WO2015152161A1 - Collimator lens - Google Patents

Collimator lens Download PDF

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Publication number
WO2015152161A1
WO2015152161A1 PCT/JP2015/059949 JP2015059949W WO2015152161A1 WO 2015152161 A1 WO2015152161 A1 WO 2015152161A1 JP 2015059949 W JP2015059949 W JP 2015059949W WO 2015152161 A1 WO2015152161 A1 WO 2015152161A1
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Prior art keywords
light source
collimator lens
lens
less
light
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PCT/JP2015/059949
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French (fr)
Japanese (ja)
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保貴 寺嶋
照夫 山下
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Hoya株式会社
保貴 寺嶋
照夫 山下
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Application filed by Hoya株式会社, 保貴 寺嶋, 照夫 山下 filed Critical Hoya株式会社
Priority to JP2016511887A priority Critical patent/JP6647195B2/en
Priority to CN201580014677.3A priority patent/CN106104351A/en
Publication of WO2015152161A1 publication Critical patent/WO2015152161A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/30—Collimators

Definitions

  • the present invention relates to a collimator lens, and more particularly to a collimator lens used to convert light from a light source into parallel light.
  • a collimator lens that is a lens that converts a divergent light beam from a light source such as a laser light source into parallel light is known.
  • collimator lens for example, a lens incorporated in an optical system of a projection type image display apparatus using a laser light source is known (Patent Documents 1 and 2).
  • the chromatic aberration characteristics are improved in order to suppress the change of the working distance (working distance) accompanying the temperature rise.
  • This lens is intended for light with a wavelength of 375 nm or more and 750 nm or less from the laser light source, and has a numerical aperture of 0.2 or more and 0.75 or less.
  • the lens thickness is D, and the focal length of the lens When D is f, D / f> 0.85 is satisfied, and (2) when Abbe number is ⁇ d, ⁇ d> 57 is satisfied.
  • the light source side surface (first surface) and the emission side surface (second surface) of the lens are convex, and at least these A diffractive structure is provided on one surface.
  • the collimator lens when used in a projection-type image display device, has a main function of converting a divergent light beam emitted from a light source such as a laser light source into a parallel light beam.
  • a light source such as a laser light source
  • image display devices have been required to improve brightness.
  • lens transmittance as well as an increase in NA for a collimator lens used in an optical system of an image display device.
  • the present invention has been made for such a problem, and an object of the present invention is to provide a collimator lens having a high NA and an improved lens transmittance.
  • a collimator lens made of a glass material that converts a light beam having a wavelength of 380 nm to 700 nm emitted from a light source into a parallel light beam, On the opposite side of the surface facing the light source, has a surface provided with a convex portion, The numerical aperture NA is 0.6 or more, The ratio t / f of the center lens thickness t to the focal length f is 1.3 or less, The maximum surface angle of the surface provided with the convex portion is 65 ° or less, The glass material has a refractive index nd of 1.59 or more, The glass material has a total content of TiO 2 , WO 3 , Nb 2 O 5 , Bi 2 O 3 of 0 to 40 wt%, A collimator lens is provided.
  • FIG. 1 is a schematic side view showing the shape of a collimator lens 1 according to a preferred embodiment of the present invention.
  • the collimator lens 1 according to this embodiment is a glass lens used for converting a light beam having a wavelength of 380 nm to 700 nm emitted from a light source such as a laser device into parallel light. Specifically, for example, it is used in an optical system of a projection type image display apparatus such as a liquid crystal projector.
  • the collimator lens 1 is a single lens and has a so-called biconvex lens shape in which an annular edge portion is provided on the outer edge. Specifically, both surfaces of the surface (light source side surface) 2 facing the light source S and the surface (exit side surface) 4 opposite to the light source side surface 2 in use are provided with convex shapes. In this embodiment, both the light source side surface 2 and the emission side surface 4 are spherical. Further, the collimator lens 1 is provided with a flange-shaped edge portion 6 at the outer edge portion. The edge portion 6 is useful for fixing to the lens fixing member in the apparatus when incorporated in a projection type image display apparatus or the like, but may not be provided.
  • the collimator lens 1 preferably has a maximum surface angle of the emission side surface 2 of 65 ° or less.
  • the maximum surface angle is more preferably 55 ° or less, and further preferably 50 ° or less.
  • the surface angle ⁇ means an angle formed by a normal line at one position within the effective diameter on the lens surface and the lens central axis Z.
  • the lens formability such as press moldability and grinding or polishing processability is improved, and the lens shape can be easily evaluated.
  • the collimator lens 1 preferably has t / f (t: center lens thickness, f: focal length) of 1.3 or less. If 1.3 is exceeded, a practically sufficient working distance (working distance) (WD), for example, a WD of 1 mm or more cannot be secured.
  • the t / f is more preferably 1.20 or less.
  • t / f is preferably 0.3 to 1.3, more preferably 0.3 to 0.85, and even more preferably 0.3 to 0.80. It is.
  • the upper and lower limits of t / f will be described in detail.
  • the upper limit of t / f is preferable in order of 1.20 or less, 1.00 or less, 0.80 or less, and 0.70 or less from the viewpoint of securing WD.
  • the lower limit of t / f is preferable in the order of 0.30 or more, 0.40 or more, and 0.50 or more from the viewpoint of lens processability.
  • working distance (WD) means, for example, as shown in FIG. 1, the light source S, specifically, a point-like light emitting portion in the light source. And the distance between the parts closest to the light source on the light source side surface 2 of the collimator lens 1.
  • the numerical aperture NA of the collimator lens 1 is 0.6 or more.
  • the upper limit of NA is preferably 0.9 or less, for example, in order to ensure WD and make the maximum surface angle 65 ° or less.
  • the upper limit of NA can be 0.85 or less, 0.80 or less, or 0.75 or less.
  • the lower limit of NA can be greater than 0.6 (0.6 ⁇ ), 0.65 or more, 0.70 or more, or 0.71 or more.
  • the collimator lens 1 As a method for manufacturing the collimator lens 1, there are a precision press molding, a grinding process, a polishing process, and the like using a glass material.
  • a material for forming the collimator lens 1 for example, glass materials (glass I and glass II) having the following two types of composition systems can be used.
  • Glass I is a glass material containing B 2 O 3 and at least one selected from rare earth oxides such as La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 .
  • Glass II is a glass material containing P 2 O 5 and at least one selected from Nb 2 O 5 , WO 3 , TiO 2 , and Bi 2 O 3 .
  • the glass material forming the collimator lens 1 preferably has a total content of TiO 2 , WO 3 , Nb 2 O 5 and Bi 2 O 3 in glass I or glass II of 0 to 40 wt%.
  • the total content of TiO 2 , WO 3 , Nb 2 O 5 , and Bi 2 O 3 is more preferably 0 to 28 wt%, and still more preferably 0 to 16 wt% from the viewpoint of improving pressability.
  • TiO 2 + WO 3 + Nb 2 O 5 + Bi 2 O 3 / ((total content of rare earth oxides) + Ta 2 O 5 ) ⁇ 1.1 is preferred. This ratio is more preferably 0.9 or less, and still more preferably 0.5 or less.
  • the glass material forming the collimator lens 1 has a refractive index nd of 1.59 or more.
  • the refractive index nd is more preferably 1.68 or more, further preferably 1.75 or more, and further preferably 1.80 or more. This is because the maximum surface angle of the exit side surface can be reduced by using such a refractive index nd.
  • the upper limit of the Abbe number of the glass material forming the collimator lens 1 is preferably 57 or less from the viewpoint of maintaining a high refractive index with a refractive index nd of 1.59 or more. Furthermore, the upper limit of the Abbe number is more preferably 50 or less or 45 or less from the viewpoint of increasing the refractive index.
