JP2003131137A - Terahertz light supplying optical system, terahertz light detection optical system and terahertz optical device using them - Google Patents
Terahertz light supplying optical system, terahertz light detection optical system and terahertz optical device using themInfo
- Publication number
- JP2003131137A JP2003131137A JP2001327025A JP2001327025A JP2003131137A JP 2003131137 A JP2003131137 A JP 2003131137A JP 2001327025 A JP2001327025 A JP 2001327025A JP 2001327025 A JP2001327025 A JP 2001327025A JP 2003131137 A JP2003131137 A JP 2003131137A
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- Prior art keywords
- light
- terahertz light
- terahertz
- optical system
- axis
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Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 128
- 238000001514 detection method Methods 0.000 title claims description 102
- 230000004907 flux Effects 0.000 claims abstract description 69
- 230000035945 sensitivity Effects 0.000 claims description 21
- 230000005855 radiation Effects 0.000 claims description 14
- 230000002093 peripheral effect Effects 0.000 claims description 7
- 239000000523 sample Substances 0.000 description 10
- 238000012545 processing Methods 0.000 description 7
- 230000005684 electric field Effects 0.000 description 6
- 238000005259 measurement Methods 0.000 description 4
- 239000008186 active pharmaceutical agent Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 101150080148 RR10 gene Proteins 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000001328 terahertz time-domain spectroscopy Methods 0.000 description 1
Classifications
-
- 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
- G01J3/28—Investigating the spectrum
- G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
-
- 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
-
- 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
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
- G01J3/0208—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、軸外し放物面鏡を
有するテラヘルツ光学系に関し、特に、テラヘルツ光を
実質的に平行光束にして供給するテラヘルツ光供給光学
系、及び、実質的に平行光束のテラヘルツ光を検出する
テラヘルツ光検出光学系に関するものである。また、本
発明は、このような光学系を用いたテラヘルツ光装置に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terahertz optical system having an off-axis parabolic mirror, and more particularly to a terahertz light supplying optical system for supplying a terahertz light into a substantially parallel light flux, and a substantially parallel terahertz light supplying optical system. The present invention relates to a terahertz light detection optical system that detects terahertz light of a light flux. The present invention also relates to a terahertz optical device using such an optical system.
【０００２】[0002]
【従来の技術】近年、物質の測定・検査・イメージ化及
びその他の種々の分野において、テラヘルツ分光法など
のテラヘルツ光の利用技術の有用性が認識されてきてお
り、テラヘルツ光学系を有する種々のテラヘルツ光装置
が、既に提供されあるいは新たに開発されようとしてい
る。このようなテラヘルツ光装置では、一般的に、テラ
ヘルツ光を実質的に平行光束にして供給するテラヘルツ
光供給光学系、及び、実質的に平行光束のテラヘルツ光
を検出するテラヘルツ光検出光学系が、用いられる。そ
して、前記テラヘルツ光供給光学系及びテラヘルツ光検
出光学系では、軸外し放物面鏡が用いられることが多
い。2. Description of the Related Art In recent years, the usefulness of terahertz light application techniques such as terahertz spectroscopy has been recognized in various fields such as measurement, inspection, imaging of substances, and various other fields. Terahertz optical devices are already being provided or are about to be developed. In such a terahertz light device, generally, a terahertz light supply optical system that supplies terahertz light in a substantially parallel light flux and a terahertz light detection optical system that detects terahertz light in a substantially parallel light flux, Used. An off-axis parabolic mirror is often used in the terahertz light supply optical system and the terahertz light detection optical system.
【０００３】ここで、軸外し放物面鏡の一例について、
図４及び図５を参照して説明する。図４は、軸外し放物
面鏡１の一例を示す概略斜視図である。図５は、図４中
のＷ−Ｗ’線に沿った概略断面図である。Here, an example of the off-axis parabolic mirror will be described.
This will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic perspective view showing an example of the off-axis parabolic mirror 1. FIG. 5 is a schematic cross-sectional view taken along the line WW ′ in FIG.
【０００４】軸外し放物面鏡１は、反射面１ａを有して
いる。図５に示すように互いに直交するＸ軸、Ｙ軸及び
Ｚ軸を定義すると、反射面１ａは、Ｘ座標をｘとすると
ともにＹ座標をｙとして、ｙ＝ａｘ２の式（ａは定数）
で表される放物線１００の一部分をＹ軸を回転軸として
回転させた回転放物面をなしている。すなわち、Ｙ軸
は、反射面１ａを規定する回転軸となっている。ＸＹ平
面は、Ｙ軸（回転軸）を含む１つの基準面（平面）とな
っている。The off-axis parabolic mirror 1 has a reflecting surface 1a. When the X axis, the Y axis, and the Z axis that are orthogonal to each other are defined as shown in FIG. 5, the reflecting surface 1a has an equation of y = ax 2 (a is a constant) with the X coordinate as x and the Y coordinate as y
A part of the parabola 100 represented by is rotated about the Y axis to form a paraboloid of revolution. That is, the Y axis is a rotation axis that defines the reflection surface 1a. The XY plane is one reference plane (plane) including the Y axis (rotation axis).
【０００５】この軸外し放物面鏡１では、反射面１ａを
ＸＺ平面に写像すると円となり、反射面１ａとＸＹ平面
とが交わる放物線上の点ＦをＸＺ平面に写像すると前記
円の中心となるようになっている。したがって、反射面
１ａとＸＹ平面とが交わる放物線の一方の端点Ｂを通り
Ｙ軸と平行な直線ＡＢと、点Ｆを通りＹ軸と平行な直線
ＥＦとの間の、Ｘ軸方向の距離ｄ１は、反射面１ａとＸ
Ｙ平面とが交わる放物線の他方の端点Ｄを通りＹ軸と平
行な直線ＣＤと、点Ｆを通りＹ軸と平行な直線ＥＦとの
間の、Ｘ軸方向の距離ｄ２と、等しい。直線ＡＢと直線
ＣＤとの間のＸ軸方向の距離をｄとすると、ｄ＝２ｄ１
＝２ｄ２となる。この軸外し放物面鏡１の焦点距離ｆ
は、線分０Ｓの長さである。In this off-axis parabolic mirror 1, when the reflecting surface 1a is mapped on the XZ plane, it becomes a circle, and when the point F on the parabola where the reflecting surface 1a and the XY plane intersect is mapped on the XZ plane, it becomes the center of the circle. It is supposed to be. Therefore, the distance d in the X-axis direction between the straight line AB passing through one end point B of the parabola that intersects the reflecting surface 1a and the XY plane and parallel to the Y axis and the straight line EF passing through the point F and parallel to the Y axis. 1 is the reflection surface 1a and X
The distance d 2 in the X-axis direction between a straight line CD passing through the other end point D of the parabola intersecting the Y plane and parallel to the Y axis and a straight line EF passing through the point F and parallel to the Y axis is equal. Assuming that the distance between the straight line AB and the straight line CD in the X-axis direction is d, d = 2d 1
= 2d 2 . Focal length f of this off-axis parabolic mirror 1
Is the length of the line segment 0S.
【０００６】反射面１ａの焦点Ｓは、Ｙ軸上に位置して
いる。この軸外し放物面鏡１では∠ＥＦＳは９０゜であ
り、したがって、軸外し放物面鏡１は９０゜軸外し放物
面鏡となっている。今、Ｙ軸を含む種々の基準面（平
面）について、当該基準面と反射面１ａとが交わる放物
線の一方の端点と焦点Ｓとを結ぶ線分と、当該基準面と
反射面１ａとが交わる放物線の他方の端点と焦点Ｓとを
結ぶ線分とがなす、挟角を考える。本例による軸外し放
物面鏡１では、この挟角が最大となる基準面がＸＹ平面
（図５の紙面）である。つまり、ＸＹ平面の挟角∠ＢＳ
Ｄは、他のいずれの基準面の挟角より大きい。本例で
は、図４も参照するとわかるように、点Ｂは放射面１ａ
上のＹ軸方向の最も＋側の点であり、点Ｄは放射面１ａ
上のＹ軸方向の最も−側の点である。The focal point S of the reflecting surface 1a is located on the Y axis. In this off-axis parabolic mirror 1, ∠EFS is 90 °, so the off-axis parabolic mirror 1 is a 90 ° off-axis parabolic mirror. Now, for various reference planes (flat surfaces) including the Y axis, a line segment connecting one end point of a parabola where the reference plane and the reflection surface 1a intersect and the focal point S intersects the reference plane and the reflection surface 1a. Consider the included angle formed by the line segment connecting the other end of the parabola and the focal point S. In the off-axis parabolic mirror 1 according to this example, the reference plane where the included angle is maximum is the XY plane (the paper surface of FIG. 5). That is, the included angle ∠BS of the XY plane
D is larger than the included angle of any other reference plane. In this example, as can be seen by also referring to FIG. 4, the point B is the radiation surface 1a.
It is the point on the most + side in the upper Y-axis direction, and point D is the radiation surface 1a.
It is the most negative point in the upper Y-axis direction.
