JP2006195327A

JP2006195327A - Optical element, its manufacturing method, lens unit using it and electronic equipment using it

Info

Publication number: JP2006195327A
Application number: JP2005008787A
Authority: JP
Inventors: Takaaki Koyo; 貴昭古用; Kazunari Nishihara; 和成西原
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2005-01-17
Filing date: 2005-01-17
Publication date: 2006-07-27

Abstract

<P>PROBLEM TO BE SOLVED: To prevent lowering of translucency of an optical element, a lens unit and electronic equipment or the like using the element. <P>SOLUTION: The optical element is equipped with a lens 4 and an optical filter 5 provided at least on one surface of the lens 4. Product of a refractive index and film thickness of the optical filter 5 is made to become smaller from a center of the lens 4 toward its outer periphery. Since optical path length in the optical filter 5 can be made equal both at a central part and at an outer peripheral part of the lens 4 thereby, wavelengths other than desired wavelength can be intercepted and only transmissivity of the desired wavelength can be kept high. Thus there is no need for providing a multilayer film and translucency can be raised as much. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、光学素子と、その製造方法と、それを用いたレンズユニットと、それを用いた電子機器に関するものである。 The present invention relates to an optical element, a manufacturing method thereof, a lens unit using the optical element, and an electronic apparatus using the optical unit.

従来この種の光学素子は、図４に示されるような構成を示していた。 Conventionally, this type of optical element has a configuration as shown in FIG.

図４において、レンズ１の上には反射防止膜２が蒸着等により成膜され、光学素子を形成していた。 In FIG. 4, an antireflection film 2 is formed on the lens 1 by vapor deposition or the like to form an optical element.

なお、この出願に関する先行技術文献情報としては、例えば、特許文献１が知られている。
特開２００３−８４１６８号公報 As prior art document information relating to this application, for example, Patent Document 1 is known.
JP 2003-84168 A

しかしながら、このような従来の光学素子を用いたレンズユニットでは、小型化が難しいことが問題となっていた。 However, the lens unit using such a conventional optical element has a problem that it is difficult to reduce the size.

すなわち、上記従来の構成において、レンズ１の表面に均一な厚さで反射防止膜２を形成していた。そのため、反射防止膜２における光路長が、図５（ａ）〜（ｃ）に示すごとくレンズ１の中心部と外周部とで異なるため、所望の波長以外の波長を持つ光が抑制できずに一部が透過し、逆に所望の波長を持つ光の透過率が下がってしまう。これを防ぐため、別に多層膜３をレンズ１裏面にも設けなければならず、透光性が低下するという課題があった。 That is, in the conventional configuration, the antireflection film 2 is formed on the surface of the lens 1 with a uniform thickness. Therefore, since the optical path length in the antireflection film 2 is different between the central portion and the outer peripheral portion of the lens 1 as shown in FIGS. 5A to 5C, light having a wavelength other than the desired wavelength cannot be suppressed. A part of the light is transmitted, and conversely, the transmittance of light having a desired wavelength is lowered. In order to prevent this, the multilayer film 3 must be separately provided on the back surface of the lens 1, which causes a problem that the translucency is lowered.

そこで本発明は、光学素子の透光性を高め、光学機器の特性を高めることを目的とする。 Therefore, an object of the present invention is to improve the translucency of an optical element and improve the characteristics of an optical device.

そして、この目的を達成するために本発明は、レンズと、このレンズの少なくとも一表面に設けた光学フィルタとを備え、この光学フィルタの屈折率と膜厚との積が、レンズの中心から外周に向けて小さくなる光学素子とした。 In order to achieve this object, the present invention includes a lens and an optical filter provided on at least one surface of the lens, and the product of the refractive index and the film thickness of the optical filter is from the center of the lens to the outer periphery. An optical element that becomes smaller toward the surface.

本発明の光学フィルタは、反射防止膜における光路長を、レンズの中心部と外周部で等しくすることができるため、所望の波長以外の波長を遮断し、且つ所望の波長の透過率のみを高く保つことができ、別に多層膜を設ける必要もなく、その分透光性を高めることができる。 In the optical filter of the present invention, since the optical path length in the antireflection film can be made equal between the central portion and the outer peripheral portion of the lens, wavelengths other than the desired wavelength are blocked, and only the transmittance of the desired wavelength is increased. Therefore, it is not necessary to provide a separate multilayer film, and the translucency can be increased.