  • the lower limit of the Abbe number is not particularly limited, but may be 20 or more.
  • the glass material forming the collimator lens 1 preferably has a glass transition temperature Tg ⁇ 630 ° C. from the viewpoint of suitability for precision press molding.
  • the glass material forming the collimator lens 1 contributes to a decrease in Tg, so that the ZnO content is preferably 3 wt% or more, more preferably 8 wt% or more, and even more preferably 10 wt% or more.
  • the total content of WO 3 , Nb 2 O 5 , and Bi 2 O 3 is suppressed to 40 wt% or less, so that the lens transmittance is improved and the laser light source emits light Light utilization efficiency can be increased.
  • the collimator lens 1 since the utilization efficiency of the emitted light from the laser light source is enhanced, the brightness of the projected image in the projection type image display apparatus is improved.
  • a laser light source laser diode (LD)), particularly a green laser, has a problem of increasing its output, but it is not easy to increase its output.
  • the transmittance of the collimator lens is improved, the brightness of the projected image is improved even when the laser output is low, and a sufficient projected image can be obtained. Furthermore, low power consumption can be achieved.
  • FIG. 2 is a block diagram schematically showing a configuration of a light source unit (illumination optical system) 10 of a projection type image display apparatus (for example, a liquid crystal projector) in which the collimator lens 1 of this embodiment is incorporated.
  • a light source unit illumination optical system
  • a projection type image display apparatus for example, a liquid crystal projector
  • the light source unit 10 includes three laser devices R, G, and B that respectively generate red light, green light, and blue light, and each laser (LD) device R, G , B are arranged on the downstream side of the collimator lens 1 respectively.
  • the collimator lens 1 converts divergent light emitted from each of the laser devices R, G, and B into parallel light.
  • the red light, the blue light, and the green light converted into parallel lights by the respective collimator lenses 1 are combined by a combining optical system 12 including a dichroic prism and transmitted to the projection optical system.
  • FIG. 3 is a block diagram schematically showing a configuration of a light source unit (illumination optical system) 14 of another projection type image display apparatus (for example, a liquid crystal projector) in which the collimator lens 1 of this embodiment is incorporated.
  • a light source unit illumination optical system
  • another projection type image display apparatus for example, a liquid crystal projector
  • the light source unit 14 includes a monochromatic light source (LD) 16 such as a near-ultraviolet laser device, and the collimator lens 1 is disposed on the downstream side of the monochromatic light source 16.
  • the collimator lens 1 converts the light emitted from the monochromatic light source 16 into parallel light.
  • the light source unit 14 includes a conversion unit 18 having three parts that convert near-ultraviolet light into red light, blue light, and green light.
  • this conversion unit 18 three parts that convert red light, blue light, and green light are sequentially arranged on the optical path of the near ultraviolet light, and the near ultraviolet light is red light, blue light, and It will be converted into green light. Then, these red light, blue light, and green light are sequentially sent to the projection optical system.
  • the collimator lens 1 of this embodiment is a collimator lens having a so-called biconvex shape, but the present invention is not limited to such a biconvex shape collimator lens.
  • the collimator lens of the present invention may have a surface provided with a convex portion on the opposite side to the surface facing the light source, and further have a predetermined condition.
  • it may have an outer shape as shown in FIGS. That is, as shown in FIG. 4, even a plano-convex lens 104 having no edge portion, a surface facing the light source S is a flat surface, and a surface 4 opposite to the surface 2 facing the light source S is a convex surface. Good. By flattening the surface facing the light source, it is advantageous in terms of securing working distance (WD) and lens processability. Further, the problem of decentering between the surface 2 facing the light source and the surface 4 on the opposite side does not occur.
  • WD working distance
  • a biconvex 105 lens that does not include the edge portion, the surface facing the light source S is a convex surface, and the surface 4 opposite to the surface 2 facing the light source S is also a convex surface. But you can.
  • a convex meniscus lens 106 that does not include an edge portion, the surface 2 facing the light source S is a concave surface, and the surface 4 opposite to the surface facing the light source S is a convex surface. But you can.
  • both the surface 2 facing the light source and the opposite surface 4 are spherical, but one or both of these surfaces may be aspherical.
  • the convex surface 4A opposite to the surface facing the light source spherical than the paraxial radius of curvature (R 0) of the (dashed), the paraxial curvature radius near the radius of curvature (R 1 )
  • the radius of curvature increases from the lens central axis Z toward the periphery (lens end 1a).
  • the paraxial radius of curvature refers to the radius of curvature on the central axis of the lens.
  • the convex surface of the surface opposite to the surface facing the light source may be an aspheric surface, and the convex surface or concave surface of the surface facing the light source may be an aspheric surface. This further improves the aberration characteristics.
  • Example 4 For example, a glass material of Example 4 described later is used, and an aspherical lens having the following specifications may be used.
  • Table 1 shows the constituents (compositions) of the glass material used to determine the maximum surface angle dependency of the lens transmittance on the exit side surface 4 in the lens shape of FIG.
  • FIG. 8 shows the relationship between the maximum surface angle of the exit side of the lens (exit side 4 in FIG. 1) and the transmittance of the lens (that is, the dependency of the transmittance on the maximum exit surface angle of the lens). ).
  • t / f is 1.3 or less.
  • FIG. 8 shows lens transmittances for NAs of 0.6, 0.65, and 0.71 at a wavelength of 430 nm (blue) for each glass material shown in Table 1 below.
  • the data of wavelength 530nm (green) and wavelength 650nm (red) are not described, generally the internal transmittance
  • lens characteristics were examined using the lens transmittance at a wavelength in this wavelength region (430 nm) as an index of lens transmittance.
  • the plot of the area surrounded by the dotted line is an embodiment of the present invention.
  • the lens transmittance on the vertical axis in FIG. 8 is normalized with the maximum value being 1. As shown in FIG. 8, the lens transmittance is good when the maximum surface angle is 55 ° or less, but deteriorates rapidly when it exceeds 65 °.
  • the data at wavelengths of 530 nm and 650 nm also showed the same tendency as the wavelength of 430 nm in FIG.
  • the lens transmittance is greatly different between the central portion and the peripheral portion. Therefore, in the parallel light converted by the collimator lens, the light passing through the central portion of the collimator lens and the center A luminance difference is produced between the light that has passed through the peripheral part of the part.
  • the upper limit of the maximum surface angle is preferably 65 ° or less, 60 ° or less, and 55 ° or less.
  • the lower limit of the maximum surface angle is preferably set to 20 ° or more from the viewpoint of setting NA to 0.6 or more.
  • Table 1 shows the index of the maximum surface angle and lens transmittance of each glass material.
  • the maximum surface angle is indicated by ⁇ when it is 65 ° or less from the result of FIG. 8, and by ⁇ when it exceeds 65 °.
  • Lens transmissivity is indicated by ⁇ ⁇ ⁇ as an index.
  • ⁇ is grade A (0.985 or more)
  • ⁇ is grade B (0.970 or more and less than 0.985)
  • x is grade C (less than 0.970).
  • the values in the parentheses are values obtained by normalizing the lens transmittance.
  • a glass material that satisfies both the maximum surface angle requirement and the lens transmittance index is shown as an example, and a glass material that does not satisfy the index is shown as a comparative example.
  • the maximum face angle is 65 ° or less
  • nd 1.59 or more
  • the total content of TiO 2 , WO 3 , Nb 2 O 5 , Bi 2 O 3 It can be seen that good lens transmittance characteristics can be obtained by suppressing the content to 40 wt% or less.
