is a schematic perspective view showing, in an enlarged manner, another example of an anti-reflection structure constituting an optical member used in the imaging device according to the first embodiment of the present invention.
[図 5D]図 5Dは、本発明の第 1の実施形態における撮像装置に用いられる光学部材 を構成する反射防止構造体の他の例を拡大して示した概略斜視図である。  FIG. 5D is a schematic perspective view showing another example of the antireflection structure constituting the optical member used in the imaging device according to the first embodiment of the present invention in an enlarged manner.
[図 5E]図 5Eは、本発明の第 1の実施形態における撮像装置に用いられる光学部材 を構成する反射防止構造体の他の例を拡大して示した概略斜視図である。  FIG. 5E is an enlarged schematic perspective view showing another example of the antireflection structure constituting the optical member used in the imaging device according to the first embodiment of the present invention.
[図 6]図 6は、本発明の第 2の実施形態における撮像装置を示す概略断面図である。  FIG. 6 is a schematic sectional view showing an imaging device according to a second embodiment of the present invention.
[図 7]図 7は、本発明の第 2の実施形態におけるシートの製造方法を示す概略図であ る。  FIG. 7 is a schematic view showing a sheet manufacturing method according to a second embodiment of the present invention.
[図 8]図 8は、従来技術における全方位撮像装置の構成を示す概略断面図である。 符号の説明 [0028] 1、 11 撮像装置 FIG. 8 is a schematic cross-sectional view showing a configuration of an omnidirectional imaging device according to a conventional technique. Explanation of reference numerals [0028] 1, 11 imaging device
2 集光光学系  2 Condensing optical system
3 撮像素子 (CCD)  3 Image sensor (CCD)
4 撮像光学ユニット  4 Imaging optical unit
5 光学部材  5 Optical components
6 第 1ミラー  6 First mirror
7 第 2ミラー  7 Second mirror
8 反射防止構造体  8 Anti-reflection structure
9 反射防止膜 (誘電体薄膜）  9 Anti-reflective coating (dielectric thin film)
10 円筒状金型  10 Cylindrical mold
12 シート  12 sheets
13 ローラー  13 rollers
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0029] (第 1の実施形態） (First Embodiment)
図 1は本発明の第 1の実施形態に係る撮像装置を示す概略断面図、図 2は撮像装 置の概略斜視図、図 3は本発明の第 1の実施形態に係る撮像装置に用いられる光学 部材を構成する反射防止構造体を示した拡大斜視図である。図 1、図 2に示すよう〖こ 、本実施の形態に係る撮像装置 1は、撮像光学ユニット 4と光学部材 5とを中心に構 成される。  FIG. 1 is a schematic cross-sectional view showing an imaging device according to a first embodiment of the present invention, FIG. 2 is a schematic perspective view of the imaging device, and FIG. 3 is used for the imaging device according to the first embodiment of the present invention. FIG. 3 is an enlarged perspective view showing an anti-reflection structure constituting an optical member. As shown in FIG. 1 and FIG. 2, the imaging apparatus 1 according to the present embodiment is mainly configured by an imaging optical unit 4 and an optical member 5.
[0030] 撮像光学ユニット 4は、集光光学系 2と撮像素子 3とを備える。集光光学系 2は、レン ズを含み、撮像素子 3上に被写体の光学的な像を形成する。撮像素子 3は、 CCD ( Charge Coupled Device)であり、集光光学系 2により形成される光学的な像を電 気的な信号に変換する。なお、撮像素子 3は、 CMOS (Complementary Metal - Oxide Semiconductor)センサまたは MOSイメージセンサでもよ!/ヽ。  The imaging optical unit 4 includes the light-collecting optical system 2 and the imaging device 3. The focusing optical system 2 includes a lens and forms an optical image of a subject on the image sensor 3. The image pickup device 3 is a CCD (Charge Coupled Device), and converts an optical image formed by the condensing optical system 2 into an electric signal. The image sensor 3 may be a CMOS (Complementary Metal-Oxide Semiconductor) sensor or a MOS image sensor!
[0031] 光学部材 5は、透明材料力もなる円筒形状の部材である。光学部材 5の一端部に は、撮像光学ユニット 4が設けられ、撮像光学ユニット 4を囲む形で凸面鏡力もなる第 2ミラー 7が設けられている。また、光学部材 5の他端部には、凹面鏡力もなる第 1ミラ 一 6が設けられている。第 2ミラー 7は、光学部材 5の側面を透過し、外部からの入射 光を第 1ミラー 6の方向へ反射させる。一方、第 1ミラー 6は、第 2ミラー 7からの反射光 を集光光学系 2に入射させる。本実施の形態において、光学部材 5は、中心軸に沿 つた長さが 30mm、内径が 20mm、肉厚が 2mmであり、例えばアクリル榭脂ゃポリエ ステル樹脂、ポリカーボネート榭脂、シクロォレフイン榭脂、ポリエチレンテレフタレー ト榭脂等の透明材料からなる。 The optical member 5 is a cylindrical member having a transparent material strength. At one end of the optical member 5, an imaging optical unit 4 is provided, and a second mirror 7 that surrounds the imaging optical unit 4 and has a convex mirror power is provided. The other end of the optical member 5 is provided with a first mirror 16 having a concave mirror power. The second mirror 7 is transmitted through the side surface of the optical member 5 and incident from the outside. Light is reflected in the direction of the first mirror 6. On the other hand, the first mirror 6 causes the light reflected from the second mirror 7 to enter the condensing optical system 2. In the present embodiment, the optical member 5 has a length along the central axis of 30 mm, an inner diameter of 20 mm, and a wall thickness of 2 mm. It is made of a transparent material such as terephthalate resin.