【０００７】本発明者は、研究の結果、図５に示すよう
に∠ＢＳＦをθ１、∠ＤＳＦをθ２とすると、θ１＜θ
２であることを認識するに至った。そこで、本発明者
は、図５中の点Ｈを想定した。点Ｈは、ＸＹ平面内にお
いて、∠ＢＳＤの二等分線が放射面１ａと交わる点であ
る。したがって、∠ＢＳＨをθ３、∠ＤＳＨをθ４とす
ると、θ３＝θ４である。直線ＧＨは、点Ｈを通りＹ軸
と平行な直線である。線分ＦＳと線分ＨＳとがなす挟角
をΔθとする。なお、従来は、θ１＜θ２であることは
全く認識されていなかった。点Ｈ、角θ１〜θ４及び直
線ＧＨは、従来は想定も認識もされていなかったもので
あるが、説明の都合上、図５中に補助的に記入してここ
で説明した。この点は、後述する図６及び図７について
も同様である。As a result of the research, the inventor of the present invention, assuming that ∠BSF is θ 1 and ∠DSF is θ 2 , as shown in FIG. 5, θ 1 <θ
We came to recognize that it was 2 . Therefore, the present inventor assumed the point H in FIG. The point H is a point where the bisector of ∠BSD intersects with the radiation surface 1a in the XY plane. Therefore, if ∠BSH is θ 3 and ∠DSH is θ 4 , then θ 3 = θ 4 . The straight line GH is a straight line passing through the point H and parallel to the Y axis. The included angle formed by the line segment FS and the line segment HS is Δθ. In the past, it was never recognized that θ 1 <θ 2 . The point H, the angles θ 1 to θ 4 and the straight line GH have not been assumed or recognized in the past, but for convenience of description, they are supplementarily entered in FIG. 5 and described here. This point also applies to FIGS. 6 and 7 described later.
【０００８】以上の説明からわかるように、軸外し放物
面鏡１の放射面１ａに、平行光束のテラヘルツ光がＹ軸
と平行に入射すると、このテラヘルツ光は、放射面１ａ
で反射された後に、焦点Ｓに集光される。例えば、直線
ＡＢに沿って点Ｂに入射した光線は線分ＢＳに沿って進
行して焦点Ｓに到達し、直線ＣＤに沿って点Ｄに入射し
た光線は線分ＤＳに沿って進行して焦点Ｓに到達し、直
線ＥＦに沿って点Ｆに入射した光線は線分ＦＳに沿って
進行して焦点Ｓに到達し、直線ＧＨに沿って点Ｈに入射
した光線は線分ＨＳに沿って進行して焦点Ｓに到達す
る。As can be seen from the above description, when terahertz light of parallel light flux enters the radiation surface 1a of the off-axis parabolic mirror 1 in parallel with the Y axis, the terahertz light is emitted from the radiation surface 1a.
After being reflected by, the light is focused on the focus S. For example, the ray incident on the point B along the straight line AB travels along the line segment BS to reach the focal point S, and the ray incident on the point D along the straight line CD travels along the line segment DS. A ray reaching the focal point S and incident on the point F along the straight line EF travels along the line segment FS to reach the focal point S, and a ray incident on the point H along the straight line GH follows the line segment HS. To reach the focal point S.
【０００９】逆に、焦点Ｓを発散中心点とする発散光束
のテラヘルツ光が軸外し放物面鏡１の放射面１ａに入射
すると、このテラヘルツ光は、放射面１ａで反射された
後に、平行光束となる。例えば、直線ＳＢに沿って点Ｂ
に入射した光線は線分ＢＡに沿って進行し、直線ＳＤに
沿って点Ｄに入射した光線は線分ＤＣに沿って進行し、
直線ＳＦに沿って点Ｆに入射した光線は線分ＦＥに沿っ
て進行し、直線ＳＨに沿って点Ｈに入射した光線は線分
ＨＧに沿って進行する。On the contrary, when the terahertz light of the divergent light flux having the focal point S as the divergence center point is incident on the radiation surface 1a of the parabolic mirror 1 off-axis, the terahertz light is reflected by the radiation surface 1a and then becomes parallel. It becomes a luminous flux. For example, point B along the straight line SB
The ray incident on the line travels along the line segment BA, the ray incident on the point D along the straight line SD travels along the line segment DC,
The light ray incident on the point F along the straight line SF travels along the line segment FE, and the light ray incident on the point H along the straight line SH travels along the line segment HG.
【００１０】図６は、前述した図４及び図５に示す軸外
し放物面鏡１を有する従来のテラヘルツ光供給光学系を
示す概略断面図であり、図５に対応している。図６にお
いて、図４及び図５中の要素等と同一又は対応する要素
等には同一符号を付し、その重複する説明は省略する。FIG. 6 is a schematic sectional view showing a conventional terahertz light supply optical system having the off-axis parabolic mirror 1 shown in FIGS. 4 and 5, and corresponds to FIG. 6, elements and the like that are the same as or correspond to the elements and the like in FIGS. 4 and 5 are denoted by the same reference numerals, and duplicated description thereof will be omitted.
【００１１】図６に示すテラヘルツ光供給光学系は、前
述した図４及び図５に示す軸外し放物面鏡１と、放射強
度に指向性を有する発散光束のテラヘルツ光を発生する
テラヘルツ光発生部２とを備え、テラヘルツ光発生部２
から発生した発散光束のテラヘルツ光を実質的に平行光
束にして外部に供給する。The terahertz light supply optical system shown in FIG. 6 generates the terahertz light which generates the terahertz light of the divergent luminous flux having directivity in the radiation intensity and the off-axis parabolic mirror 1 shown in FIGS. 4 and 5 described above. And a terahertz light generation unit 2
The terahertz light of the divergent light flux generated from the above is converted into a substantially parallel light flux and supplied to the outside.
【００１２】テラヘルツ光発生部２は、テラヘルツ光発
生源としてのダイポールアンテナ、ボウタイアンテナ等
を用いた公知の光スイッチ素子３と、光スイッチ素子３
のテラヘルツ光発生点Ｊから発生したテラヘルツ光の発
散角を狭めるように作用するシリコン等からなる超半球
レンズ（hyper-hemispherical lens）４とを有してい
る。光スイッチ素子３と超半球レンズ４とは一体化さ
れ、超半球レンズ４の光軸は、テラヘルツ光発生点Ｊを
通る、光スイッチ素子３の光導電層の膜面の法線と一致
している。ここでは、超半球レンズ４の光軸をテラヘル
ツ光発生部２の光軸と呼ぶ。テラヘルツ光発生部２がこ
のような構成を有しているので、テラヘルツ光発生部２
から発生される発散光束（超半球レンズ４の外側の発散
光束）は放射強度に指向性を有し、この発散光束では、
テラヘルツ光発生部２の光軸方向の放射強度が最も高
く、この光軸方向から外れるに従って放射強度が低くな
る。The terahertz light generation section 2 is a known optical switch element 3 using a dipole antenna, a bowtie antenna or the like as a terahertz light generation source, and an optical switch element 3.
And a hyper-hemispherical lens 4 made of silicon or the like that acts to narrow the divergence angle of the terahertz light generated from the terahertz light generation point J. The optical switch element 3 and the super-hemispherical lens 4 are integrated, and the optical axis of the super-hemispherical lens 4 coincides with the normal line of the film surface of the photoconductive layer of the optical switch element 3 which passes through the terahertz light generation point J. There is. Here, the optical axis of the super-hemispherical lens 4 is referred to as the optical axis of the terahertz light generating unit 2. Since the terahertz light generating section 2 has such a configuration, the terahertz light generating section 2
The divergent light flux (divergent light flux outside the super-hemispherical lens 4) generated from the radiant intensity has directivity.
The radiant intensity of the terahertz light generation unit 2 in the optical axis direction is the highest, and the radiant intensity decreases as the distance from the optical axis direction increases.
【００１３】図６に示す従来のテラヘルツ光供給光学系
では、テラヘルツ光発生部２から発生される発散光束の
発散中心点が軸外し放物面鏡１の焦点Ｓに位置し、か
つ、テラヘルツ光発生部２の光軸が直線ＦＳと一致する
ように、テラヘルツ光発生部２が配置されている。In the conventional terahertz light supplying optical system shown in FIG. 6, the divergence center point of the divergent light beam generated from the terahertz light generating section 2 is located at the focal point S of the parabolic mirror 1 which is off-axis, and the terahertz light is generated. The terahertz light generation unit 2 is arranged so that the optical axis of the generation unit 2 coincides with the straight line FS.
【００１４】図６に示す例では、軸外し放物面鏡１の反
射面１ａの全領域が、テラヘルツ光発生部２から発生し
た発散光束によるテラヘルツ光入射領域となっている。
テラヘルツ光発生部２から発生した発散光束には、反射
面１ａから外れる光束も存在するが、反射面１ａから外
れる光束は平行光束となり得ない無効光束であるので、
その図示は省略している。In the example shown in FIG. 6, the entire area of the reflecting surface 1a of the off-axis parabolic mirror 1 is the terahertz light incident area due to the divergent light beam generated from the terahertz light generating section 2.
Although the divergent light flux generated from the terahertz light generation unit 2 includes a light flux that deviates from the reflecting surface 1a, the light flux that deviates from the reflecting surface 1a is an ineffective light flux that cannot be a parallel light flux.
The illustration is omitted.