  • the glass material of Comparative Example 1 does not satisfy the requirement of the maximum surface angle.
  • Table 1 also shows that the glass material of Comparative Example 2 having a large total content of TiO 2 , WO 3 , Nb 2 O 5 , and Bi 2 O 3 in the glass has insufficient lens transmittance. These metal ions in the glass are considered to have a large ultraviolet absorption and deteriorate the lens transmittance.
  • the collimator lens 1 of the first embodiment is a collimator lens made of a glass material that converts a light beam having a wavelength of 380 nm to 700 nm emitted from a light source S into a parallel light beam.
  • the collimator lens 1 has a surface 4 provided with a convex portion on the opposite side to the surface 2 facing the light source S.
  • the numerical aperture NA is 0.6 or more
  • t / f is 1.3 or less (t: central lens thickness, f: focal length).
  • the maximum surface angle ⁇ 65 ° of the surface 4 provided with the convex portions is not more than 65 °.
  • the glass material forming the collimator lens 1 has a refractive index nd of 1.59 or more and a total content of TiO 2 , WO 3 , Nb 2 O 5 and Bi 2 O 3 is 0 to 40 wt%.
  • the convex portion provided on the surface 4 opposite to the surface facing the light source S can be an aspherical surface.
  • the surface facing the light source S may be a flat surface.
  • a convex portion is provided on the surface facing the light source S.
  • the convex portion provided on the surface facing the light source may be an aspherical surface.
  • the present invention may have a configuration in which a concave portion is provided on the surface facing the light source S, like the collimator lens 106 of the embodiment shown in FIG.
  • the light source S may be a light source used in an illumination optical system.
  • the illumination optical system may be an illumination optical system of a projection type image display apparatus.
  • the light source S may be a laser light source.
  • the present invention may be an illumination optical system using the collimator lenses summarized above. Furthermore, the present invention may be a projection type image display apparatus provided with such an illumination optical system.
  • Collimator lens 2 Light source side surface 4: Emission side surface S: Light source t: Center lens thickness f: Focal length

Abstract

　The purpose of the present invention is to provide a collimator lens having a high NA, and improved lens transmittance. According to the present invention, there is provided a collimator lens (1) comprising a glass material, for converting light rays of 380 to 700 nm wavelength outputted from a light source (S) into a parallel beam, wherein the opposite side from the surface facing the light source has a surface provided with a protruding portion; the numerical aperture (NA) is 0.6 or above; the ratio (t/f) of the center lens thickness to the focal distance (f) is 1.3 or below; the maximum surface angle of the surface provided with the protruding portion is 65° or less; the refractive index (nd) is 1.59 or greater; and the total content of TiO2, WO3, Nb2O5, and Bi2O13 of the glass material is 0-40 wt%.

Description

コリメータレンズCollimator lens
　本発明は、コリメータレンズに関連し、詳細には、光源からの光線を平行光に変換するために使用されるコリメータレンズに関連する。 The present invention relates to a collimator lens, and more particularly to a collimator lens used to convert light from a light source into parallel light.
　レーザ光源等の光源からの発散光束を平行光に変換するレンズであるコリメータレンズが知られている。 A collimator lens that is a lens that converts a divergent light beam from a light source such as a laser light source into parallel light is known.
　このようなコリメータレンズとしては、例えば、レーザ光源を用いた投射型画像表示装置の光学系に組み込まれるものが知られている（特許文献１、２）。 As such a collimator lens, for example, a lens incorporated in an optical system of a projection type image display apparatus using a laser light source is known (Patent Documents 1 and 2).
　特許文献１のコリメータレンズでは、温度上昇に伴う作動距離（ワーキングディスタンス）の変化を抑えるために色収差特性が改善されている。そして、このレンズは、レーザ光源からの波長が３７５ｎｍ以上７５０ｎｍ以下の光を対象とし、開口数が０．２以上０．７５以下であり、（１）レンズの厚さをＤ、レンズの焦点距離をｆとしたとき、Ｄ／ｆ＞０．８５が成立し、且つ（２）アッベ数をνｄとしたとき、νｄ＞５７が成立することを特徴としている。 In the collimator lens of Patent Document 1, the chromatic aberration characteristics are improved in order to suppress the change of the working distance (working distance) accompanying the temperature rise. This lens is intended for light with a wavelength of 375 nm or more and 750 nm or less from the laser light source, and has a numerical aperture of 0.2 or more and 0.75 or less. (1) The lens thickness is D, and the focal length of the lens When D is f, D / f> 0.85 is satisfied, and (2) when Abbe number is νd, νd> 57 is satisfied.
　また、特許文献２のコリメータレンズでは、コリメートされた平行光の像面スポットの増大を防ぐために、レンズの光源側面（第１面）及び射出側面（第２面）を凸形状とし、これらの少なくとも一方の面に回折構造が設けられている。 Further, in the collimator lens of Patent Document 2, in order to prevent an increase in the image plane spot of collimated parallel light, the light source side surface (first surface) and the emission side surface (second surface) of the lens are convex, and at least these A diffractive structure is provided on one surface.
国際公開ＷＯ２０１０／１１６８６２International Publication WO2010 / 116862 特開２０１１－１４５３８７号公報JP 2011-145387 A
　例えば、投影型画像表示装置に用いられる場合、コリメータレンズは、レーザ光源等の光源から射出する発散光束を平行光束に変換することを主な機能とする。近年、投影画像の大型化や高精細化等の要求に伴い、画像表示装置に輝度向上が求められている。これに伴い、画像表示装置の光学系に用いられるコリメータレンズに対して、高ＮＡ化とともに、レンズ透過率の向上が求められている。 For example, when used in a projection-type image display device, the collimator lens has a main function of converting a divergent light beam emitted from a light source such as a laser light source into a parallel light beam. In recent years, with the demand for larger projection images and higher definition, image display devices have been required to improve brightness. Along with this, there has been a demand for an improvement in lens transmittance as well as an increase in NA for a collimator lens used in an optical system of an image display device.
　本発明はこのような課題に対してなされたものであり、高ＮＡ化とともに、レンズ透過率が向上したコリメータレンズを提供することを目的とする。 The present invention has been made for such a problem, and an object of the present invention is to provide a collimator lens having a high NA and an improved lens transmittance.
　本発明によれば、
　光源から射出された波長３８０ｎｍ～７００ｎｍの光線を平行光束に変換する、ガラス材料からなるコリメータレンズであって、
　前記光源に対向する面と反対側に、凸部が設けられた面を有し、
　開口数ＮＡが０．６以上であり、
　焦点距離ｆに対する中心レンズ厚ｔの割合ｔ／ｆが１．３以下であり、
　前記凸部が設けられた面の最大面角度が６５°以下であり、
　前記ガラス材料は屈折率ｎｄが１．５９以上であり、
　前記ガラス材料のＴｉＯ2、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量が０～４０ｗｔ％である、
　コリメータレンズが提供される。 According to the present invention,
A collimator lens made of a glass material that converts a light beam having a wavelength of 380 nm to 700 nm emitted from a light source into a parallel light beam,
On the opposite side of the surface facing the light source, has a surface provided with a convex portion,
The numerical aperture NA is 0.6 or more,
The ratio t / f of the center lens thickness t to the focal length f is 1.3 or less,
The maximum surface angle of the surface provided with the convex portion is 65 ° or less,
The glass material has a refractive index nd of 1.59 or more,
The glass material has a total content of TiO 2 , WO 3 , Nb 2 O 5 , Bi 2 O 3 of 0 to 40 wt%,
A collimator lens is provided.