[0032] 図 1および図 3に示すように、光学部材 5の内周面には、微細な反射防止構造体 8 が形成されている。反射防止構造体とは、所定の形状を有する構造単位が、入射光 のうち撮像に寄与する光の波長の下限値よりも小さいピッチ、すなわち撮像光の最短 波長よりも小さいピッチで周期的にアレイ状に配列されたものである。このように所定 の形状を有する構造単位を周期的にアレイ状に配列させることによって、撮像光に対 して、見かけ上屈折率を連続的に変化させ、空気層との界面での透過 Z反射特性の 入射角依存性及び波長依存性が少ない反射防止機能面を形成させることができる。  As shown in FIGS. 1 and 3, a fine antireflection structure 8 is formed on the inner peripheral surface of the optical member 5. An anti-reflection structure is a structure in which structural units having a predetermined shape are periodically arrayed at a pitch smaller than the lower limit of the wavelength of light that contributes to imaging of incident light, that is, at a pitch smaller than the shortest wavelength of imaging light. They are arranged in a shape. By periodically arranging the structural units having a predetermined shape in an array as described above, the apparent refractive index of the imaging light is continuously changed, and the transmission Z reflection at the interface with the air layer is performed. It is possible to form an antireflection function surface having little dependence on the incident angle and wavelength of the characteristics.
[0033] 光学部材の内周面に形成される反射防止構造体とは、反射を低減すべき光の反 射を防止するために、表面に微細構造が形成された部材を意味し、反射を低減すベ き光を完全に反射させない態様だけではなぐ所定波長の反射を低減すべき光の反 射を防止する効果を有する態様も含むものである。本実施形態に用いることができる 反射防止構造体としては、例えば図 3の概略拡大図に示すような、高さ Hの円錐形状 の突起を構造単位とし、これら円錐形状の突起がピッチ Pで周期的にアレイ状に配列 された構造体があげられる。本実施の形態における反射防止構造体 8は、ピッチ Pが 0. 15 mゝ高さ H力 O. 15 /z mの円錐形状を有している。  The anti-reflection structure formed on the inner peripheral surface of the optical member means a member having a fine structure formed on the surface in order to prevent reflection of light whose reflection is to be reduced. This includes not only an embodiment in which the light to be reduced is not completely reflected but also an embodiment having an effect of preventing reflection of light whose reflection at a predetermined wavelength should be reduced. As an anti-reflection structure that can be used in the present embodiment, for example, as shown in a schematic enlarged view of FIG. 3, a conical protrusion having a height H is used as a structural unit, and these conical protrusions are periodically arranged at a pitch P. Structures that are typically arranged in an array. The anti-reflection structure 8 in the present embodiment has a conical shape with a pitch P of 0.15 m ゝ a height H of 0.15 / z m.
[0034] なおピッチ Pとは、反射防止構造体が多数の微細構造単位の二次元的な配列によ り構成されている場合には、最も密な配列方向におけるピッチを意味する。  [0034] Note that the pitch P means the pitch in the densest arrangement direction when the antireflection structure is composed of a two-dimensional arrangement of a large number of microstructure units.
[0035] 構造単位のピッチ Pは、反射防止構造体中、一配列方向において実質上略一定で あり、入射光のうち撮像に寄与する光の最短波長よりも小さければよいが、界面での 透過 Z反射特性の入射角依存性及び波長依存性をより一層低減させることができる という点から、力かるピッチ Pは撮像光の最短波長の 1Z2以下、さらには 1Z3以下で あることが好ましい。  [0035] The pitch P of the structural units is substantially substantially constant in one array direction in the antireflection structure, and may be smaller than the shortest wavelength of light that contributes to imaging among incident light. From the viewpoint that the incident angle dependence and the wavelength dependence of the Z reflection characteristic can be further reduced, the strong pitch P is preferably 1Z2 or less, more preferably 1Z3 or less, which is the shortest wavelength of the imaging light.
[0036] また、構造単位の高さ Hには特に限定がなぐ反射防止構造体中、全ての構造単 位の高さ Hが必ずしも一定でなくてもよいが、力かる高さ Hが高いほど、入射光に対 する反射防止機能が向上するという利点がある。したがって高さ Hは、少なくとも前記 ピッチ P以上 (最小の構造単位の高さがピッチ以上）、さらには少なくともピッチ Pの 3 倍以上 (最小の構造単位の高さがピッチの 3倍以上)であることが好ま U、。なおやは り、例えば後述するような反射防止構造体の製造性を考慮すると、かかる高さ Hがあ る程度の大きさまでであることが望ましぐ通常高くともピッチ Pの 4倍程度以下 (最大 の構造単位の高さがピッチの 5倍程度以下)であることが好ましい。 [0036] The height H of the structural unit is not particularly limited. Although the height H is not necessarily constant, the higher the force H, the better the antireflection function against incident light. Accordingly, the height H is at least the pitch P or more (the minimum structural unit height is the pitch or more), and is at least three times or more the pitch P (the minimum structural unit height is three or more times the pitch). U, which is preferred. In consideration of the manufacturability of the anti-reflection structure as described later, it is desirable that the height H is not larger than a certain level. The maximum height of the structural unit is preferably about 5 times or less the pitch).