【００１５】テラヘルツ光発生部２の光軸が直線ＦＳと
一致しているので、テラヘルツ光発生部２から発生する
発散光束のうち放射強度の最も高い方向に向かう基準光
線（線分ＳＦに沿って点Ｆに向かう光線）が、基準面で
あるＸＹ平面内に含まれている。また、テラヘルツ光発
生部２の光軸が直線ＦＳと一致しているので、軸外し放
物面鏡１の反射面１ａのテラヘルツ光入射領域（本例で
は、反射面１の全領域）の周縁とＸＹ平面とが交わる２
つの点Ｂ，Ｄにそれぞれ到達する前記発散光束に含まれ
る２本の光線のうちの一方の光線（線分ＳＢに沿って点
Ｂに到達する光線）と前記基準光線とが、ＸＹ平面内に
おいてなす角度θ１の絶対値と、前記２本の光線のうち
の他方の光線（線分ＳＤに沿って点Ｄに到達する光線）
と前記基準光線とが、ＸＹ平面内においてなす角度θ２
の絶対値とは、異なっている。既に説明したように、θ
１＜θ２である。Since the optical axis of the terahertz light generating section 2 coincides with the straight line FS, a reference ray (along the line segment SF) of the divergent light flux generated from the terahertz light generating section 2 in the direction of the highest radiant intensity. The light ray toward the point F) is included in the XY plane that is the reference plane. Further, since the optical axis of the terahertz light generation unit 2 coincides with the straight line FS, the peripheral edge of the terahertz light incident area (the entire area of the reflection surface 1 in this example) of the reflection surface 1a of the off-axis parabolic mirror 1 is detected. Intersects with the XY plane
In the XY plane, one of the two rays (the ray that reaches the point B along the line segment SB) and the reference ray that are included in the divergent light flux that reach each of the two points B and D are in the XY plane. The absolute value of the formed angle θ 1 and the other ray of the two rays (the ray reaching the point D along the line segment SD)
And the reference ray form an angle θ 2 in the XY plane.
Is different from the absolute value of. As already explained,
1 <θ 2 .
【００１６】図６に示す従来のテラヘルツ光供給光学系
によれば、図６に示すように、テラヘルツ光発生部２か
ら発生した発散光束は、軸外し放物面鏡１の反射面１ａ
により反射されて平行光束となって、外部に供給され
る。According to the conventional terahertz light supply optical system shown in FIG. 6, as shown in FIG. 6, the divergent light flux generated from the terahertz light generating section 2 is reflected off the reflecting surface 1a of the off-axis parabolic mirror 1.
Is reflected by the light beam to be a parallel light beam and is supplied to the outside.
【００１７】図７は、前述した図４及び図５に示す軸外
し放物面鏡１を有する従来のテラヘルツ光検出光学系を
示す概略断面図であり、図５及び図６に対応している。
図７において、図４乃至図６中の要素等と同一又は対応
する要素等には同一符号を付し、その重複する説明は省
略する。FIG. 7 is a schematic sectional view showing a conventional terahertz light detecting optical system having the off-axis parabolic mirror 1 shown in FIGS. 4 and 5, and corresponds to FIGS. 5 and 6. .
In FIG. 7, elements or the like that are the same as or correspond to the elements or the like in FIGS. 4 to 6 are denoted by the same reference numerals, and overlapping description thereof will be omitted.
【００１８】図７に示す従来のテラヘルツ光検出光学系
は、前述した図４及び図５に示す軸外し放物面鏡１と、
収束中心点に収束しようとする収束光束のテラヘルツ光
を前記収束中心点に対応するテラヘルツ光検出点Ｊで受
光し検出感度に指向性を有するテラヘルツ光検出部５と
を備え、軸外し放物面鏡１の反射面１ａに反射面１ａを
規定する回転軸（Ｙ軸）と平行に入射される平行光束の
テラヘルツ光を検出する。図７に示す例では、軸外し放
物面鏡１の反射面１ａの全領域が、外部からの平行光束
によるテラヘルツ光入射領域となっている。The conventional terahertz light detecting optical system shown in FIG. 7 includes the off-axis parabolic mirror 1 shown in FIGS.
An off-axis parabolic surface, which is provided with a terahertz light detecting section 5 which receives terahertz light of a convergent light beam which is about to converge at a convergence center point at a terahertz light detection point J corresponding to the convergence center point and has directivity in detection sensitivity. The terahertz light of the parallel light flux that is incident on the reflecting surface 1a of the mirror 1 in parallel with the rotation axis (Y axis) that defines the reflecting surface 1a is detected. In the example shown in FIG. 7, the entire area of the reflecting surface 1a of the off-axis parabolic mirror 1 is the terahertz light incident area due to the parallel light flux from the outside.
【００１９】テラヘルツ光検出部５は、図６中のテラヘ
ルツ光発生部２と全く同一の構成を有し、光スイッチ素
子３及び超半球レンズ４を有している。ただし、テラヘ
ルツ光検出部５では、テラヘルツ光発生部２の場合と光
の進行方向が逆になるので、超半球レンズ４は、外部か
ら入射される収束光束のテラヘルツ光の収束角を大きく
するように作用することになる。また、点Ｊは、テラヘ
ルツ光発生部２ではテラヘルツ光発生点であるのに対
し、テラヘルツ光検出部５ではテラヘルツ光検出点とな
る。超半球レンズ４の光軸は、テラヘルツ光検出点Ｊを
通る、光スイッチ素子３の光導電層の膜面の法線と一致
している。ここでは、超半球レンズ４の光軸をテラヘル
ツ光検出部５の光軸と呼ぶ。テラヘルツ光検出部５がこ
のような構成を有しているので、テラヘルツ光検出部５
に入射する収束光束（超半球レンズ４の外側の収束光
束）に関してテラヘルツ光検出部５はテラヘルツ光の検
出感度に指向性を有し、この収束光束では、テラヘルツ
光検出部５の光軸方向の検出感度が最も高く、この光軸
方向から外れるに従って検出感度が低くなる。The terahertz light detecting section 5 has exactly the same structure as the terahertz light generating section 2 in FIG. 6, and has an optical switch element 3 and a super hemispherical lens 4. However, in the terahertz light detection unit 5, the traveling direction of light is opposite to that in the case of the terahertz light generation unit 2, so that the super-hemispherical lens 4 increases the convergence angle of the terahertz light of the converged light flux incident from the outside. Will act on. Further, the point J is a terahertz light generation point in the terahertz light generation unit 2, whereas it is a terahertz light detection point in the terahertz light detection unit 5. The optical axis of the super-hemispherical lens 4 coincides with the normal line of the film surface of the photoconductive layer of the optical switch element 3, which passes through the terahertz light detection point J. Here, the optical axis of the super-hemispherical lens 4 is referred to as the optical axis of the terahertz light detection unit 5. Since the terahertz light detection unit 5 has such a configuration, the terahertz light detection unit 5
The convergent light beam (convergent light beam outside the super-hemispherical lens 4) incident on the terahertz light detection unit 5 has a directivity in the detection sensitivity of the terahertz light. The detection sensitivity is the highest, and the detection sensitivity decreases as the position deviates from the optical axis direction.
【００２０】図７に示す従来のテラヘルツ光検出光学系
におけるテラヘルツ光検出部５と軸外し放物面鏡１との
位置関係は、図６に示す従来のテラヘルツ光供給光学系
におけるテラヘルツ光発生部２と軸外し放物面鏡１との
位置関係と同一に設定されている。すなわち、図７に示
す従来のテラヘルツ光検出光学系では、テラヘルツ光検
出点Ｊに集光されるべき収束光束（超半球レンズ４の外
側の収束光束）の収束中心点が軸外し放物面鏡１の焦点
Ｓに位置し、かつ、テラヘルツ光検出部５の光軸が直線
ＦＳと一致するように、テラヘルツ光発生部２が配置さ
れている。The positional relationship between the terahertz light detecting section 5 and the off-axis parabolic mirror 1 in the conventional terahertz light detecting optical system shown in FIG. 7 is the same as the terahertz light generating section in the conventional terahertz light supplying optical system shown in FIG. 2 and the off-axis parabolic mirror 1 are set to have the same positional relationship. That is, in the conventional terahertz light detection optical system shown in FIG. 7, the convergence center point of the convergent light beam (convergent light beam outside the super-hemispherical lens 4) to be condensed at the terahertz light detection point J is an off-axis parabolic mirror. The terahertz light generation unit 2 is arranged so that it is located at the focal point S of 1 and the optical axis of the terahertz light detection unit 5 coincides with the straight line FS.
【００２１】テラヘルツ光検出部５の光軸が直線ＦＳと
一致しているので、テラヘルツ光検出部５に入射する収
束光束のうちテラヘルツ光検出部５の検出感度の最も高
い方向から前記収束中心点に向かう基準光線（直線ＦＳ
に沿って焦点Ｓに向かう光線）が、基準面であるＸＹ平
面内に含まれている。また、テラヘルツ光検出部５の光
軸が直線ＦＳと一致しているので、軸外し放物面鏡１の
反射面１ａのテラヘルツ光入射領域（本例では、反射面
１ａの全領域）の周縁とＸＹ平面とが交わる２つの点
Ｂ，Ｄからそれぞれテラヘルツ光検出点Ｊに到達する前
記収束光束に含まれる２本の光線のうちの一方の光線
（線分ＢＳに沿った後に点Ｊに到達する光線）と前記基
準光線とが、ＸＹ平面内においてなす角度θ１の絶対値
と、前記２本の光線のうちの他方の光線（線分ＤＳに沿
った後に点Ｊに到達する光線）と前記基準光線とが、Ｘ
Ｙ平面内においてなす角度θ２の絶対値とは、異なって
いる。既に説明したように、θ１＜θ２である。Since the optical axis of the terahertz light detection unit 5 coincides with the straight line FS, the convergence center point is selected from the direction in which the detection sensitivity of the terahertz light detection unit 5 is the highest among the converged light beams entering the terahertz light detection unit 5. Reference ray (straight line FS)
A ray of light that goes toward the focal point S along) is included in the XY plane that is the reference plane. Further, since the optical axis of the terahertz light detection unit 5 coincides with the straight line FS, the peripheral edge of the terahertz light incident area (the entire area of the reflection surface 1a in this example) of the reflection surface 1a of the off-axis parabolic mirror 1 is detected. And one of the two light rays included in the converged light flux that reach the terahertz light detection point J from two points B and D where the XY plane intersects the point (after reaching the point J after reaching the line segment BS). Ray) and the reference ray, the absolute value of the angle θ 1 formed in the XY plane, and the other ray of the two rays (the ray that reaches the point J after following the line segment DS). The reference ray is X
It is different from the absolute value of the angle θ 2 formed in the Y plane. As already described, θ 1 <θ 2 .