　本発明によれば、高ＮＡ化とともに、レンズ透過率が向上したコリメータレンズが提供される。 According to the present invention, it is possible to provide a collimator lens having an improved lens transmittance as well as an increase in NA.
本発明の好ましい実施形態のコリメータレンズの形状を示す概略的な側面図である。It is a schematic side view which shows the shape of the collimator lens of preferable embodiment of this invention. 図１のコリメータレンズが組み込まれた投影型画像表示装置の光源部の構成を概略的に示すブロック図である。It is a block diagram which shows schematically the structure of the light source part of the projection type image display apparatus incorporating the collimator lens of FIG. 図１のコリメータレンズが組み込まれた他の投影型画像表示装置の光源部の構成を概略的に示すブロック図である。It is a block diagram which shows roughly the structure of the light source part of the other projection type image display apparatus incorporating the collimator lens of FIG. 本発明の他の好ましい実施態様のコリメータレンズの形状を示す概略的な側面図である。It is a schematic side view which shows the shape of the collimating lens of the other preferable embodiment of this invention. 本発明の別の好ましい実施態様のコリメータレンズの形状を示す概略的な側面図である。It is a schematic side view which shows the shape of the collimating lens of another preferable embodiment of this invention. 本発明の更に別の好ましい実施態様のコリメータレンズの形状を示す概略的な側面図である。It is a schematic side view which shows the shape of the collimator lens of another preferable embodiment of this invention. 本発明のコリメータレンズで用いられる非球面の一例の構成を説明するための図面である。It is drawing for demonstrating the structure of an example of the aspherical surface used with the collimator lens of this invention. 本発明のＮＡ０．６以上のレンズにおける、レンズの射出側面の最大面角度とレンズの透過率の関係を示す図面である。It is drawing which shows the relationship between the maximum surface angle of the exit side of a lens, and the transmittance | permeability of a lens in the lens of NA0.6 or more of this invention.
　以下、本発明の好ましい実施形態を図面に沿って説明する。図１は、本発明の好ましい実施態様のコリメータレンズ１の形状を示す概略的な側面図である。本実施態様のコリメータレンズ１は、レーザ装置等の光源から射出される波長３８０ｎｍ乃至７００ｎｍの光線を平行光に変換するために使用されるガラスレンズである。具体的には、例えば、液晶プロジェクタ等の投影型画像表示装置の光学系で使用される。 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view showing the shape of a collimator lens 1 according to a preferred embodiment of the present invention. The collimator lens 1 according to this embodiment is a glass lens used for converting a light beam having a wavelength of 380 nm to 700 nm emitted from a light source such as a laser device into parallel light. Specifically, for example, it is used in an optical system of a projection type image display apparatus such as a liquid crystal projector.
　図１に示されているように、コリメータレンズ１は、単レンズであって、外縁に環状のコバ部が設けられた所謂両凸レンズ形状を有している。詳細には、使用時に光源Ｓに対向する面（光源側面）２と、この光源側面２と反対側の面（射出側面）４の両面が凸面形状を備えている。本実施態様では、光源側面２および射出側面４の両面が球面である。さらに、コリメータレンズ１は、外縁部に、フランジ状のコバ部６を備えている。なお、コバ部６は、投影型画像表示装置等に組み込む際に装置内のレンズ固定部材に固定するためには有用であるが、設けなくてもよい。 As shown in FIG. 1, the collimator lens 1 is a single lens and has a so-called biconvex lens shape in which an annular edge portion is provided on the outer edge. Specifically, both surfaces of the surface (light source side surface) 2 facing the light source S and the surface (exit side surface) 4 opposite to the light source side surface 2 in use are provided with convex shapes. In this embodiment, both the light source side surface 2 and the emission side surface 4 are spherical. Further, the collimator lens 1 is provided with a flange-shaped edge portion 6 at the outer edge portion. The edge portion 6 is useful for fixing to the lens fixing member in the apparatus when incorporated in a projection type image display apparatus or the like, but may not be provided.
　コリメータレンズ１は、射出側面２の最大面角度が６５°以下が好ましい。この最大面角度は、５５°以下が更に好ましく、５０°以下が一層好ましい。尚、面角度θとは、レンズ面上有効径内の一位置における法線とレンズ中心軸Ｚとがなす角度を意味する。最大面角度が６５°以下であると、プレス成形性や研削または研磨加工性等のレンズ加工性が良好なものとなり、さらにレンズの形状評価が容易になる効果がある。 The collimator lens 1 preferably has a maximum surface angle of the emission side surface 2 of 65 ° or less. The maximum surface angle is more preferably 55 ° or less, and further preferably 50 ° or less. The surface angle θ means an angle formed by a normal line at one position within the effective diameter on the lens surface and the lens central axis Z. When the maximum surface angle is 65 ° or less, the lens formability such as press moldability and grinding or polishing processability is improved, and the lens shape can be easily evaluated.
　さらに、コリメータレンズ１は、ｔ／ｆ（ｔ：中心レンズ厚、ｆ：焦点距離）が、１．３以下が好ましい。１．３を超えると実用上十分なワーキングディスタンス（作動距離）（Ｗｏｒｋｉｎｇ　Ｄｉｓｔａｎｃｅ；　ＷＤ）、例えば１ｍｍ以上のＷＤを確保することができなくなるためである。このｔ／ｆは、１．２０以下がより好ましい。十分なＷＤの確保に加え、レンズ加工性の観点から、ｔ／ｆは好ましくは０．３～１．３、更に好ましくは０．３～０．８５、一層好ましくは０．３～０．８０である。 Furthermore, the collimator lens 1 preferably has t / f (t: center lens thickness, f: focal length) of 1.3 or less. If 1.3 is exceeded, a practically sufficient working distance (working distance) (WD), for example, a WD of 1 mm or more cannot be secured. The t / f is more preferably 1.20 or less. In addition to securing sufficient WD, from the viewpoint of lens processability, t / f is preferably 0.3 to 1.3, more preferably 0.3 to 0.85, and even more preferably 0.3 to 0.80. It is.
　さらに、ｔ／ｆの上限と下限について詳述する。ｔ／ｆの上限は、ＷＤの確保の観点から、１．２０以下、１．００以下、０．８０以下、０．７０以下の順に好ましい。ｔ／ｆの下限は、レンズ加工性の観点から、０．３０以上、０．４０以上、０．５０以上の順に好ましい。 Furthermore, the upper and lower limits of t / f will be described in detail. The upper limit of t / f is preferable in order of 1.20 or less, 1.00 or less, 0.80 or less, and 0.70 or less from the viewpoint of securing WD. The lower limit of t / f is preferable in the order of 0.30 or more, 0.40 or more, and 0.50 or more from the viewpoint of lens processability.
　尚、本明細書において、「ワーキングディスタンス（作動距離）（Ｗｏｒｋｉｎｇ　Ｄｉｓｔａｎｃｅ　；ＷＤ）」とは、例えば、図１に示されているように、光源Ｓ、詳細には光源中の点状の発光部位と、コリメータレンズ１の光源側面２の最も光源に近い部位の間の距離を指す。 In this specification, “working distance (WD)” means, for example, as shown in FIG. 1, the light source S, specifically, a point-like light emitting portion in the light source. And the distance between the parts closest to the light source on the light source side surface 2 of the collimator lens 1.
　また、コリメータレンズ１の開口数ＮＡは０．６以上である。ＮＡの上限は、ＷＤの確保と最大面角度を６５°以下とするため、例えば０．９以下が好ましい。 Further, the numerical aperture NA of the collimator lens 1 is 0.6 or more. The upper limit of NA is preferably 0.9 or less, for example, in order to ensure WD and make the maximum surface angle 65 ° or less.