[0037] 円筒形状の光学部材 5の外周面には、入射光の反射を防止するための反射防止 膜 9が形成されている。反射防止膜 9は、フッ化マグネシウム、酸ィ匕アルミニウム等の 誘電体材料からなる誘電体多層膜である。これにより、充分な撮像光を光学部材 5の 内部に取り込むことができる。  An antireflection film 9 for preventing reflection of incident light is formed on the outer peripheral surface of the cylindrical optical member 5. The anti-reflection film 9 is a dielectric multilayer film made of a dielectric material such as magnesium fluoride and aluminum oxide. As a result, sufficient imaging light can be taken into the optical member 5.
[0038] 次に、上記の構成を有する撮像装置 1を用いた撮影動作について、図 1を参照して 説明する。図 1に示すように、撮像装置 1の周囲 360° の光は、光学部材 5の側面を 透過し、内部に入射する。光学部材 5の内部に入射した光は、第 2ミラー 7で反射さ れる。第 2ミラー 7では、その曲面形状により、反射された光の大部分は、第 1ミラー 6 の方向へ向かう。第 1ミラー 6で反射された光は、撮像光学ユニット 4の集光光学系 2 に入射し、撮像素子 3上に集束される。これにより、撮像素子 3によって、撮像装置 1 の周囲 360° の画像を得ることができる。ここで、撮像装置 1の周方向からの光には、 紫外線帯域波長（150ηπ！〜 400nm)、可視帯域波長（400ηπ！〜 700nm)、近赤外 帯域波長（700ηπ！〜 2 μ m)、遠赤外帯域波長（2 π！〜 13 m)等、複数の帯域波 長の光が含まれる。  Next, a photographing operation using the imaging device 1 having the above configuration will be described with reference to FIG. As shown in FIG. 1, light at 360 ° around the imaging device 1 passes through the side surface of the optical member 5 and enters the inside. The light that has entered the inside of the optical member 5 is reflected by the second mirror 7. In the second mirror 7, most of the reflected light is directed toward the first mirror 6 due to its curved surface shape. The light reflected by the first mirror 6 is incident on the condenser optical system 2 of the imaging optical unit 4 and is focused on the imaging device 3. Thus, an image of 360 ° around the image pickup device 1 can be obtained by the image pickup device 3. Here, the light from the circumferential direction of the imaging device 1 includes an ultraviolet band wavelength (150ηπ! To 400 nm), a visible band wavelength (400ηπ! To 700 nm), a near-infrared band wavelength (700ηπ! To 2 μm), Includes light with multiple band wavelengths, such as infrared band wavelengths (2π! ~ 13 m).
[0039] し力しながら、撮像装置 1に入射する有効画角以外力もの周辺光は、第 2ミラー 7で 反射された後、第 1ミラー 6へ直接に入射せず、光学部材 5の内周面に入射する場合 がある。このため、従来の全方位撮像装置では、上記のように円筒形状の内周面に 入射した光は、内面反射光として集光光学系に入射し、フレアやゴーストの原因とな るノイズを発生させていた。そこで、本実施の形態に係る撮像装置 1において、光学 部材 5の内周面に反射防止構造体 8を形成することにより、内面反射光の発生を防 止することができる。したがって、本実施の形態に係る撮像装置 1は、反射防止構造 体 8により、ノイズ成分を低減させ、高品質の全方位撮影画像を得ることができる。 The peripheral light incident on the imaging device 1 with a force other than the effective angle of view is reflected by the second mirror 7, does not directly enter the first mirror 6, but remains inside the optical member 5. It may be incident on the peripheral surface. For this reason, in the conventional omnidirectional imaging device, the light incident on the inner peripheral surface of the cylindrical shape as described above enters the condensing optical system as internally reflected light, and generates noise that causes flare and ghost. I was letting it. Therefore, in the imaging device 1 according to the present embodiment, by forming the anti-reflection structure 8 on the inner peripheral surface of the optical member 5, it is possible to prevent the generation of reflected light on the inner surface. Therefore, the imaging device 1 according to the present embodiment has an anti-reflection structure. The body 8 can reduce noise components and obtain high-quality omnidirectional images.
[0040] 本実施の形態に係る撮像装置 1に含まれる光学部材 5は、例えば以下のように製 造することができる。すなわち、図 4に示すように、光学部材 5は、反射防止構造体 8 とは反転した形状が形成された円筒状の金型を光学部材 5に転写する方法により得 ることができる。図 4中、円筒状金型 10は、その表面にニッケルカ ツキされ、光学部 材 5よりも径の小さい金型用特殊鋼力もなる。円筒状金型 10の外周面には、円錐形 状の陥没がピッチ Pで周期的にアレイ状に配列された構造を有する形状が形成され ている（第 1工程)。 [0040] The optical member 5 included in the imaging device 1 according to the present embodiment can be manufactured, for example, as follows. That is, as shown in FIG. 4, the optical member 5 can be obtained by a method of transferring a cylindrical mold having a shape inverted from the anti-reflection structure 8 to the optical member 5. In FIG. 4, the cylindrical mold 10 is nickel-coated on its surface, and also has a special steel force for a mold having a smaller diameter than the optical member 5. A shape having a structure in which conical depressions are periodically arranged in an array at a pitch P is formed on the outer peripheral surface of the cylindrical mold 10 (first step).