【００２２】図７に示す従来のテラヘルツ光検出光学系
によれば、図７に示すように、外部から軸外し放物面鏡
１の反射面１ａに入射した平行光束は、軸外し放物面鏡
１の反射面１ａにより反射されて収束光束となり、更に
テラヘルツ光検出点Ｊに集光されて検出される。According to the conventional terahertz light detecting optical system shown in FIG. 7, as shown in FIG. 7, the parallel light flux incident on the reflecting surface 1a of the off-axis parabolic mirror 1 from the outside is an off-axis parabolic surface. It is reflected by the reflecting surface 1a of the mirror 1 to form a convergent light beam, which is further focused on the terahertz light detection point J and detected.
【００２３】[0023]
【発明が解決しようとする課題】本発明者の研究の結
果、前述した図６に示す従来のテラヘルツ光供給光学系
では、テラヘルツ光発生部２が放射強度に指向性を有す
ることに起因して、平行光束として供給するテラヘルツ
光の利用効率が低下していることが判明した。すなわ
ち、テラヘルツ光発生部２が放射強度に指向性を有する
ため、図６においてテラヘルツ光発生部２の光軸が直線
ＦＳと一致しておりθ１＜θ２であることから、テラヘ
ルツ光発生部２から点Ｂへ向かう光線よりわずかに発散
角度が大きい光線（線分ＳＢをＳを中心として反時計方
向にわずかに回転させた線分に沿って進行する光線）の
放射強度は、テラヘルツ光発生部２から点Ｄへ向かう光
線（線分ＳＤに沿って進行する光線）の放射強度に比べ
て、高い。ところが、相対的に放射強度の高い前者の光
線は軸外し放物面鏡１の反射面１ａから外れてしまい平
行光束の一部となり得ず、代わりに、相対的に放射強度
の低い後者の光線が平行光束の一部となる。したがっ
て、得られる平行光束の全体としての強度には、両者の
差に相当する損失が発生しており、平行光束として供給
するテラヘルツ光の利用効率が低下していた。As a result of the research conducted by the present inventor, in the conventional terahertz light supplying optical system shown in FIG. 6, the terahertz light generating section 2 has a directivity in radiation intensity. , It was found that the utilization efficiency of the terahertz light supplied as a parallel light flux was reduced. That is, since the terahertz light generation unit 2 has a directivity in the radiation intensity, the optical axis of the terahertz light generation unit 2 coincides with the straight line FS in FIG. 6 and θ 1 <θ 2 is satisfied. The radiation intensity of a ray having a divergence angle slightly larger than the ray going from 2 to the point B (a ray traveling along a line segment slightly rotated counterclockwise about the line segment SB about S) is terahertz light generation. It is higher than the radiant intensity of the light ray (light ray traveling along the line segment SD) traveling from the portion 2 to the point D. However, the former ray of relatively high radiant intensity deviates from the reflecting surface 1a of the off-axis parabolic mirror 1 and cannot be a part of the parallel light flux. Instead, the latter ray of relatively low radiant intensity is used. Becomes a part of the parallel light flux. Therefore, a loss corresponding to the difference between the two is generated in the intensity of the obtained parallel light flux as a whole, and the utilization efficiency of the terahertz light supplied as the parallel light flux is reduced.
【００２４】また、本発明者の研究の結果、前述した図
７に示す従来のテラヘルツ光検出光学系では、テラヘル
ツ光検出部５が検出感度に指向性を有することに起因し
て、検出するテラヘルツ光の利用効率が低下しているこ
とが判明した。すなわち、テラヘルツ光検出部５が検出
感度に指向性を有するため、図７においてテラヘルツ光
検出部５の光軸が直線ＦＳと一致しておりθ１＜θ２で
あることから、点Ｂからテラヘルツ光検出部５へ向かう
光線よりわずかに収束角度が大きい光線（線分ＢＳをＳ
を中心として反時計方向にわずかに回転させた線分に沿
って進行する光線）の検出感度は、点Ｄからテラヘルツ
光検出部５へ向かう光線（線分ＤＳに沿って進行する光
線）の検出感度に比べて、高い。ところが、相対的に検
出感度の高い前者の光線は軸外し放物面鏡１の反射面１
ａから外れてしまいテラヘルツ光検出点Ｊに到達し得
ず、代わりに、相対的に検出感度の低い後者の光線がテ
ラヘルツ光検出点Ｊに到達する。したがって、平行光束
のテラヘルツ光の全体としての検出感度には、両者の差
に相当する損失が発生しており、検出するテラヘルツ光
の利用効率が低下していた。Further, as a result of the research conducted by the present inventor, in the conventional terahertz light detection optical system shown in FIG. 7, the terahertz light detection unit 5 detects the terahertz light due to the detection sensitivity having directivity. It was found that the light utilization efficiency was reduced. That is, since the terahertz light detection unit 5 has directivity in detection sensitivity, the optical axis of the terahertz light detection unit 5 in FIG. 7 coincides with the straight line FS, and θ 1 <θ 2 is satisfied. A ray having a slightly larger convergence angle than the ray going to the light detection unit 5 (the line segment BS is
The detection sensitivity of a light ray traveling along a line segment slightly rotated counterclockwise around the center is the detection of a light beam traveling from the point D to the terahertz light detection unit 5 (a light ray traveling along the line segment DS). High compared to sensitivity. However, the former light beam, which has a relatively high detection sensitivity, is reflected off the reflecting surface 1 of the off-axis parabolic mirror 1.
Since it deviates from “a” and cannot reach the terahertz light detection point J, the latter ray having relatively low detection sensitivity reaches the terahertz light detection point J instead. Therefore, the detection sensitivity of the terahertz light of the parallel light flux as a whole has a loss corresponding to the difference between the two, and the utilization efficiency of the terahertz light to be detected is reduced.
【００２５】本発明は、このような事情に鑑みてなされ
たもので、平行光束として供給するテラヘルツ光の利用
効率を高めることができるテラヘルツ光供給光学系及び
これを用いたテラヘルツ光装置を提供することを目的と
する。また、本発明は、検出するテラヘルツ光の利用効
率を高めることができるテラヘルツ光検出光学系及びこ
れを用いたテラヘルツ光装置を提供することを目的とす
る。The present invention has been made in view of the above circumstances, and provides a terahertz light supply optical system and a terahertz light device using the terahertz light supply optical system capable of enhancing the utilization efficiency of the terahertz light supplied as a parallel light flux. The purpose is to It is another object of the present invention to provide a terahertz light detection optical system capable of increasing the utilization efficiency of the detected terahertz light and a terahertz light device using the same.
【００２６】[0026]
【課題を解決するための手段】前記課題を解決するた
め、本発明の第１の態様によるテラヘルツ光供給光学系
は、放射強度に指向性を有する発散光束のテラヘルツ光
を発生するテラヘルツ光発生部と、軸外し放物面鏡とを
備え、前記テラヘルツ光発生部から発生したテラヘルツ
光を実質的に平行光束にして供給するテラヘルツ光供給
光学系において、（ａ）前記発散光束の発散中心点が、
前記軸外し放物面鏡の焦点の付近又は前記焦点と光学的
に等価な位置の付近に位置すること、（ｂ）前記発散光
束のうち前記放射強度の最も高い方向に向かう基準光線
が、少なくとも前記軸外し放物面鏡の回転放物面をなす
反射面の付近で、前記反射面を規定する回転軸を含む所
定の基準面内に実質的に含まれること、及び、（ｃ）前
記反射面のテラヘルツ光入射領域の周縁と前記基準面と
が交わる２つの点にそれぞれ到達する前記発散光束に含
まれる２本の光線のうちの一方の光線と前記基準光線と
が、少なくとも前記反射面の付近で、前記基準面内にお
いてなす角度の絶対値と、前記２本の光線のうちの他方
の光線と前記基準光線とが、少なくとも前記反射面の付
近で、前記基準面内においてなす角度の絶対値とが、略
等しいこと、の各条件を満たすように、前記テラヘルツ
光発生部と前記軸外し放物面鏡との光学的な位置関係が
設定されたものである。In order to solve the above-mentioned problems, a terahertz light supply optical system according to a first aspect of the present invention is a terahertz light generating section for generating terahertz light of a divergent luminous flux having directivity in radiation intensity. And an off-axis parabolic mirror, which supplies the terahertz light generated from the terahertz light generating section into a substantially parallel light beam and supplies the terahertz light, wherein (a) the divergence center point of the divergent light beam is ,
Being located near the focal point of the off-axis parabolic mirror or near a position optically equivalent to the focal point; and (b) at least the reference light beam in the direction of the highest radiant intensity of the divergent light flux, Being substantially within a predetermined reference plane including a rotation axis defining the reflecting surface in the vicinity of the reflecting surface forming the paraboloid of revolution of the off-axis parabolic mirror; and (c) the reflection. At least one of the two light rays included in the divergent light flux reaching the two points where the peripheral edge of the terahertz light incident area of the surface and the reference surface intersect and the reference light ray are at least In the vicinity, the absolute value of the angle formed in the reference plane, and the absolute value of the angle formed in the reference plane by the other ray of the two rays and the reference ray at least near the reflection surface. Value is almost equal, So as to satisfy the matter, in which optical positional relationship between the axis paraboloidal mirror and the terahertz light generator is set.