　さらに、ＮＡの上限は、０．８５以下、０．８０以下、または０．７５以下とすることができる。ＮＡの下限は、０．６超（０．６＜）、０．６５以上、０．７０以上、または０．７１以上とすることができる。 Furthermore, the upper limit of NA can be 0.85 or less, 0.80 or less, or 0.75 or less. The lower limit of NA can be greater than 0.6 (0.6 <), 0.65 or more, 0.70 or more, or 0.71 or more.
　コリメータレンズ１を製造する方法には、ガラス材料を用いた、精密プレス成形や研削加工、研磨加工による方法等がある。
　コリメータレンズ１を形成する材料として、例えば以下の２種類の組成系を有するガラス材料（ガラスＩ、ガラスＩＩ）を用いることができる。 As a method for manufacturing the collimator lens 1, there are a precision press molding, a grinding process, a polishing process, and the like using a glass material.
As a material for forming the collimator lens 1, for example, glass materials (glass I and glass II) having the following two types of composition systems can be used.
　ガラスＩは、Ｂ2Ｏ3を含有するとともに、Ｌａ2Ｏ3、Ｇｄ2Ｏ3、及びＹ2Ｏ3等の希土類酸化物から選択される少なくとも一種を含有するガラス材料である。
　ガラスＩＩは、Ｐ2Ｏ5を含有するとともに、Ｎｂ2Ｏ5、ＷＯ3、ＴｉＯ2、及びＢｉ2Ｏ3から選択される少なくとも一種を含有するガラス材料である。 Glass I is a glass material containing B 2 O 3 and at least one selected from rare earth oxides such as La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 .
Glass II is a glass material containing P 2 O 5 and at least one selected from Nb 2 O 5 , WO 3 , TiO 2 , and Bi 2 O 3 .
　コリメータレンズ１を形成するガラス材料には、ガラスＩまたはガラスＩＩにおいて、ＴｉＯ2、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量が０～４０ｗｔ％であることが好ましい。ＴｉＯ2、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量は、プレス性向上等の観点から、０～２８ｗｔ％がより好ましく、０～１６ｗｔ％が、更に好ましい。 The glass material forming the collimator lens 1 preferably has a total content of TiO 2 , WO 3 , Nb 2 O 5 and Bi 2 O 3 in glass I or glass II of 0 to 40 wt%. The total content of TiO 2 , WO 3 , Nb 2 O 5 , and Bi 2 O 3 is more preferably 0 to 28 wt%, and still more preferably 0 to 16 wt% from the viewpoint of improving pressability.
　また、コリメータレンズ１を形成するガラス材料として、ガラスＩの中では、レンズ透過率の観点から、ＴｉＯ2＋ＷＯ3＋Ｎｂ2Ｏ5＋Ｂｉ2Ｏ3／（（希土類酸化物の合計含有量）＋Ｔａ2Ｏ5）≦１．１であることが好ましい。この割合は、０．９以下がより好ましく、０．５以下が更に好ましい。 Further, as a glass material for forming the collimator lens 1, in the glass I, from the viewpoint of lens transmittance, TiO 2 + WO 3 + Nb 2 O 5 + Bi 2 O 3 / ((total content of rare earth oxides) + Ta 2 O 5 ) ≦ 1.1 is preferred. This ratio is more preferably 0.9 or less, and still more preferably 0.5 or less.
　コリメータレンズ１を形成するガラス材料は、屈折率ｎｄが１．５９以上である。この屈折率ｎｄは、１．６８以上がより好ましく、１．７５以上が更に好ましく、１．８０以上がいっそう好ましい。このような屈折率ｎｄにすることにより、射出側面の最大面角度を小さくすることができるからである。 The glass material forming the collimator lens 1 has a refractive index nd of 1.59 or more. The refractive index nd is more preferably 1.68 or more, further preferably 1.75 or more, and further preferably 1.80 or more. This is because the maximum surface angle of the exit side surface can be reduced by using such a refractive index nd.
　コリメータレンズ１を形成するガラス材料のアッベ数は、屈折率ｎｄが１．５９以上の高屈折率化を維持する観点から、その上限は５７以下であることが好ましい。さらに、アッベ数の上限は、高屈折率化の観点から、５０以下、または４５以下がより好ましい。アッベ数の下限は、特に制限はないが、２０以上が挙げられる。 The upper limit of the Abbe number of the glass material forming the collimator lens 1 is preferably 57 or less from the viewpoint of maintaining a high refractive index with a refractive index nd of 1.59 or more. Furthermore, the upper limit of the Abbe number is more preferably 50 or less or 45 or less from the viewpoint of increasing the refractive index. The lower limit of the Abbe number is not particularly limited, but may be 20 or more.
　さらに、コリメータレンズ１を形成するガラス材料は、精密プレス成形への適性の観点から、ガラス転移温度Ｔｇ≦６３０℃であることが好ましい。
　これに関連し、コリメータレンズ１を形成するガラス材料では、Ｔｇ低下に寄与することから、ＺｎＯ含有量が３ｗｔ％以上が好ましく、８ｗｔ％以上が更に好ましく、１０ｗｔ％以上であることがいっそう好ましい。 Further, the glass material forming the collimator lens 1 preferably has a glass transition temperature Tg ≦ 630 ° C. from the viewpoint of suitability for precision press molding.
In this connection, the glass material forming the collimator lens 1 contributes to a decrease in Tg, so that the ZnO content is preferably 3 wt% or more, more preferably 8 wt% or more, and even more preferably 10 wt% or more.
　このような本実施態様のコリメータレンズ１では、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量を４０ｗｔ％以下に抑えているため、レンズ透過率が向上し、レーザ光源からの射出光の利用効率を高めることができる。 In such a collimator lens 1 of this embodiment, the total content of WO 3 , Nb 2 O 5 , and Bi 2 O 3 is suppressed to 40 wt% or less, so that the lens transmittance is improved and the laser light source emits light Light utilization efficiency can be increased.
　また、コリメータレンズ１では、レーザ光源からの射出光の利用効率が高められるため、投影型画像表示装置における投影画像の輝度が向上する。
　現在、レーザ光源（レーザ・ダイオード（Ｌａｓｅｒ　Ｄｉｏｄｅ；ＬＤ））、特に緑色レーザは高出力化が課題であるが、高出力化は容易ではない。しかしながら、コリメータレンズの透過率が向上すれば、レーザ出力が低くても投影画像の輝度が向上し、十分な投影画像が得られるようになる。さらに、低消費電力化も達成できる。 Moreover, in the collimator lens 1, since the utilization efficiency of the emitted light from the laser light source is enhanced, the brightness of the projected image in the projection type image display apparatus is improved.
Currently, a laser light source (laser diode (LD)), particularly a green laser, has a problem of increasing its output, but it is not easy to increase its output. However, if the transmittance of the collimator lens is improved, the brightness of the projected image is improved even when the laser output is low, and a sufficient projected image can be obtained. Furthermore, low power consumption can be achieved.
　図２は、本実施態様のコリメータレンズ１が組み込まれた投影型画像表示装置（例えば、液晶プロジェクタ）の光源部（照明光学系）１０の構成を概略的に示すブロック図である。 FIG. 2 is a block diagram schematically showing a configuration of a light source unit (illumination optical system) 10 of a projection type image display apparatus (for example, a liquid crystal projector) in which the collimator lens 1 of this embodiment is incorporated.