（実施の形態１）
以下、本発明の実施の形態１における光学素子について図面を参照しながら説明する。 (Embodiment 1)
The optical element according to Embodiment 1 of the present invention will be described below with reference to the drawings.

図１に示すように、ガラス製あるいはプラスチック製のレンズ４の表面に光学フィルタ５を形成する方法としては、真空蒸着、スパッタなどが挙げられる。本実施の形態では真空蒸着の一種であるＦＢ蒸着を用いた。あらかじめ設置しておいた材料（図示せず）に電子銃を照射し、材料（図示せず）の温度を１５００℃〜２０００℃まで上昇させ気化させる。ここで、その材料（図示せず）としては酸化シリコン、フッ化マグネシウム、酸化アルミニウム、酸化タンタル、酸化チタンなどを用いることができるが、本実施の形態では酸化シリコンを用いた。その後、その気化した材料（図示せず）が上方に設置したレンズ４表面に付着することにより光学フィルタ５を形成することができるのだが、その際、図２に示すように、中心に行くに従って開口面積が大きくなるようなスリット６をレンズ４付近、蒸着面側に備え回転させておく。この時、この回転数を数十ｒｐｍ程度以上の高速回転にすることで、光学フィルタ５の蒸着量を、レンズ４中心を中心とする円周上において同一にすることができる。なお、本実施の形態ではスリット６を回転させたが、レンズ４を回転させてもよい。ただし、スリット６を回転させる方がより高精度な蒸着ができるため好ましい。 As shown in FIG. 1, examples of the method for forming the optical filter 5 on the surface of the glass or plastic lens 4 include vacuum deposition and sputtering. In this embodiment, FB vapor deposition, which is a kind of vacuum vapor deposition, is used. A previously installed material (not shown) is irradiated with an electron gun, and the temperature of the material (not shown) is raised to 1500 ° C. to 2000 ° C. and vaporized. Here, silicon oxide, magnesium fluoride, aluminum oxide, tantalum oxide, titanium oxide, or the like can be used as the material (not shown), but silicon oxide is used in this embodiment mode. Thereafter, the vaporized material (not shown) adheres to the surface of the lens 4 placed above, whereby the optical filter 5 can be formed. At this time, as shown in FIG. A slit 6 with a large opening area is provided in the vicinity of the lens 4 and on the vapor deposition surface side, and is rotated. At this time, the amount of vapor deposition of the optical filter 5 can be made equal on the circumference centered on the center of the lens 4 by setting the number of rotations to a high speed of about several tens rpm. Although the slit 6 is rotated in the present embodiment, the lens 4 may be rotated. However, it is preferable to rotate the slit 6 because highly accurate vapor deposition can be performed.

上記方法により、光学フィルタ５の膜厚を、レンズ４の中心から外周に向けて小さくし、且つレンズ４中心を中心とする円周上において同一とすることができる。 By the above method, the film thickness of the optical filter 5 can be reduced from the center of the lens 4 toward the outer periphery, and can be the same on the circumference centered on the center of the lens 4.

このような構成により、光学フィルタ５における光路長を、図５（ｄ）〜（ｆ）に示すごとくレンズ４の中心部と外周部とにおいて等しくすることができるため、所望の波長以外の波長を持つ光を遮断し、且つ所望の波長を持つ光を減衰させない。よって、別に多層膜（図示せず）等をレンズ４裏面に設ける必要が無いため、透光性の低下が防止できる。 With such a configuration, the optical path length in the optical filter 5 can be made equal in the central portion and the outer peripheral portion of the lens 4 as shown in FIGS. It blocks the light it has and does not attenuate the light with the desired wavelength. Therefore, it is not necessary to separately provide a multilayer film (not shown) or the like on the back surface of the lens 4, so that a decrease in translucency can be prevented.

なお、本実施の形態では凸型のレンズ４を例に挙げたが、凹レンズでも同様の方法で同様の効果を得ることができる。 In the present embodiment, the convex lens 4 is taken as an example, but the same effect can be obtained by a similar method even with a concave lens.