【００２７】なお、前記第１の態様において、前記所定
の基準面としては、例えば、前記回転軸を含む種々の基
準面のうち、当該基準面と前記反射面とが交わる放物線
の一方の端点と前記焦点とを結ぶ線分と、当該基準面と
前記反射面とが交わる放物線の他方の端点と前記焦点と
を結ぶ線分とがなす、挟角が、最大となる基準面とする
ことができる。In the first aspect, the predetermined reference surface is, for example, one end point of a parabola where the reference surface and the reflection surface intersect, among various reference surfaces including the rotation axis. The angle between the line segment that connects the focal point and the line segment that connects the focal point and the other end point of the parabola that intersects the reference surface and the reflection surface can be the reference surface that maximizes the angle. .
【００２８】本発明の第２の態様によるテラヘルツ光検
出光学系は、収束中心点に収束しようとする収束光束の
テラヘルツ光を前記収束中心点に対応するテラヘルツ光
検出点で受光し検出感度に指向性を有するテラヘルツ光
検出部と、軸外し放物面鏡とを備え、前記軸外し放物面
鏡の回転放物面をなす反射面に該反射面を規定する回転
軸と実質的に平行に入射される、実質的に平行光束のテ
ラヘルツ光を検出するテラヘルツ光検出光学系におい
て、（ａ）前記収束中心点が、前記軸外し放物面鏡の焦
点の付近又は前記焦点と光学的に等価な位置の付近に位
置すること、（ｂ）前記収束光束のうち前記検出感度の
最も高い方向から前記収束中心点に向かう基準光線が、
少なくとも前記反射面の付近で、前記回転軸を含む所定
の基準面内に実質的に含まれること、及び、（ｃ）前記
反射面のテラヘルツ光入射領域の周縁と前記基準面とが
交わる２つの点からそれぞれ前記テラヘルツ光検出点に
到達する前記収束光束に含まれる２本の光線のうちの一
方の光線と前記基準光線とが、少なくとも前記反射面の
付近で、前記基準面内においてなす角度の絶対値と、前
記２本の光線のうちの他方の光線と前記基準光線とが、
少なくとも前記反射面の付近で、前記基準面内において
なす角度の絶対値とが、略等しいこと、の各条件を満た
すように、前記テラヘルツ光検出部と前記軸外し放物面
鏡との光学的な位置関係が設定されたものである。In the terahertz light detection optical system according to the second aspect of the present invention, the terahertz light of the convergent light beam which is about to converge at the convergence center point is received at the terahertz light detection point corresponding to the convergence center point and directed to the detection sensitivity. Comprising a terahertz light detection unit having an optical property and an off-axis paraboloidal mirror, and substantially parallel to the rotation axis defining the reflection surface on the reflection surface forming the paraboloid of rotation of the off-axis parabolic mirror. In a terahertz light detection optical system for detecting an incident substantially parallel light flux of terahertz light, (a) the convergence center point is near the focus of the off-axis parabolic mirror or is optically equivalent to the focus. (B) the reference light beam from the direction with the highest detection sensitivity in the convergent light flux toward the convergence center point,
At least in the vicinity of the reflecting surface, it is substantially included in a predetermined reference surface including the rotation axis, and (c) two intersecting edges of the terahertz light incident region of the reflecting surface and the reference surface. Of the angle between one of the two light rays included in the convergent light flux and the reference light ray that reach the terahertz light detection point from the point at least near the reflection surface in the reference surface. The absolute value, the other ray of the two rays and the reference ray,
At least in the vicinity of the reflecting surface, the absolute value of the angle formed in the reference surface is substantially equal, so that the terahertz light detection unit and the off-axis parabolic mirror are optically provided. The positional relationship is set.
【００２９】なお、前記第２の態様において、前記所定
の基準面としては、例えば、前記回転軸を含む種々の基
準面のうち、当該基準面と前記反射面とが交わる放物線
の一方の端点と前記焦点とを結ぶ線分と、当該基準面と
前記反射面とが交わる放物線の他方の端点と前記焦点と
を結ぶ線分とがなす、挟角が、最大となる基準面とする
ことができる。In the second aspect, the predetermined reference surface is, for example, one of the end points of a parabola where the reference surface and the reflection surface intersect among the various reference surfaces including the rotation axis. The angle between the line segment that connects the focal point and the line segment that connects the focal point and the other end point of the parabola that intersects the reference surface and the reflection surface can be the reference surface that maximizes the angle. .
【００３０】本発明の第３の態様によるテラヘルツ光装
置は、テラヘルツ光発生部と、該テラヘルツ光発生部か
ら発生し所定の光路を経て到達するテラヘルツ光を検出
するテラヘルツ光検出部と、を備えたテラヘルツ光装置
において、前記第１の態様によるテラヘルツ光供給光学
系及び前記第２の態様によるテラヘルツ光検出光学系の
うちの両方又はいずれか一方を備えたものである。A terahertz light generating device according to a third aspect of the present invention comprises a terahertz light generating section and a terahertz light detecting section for detecting terahertz light generated from the terahertz light generating section and arriving via a predetermined optical path. Also, the terahertz light device includes both or one of the terahertz light supply optical system according to the first aspect and the terahertz light detection optical system according to the second aspect.
【００３１】[0031]
【発明の実施の形態】以下、本発明によるテラヘルツ光
供給光学系、テラヘルツ光検出光学系、及びこれを用い
たテラヘルツ光装置について、図面を参照して説明す
る。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A terahertz light supply optical system, a terahertz light detection optical system, and a terahertz light device using the same according to the present invention will be described below with reference to the drawings.
【００３２】［第１の実施の形態］[First Embodiment]
【００３３】図１は、本発明の第１の実施の形態による
テラヘルツ光供給光学系を示す概略断面図であり、図５
及び図６に対応している。図１において、図４乃至図６
中の要素等と同一又は対応する要素等には同一符号を付
し、その重複する説明は省略する。FIG. 1 is a schematic sectional view showing a terahertz light supply optical system according to the first embodiment of the present invention, and FIG.
And correspond to FIG. In FIG. 1, FIGS.
Elements that are the same as or correspond to the elements inside are given the same reference numerals, and duplicate descriptions thereof are omitted.
【００３４】本実施の形態によるテラヘルツ光供給光学
系は、前述した図６に示す従来のテラヘルツ光供給光学
系と同じく、前述した図４及び図５に示す軸外し放物面
鏡１と、放射強度に指向性を有する発散光束のテラヘル
ツ光を発生するテラヘルツ光発生部２とを備え、テラヘ
ルツ光発生部２から発生した発散光束のテラヘルツ光を
実質的に平行光束にして外部に供給する。本実施の形態
で用いるテラヘルツ光発生部２も、前述した図６に示す
従来のテラヘルツ光供給光学系で用いるテラヘルツ光発
生部２と同一である。もっとも、本発明では、テラヘル
ツ光発生部２の構成はこのような構成に限定されるもの
ではない。The terahertz light supply optical system according to the present embodiment is similar to the conventional terahertz light supply optical system shown in FIG. 6 described above, and the off-axis parabolic mirror 1 shown in FIGS. A terahertz light generation unit 2 that generates terahertz light of a divergent light flux having intensity directivity is provided, and the terahertz light of the divergent light flux generated from the terahertz light generation unit 2 is supplied to the outside as a substantially parallel light flux. The terahertz light generator 2 used in this embodiment is also the same as the terahertz light generator 2 used in the conventional terahertz light supply optical system shown in FIG. 6 described above. However, in the present invention, the configuration of the terahertz light generation unit 2 is not limited to such a configuration.
【００３５】本実施の形態によるテラヘルツ光供給光学
系が図６に示す従来のテラヘルツ光供給光学系と異なる
所は、テラヘルツ光発生部２の軸外し放物面鏡１に対す
る配置のみである。すなわち、本実施の形態では、図１
に示すように、テラヘルツ光発生部２を、図６に示す位
置から、焦点Ｓを通りＺ軸と平行な直線の回りに角度Δ
θだけ時計方向に回転移動させて、テラヘルツ光発生部
２の光軸が直線ＨＳと一致するように、配置している。The terahertz light supplying optical system according to this embodiment differs from the conventional terahertz light supplying optical system shown in FIG. 6 only in the arrangement of the terahertz light generating section 2 with respect to the off-axis parabolic mirror 1. That is, in this embodiment, as shown in FIG.
As shown in FIG. 6, the terahertz light generating unit 2 is rotated from the position shown in FIG.
It is arranged so that the optical axis of the terahertz light generation unit 2 coincides with the straight line HS by rotating clockwise by θ.
【００３６】ここで、回転させるべき角度Δθは、図５
に示す前述した幾何学的な関係から、直線ＡＢと直線Ｃ
Ｄとの間のＸ軸方向の距離ｄ及び軸外し放物面鏡の焦点
距離ｆを用いて、次の数１で表すことができる。Here, the angle Δθ to be rotated is shown in FIG.
From the above-mentioned geometrical relationship shown in, the straight line AB and the straight line C
By using the distance d in the X-axis direction with respect to D and the focal length f of the off-axis parabolic mirror, it can be expressed by the following formula 1.
【００３７】[0037]
【数１】 [Equation 1]
【００３８】例えば、軸外し放物面鏡１として、ｄ＝５
０．８ｍｍ、ｆ＝５０．８ｍｍの９０゜軸外し放物面鏡
を用いる場合、数１に従って計算すると、回転させるべ
き角度Δθは約１．７９゜となる。For example, as the off-axis parabolic mirror 1, d = 5
When a 90 ° off-axis parabolic mirror of 0.8 mm and f = 50.8 mm is used, the angle Δθ to be rotated is about 1.79 ° when calculated according to the formula 1.