[0041] 図に示すように円筒状金型 10は、反射防止構造体 8とは反転した形状が形成され た外周面を光学部材 5の内周面に接するように設置される。そして、円筒状金型 10 を光学部材 5の内面で圧接することにより、反射防止構造体 8が光学部材 5の内周面 に転写される。さらに、円筒状金型 10を加熱加圧しながら同時に回転させることで光 学部材 5の内周面の全面に反射防止構造体 8を転写することができる（第 2工程)。な お、外径が 10mmの円筒状金型 10を用いて、中心軸に沿った長さが 30mm、内径 2 Omm,肉厚 2mmのアクリル榭脂からなる光学部材 5の内周面に反射防止構造体 8 を転写する場合、加熱温度は 100°C〜130°C、加圧力は 980N程度であることが望 ましい。  As shown in the figure, the cylindrical mold 10 is installed such that the outer peripheral surface having a shape inverted from the anti-reflection structure 8 is in contact with the inner peripheral surface of the optical member 5. Then, by pressing the cylindrical mold 10 against the inner surface of the optical member 5, the antireflection structure 8 is transferred to the inner peripheral surface of the optical member 5. Furthermore, the antireflection structure 8 can be transferred onto the entire inner peripheral surface of the optical member 5 by simultaneously rotating the cylindrical mold 10 while heating and pressing (second step). In addition, using a cylindrical mold 10 with an outer diameter of 10 mm, the inner peripheral surface of the optical member 5 made of acrylic resin with a length along the central axis of 30 mm, an inner diameter of 2 Omm, and a wall thickness of 2 mm is used to prevent reflection. When transferring the structure 8, it is desirable that the heating temperature be 100 ° C to 130 ° C and the pressing force be about 980N.
[0042] このように、本実施の形態に係る撮像装置は、円筒形状の光学部材の内周面に反 射防止構造体を備えるので、入射光が内周面で反射することを防止する。したがって 、ノイズ成分が低減された高品質の全方位画像を得ることができる。  As described above, since the imaging device according to the present embodiment includes the antireflection structure on the inner peripheral surface of the cylindrical optical member, it prevents incident light from being reflected on the inner peripheral surface. Therefore, a high-quality omnidirectional image with reduced noise components can be obtained.
[0043] また、本実施の形態における光学部材の製造方法は、反射防止構造体とは反転し た形状を有する円筒状の金型を用いた転写方法により、平面状の光学部材だけでな ぐ円筒形状等の曲面を有する光学部材にも容易に反射防止構造体を形成すること ができる。  Further, in the method of manufacturing an optical member according to the present embodiment, a transfer method using a cylindrical mold having a shape inverted from that of the anti-reflection structure allows only a planar optical member to be used. An antireflection structure can be easily formed on an optical member having a curved surface such as a cylindrical shape.
[0044] なお、本実施の形態において、反射防止構造体として構造単位が円錐形状の構造 体を用いた力 必ずしもこのような形状の構造体に限定されるものではない。例えば 図 5Aに示すように、構造単位が正六角錐形状や、四角錐形状などの角錐形状の構 造体であってもよい。また、力かる構造単位の形状は必ずしも錐状に限定されるもの でもなぐ図 5B、図 5Cに示すような先端が丸くなっている釣鐘状であっても、図 5Dに 示すような円錐台形状や図 5Eに示すような角錐台形状などの錐台状であってもよい 。また、各構造単位は厳密な幾何学的な形状である必要はなぐ実質的に錐状、釣 鐘状、錐台状などであればよい。また反射防止構造体は、少なくとも、撮像素子が感 度を有する波長領域のうち、最も短 ヽ波長よりも小さ 、ピッチであればょ 、。 In the present embodiment, a force using a conical structure as the antireflection structure is not necessarily limited to the structure having such a shape. For example, as shown in FIG. 5A, the structural unit may be a pyramid-shaped structure such as a regular hexagonal pyramid or a quadrangular pyramid. In addition, the shape of the strong structural unit is not necessarily limited to a cone. However, even if it is a bell shape with a rounded tip as shown in Figs. 5B and 5C, it may have a frustum shape such as a truncated cone shape as shown in Fig. 5D or a truncated pyramid shape as shown in Fig. 5E. May be. Further, each structural unit does not need to have a strict geometric shape, and may be substantially a cone, a bell, a truncated cone, or the like. Further, the antireflection structure should be at least a pitch smaller than the shortest wavelength in the wavelength region where the image sensor has sensitivity.
[0045] なお、本実施の形態において、反射防止構造体は、光学部材の内周面の全面に 形成されたが、これに限られない。例えば、光学部材の内周面のうち、撮像装置側の 半分の領域にのみ反射防止構造体を形成してもよい。このように、撮像に寄与する 入射光およびフレアやゴーストの原因となる光が入射する領域にのみ、反射防止構 造体を備えることにより、低コストで反射防止構造体を備えた撮像装置を提供すること ができる。 In the present embodiment, the antireflection structure is formed on the entire inner peripheral surface of the optical member, but is not limited to this. For example, the anti-reflection structure may be formed only in a half area on the imaging device side of the inner peripheral surface of the optical member. As described above, by providing the anti-reflection structure only in the area where the incident light contributing to imaging and the light causing flare and ghost are incident, an imaging device having the anti-reflection structure at low cost is provided. can do.