（実施の形態２）
以下、本発明の実施の形態２における光学素子について図面を参照しながら説明する。 (Embodiment 2)
Hereinafter, an optical element according to Embodiment 2 of the present invention will be described with reference to the drawings.

図１に示すように、ガラス製のレンズ４の表面に光学フィルタ５を形成する方法としては、真空蒸着、スパッタ、ＥＢ蒸着などが挙げられる。本実施の形態ではＥＢ蒸着を用いた。あらかじめ設置しておいた材料（図示せず）に電子銃を照射し、材料（図示せず）の温度を１５００℃〜２０００℃まで上昇させ気化させる。ここで、その材料（図示せず）としては酸化シリコン、フッ化マグネシウム、酸化アルミニウム、酸化タンタル、酸化チタンなどを用いることができるが、本実施の形態では酸化シリコンを用いた。その後、その気化した材料（図示せず）が上方に設置したレンズ４表面に付着することにより表面に均一な膜厚を持った光学フィルタ５を形成する。この時、所望の波長よりもやや短波長側の光を透過するような膜厚に設定しておく。 As shown in FIG. 1, examples of a method for forming the optical filter 5 on the surface of the glass lens 4 include vacuum deposition, sputtering, and EB deposition. In this embodiment, EB deposition is used. A previously installed material (not shown) is irradiated with an electron gun, and the temperature of the material (not shown) is raised to 1500 ° C. to 2000 ° C. and vaporized. Here, silicon oxide, magnesium fluoride, aluminum oxide, tantalum oxide, titanium oxide, or the like can be used as the material (not shown), but silicon oxide is used in this embodiment mode. Thereafter, the vaporized material (not shown) adheres to the surface of the lens 4 placed above, thereby forming an optical filter 5 having a uniform film thickness on the surface. At this time, the film thickness is set so as to transmit light slightly shorter than the desired wavelength.

次に、図３に示すように、ヒータ７を光学フィルタ５中心部に当接させ、ヒータ７を２５０℃〜３５０℃に保持する。そうすることにより、光学フィルタ５中心部の光路長を大きくし、透過する波長を長波長側にシフトさせることができる。ここで、２５０℃〜３５０℃としたのは、高温すぎるとレンズ４形状が変化してしまうということ、また、低温すぎると光路長を変化させづらいということによる。 Next, as shown in FIG. 3, the heater 7 is brought into contact with the center of the optical filter 5, and the heater 7 is held at 250 ° C. to 350 ° C. By doing so, the optical path length at the center of the optical filter 5 can be increased, and the transmitted wavelength can be shifted to the longer wavelength side. Here, the reason why the temperature is set to 250 ° C. to 350 ° C. is that the shape of the lens 4 changes if the temperature is too high, and that the optical path length is difficult to change if the temperature is too low.

ここで、ヒータ８を光学フィルタ５外周部に当接させ、２００℃未満に保っておく。これは、ヒータ８の熱が光学フィルタ５中心部から外周部へと伝わるのを防ぐためである。 Here, the heater 8 is brought into contact with the outer peripheral portion of the optical filter 5 and kept at less than 200 ° C. This is to prevent the heat of the heater 8 from being transmitted from the central portion of the optical filter 5 to the outer peripheral portion.

このような構成により、光学フィルタ５における光路長を、図５（ｄ）〜（ｆ）に示すごとくレンズ４の中心部と外周部とにおいて等しくすることが可能となるため、所望の波長以外の波長を持つ光を遮断し、且つ所望の波長を持つ光を減衰させない。よって、別に多層膜（図示せず）等をレンズ４裏面に設ける必要が無いため、透光性の低下を防止できる。 With such a configuration, the optical path length in the optical filter 5 can be made equal in the central portion and the outer peripheral portion of the lens 4 as shown in FIGS. It blocks light having a wavelength and does not attenuate light having a desired wavelength. Therefore, it is not necessary to separately provide a multilayer film (not shown) or the like on the back surface of the lens 4, so that a decrease in translucency can be prevented.