【００３９】本実施の形態では、テラヘルツ光発生部２
が前述したように配置されているので、テラヘルツ光発
生部２から発生される発散光束の発散中心点が、軸外し
放物面鏡１の焦点Ｓ（必ずしも厳密に焦点Ｓの位置でな
くてもよい）に位置している。また、テラヘルツ光発生
部２から発生される発散光束のうち放射強度の最も高い
方向に向かう基準光線（本実施の形態では、テラヘルツ
光発生部２の光軸に沿った光線）が、軸外し放物面鏡１
の回転軸（Ｙ軸）を含む所定の基準面（本実施の形態で
は、ＸＹ平面）内に実質的に含まれている。In the present embodiment, the terahertz light generating section 2
Are arranged as described above, the divergence center point of the divergent light beam generated from the terahertz light generation unit 2 is the focus S of the off-axis parabolic mirror 1 (even if the focus S is not strictly located at the position. Good) located. In addition, the reference ray (the ray along the optical axis of the terahertz light generating section 2) heading in the direction of the highest radiation intensity in the divergent light flux generated from the terahertz light generating section 2 is emitted off-axis. Object mirror 1
It is substantially included in a predetermined reference plane (the XY plane in the present embodiment) including the rotation axis (Y axis).
【００４０】さらに、本実施の形態では、テラヘルツ光
発生部２が前述したように配置されているので、軸外し
放物面鏡１の反射面１ａのテラヘルツ光入射領域（本実
施の形態では、反射面１の全領域）の周縁とＸＹ平面と
が交わる２つの点Ｂ，Ｄにそれぞれ到達する前記発散光
束に含まれる２本の光線のうちの一方の光線（線分ＳＢ
に沿って点Ｂに到達する光線）と前記基準光線とが、Ｘ
Ｙ平面内においてなす角度θ３の絶対値と、前記２本の
光線のうちの他方の光線（線分ＳＤに沿って点Ｄに到達
する光線）と前記基準光線とが、ＸＹ平面内においてな
す角度θ４の絶対値とが、等しくなっている。もっと
も、本発明では、両者の角度の絶対値は、厳密に等しく
なくてよく、実質的に等しくてもよいし、略等しくても
よい。ここで、略等しいとは、角度θ３と角度θ４との
差の絶対値が角度θ１と角度θ２との差の絶対値より小
さいことをいう。すなわち、本発明では、テラヘルツ光
発生部２の光軸が直線ＨＳに対して絶対値が角度θ１と
角度θ２との差の絶対値より小さい角度だけずれていて
もよい。Furthermore, in the present embodiment, since the terahertz light generating section 2 is arranged as described above, the terahertz light incident area of the reflecting surface 1a of the off-axis parabolic mirror 1 (in the present embodiment, One of the two light rays (line segment SB) included in the divergent light flux reaching each of two points B and D where the peripheral edge of the entire reflection surface 1) and the XY plane intersect.
(A ray reaching point B along) and the reference ray are X
The absolute value of the angle θ 3 formed in the Y plane, the other ray of the two rays (the ray reaching the point D along the line segment SD) and the reference ray are formed in the XY plane. The absolute value of the angle θ 4 is equal. However, in the present invention, the absolute values of the two angles need not be exactly equal, and may be substantially equal or substantially equal. Here, “substantially equal” means that the absolute value of the difference between the angle θ 3 and the angle θ 4 is smaller than the absolute value of the difference between the angle θ 1 and the angle θ 2 . That is, in the present invention, the optical axis of the terahertz light generation unit 2 may be displaced from the straight line HS by an angle whose absolute value is smaller than the absolute value of the difference between the angle θ 1 and the angle θ 2 .
【００４１】本実施の形態によれば、テラヘルツ光発生
部２の光軸が直線ＨＳと一致しておりθ３＝θ４である
ので、図６に示す従来技術と比較して、テラヘルツ光発
生部２の光軸に近く放射強度の高い発散光束が軸外し放
物面鏡１の反射面１ａに入射され、この光束によって平
行光束が形成されることになる。したがって、本実施の
形態によれば、平行光束として供給するテラヘルツ光の
利用効率を高めることができる。According to the present embodiment, since the optical axis of the terahertz light generating section 2 coincides with the straight line HS and θ 3 = θ 4 , the terahertz light generation is performed as compared with the conventional technique shown in FIG. A divergent light beam having a high radiant intensity near the optical axis of the portion 2 is incident on the reflecting surface 1a of the parabolic mirror 1 off axis, and this light beam forms a parallel light beam. Therefore, according to the present embodiment, it is possible to improve the utilization efficiency of the terahertz light supplied as the parallel light flux.
【００４２】なお、本発明では、例えば、図１におい
て、軸外し放物面鏡１とテラヘルツ光発生部２との間
に、光路を折り曲げる平面反射鏡を配置してもよい。こ
の場合、テラヘルツ光発生部２は、当該平面反射鏡に関
して図１に示す位置と光学的に等価な位置に配置すれば
よい。また、本発明によるテラヘルツ光供給光学系で
は、軸外し放物面鏡１の反射面１ａの全領域を、発散光
束のテラヘルツ光が入射されるテラヘルツ光入射領域と
する必要はないし、また、回転放物面の全ての領域が反
射面１ａでなくてもよい。さらに、本発明によるテラヘ
ルツ光供給光学系において使用し得る軸外し放物面鏡
は、９０゜軸外し放物面鏡に限定されるものではなく、
例えば、４５゜軸外し放物面鏡を用いることもできる。In the present invention, for example, in FIG. 1, a plane reflecting mirror for bending the optical path may be arranged between the off-axis parabolic mirror 1 and the terahertz light generating section 2. In this case, the terahertz light generating section 2 may be arranged at a position optically equivalent to the position shown in FIG. 1 with respect to the plane reflecting mirror. Further, in the terahertz light supply optical system according to the present invention, it is not necessary to set the entire area of the reflecting surface 1a of the off-axis parabolic mirror 1 as the terahertz light incident area on which the terahertz light of the divergent light flux is incident, and the rotation is possible. The entire area of the paraboloid may not be the reflective surface 1a. Furthermore, the off-axis parabolic mirror that can be used in the terahertz light supply optical system according to the present invention is not limited to the 90 ° off-axis parabolic mirror.
For example, a 45 ° off-axis parabolic mirror can be used.
【００４３】［第２の実施の形態］[Second Embodiment]
【００４４】図２は、本発明の第２の実施の形態による
テラヘルツ光検出光学系を示す概略断面図であり、図５
及び図７に対応している。図２において、図４、図５及
び図７中の要素等と同一又は対応する要素等には同一符
号を付し、その重複する説明は省略する。FIG. 2 is a schematic sectional view showing a terahertz light detecting optical system according to the second embodiment of the present invention, and FIG.
And correspond to FIG. 7. In FIG. 2, elements and the like that are the same as or correspond to the elements and the like in FIGS. 4, 5 and 7 are assigned the same reference numerals, and overlapping descriptions thereof are omitted.
【００４５】本実施の形態によるテラヘルツ光検出光学
系は、前述した図７に示す従来のテラヘルツ光検出光学
系と同じく、前述した図４及び図５に示す軸外し放物面
鏡１と、収束中心点に収束しようとする収束光束のテラ
ヘルツ光を前記収束中心点に対応するテラヘルツ光検出
点Ｊで受光し検出感度に指向性を有するテラヘルツ光検
出部５とを備え、軸外し放物面鏡１の反射面１ａに反射
面１ａを規定する回転軸（Ｙ軸）と平行に入射される平
行光束のテラヘルツ光を検出する。本実施の形態で用い
るテラヘルツ光検出部５も、前述した図７に示す従来の
テラヘルツ光検出光学系で用いるテラヘルツ光検出部５
と同一である。もっとも、本発明では、テラヘルツ光検
出部５の構成はこのような構成に限定されるものではな
い。The terahertz light detecting optical system according to this embodiment is similar to the conventional terahertz light detecting optical system shown in FIG. 7 and the off-axis parabolic mirror 1 shown in FIGS. An off-axis parabolic mirror, which is provided with a terahertz light detecting section 5 which receives the terahertz light of a convergent light beam which is about to converge at the center point at a terahertz light detection point J corresponding to the convergence center point and has directivity in detection sensitivity. The terahertz light of the parallel light flux incident on the first reflecting surface 1a in parallel with the rotation axis (Y axis) defining the reflecting surface 1a is detected. The terahertz light detection unit 5 used in this embodiment is also the terahertz light detection unit 5 used in the conventional terahertz light detection optical system shown in FIG.
Is the same as However, in the present invention, the configuration of the terahertz light detection unit 5 is not limited to such a configuration.
【００４６】本実施の形態によるテラヘルツ光検出光学
系が図７に示す従来のテラヘルツ光検出光学系と異なる
所は、テラヘルツ光検出部５の軸外し放物面鏡１に対す
る配置のみである。すなわち、本実施の形態では、図１
に示すように、テラヘルツ光検出部５を、図７に示す位
置から、焦点Ｓを通りＺ軸と平行な直線の回りに角度Δ
θだけ時計方向に回転移動させて、テラヘルツ光検出部
５の光軸が直線ＨＳと一致するように、配置している。
ここで、回転させるべき角度Δθは、前述した数１によ
り算出することができる。The terahertz light detecting optical system according to the present embodiment differs from the conventional terahertz light detecting optical system shown in FIG. 7 only in the arrangement of the terahertz light detecting unit 5 with respect to the off-axis parabolic mirror 1. That is, in this embodiment, as shown in FIG.
As shown in, the terahertz light detection unit 5 is moved from the position shown in FIG. 7 to an angle Δ about a straight line passing through the focal point S and parallel to the Z axis.