[0046] なお、本実施の形態において、第 1及び第 2ミラーと、円筒形状の光学部材とは別 体の部材とした力 必ずしもこの構成に限定されるものではない。例えば、光学部材 と第 1あるいは第 2ミラーとがー体に形成された光学部材としてもよい。  In the present embodiment, the first and second mirrors and the force formed as a member separate from the cylindrical optical member are not necessarily limited to this configuration. For example, an optical member in which an optical member and a first or second mirror are formed in a body may be used.
[0047] なお、本実施の形態に係る撮像装置は、光学部材の外周面に誘電体材料力 なる 反射防止膜を備えたが、これに限られない。充分な撮像光を光学部材の内部に取り 込むことができる場合には、必ずしも反射防止膜を形成する必要はない。  Note that the imaging device according to the present embodiment includes an antireflection film made of a dielectric material on the outer peripheral surface of the optical member, but is not limited to this. If sufficient imaging light can be taken into the optical member, it is not always necessary to form an antireflection film.
[0048] なお、本実施の形態における光学部材の製造方法は、透明材料からなる光学部材 の製造に用いたが、これに限られない。上述した製造方法は、黒色材料等の透明以 外の材料力もなる部材にお 、ても用いることができる。  Although the method for manufacturing an optical member according to the present embodiment has been used for manufacturing an optical member made of a transparent material, the present invention is not limited to this. The above-described manufacturing method can also be used for members having a material strength other than transparent, such as a black material.
[0049] なお、本実施の形態における光学部材の製造方法は、金型には反射防止構造体 とは反転した形状を有する陥没形状としたが、突出形状としてもよい。  In the method for manufacturing an optical member according to the present embodiment, the mold has a depressed shape having an inverted shape of the antireflection structure, but may have a protruded shape.
[0050] (第 2の実施形態）  (Second Embodiment)
図 6は、本発明の第 2の実施形態に係る撮像装置の構成を示す概略断面図である 。第 2の実施形態に係る撮像装置は、第 1の実施形態に係る撮像装置とほぼ同様の 構成を備えるが、以下の点で異なる。すなわち、本実施の形態に係る撮像装置 11は 、円筒形状の光学部材 5の内周面にシート 12を備える。なお図 6中、第 1の実施形態 と同じ参照符号は、等しい構成要素を示す。以下、第 1の実施形態と異なる箇所につ いて説明する。 FIG. 6 is a schematic cross-sectional view illustrating a configuration of an imaging device according to the second embodiment of the present invention. The imaging device according to the second embodiment has substantially the same configuration as the imaging device according to the first embodiment, but differs in the following points. That is, the imaging device 11 according to the present embodiment includes the sheet 12 on the inner peripheral surface of the cylindrical optical member 5. In FIG. 6, the same reference numerals as those in the first embodiment denote the same components. Hereinafter, differences from the first embodiment will be described. Will be described.
[0051] 光学部材 5の内周面に形成されるシート 12は、アクリル榭脂ゃポリエステル榭脂、 ポリカーボネート榭脂、シクロォレフイン榭脂、ポリエチレンテレフタラート榭脂等の透 明材料力 なり、表面には反射防止構造体 8が形成されている。反射防止構造体 8 は、第 1の実施形態と同様に、ピッチ 0. 15 /ζ πι、高さ 0. 15 mの円錐形状を有し、 入射光に対して、見かけ上屈折率を連続的に変化させ、空気層との界面での透過 Z 反射特性の入射角依存性及び波長依存性が少ない反射防止機能面が形成される。 なおシート 12の厚さは、反射防止構造体 8を含めて 0. 05mmとしている。  [0051] The sheet 12 formed on the inner peripheral surface of the optical member 5 is made of a transparent material such as acrylic resin, polyester resin, polycarbonate resin, cycloolefin resin, polyethylene terephthalate resin, and the like. An anti-reflection structure 8 is formed. As in the first embodiment, the antireflection structure 8 has a cone shape with a pitch of 0.15 / ζπι and a height of 0.15 m, and apparently has a continuous refractive index with respect to incident light. To form an anti-reflection function surface having little incident angle dependence and wavelength dependence of the transmission Z reflection characteristic at the interface with the air layer. The thickness of the sheet 12 including the antireflection structure 8 is 0.05 mm.
[0052] 反射防止構造体 8が形成されたシート 12は、円筒形状の光学部材 5の内周面に貼 り合わせられる。この際、光学部材 5とシート 12とは、熱または光硬化榭脂等によって 貼り合わせることができる。これにより、撮像装置 11に入射する有効画角以外からの 周辺光は、第 2ミラー 7で反射された後、第 1ミラー 6へ直接に入射せず、光学部材 5 の内周面に入射する場合においても、内面反射光の発生を防止することができる。  [0052] The sheet 12 on which the antireflection structure 8 is formed is attached to the inner peripheral surface of the cylindrical optical member 5. At this time, the optical member 5 and the sheet 12 can be bonded by heat or photo-curing resin. Accordingly, the peripheral light incident on the imaging device 11 from other than the effective angle of view is reflected by the second mirror 7 and then does not directly enter the first mirror 6 but enters the inner peripheral surface of the optical member 5. Even in such a case, it is possible to prevent the generation of the internally reflected light.