　図２に示されているように、光源部１０は、それぞれが赤色光、緑色光、および青色光を発生させる３つのレーザ装置Ｒ、Ｇ、Ｂを備え、各レーザ（ＬＤ）装置Ｒ、Ｇ、Ｂの下流側にコリメータレンズ１がそれぞれ配置されている。コリメータレンズ１は、各レーザ装置Ｒ、Ｇ、Ｂから射出された発散光を平行光に変換する。 As shown in FIG. 2, the light source unit 10 includes three laser devices R, G, and B that respectively generate red light, green light, and blue light, and each laser (LD) device R, G , B are arranged on the downstream side of the collimator lens 1 respectively. The collimator lens 1 converts divergent light emitted from each of the laser devices R, G, and B into parallel light.
　この光源部１０では、各コリメータレンズ１によって平行光とされた赤色光、青色光、および緑色光は、ダイクロイックプリズム等を備えた合波光学系１２によって合波され、投影光学系に送られる。 In the light source unit 10, the red light, the blue light, and the green light converted into parallel lights by the respective collimator lenses 1 are combined by a combining optical system 12 including a dichroic prism and transmitted to the projection optical system.
　図３は、本実施態様のコリメータレンズ１が組み込まれた他の投影型画像表示装置（例えば、液晶プロジェクタ）の光源部（照明光学系）１４の構成を概略的に示すブロック図である。 FIG. 3 is a block diagram schematically showing a configuration of a light source unit (illumination optical system) 14 of another projection type image display apparatus (for example, a liquid crystal projector) in which the collimator lens 1 of this embodiment is incorporated.
　図３に示されているように、光源部１４は、近紫外光レーザ装置のような単色光源（ＬＤ）１６を備え、単色光源１６の下流側にコリメータレンズ１が配置されている。コリメータレンズ１は、単色光源１６から射出された光線を平行光に変換する。 As shown in FIG. 3, the light source unit 14 includes a monochromatic light source (LD) 16 such as a near-ultraviolet laser device, and the collimator lens 1 is disposed on the downstream side of the monochromatic light source 16. The collimator lens 1 converts the light emitted from the monochromatic light source 16 into parallel light.
　この光源部１４は、近紫外光を赤色光、青色光、および緑色光に変換する３つの部分を備えた変換部１８を備えている。この変換部１８では、赤色光、青色光、および緑色光に変換する３つの部分が順次、近紫外光の光路上に配置され、近紫外光を一定時間毎に、赤色光、青色光、および緑色光に変換していく。そして、これらの赤色光、青色光、および緑色光が、順次、投影光学系に送られる。 The light source unit 14 includes a conversion unit 18 having three parts that convert near-ultraviolet light into red light, blue light, and green light. In this conversion unit 18, three parts that convert red light, blue light, and green light are sequentially arranged on the optical path of the near ultraviolet light, and the near ultraviolet light is red light, blue light, and It will be converted into green light. Then, these red light, blue light, and green light are sequentially sent to the projection optical system.
　例えば、この実施形態のコリメータレンズ１は、所謂両凸形状を備えたコリメータレンズであったが、本発明は、このような両凸形状のコリメータレンズに限定されるものではない。本発明のコリメータレンズは、光源に対向する面と反対側に凸部が設けられた面を有し、さらに所定の条件を備えていればよい。 For example, the collimator lens 1 of this embodiment is a collimator lens having a so-called biconvex shape, but the present invention is not limited to such a biconvex shape collimator lens. The collimator lens of the present invention may have a surface provided with a convex portion on the opposite side to the surface facing the light source, and further have a predetermined condition.
　したがって、例えば、図４ないし図６に示されているような外形を備えたものであってもよい。すなわち、図４に示されているような、コバ部を備えず、光源Ｓに対向する面が平面であり、光源Ｓに対向する面２と反対側の面４が凸面である平凸レンズ１０４でもよい。光源に対向する面を平坦にすることにより、ワーキングディスタンス（ＷＤ）の確保やレンズ加工性の点で有利になる。また、光源に対向する面２と反対側の面４との間での偏心（ディセンタ）の問題が発生しなくなる。 Therefore, for example, it may have an outer shape as shown in FIGS. That is, as shown in FIG. 4, even a plano-convex lens 104 having no edge portion, a surface facing the light source S is a flat surface, and a surface 4 opposite to the surface 2 facing the light source S is a convex surface. Good. By flattening the surface facing the light source, it is advantageous in terms of securing working distance (WD) and lens processability. Further, the problem of decentering between the surface 2 facing the light source and the surface 4 on the opposite side does not occur.
　また、図５に示されているような、コバ部を備えず、光源Ｓに対向する面が凸面であり、光源Ｓに対向する面２と反対側の面４も凸面である両凸１０５レンズでもよい。さらに、図６に示されているような、コバ部を備えず、光源Ｓに対向する面２が凹面であり、光源Ｓに対向する面と反対側の面４が凸面である凸メニスカスレンズ１０６でもよい。 Further, as shown in FIG. 5, a biconvex 105 lens that does not include the edge portion, the surface facing the light source S is a convex surface, and the surface 4 opposite to the surface 2 facing the light source S is also a convex surface. But you can. Further, as shown in FIG. 6, a convex meniscus lens 106 that does not include an edge portion, the surface 2 facing the light source S is a concave surface, and the surface 4 opposite to the surface facing the light source S is a convex surface. But you can.
　前記実施態様のコリメータレンズ１では、光源に対向する面２および反対側の面４の両面が球面であったが、これらの面の一方または両方が非球面であっても良い。 In the collimator lens 1 of the above embodiment, both the surface 2 facing the light source and the opposite surface 4 are spherical, but one or both of these surfaces may be aspherical.
　図７に示すように、特に、光源に対向する面の反対側の凸面４Ａは、球面（点線）の近軸曲率半径（Ｒ0）よりも、近軸曲率半径の周辺の曲率半径（Ｒ1またはＲ2）が大きくなるような非球面（実線）とすることが好ましい。レンズ周辺部での面角度が小さくなり、レンズ透過率向上に寄与するためである。この場合、図７に示されているように、レンズ中心軸Ｚから周辺（レンズ端部１ａ）に向かって曲率半径が増加していることが好ましい。ここで、近軸曲率半径とは、レンズの中心軸上における曲率半径のことを指す。 As shown in FIG. 7, in particular, the convex surface 4A opposite to the surface facing the light source, spherical than the paraxial radius of curvature (R 0) of the (dashed), the paraxial curvature radius near the radius of curvature (R 1 Alternatively, it is preferable to use an aspheric surface (solid line) that increases R 2 ). This is because the surface angle at the periphery of the lens is reduced, contributing to an improvement in lens transmittance. In this case, as shown in FIG. 7, it is preferable that the radius of curvature increases from the lens central axis Z toward the periphery (lens end 1a). Here, the paraxial radius of curvature refers to the radius of curvature on the central axis of the lens.
　光源に対向する面の反対側の面の凸面を非球面とするとともに、光源に対向する面の凸面または凹面を非球面としてもよい。これにより、収差特性が更に改善される。 The convex surface of the surface opposite to the surface facing the light source may be an aspheric surface, and the convex surface or concave surface of the surface facing the light source may be an aspheric surface. This further improves the aberration characteristics.
　例えば、後述する実施例４の硝材が用いられ、以下のようなスペックを有する非球面レンズでもよい。 For example, a glass material of Example 4 described later is used, and an aspherical lens having the following specifications may be used.