なお、本実施の形態では１回のみの加熱としたが、複数回加熱と冷却を繰り返す方法を用いるとなお良い。例えば、まず光学フィルタ５の中央部分を２５０℃程度で加熱すると同時に外周部を２００℃未満に保持し、その後常温まで冷却し、次に光学フィルタ５の中央部の中心部を３００℃程度で加熱しながら外周部を２００℃未満に保持するという方法である。この方法であれば、部分部分の特性変化量をコントロールしやすいという利点がある。ここで、一度高温で加熱した部分はそれよりも低い温度では特性変化しないため、この例において中央部分を２５０℃程度で加熱、中央部の中心部を３００℃で加熱したように、低温から高温へと段階を踏むことが好ましい。 Note that although heating is performed only once in this embodiment mode, it is more preferable to use a method of repeating heating and cooling a plurality of times. For example, first, the central portion of the optical filter 5 is heated at about 250 ° C., and at the same time the outer peripheral portion is kept below 200 ° C., then cooled to room temperature, and then the central portion of the central portion of the optical filter 5 is heated at about 300 ° C. However, it is a method of keeping the outer peripheral portion below 200 ° C. This method has an advantage that it is easy to control the characteristic change amount of the partial portion. Here, since the part once heated at a high temperature does not change its characteristics at a lower temperature, in this example, the central part is heated at about 250 ° C., and the central part at 300 ° C. is heated at a low temperature to a high temperature. It is preferable to go through the steps.

本発明の光学素子は、フィルター特性と透光性にすぐれ、各種レンズユニットや電子機器などにおいて有用である。 The optical element of the present invention is excellent in filter characteristics and translucency, and is useful in various lens units and electronic devices.

（ａ）本発明の光学素子の斜視図、（ｂ）本発明の光学素子の断面図(A) The perspective view of the optical element of this invention, (b) Sectional drawing of the optical element of this invention （ａ）本発明の実施の形態１におけるスリットとレンズを示す斜視図、（ｂ）本発明の実施の形態１におけるスリットとレンズを示す正面図(A) The perspective view which shows the slit and lens in Embodiment 1 of this invention, (b) The front view which shows the slit and lens in Embodiment 1 of this invention 本発明の実施の形態２におけるヒータとレンズを示す断面図Sectional drawing which shows the heater and lens in Embodiment 2 of this invention 従来の光学素子の断面図Sectional view of a conventional optical element （ａ）〜（ｃ）は従来の光学素子の断面図、特性図、特性図、（ｄ）〜（ｆ）は本発明の一実施形態の光学素子の断面図、特性図、特性図(A)-(c) is sectional drawing, characteristic figure, characteristic figure of the conventional optical element, (d)-(f) is sectional drawing, characteristic figure, characteristic figure of the optical element of one Embodiment of this invention.

Explanation of symbols

４レンズ
５光学フィルタ
６スリット
７ヒータ
８ヒータ 4 Lens 5 Optical filter 6 Slit 7 Heater 8 Heater

Claims

An optical element comprising a lens and an optical filter provided on at least one surface of the lens, wherein the product of the refractive index and the film thickness of the optical filter decreases from the center of the lens toward the outer periphery.

An optical element, wherein the optical filter according to claim 1 is an antireflection film.

An optical element, wherein the optical filter according to claim 1 is an infrared cut filter.

The optical element according to claim 1, wherein the product of the refractive index and the film thickness of the optical filter is the same on a circumference centered on the lens center.

A lens unit using the optical element according to claim 1.

An electronic apparatus using the optical element according to claim 1.

A method of manufacturing an optical element, comprising: a slit having an opening area that increases toward the center in front of an optical filter vapor deposition surface of a lens; and vapor deposition while rotating at least one of the slit and the lens.

An optical filter is deposited on the lens surface, and then the center of the optical filter is heated at a first temperature, and at the same time, the outer periphery of the optical filter is maintained at a second temperature lower than the first temperature. Device manufacturing method.

Depositing an optical filter on the lens surface, and then heating the central portion of the optical filter at a first temperature, while maintaining the outer periphery of the optical filter at a second temperature lower than the first temperature; Thereafter, the entire lens is cooled at a third temperature lower than the second temperature, and thereafter, the central portion of the central portion of the optical filter is heated at a fourth temperature higher than the first temperature. A method for manufacturing an optical element, wherein the outer peripheral portion of the optical filter is held at a fifth temperature lower than the fourth temperature.