[0053] なお、シート 12と光学部材 5の屈折率の差は、 0. 2以下であることが望ましい。屈 折率の差を 0. 2以下とすることにより、シート 12と光学部材 5との界面で発生する反 射をフレアやゴーストを発生させない程度まで抑えることができる。さらには、シート 1 2と光学部材 5との屈折率の差は 0. 1以下であるのが望ましい。これにより、シート 12 と光学部材 5との界面で発生する反射をさらに一層低減可能となり、迷光の発生を効 率よく抑えることができる。例えば、波長が d線（587. 6nm)のとき、光学部材 5に屈 折率が 1. 491のアクリル榭脂を用い、一方、シート 12に屈折率が 1. 607のポリエス テル榭脂 (例えば、商品名：OKP4、大阪ガスケミカル株式会社製)を用いることによ り、両者の屈折率の差を 0. 116とすることができる。これにより、光学部材 5とシート 1 2との屈折率の差を 0. 2以下とすることができる。また例えば、光学部材 5にアクリル 榭脂を用い、シート 12に屈折率が 1. 586のポリカーボネート榭脂を用いることにより 、光学部材 5とシート 12との屈折率の差を 0. 095とすることができる。これにより、屈 折率の差を 0. 1以下とすることができるので光学部材 5とシート 12との界面で発生す る反射をさらに一層低減させることができる。また例えば、光学部材 5にアクリル榭脂 を用い、シート 12に屈折率が 1. 525のシクロォレフィン榭脂（例えば、商品名：ゼォ ックス ZEONEX 480R、日本ゼオン株式会社製）を用いてもよい。これにより、光 学部材 5とシート 12との屈折率の差を 0. 034とすることができるので、界面での反射 をさらに一層低減させることが可能である。さらに例えば、光学部材 5およびシート 12 にアクリル榭脂を用いることにより、両者の屈折率の差を無くし、界面での反射の発生 を防止することができる。 Note that the difference between the refractive indices of the sheet 12 and the optical member 5 is desirably 0.2 or less. By setting the difference in the refractive index to 0.2 or less, it is possible to suppress the reflection generated at the interface between the sheet 12 and the optical member 5 to such an extent that flare or ghost does not occur. Further, it is desirable that the difference in the refractive index between the sheet 12 and the optical member 5 be 0.1 or less. This makes it possible to further reduce the reflection occurring at the interface between the sheet 12 and the optical member 5, and to efficiently suppress the generation of stray light. For example, when the wavelength is d-line (587.6 nm), an acrylic resin having a refractive index of 1.491 is used for the optical member 5, while a polyester resin having a refractive index of 1.607 is used for the sheet 12 (for example, By using OKP4 (trade name, manufactured by Osaka Gas Chemical Co., Ltd.), the difference between the refractive indices of both can be 0.116. Thereby, the difference in the refractive index between the optical member 5 and the sheet 12 can be set to 0.2 or less. Also, for example, by using acrylic resin for the optical member 5 and using polycarbonate resin having a refractive index of 1.586 for the sheet 12, the difference in the refractive index between the optical member 5 and the sheet 12 is set to 0.095. Can be. Thereby, the difference in the refractive index can be set to 0.1 or less, so that the reflection generated at the interface between the optical member 5 and the sheet 12 can be further reduced. Further, for example, an acrylic resin is used for the optical member 5 and a cycloolefin resin having a refractive index of 1.525 (for example, trade name: Zeo) is used for the sheet 12. ZEONEX 480R, manufactured by Nippon Zeon Co., Ltd.). Thereby, the difference in the refractive index between the optical member 5 and the sheet 12 can be set to 0.034, so that the reflection at the interface can be further reduced. Further, for example, by using acrylic resin for the optical member 5 and the sheet 12, it is possible to eliminate the difference in refractive index between the two and to prevent the occurrence of reflection at the interface.
[0054] 本実施の形態の光学部材 5は、例えば以下のように製造することができる。まず、反 射防止構造体 8の構造とは反転した形状に精密加工されたプレス面を有するマスタ 型を作製する。そして、作製されたマスタ型を用いて、加熱軟化したガラスをプレス成 形し、反射防止構造成形用金型を得る。さらに、この反射防止構造成形用金型を用 いて、厚みが 0. 05mmのアクリル榭脂材、ポリエステル榭脂材、ポリカーボネート榭 脂材、シクロォレフイン榭脂材ある 、はポリエチレンテレフタレート榭脂材をプレス成 形することにより、反射防止構造体を備えたシート 12が作製される。このように作製さ れたシート 12は、上述した紫外線硬化榭脂等を用いて光学部材 5の内周面に貼り合 わせられる。 The optical member 5 of the present embodiment can be manufactured, for example, as follows. First, a master mold having a pressed surface precisely machined into a shape inverted from the structure of the antireflection structure 8 is manufactured. Then, the heat-softened glass is press-molded using the produced master mold to obtain a mold for molding an anti-reflection structure. Furthermore, using the anti-reflection structure molding die, a 0.05 mm thick acrylic resin, polyester resin, polycarbonate resin, cycloolefin resin, or polyethylene terephthalate resin is press-formed. By shaping, the sheet 12 provided with the antireflection structure is produced. The sheet 12 manufactured in this manner is bonded to the inner peripheral surface of the optical member 5 using the above-described ultraviolet curable resin or the like.