It is arranged so that the optical axis of the terahertz light detection unit 5 coincides with the straight line HS by rotating clockwise by θ.
Here, the angle Δθ to be rotated can be calculated by the above-mentioned formula 1.
【００４７】本実施の形態では、テラヘルツ光検出部５
が前述したように配置されているので、テラヘルツ光検
出点Ｊに集光されるべき収束光束（超半球レンズ４の外
側の収束光束）の収束中心点が軸外し放物面鏡１の焦点
Ｓ（必ずしも厳密に焦点Ｓの位置でなくてもよい）に位
置している。また、テラヘルツ光検出部５に入射する収
束光束のうちテラヘルツ光検出部５の検出感度の最も高
い方向から前記収束中心点に向かう基準光線（本実施の
形態では、テラヘルツ光検出部５の光軸に沿った光線）
が、基準面であるＸＹ平面内に実質的に含まれている。In the present embodiment, the terahertz light detecting section 5
Are arranged as described above, the center point of convergence of the convergent light beam (convergent light beam outside the super-hemispherical lens 4) to be condensed at the terahertz light detection point J is the off-axis focus S of the parabolic mirror 1. (The position is not necessarily strictly the position of the focus S). Further, in the convergent light flux entering the terahertz light detection unit 5, a reference light beam that goes from the direction with the highest detection sensitivity of the terahertz light detection unit 5 toward the convergence center point (in the present embodiment, the optical axis of the terahertz light detection unit 5). Rays along)
Are substantially included in the XY plane that is the reference plane.
【００４８】さらに、本実施の形態では、テラヘルツ光
検出部５が前述したように配置されているので、軸外し
放物面鏡１の反射面１ａのテラヘルツ光入射領域（本例
では、反射面１の全領域）の周縁とＸＹ平面とが交わる
２つの点Ｂ，Ｄからそれぞれテラヘルツ光検出点Ｊに到
達する前記収束光束に含まれる２本の光線のうちの一方
の光線（線分ＢＳに沿った後に点Ｊに到達する光線）と
前記基準光線とが、ＸＹ平面内においてなす角度θ３の
絶対値と、前記２本の光線のうちの他方の光線（線分Ｄ
Ｓに沿った後に点Ｊに到達する光線）と前記基準光線と
が、ＸＹ平面内においてなす角度θ４の絶対値とが、等
しくなっている。もっとも、本発明では、両者の角度の
絶対値は、厳密に等しくなくてよく、実質的に等しくて
もよいし、略等しくてもよい。ここで、略等しいとは、
角度θ３と角度θ４との差の絶対値が角度θ１と角度θ
２との差の絶対値より小さいことをいう。すなわち、本
発明では、テラヘルツ光検出部５の光軸が直線ＨＳに対
して絶対値が角度θ１と角度θ２との差の絶対値より小
さい角度だけずれていてもよい。Furthermore, in the present embodiment, since the terahertz light detecting section 5 is arranged as described above, the terahertz light incident area (in this example, the reflecting surface) of the reflecting surface 1a of the off-axis parabolic mirror 1 is reflected. One of the two light rays (in the line segment BS) included in the converged light flux reaching the terahertz light detection point J from two points B and D where the peripheral edge of the entire area (1) and the XY plane intersect. The absolute value of the angle θ 3 formed in the XY plane by the ray after reaching the point J) and the reference ray, and the other ray (line segment D) of the two rays.
The ray that reaches point J after traveling along S) and the reference ray are equal in absolute value of the angle θ 4 formed in the XY plane. However, in the present invention, the absolute values of the two angles need not be exactly equal, and may be substantially equal or substantially equal. Here, being approximately equal means
The absolute value of the difference between the angle θ 3 and the angle θ 4 is the angle θ 1 and the angle θ.
It is smaller than the absolute value of the difference from 2 . That is, in the present invention, the optical axis of the terahertz light detection unit 5 may be displaced from the straight line HS by an angle whose absolute value is smaller than the absolute value of the difference between the angle θ 1 and the angle θ 2 .
【００４９】本実施の形態によれば、テラヘルツ光検出
部５の光軸が直線ＨＳと一致しておりθ３＝θ４である
ので、図７に示す従来技術と比較して、テラヘルツ光検
出部５の光軸に近く検出感度の高い方向から収束光束が
テラヘルツ光検出部５に入射され、これによって平行光
束が検出されることになる。したがって、本実施の形態
によれば、平行光束のテラヘルツ光の検出感度が高ま
り、検出する平行光束のテラヘルツ光の利用効率を高め
ることができる。According to the present embodiment, the optical axis of the terahertz light detecting section 5 coincides with the straight line HS and θ 3 = θ 4 , so that the terahertz light detection is performed as compared with the conventional technique shown in FIG. The convergent light beam enters the terahertz light detection unit 5 from a direction close to the optical axis of the unit 5 and having high detection sensitivity, and the parallel light beam is detected thereby. Therefore, according to the present embodiment, the detection sensitivity of the terahertz light of the parallel light flux is enhanced, and the utilization efficiency of the terahertz light of the parallel light flux to be detected can be enhanced.
【００５０】なお、本発明では、例えば、図２におい
て、軸外し放物面鏡１とテラヘルツ光検出部５との間
に、光路を折り曲げる平面反射鏡を配置してもよい。こ
の場合、テラヘルツ光検出部５は、当該平面反射鏡に関
して図１に示す位置と光学的に等価な位置に配置すれば
よい。また、本発明によるテラヘルツ光検出光学系で
は、軸外し放物面鏡１の反射面１ａの全領域を、平行光
束のテラヘルツ光が入射されるテラヘルツ光入射領域と
する必要はないし、また、回転放物面の全ての領域が反
射面１ａでなくてもよい。さらに、本発明によるテラヘ
ルツ光検出光学系において使用し得る軸外し放物面鏡
は、９０゜軸外し放物面鏡に限定されるものではなく、
例えば、４５゜軸外し放物面鏡を用いることもできる。In the present invention, for example, in FIG. 2, a flat reflecting mirror for bending the optical path may be arranged between the off-axis parabolic mirror 1 and the terahertz light detecting section 5. In this case, the terahertz light detection unit 5 may be arranged at a position optically equivalent to the position shown in FIG. 1 with respect to the plane reflecting mirror. Further, in the terahertz light detection optical system according to the present invention, it is not necessary to set the entire region of the reflecting surface 1a of the off-axis parabolic mirror 1 to the terahertz light incident region on which the terahertz light of the parallel light flux is incident, and the rotation is performed. The entire area of the paraboloid may not be the reflective surface 1a. Further, the off-axis parabolic mirror that can be used in the terahertz light detection optical system according to the present invention is not limited to the 90 ° off-axis parabolic mirror.
For example, a 45 ° off-axis parabolic mirror can be used.
【００５１】［第３の実施の形態］[Third Embodiment]
【００５２】図３は、本発明の第３の実施の形態による
テラヘルツ光装置を模式的に示す概略構成図である。FIG. 3 is a schematic configuration diagram schematically showing a terahertz optical device according to the third embodiment of the present invention.
【００５３】本実施の形態によるテラヘルツ光装置で
は、図３に示すように、レーザ光源等からなるフェムト
秒パルス光源１１から放射されたフェムト秒パルス光Ｌ
１が、ビームスプリッタ１２で２つのパルス光Ｌ２，Ｌ
３に分割される。In the terahertz optical device according to this embodiment, as shown in FIG. 3, the femtosecond pulse light L emitted from the femtosecond pulse light source 11 including a laser light source or the like.
1 is a beam splitter 12 and two pulsed lights L2, L
It is divided into three.
【００５４】ビームスプリッタ１２で分割された一方の
パルス光Ｌ２は、テラヘルツ光発生部１７の光スイッチ
素子を励起してこのテラヘルツ光発生部１７にテラヘル
ツパルス光を発生させるためのポンプ光（パルス励起
光）となる。このポンプ光Ｌ２は、光チョッパ１３によ
りチョッピングされた後に、平面鏡１４，１５，１６を
経て、テラヘルツ光発生部１７に導かれる。なお、図面
には示していないが、テラヘルツ光発生部１７の光スイ
ッチ素子には、バイアス電源によりバイアス電圧が印加
される。The one pulsed light L2 split by the beam splitter 12 is a pumping light (pulse excitation) for exciting the optical switch element of the terahertz light generating section 17 to generate terahertz pulsed light in the terahertz light generating section 17. Light). The pump light L2 is chopped by the optical chopper 13 and then guided to the terahertz light generation unit 17 via the plane mirrors 14, 15, and 16. Although not shown in the drawing, a bias voltage is applied to the optical switch element of the terahertz light generation unit 17 by a bias power supply.
【００５５】ビームスプリッタ１２で分割された他方の
パルス光Ｌ３は、テラヘルツパルス光を検出するタイミ
ングを定めるプローブ光（サンプリングパルス光）とな
る。このプローブ光Ｌ３は、平面鏡１８、２枚もしくは
３枚の平面鏡が組み合わされてなる可動鏡１９、更には
平面鏡２０を経て、テラヘルツ光検出部２１へ導かれ
る。本実施の形態では、テラヘルツ光検出部２１は、光
スイッチ素子を有している。The other pulsed light L3 split by the beam splitter 12 becomes probe light (sampling pulsed light) that determines the timing for detecting the terahertz pulsed light. The probe light L3 is guided to the terahertz light detection unit 21 via the plane mirror 18, the movable mirror 19 formed by combining two or three plane mirrors, and further the plane mirror 20. In the present embodiment, the terahertz light detection unit 21 has an optical switch element.