　焦点距離（ｍｍ）　　　　　２．１４
　ＮＡ　　　　　　　　　　　０．７
　中心厚み（ｍｍ）　　　　　１．８
　平行光側有効直径（ｍｍ）　３ Focal length (mm) 2.14
NA 0.7
Center thickness (mm) 1.8
Parallel light side effective diameter (mm) 3
（非球面データ）
　　　　　　　　　　　光源側面　　　　　　　平行光側面
　Ｒ　　　　　　　　　９．３３　　　　　　　－１．９４７
　Ｋ　　　　　　　　　　　　０　　　　　　　－１．０６
　Ａ４　　－５．８４１Ｅ－０２　　　　　　　－１．１６９Ｅ－０２
　Ａ６　　　３．５６４Ｅ－０２　　　　　　　－８．９６８Ｅ－０４
　Ａ８　　－１．２１１Ｅ－０２　　　　　　　　５．８６４Ｅ－０５
　Ａ１０　　１．８６９Ｅ－０３　　　　　　　　４．９５１Ｅ－０５ (Aspheric data)
Light source side Parallel light side R 9.33 -1.947
K 0 -1.06
A4 -5.841E-02 -1.169E-02
A6 3.564E-02-8.968E-04
A8 -1.211E-02 5.864E-05
A10 1.869E-03 4.951E-05
　表１は、図４のレンズ形状において、レンズ透過率の射出側面４の最大面角度依存性を求める際に用いた硝材の構成成分（組成）を示したものである。 Table 1 shows the constituents (compositions) of the glass material used to determine the maximum surface angle dependency of the lens transmittance on the exit side surface 4 in the lens shape of FIG.
　図８は、本発明のＮＡ０．６以上のレンズにおける、レンズの射出側面（図１における射出側面４）の最大面角度とレンズの透過率の関係（すなわち透過率の射出側面最大面角度依存性）を示す図面である。尚、ｔ／ｆは、１．３以下である。ｔ／ｆは、ＮＡ＝０．６０については、０．３０、０．４０、０．５０、０．６０、０．７５、０．８０、１．００、１．２０、１．３０、ＮＡ＝０．６５については、０．３０、０．４０、０．５０、０．６０、０．７５、０．８０、１．００、１．２０、１．３０、ＮＡ＝０．７１については、０．４０、０．６０、０．７１、０．８０、０．９０、１．００、１．１０、１．２０、１．２８、１．３０とした。 FIG. 8 shows the relationship between the maximum surface angle of the exit side of the lens (exit side 4 in FIG. 1) and the transmittance of the lens (that is, the dependency of the transmittance on the maximum exit surface angle of the lens). ). Note that t / f is 1.3 or less. t / f is 0.30, 0.40, 0.50, 0.60, 0.75, 0.80, 1.00, 1.20, 1.30, NA for NA = 0.60. = 0.65 for 0.30, 0.40, 0.50, 0.60, 0.75, 0.80, 1.00, 1.20, 1.30, NA = 0.71 0.40, 0.60, 0.71, 0.80, 0.90, 1.00, 1.10, 1.20, 1.28, 1.30.
　具体的には、図８は、下記表１に示す各硝材について、波長４３０ｎｍ（青色）におけるＮＡ０．６、０．６５、０．７１の場合のレンズ透過率を示している。なお、波長５３０ｎｍ（緑色）、波長６５０ｎｍ（赤色）のデータは記載していないが、一般的にガラス材料の内部透過率は、短波長側である紫色の４５０ｎｍ近辺以下になると急激に低下する。本明細書では、この波長域の波長（４３０ｎｍ）でのレンズ透過率をレンズ透過率の指標としてレンズの特性を検討した。
　なお、図８中で、点線で囲まれた領域のプロットは、本願発明の実施例である。 Specifically, FIG. 8 shows lens transmittances for NAs of 0.6, 0.65, and 0.71 at a wavelength of 430 nm (blue) for each glass material shown in Table 1 below. In addition, although the data of wavelength 530nm (green) and wavelength 650nm (red) are not described, generally the internal transmittance | permeability of glass material will fall rapidly, if it is below 450 nm of purple which is a short wavelength side. In this specification, lens characteristics were examined using the lens transmittance at a wavelength in this wavelength region (430 nm) as an index of lens transmittance.
In FIG. 8, the plot of the area surrounded by the dotted line is an embodiment of the present invention.
　図８の縦軸のレンズ透過率は、最大値を１として正規化している。図８に示されているように、レンズ透過率は、最大面角度が５５°以下において良好なものとなるが、６５°を超えると急激に悪化する。波長５３０ｎｍ、波長６５０ｎｍのデータも、図８の波長４３０ｎｍと同様な傾向を示した。 The lens transmittance on the vertical axis in FIG. 8 is normalized with the maximum value being 1. As shown in FIG. 8, the lens transmittance is good when the maximum surface angle is 55 ° or less, but deteriorates rapidly when it exceeds 65 °. The data at wavelengths of 530 nm and 650 nm also showed the same tendency as the wavelength of 430 nm in FIG.
　なお、最大面角度が６５°を超えるコリメータレンズでは、中心部と周辺部とでレンズ透過率が大きく異なるため、コリメータレンズにより変換された平行光において、コリメータレンズの中心部を通過した光と中心部周辺の周辺部を通過した光との間で輝度差が生じてしまう。輝度差を抑制しつつ、レンズ透過率を高める観点から、最大面角度の上限は、６５°以下、６０°以下、５５°以下の順に好ましい。最大面角度の下限は、ＮＡを０．６以上にする観点から、２０°以上とすることが好ましい。 In a collimator lens having a maximum surface angle exceeding 65 °, the lens transmittance is greatly different between the central portion and the peripheral portion. Therefore, in the parallel light converted by the collimator lens, the light passing through the central portion of the collimator lens and the center A luminance difference is produced between the light that has passed through the peripheral part of the part. From the viewpoint of increasing the lens transmittance while suppressing the luminance difference, the upper limit of the maximum surface angle is preferably 65 ° or less, 60 ° or less, and 55 ° or less. The lower limit of the maximum surface angle is preferably set to 20 ° or more from the viewpoint of setting NA to 0.6 or more.
　表１には、各硝材の最大面角度とレンズ透過率の指標を示している。最大面角度は、図８の結果から６５°以下の場合は○、６５°を超える場合は×で示す。 Table 1 shows the index of the maximum surface angle and lens transmittance of each glass material. The maximum surface angle is indicated by ◯ when it is 65 ° or less from the result of FIG. 8, and by × when it exceeds 65 °.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　レンズ透過率は指標として◎○×で示す。ここで、◎はグレードＡ（０．９８５以上）、○はグレードＢ（０．９７０以上、かつ０．９８５未満）、×はグレードＣ（０．９７０未満）である。前記（　）内の値はレンズ透過率を正規化した値である。最大面角度の要件とレンズ透過率の双方の指標を満たす硝材は実施例、満たさない硝材は比較例として示す。 Lens transmissivity is indicated by ◎ ○ × as an index. Here, ◎ is grade A (0.985 or more), ◯ is grade B (0.970 or more and less than 0.985), and x is grade C (less than 0.970). The values in the parentheses are values obtained by normalizing the lens transmittance. A glass material that satisfies both the maximum surface angle requirement and the lens transmittance index is shown as an example, and a glass material that does not satisfy the index is shown as a comparative example.
　表１から、実施例１～７に示す硝材では、最大面角度を６５°以下とし、ｎｄ＝１．５９以上、ＴｉＯ2、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量を４０ｗｔ％以下に抑えることで良好なレンズ透過率特性を得ることができることがわかる。 From Table 1, in the glass materials shown in Examples 1 to 7, the maximum face angle is 65 ° or less, nd = 1.59 or more, and the total content of TiO 2 , WO 3 , Nb 2 O 5 , Bi 2 O 3 It can be seen that good lens transmittance characteristics can be obtained by suppressing the content to 40 wt% or less.