[0055] また、光学部材 5に貼り合わせられるシート 12は、反射防止構造体と同一形状を転 写する方法によっても得ることができる。図 7に示すように、一対のローラーのうち、一 方のローラー面 13には、反射防止構造体の構造とは反転した形状が形成されている 。アクリル榭脂等のシートは、回転可能な一対のローラーにより案内されて、反射防 止構造体と同一の形状が転写される。これにより、反射防止構造体が連続的に形成 されたシートを得ることができる。なお、金型に形成される形状は反射防止構造体と は反転させた陥没形状に限られず、突出形状としてもよい。  The sheet 12 to be bonded to the optical member 5 can also be obtained by a method of transferring the same shape as the antireflection structure. As shown in FIG. 7, one of the roller surfaces 13 of the pair of rollers has a shape inverted from the structure of the antireflection structure. A sheet of acrylic resin or the like is guided by a pair of rotatable rollers, and the same shape as that of the antireflection structure is transferred. Thereby, it is possible to obtain a sheet on which the antireflection structure is continuously formed. The shape formed on the mold is not limited to the depressed shape inverted from the antireflection structure, but may be a protruding shape.
[0056] このように、本実施の形態に係る撮像装置において、光学部材の内周面には、入 射光の反射を防止する反射防止構造体を備えたシートが形成されて 、るので、内面 反射光の発生を防止することができる。したがって、ノイズ成分が低減された高品質 の全方位画像を得ることができる。  As described above, in the imaging device according to the present embodiment, the sheet provided with the anti-reflection structure for preventing the reflection of the incident light is formed on the inner peripheral surface of the optical member. Generation of reflected light can be prevented. Therefore, a high-quality omnidirectional image with reduced noise components can be obtained.
[0057] また本実施の形態におけるシートを用いることにより、平面状の光学部材だけでなく 、円筒形状等の曲面を有する光学部材にも容易に反射防止構造体を形成すること ができる。 [0058] なお、本実施の形態において、反射防止構造体が形成されたシートは、光学部材 の内周面の全面に貼り合わせられた力 これに限られない。例えば、光学部材の内 周面のうち、撮像装置側の半分の領域のみにシートを貼り合わしてもよい。この際、 例えば真空吸着機を用いてシート上の反射防止構造体が設けられていない部分を 吸着して貼り付け作業を行うことにより、光学部材の一部の領域にシートを貼り合わ せることができる。このように、撮像に寄与する入射光およびフレアやゴーストの原因 となる光が入射する領域にのみ、反射防止構造体を備えることにより、低コストで反射 防止構造体を備えた撮像装置を提供することができる。 Further, by using the sheet according to the present embodiment, the antireflection structure can be easily formed not only on a planar optical member but also on an optical member having a curved surface such as a cylindrical shape. [0058] In the present embodiment, the sheet on which the antireflection structure is formed is not limited to the force bonded to the entire inner peripheral surface of the optical member. For example, the sheet may be bonded only to a half area on the imaging device side of the inner peripheral surface of the optical member. At this time, the sheet can be attached to a partial area of the optical member by, for example, using a vacuum suction machine to adsorb a portion of the sheet on which the antireflection structure is not provided and perform the attaching operation. it can. As described above, by providing the antireflection structure only in the region where the incident light contributing to imaging and the light causing flare or ghost are incident, an imaging device having the antireflection structure at low cost is provided. be able to.
[0059] なお、実施の形態 1および 2にお 、て、光学部材には榭脂を用いた力 ガラスでもよ い。  [0059] In the first and second embodiments, the optical member may be a force glass using resin.
産業上の利用可能性  Industrial applicability
[0060] 本発明の撮像装置は、高画質の撮像画像が要望されて!、る、監視装置や移動型 ロボットの視覚センサ、車載撮像装置などに好適である。 The imaging device of the present invention is suitable for a monitoring device, a visual sensor of a mobile robot, an in-vehicle imaging device, and the like where a high-quality captured image is demanded.

Claims

請求の範囲 The scope of the claims
[1] 入射した光を集光し光学的な像を形成する集光光学系と前記集光光学系により形 成される光学的な像を電気的な画像信号に変換して出力する撮像素子とを含む撮 像光学ユニットに接続可能な円筒形状を有する光学部材であって、  [1] A condensing optical system that condenses incident light to form an optical image, and an imaging device that converts an optical image formed by the condensing optical system into an electric image signal and outputs the signal. An optical member having a cylindrical shape connectable to an imaging optical unit including:
所定の形状を有する構造単位が入射する光のうち撮像に寄与する光の最短波長よ りも小さいピッチで周期的にアレイ状に配列された反射防止構造体を前記光学部材 の側面の内周面に備えることを特徴とする、光学部材。  An anti-reflection structure that is periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among light incident on a structural unit having a predetermined shape is an inner peripheral surface of a side surface of the optical member. An optical member, comprising:
[2] 前記反射防止構造体は、  [2] The anti-reflection structure,
前記光学部材の内周面に透明材料力もなるシートと一体して形成されていること を特徴とする、請求項 1に記載の光学部材。  2. The optical member according to claim 1, wherein an inner peripheral surface of the optical member is formed integrally with a sheet having a transparent material strength.
[3] 前記光学部材は、少なくとも側面が透明材料力もなることを特徴とする、請求項 1に 記載の光学部材。  3. The optical member according to claim 1, wherein at least the side surface of the optical member also has a transparent material force.
[4] 前記光学部材の少なくとも一端部に曲面形状の反射面を有する反射ミラーをさらに 備え、  [4] The optical member further includes a reflecting mirror having a curved reflecting surface on at least one end of the optical member,
前記集光光学系は、前記反射ミラーにより反射された光を受光して光学的な像を 形成することを特徴とする、請求項 1に記載の光学部材。  2. The optical member according to claim 1, wherein the focusing optical system receives the light reflected by the reflection mirror and forms an optical image.
[5] 前記反射防止構造体の構造単位が、少なくともピッチ以上の高さを有することを特 徴とする、請求項 1に記載の光学部材。 5. The optical member according to claim 1, wherein the structural unit of the antireflection structure has a height of at least a pitch.
[6] 前記反射防止構造体の構造単位が、略錐状の突出形状及び Z又は略錐状の陥 没形状であることを特徴とする、請求項 1に記載の光学部材。 6. The optical member according to claim 1, wherein the structural units of the antireflection structure have a substantially conical protruding shape and a Z or substantially conical depressed shape.
[7] 前記反射防止構造体の構造単位が、略円形状、略矩形状、略正六角形状のいず れかが選択される突出形状及び Z又は陥没形状を有することを特徴とする、請求項[7] The structural unit of the anti-reflection structure has a protruding shape and a Z or a depressed shape selected from any of a substantially circular shape, a substantially rectangular shape, and a substantially regular hexagonal shape. Term
1に記載の光学部材。 2. The optical member according to 1.
[8] 前記シートと前記光学部材との最短波長に対する屈折率の差は、 0. 2以下である ことを特徴とする、請求項 2に記載の光学部材。  [8] The optical member according to claim 2, wherein a difference in refractive index between the sheet and the optical member with respect to a shortest wavelength is 0.2 or less.
[9] 前記シートと前記光学部材との最短波長に対する屈折率の差は、 0. 1以下である ことを特徴とする、請求項 8に記載の光学部材。 9. The optical member according to claim 8, wherein the difference between the refractive index of the sheet and the optical member with respect to the shortest wavelength is 0.1 or less.
[10] 被写体の光学的な像を電気的な画像信号として出力可能な撮像装置であって、 曲面形状の反射面を有する反射ミラーと、 [10] An imaging device capable of outputting an optical image of a subject as an electric image signal, A reflecting mirror having a curved reflecting surface;
前記反射面によって反射された光を受光して光学的な像を形成する集光光学系と 前記集光光学系により形成された光学的な像を電気的な画像信号に変換して出 力する撮像素子と、  A condensing optical system that receives the light reflected by the reflecting surface and forms an optical image, and converts an optical image formed by the condensing optical system into an electric image signal and outputs the electric image signal. An image sensor;
所定の形状を有する構造単位が入射する光のうち撮像に寄与する光の最短波長よ りも小さいピッチで周期的にアレイ状に配列された反射防止構造体を前記光学部材 の側面の内周面に備えることを特徴とする、撮像装置。  An anti-reflection structure that is periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among light incident on a structural unit having a predetermined shape is an inner peripheral surface of a side surface of the optical member. An imaging device, comprising:
[11] 所定の形状を有する構造単位が入射する光のうち撮像に寄与する光の最短波長よ りも小さいピッチで周期的にアレイ状に配列された反射防止構造体を備えた円筒形 状を有する光学部材の製造方法であって、 [11] A cylindrical unit having an anti-reflection structure that is periodically arranged in an array at a pitch smaller than the shortest wavelength of light contributing to imaging among the incident light of a structural unit having a predetermined shape. A method for producing an optical member having
前記反射防止構造体とは反転した形状を転写面に有する金型を用意する第 1工程 と、  A first step of preparing a mold having an inverted shape on the transfer surface with the antireflection structure,
用意された前記金型を熱プレスして前記反射防止構造体と等しい形状を前記光学 部材の内周面に転写する第 2工程とを備えることを特徴とする、光学部材の製造方 法。  A second step of hot-pressing the prepared mold and transferring the same shape as the anti-reflection structure to the inner peripheral surface of the optical member.
[12] 前記金型は、  [12] The mold is
前記反射防止構造体とは反転した形状を外周面に有する円筒状金型であり、 前記第 1工程は、  The anti-reflection structure is a cylindrical mold having an inverted shape on the outer peripheral surface, the first step,
前記円筒状金型を加熱加圧しながら、かつ同時に回転させて、前記反射防止構 造体と等 U、形状を前記光学部材の内周面に転写することを特徴とする、請求項 11 に記載の光学部材の製造方法。  The method according to claim 11, wherein the cylindrical mold is heated and pressurized and simultaneously rotated to transfer the shape of the anti-reflection structure and the like to the inner peripheral surface of the optical member. A method for manufacturing an optical member.
[13] 前記金型の前記転写面は、構造単位が略錐状の突出形状及び Z又は略錐状の 陥没形状を有することを特徴とする、請求項 11に記載の光学部材の製造方法。 13. The method for manufacturing an optical member according to claim 11, wherein the transfer surface of the mold has a structural unit having a substantially conical protruding shape and a Z or substantially conical depressed shape.
PCT/JP2005/008868 2004-05-17 2005-05-16 Optical member, imaging device using optical member, and method of producing optical member WO2005111668A1 (en)

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CN109541787B (en) * 2018-12-04 2020-10-16 湖北久之洋红外***股份有限公司 Non-refrigeration type dual-waveband panoramic staring imaging optical system

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