　表１から、比較例１の硝材は、最大面角度の要件を満たしていないことがわかる。また、表１から、ガラス中のＴｉＯ2、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量が多い比較例２の硝材は、レンズ透過率が不十分であることがわかる。ガラス中でのこれら金属イオンは紫外線吸収が大きく、レンズ透過率を悪化させていると考えられる。 From Table 1, it can be seen that the glass material of Comparative Example 1 does not satisfy the requirement of the maximum surface angle. Table 1 also shows that the glass material of Comparative Example 2 having a large total content of TiO 2 , WO 3 , Nb 2 O 5 , and Bi 2 O 3 in the glass has insufficient lens transmittance. These metal ions in the glass are considered to have a large ultraviolet absorption and deteriorate the lens transmittance.
　本発明の前記実施形態に限定されることなく、特許請求の範囲に記載された技術的思想の範囲内で種々の変更、変形が可能である。 The present invention is not limited to the above-described embodiment, and various changes and modifications can be made within the scope of the technical idea described in the claims.
　以下、図面を参照しながら、本発明を総括する。
　第１の実施形態のコリメータレンズ１は、図１に示されているように、光源Ｓから射出された波長３８０ｎｍ～７００ｎｍの光線を平行光束に変換する、ガラス材料からなるコリメータレンズである。コリメータレンズ１は、光源Ｓに対向する面２と反対側に凸部が設けられた面４を有している。このコリメータレンズ１では、開口数ＮＡが０．６以上であり、ｔ／ｆが１．３以下（ｔ：中心レンズ厚、ｆ：焦点距離）である。さらに、凸部が設けられた面４の最大面角度θ６５°以下である。またコリメータレンズ１を形成するガラス材料は、屈折率ｎｄが１．５９以上であり、ＴｉＯ2、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量が０～４０ｗｔ％である。 The present invention will be summarized below with reference to the drawings.
As shown in FIG. 1, the collimator lens 1 of the first embodiment is a collimator lens made of a glass material that converts a light beam having a wavelength of 380 nm to 700 nm emitted from a light source S into a parallel light beam. The collimator lens 1 has a surface 4 provided with a convex portion on the opposite side to the surface 2 facing the light source S. In this collimator lens 1, the numerical aperture NA is 0.6 or more, and t / f is 1.3 or less (t: central lens thickness, f: focal length). Further, the maximum surface angle θ65 ° of the surface 4 provided with the convex portions is not more than 65 °. The glass material forming the collimator lens 1 has a refractive index nd of 1.59 or more and a total content of TiO 2 , WO 3 , Nb 2 O 5 and Bi 2 O 3 is 0 to 40 wt%.
　コリメータレンズ１では、光源Ｓに対向する面と反対側の面４に設けられた凸部を非球面とすることができる。 In the collimator lens 1, the convex portion provided on the surface 4 opposite to the surface facing the light source S can be an aspherical surface.
　また、コリメータレンズ１において、光源Ｓに対向する面が平坦面でもよい。 In the collimator lens 1, the surface facing the light source S may be a flat surface.
　さらに、コリメータレンズ１では、例えば図１に示されているように、光源Ｓに対向する面に、凸部が設けられている。
　この光源に対向する面に設けられた凸部が非球面でもよい。 Furthermore, in the collimator lens 1, for example, as shown in FIG. 1, a convex portion is provided on the surface facing the light source S.
The convex portion provided on the surface facing the light source may be an aspherical surface.
　また、本発明は、図６に示されている実施態様のコリメータレンズ１０６のように、光源Ｓに対向する面に、凹部が設けられている構成でもよい。 Further, the present invention may have a configuration in which a concave portion is provided on the surface facing the light source S, like the collimator lens 106 of the embodiment shown in FIG.
　本発明のコリメータレンズでは、光源Ｓは照明光学系に使用される光源であってもよい。
　また、本発明のコリメータレンズでは、この照明光学系が、投影型画像表示装置の照明光学系であってもよい。 In the collimator lens of the present invention, the light source S may be a light source used in an illumination optical system.
In the collimator lens of the present invention, the illumination optical system may be an illumination optical system of a projection type image display apparatus.
　図２および図３に示されているように、本発明のコリメータレンズでは、光源Ｓがレーザ光源であってもよい。 2 and 3, in the collimator lens of the present invention, the light source S may be a laser light source.
　さらに、本発明は、上記総括した各コリメータレンズを使用して照明光学系でもよい。
　さらにまた、本発明は、このような照明光学系を備えた投写型画像表示装置でもよい。 Furthermore, the present invention may be an illumination optical system using the collimator lenses summarized above.
Furthermore, the present invention may be a projection type image display apparatus provided with such an illumination optical system.
　１：コリメータレンズ
　２：光源側面
　４：射出側面
　Ｓ：光源
　ｔ：中心レンズ厚
　ｆ：焦点距離 1: Collimator lens 2: Light source side surface 4: Emission side surface S: Light source t: Center lens thickness f: Focal length

Claims (7)

  1. 　光源から射出された波長３８０ｎｍ～７００ｎｍの光線を平行光束に変換する、ガラス材料からなるコリメータレンズであって、
    　前記光源に対向する面と反対側に、凸部が設けられた面を有し、
    　開口数ＮＡが０．６以上であり、
    　焦点距離ｆに対する中心レンズ厚ｔの割合ｔ／ｆが１．３以下であり、
    　前記凸部が設けられた面の最大面角度が６５°以下であり、
    　前記ガラス材料は屈折率ｎｄが１．５９以上であり、
    　前記ガラス材料のＴｉＯ2、ＷＯ3、Ｎｂ2Ｏ5、Ｂｉ2Ｏ3の合計含有量が０～４０ｗｔ％である、
    　コリメータレンズ。     A collimator lens made of a glass material that converts a light beam having a wavelength of 380 nm to 700 nm emitted from a light source into a parallel light beam,
    On the opposite side of the surface facing the light source, has a surface provided with a convex portion,
    The numerical aperture NA is 0.6 or more,
    The ratio t / f of the center lens thickness t to the focal length f is 1.3 or less,
    The maximum surface angle of the surface provided with the convex portion is 65 ° or less,
    The glass material has a refractive index nd of 1.59 or more,
    The glass material has a total content of TiO 2 , WO 3 , Nb 2 O 5 , Bi 2 O 3 of 0 to 40 wt%,
    Collimator lens.
  2. 　前記光源に対向する面と反対側の面に設けられた凸部が非球面である、
    　請求項１に記載のコリメータレンズ。     The convex portion provided on the surface opposite to the surface facing the light source is an aspheric surface,
    The collimator lens according to claim 1.
  3. 　前記光源に対向する面が平坦面である、
    　請求項１または２に記載のコリメータレンズ。     The surface facing the light source is a flat surface.
    The collimator lens according to claim 1 or 2.
  4. 　前記光源に対向する面に、凸部が設けられている、
    　請求項１または２に記載のコリメータレンズ。     A convex portion is provided on the surface facing the light source,
    The collimator lens according to claim 1 or 2.
  5. 　前記光源に対向する面に設けられた凸部が非球面である、
    　請求項４に記載のコリメータレンズ。     The convex portion provided on the surface facing the light source is an aspherical surface,
    The collimator lens according to claim 4.
  6. 　前記光源に対向する面に、凹部が設けられている、
    　請求項１または２に記載のコリメータレンズ。     A recess is provided on the surface facing the light source,
    The collimator lens according to claim 1 or 2.
  7. 　前記光源に対向する面に設けられた凹部が非球面である、
    　請求項６に記載のコリメータレンズ。     The recess provided on the surface facing the light source is aspheric.
    The collimator lens according to claim 6.
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