【００５６】プローブ光Ｌ３の光路上に配置された可動
鏡１９は、制御・演算処理部３０による制御下で、移動
機構２２により矢印Ｖ方向に移動可能となっている。可
動鏡１９の移動量に応じて、プローブ光Ｌ３の光路長が
変わり、プローブ光Ｌ３がテラヘルツ光検出部２１へ到
達する時間が遅延する。すなわち、本実施の形態では、
可動鏡１９及び移動機構２２が、プローブ光Ｌ３の時間
遅延装置を構成している。The movable mirror 19 arranged on the optical path of the probe light L3 can be moved in the direction of arrow V by the moving mechanism 22 under the control of the control / arithmetic processing unit 30. The optical path length of the probe light L3 changes according to the amount of movement of the movable mirror 19, and the time for the probe light L3 to reach the terahertz light detection unit 21 is delayed. That is, in the present embodiment,
The movable mirror 19 and the moving mechanism 22 constitute a time delay device for the probe light L3.
【００５７】テラヘルツ光発生部１７に導かれたポンプ
光Ｌ２により、テラヘルツ光発生部１７の光スイッチ素
子が励起されてテラヘルツパルス光Ｌ４を放射する。テ
ラヘルツパルス光Ｌ４としては、概ね０．１×１０１２
から１００×１０１２ヘルツまでの周波数領域の光が望
ましい。このテラヘルツパルス光Ｌ４は、軸外し放物面
鏡２３を経て平行光束に変換された後、軸外し放物面鏡
２４により集光位置に集光される。本実施の形態では、
この集光位置には、被測定物４０の測定部位が配置され
る。The pump light L2 guided to the terahertz light generating section 17 excites the optical switch element of the terahertz light generating section 17 to emit the terahertz pulse light L4. The terahertz pulse light L4 is approximately 0.1 × 10 12
To 100 × 10 12 Hertz in the frequency range is desirable. The terahertz pulse light L4 is converted into a parallel light flux via the off-axis parabolic mirror 23, and then is converged on the converging position by the off-axis parabolic mirror 24. In this embodiment,
The measurement site of the DUT 40 is arranged at this light collection position.
【００５８】被測定物４０を透過したテラヘルツパルス
光Ｌ５は、軸外し放物面鏡２５により平行光束に変換さ
れた後、軸外し放物面鏡２６により収束光束に変換され
て、テラヘルツ光検出部２１に入射され、テラヘルツ光
検出部２１により検出されて電気信号に変換される。The terahertz pulse light L5 transmitted through the object 40 to be measured is converted into a parallel light flux by the off-axis parabolic mirror 25, and then converted into a convergent light flux by the off-axis parabolic mirror 26 for terahertz light detection. The light enters the unit 21, is detected by the terahertz light detection unit 21, and is converted into an electric signal.
【００５９】この電流信号は、電流計２７で電圧信号に
変換された後、ロックイン増幅器２８により、光チョッ
パー１３のチョッピングと同期してロックイン検出され
る。ロックイン増幅器２８の出力信号は、テラヘルツ光
の電場強度の検出信号として、Ａ／Ｄ変換器２９により
Ａ／Ｄ変換され、これがコンピュータ等からなる制御・
演算処理部３０に供給される。This current signal is converted into a voltage signal by the ammeter 27 and then lock-in detected by the lock-in amplifier 28 in synchronization with the chopping of the optical chopper 13. The output signal of the lock-in amplifier 28 is A / D converted by the A / D converter 29 as a detection signal of the electric field strength of the terahertz light, and this is controlled by a computer or the like.
It is supplied to the arithmetic processing unit 30.
【００６０】フェムト秒パルス光源１１から放射される
フェムト秒パルス光Ｌ１の繰り返し周期は、数ｋＨｚか
ら１００ＭＨｚオーダーである。したがって、テラヘル
ツ光発生部１７から放射されるテラヘルツパルス光Ｌ４
も、数ｋＨｚから１００ＭＨｚオーダーの繰り返しで放
射される。現在のテラヘルツ光検出部２１では、このテ
ラヘルツパルス光の波形を瞬時に、その形状のまま計測
することは不可能である。The repetition period of the femtosecond pulse light L1 emitted from the femtosecond pulse light source 11 is on the order of several kHz to 100 MHz. Therefore, the terahertz pulse light L4 emitted from the terahertz light generation unit 17
Is also radiated in a repetition of several kHz to 100 MHz order. With the current terahertz light detection unit 21, it is impossible to measure the waveform of this terahertz pulse light instantly in its shape.
【００６１】したがって、本実施の形態では、同じ波形
のテラヘルツパルス光Ｌ５が数ｋＨｚから１００ＭＨｚ
オーダーの繰り返しで到来することを利用して、ポンプ
光Ｌ２とプローブ光Ｌ３との間に時間遅延を設けてテラ
ヘルツパルス光Ｌ５の波形を計測する、いわゆるポンプ
−プローブ法を採用している。すなわち、テラヘルツ光
検出部２１の光スイッチ素子を作動させるポンプ光Ｌ２
に対して、テラヘルツ光検出部２１の光スイッチ素子を
作動させるタイミングを時間τだけ遅らせることによ
り、時間τだけ遅れた時点でのテラヘルツパルス光Ｌ５
の電場強度をテラヘルツ光検出部２１で測定できる。言
い換えれば、プローブ光Ｌ３は、テラヘルツ光検出部２
１に対してゲートをかけていることになる。また、可動
鏡１９を徐々に移動させることは、遅延時間τを徐々に
変えることにほかならない。前記時間遅延装置によって
ゲートをかけるタイミングをずらしながら、繰り返し到
来するテラヘルツパルス光Ｌ５の各遅延時間τごとの時
点の電場強度をテラヘルツ光検出部２１から電気信号と
して順次得ることによって、テラヘルツパルス光Ｌ５の
電場強度の時系列波形Ｅ（τ）を計測することができ
る。Therefore, in the present embodiment, the terahertz pulse light L5 having the same waveform is from several kHz to 100 MHz.
The so-called pump-probe method is employed in which the waveform of the terahertz pulse light L5 is measured by providing a time delay between the pump light L2 and the probe light L3 by utilizing the fact that the light arrives by repeating the order. That is, the pump light L2 for operating the optical switch element of the terahertz light detection unit 21.
On the other hand, by delaying the timing for operating the optical switch element of the terahertz light detection unit 21 by the time τ, the terahertz pulse light L5 at the time point delayed by the time τ.
The electric field strength can be measured by the terahertz light detection unit 21. In other words, the probe light L3 is transmitted to the terahertz light detection unit 2
It means that the gate is applied to 1. Further, gradually moving the movable mirror 19 is nothing but gradually changing the delay time τ. The terahertz pulse light L5 is sequentially obtained as an electric signal from the terahertz light detection unit 21 while sequentially obtaining the electric field intensity at each time point of each delay time τ of the terahertz pulse light L5 that repeatedly arrives while shifting the timing of applying the gate by the time delay device. The time-series waveform E (τ) of the electric field strength can be measured.
【００６２】本実施の形態では、テラヘルツパルス光の
電場強度の時系列波形Ｅ（τ）の計測時には、制御・演
算処理部３０が、移動機構２２に制御信号を与えて、前
記遅延時間τを徐々に変化させながら、Ａ／Ｄ変換器２
９からのデータを制御・演算処理部３０内の図示しない
メモリに順次格納する。これによって、最終的に、テラ
ヘルツパルス光の電場強度の時系列波形Ｅ（τ）を示す
データ全体をメモリに格納する。このような時系列波形
Ｅ（τ）を示すデータを、被測定物４０を図３に示す位
置に配置した場合と配置しない場合について取得する。
制御・演算処理部３０は、これらのデータに基づいて、
被測定物の所望の特性を求め、これをＣＲＴ等の表示部
３１に表示させる。例えば、制御・演算処理部３０は、
公知の手法（ドュヴィラレットら（Lionel Duvillaret,
Frederic Garet, and Jean-Louis Coutaz）の論文（"A
Reliable Method for Extraction of Material Parame
ters in Terahertz Time-Domain Spectroscopy", IEEE
Journal of Selected Topics in Quantum Electronics,
Vol.2, No.3, pp.739-746（1996））によって、被測定
物４０の複素屈折率を演算し、これを表示部３１に表示
させる。In the present embodiment, when measuring the time-series waveform E (τ) of the electric field strength of the terahertz pulsed light, the control / arithmetic processing section 30 gives a control signal to the moving mechanism 22 to set the delay time τ. While gradually changing, the A / D converter 2
The data from 9 are sequentially stored in a memory (not shown) in the control / arithmetic processing unit 30. Thus, finally, the entire data showing the time-series waveform E (τ) of the electric field intensity of the terahertz pulsed light is stored in the memory. Data indicating such a time-series waveform E (τ) is acquired for the case where the DUT 40 is arranged at the position shown in FIG. 3 and the case where it is not arranged.
The control / arithmetic processing unit 30 is based on these data,
A desired characteristic of the object to be measured is obtained and displayed on the display unit 31 such as a CRT. For example, the control / arithmetic processing unit 30
Known methods (Lionel Duvillaret,
Frederic Garet, and Jean-Louis Coutaz) 's paper ("A
Reliable Method for Extraction of Material Parame
ters in Terahertz Time-Domain Spectroscopy ", IEEE
Journal of Selected Topics in Quantum Electronics,
Vol.2, No.3, pp.739-746 (1996)), the complex refractive index of the DUT 40 is calculated and displayed on the display unit 31.
【００６３】そして、本実施の形態では、図３中のテラ
ヘルツ光発生部１７及び軸外し放物面鏡２３として、前
述した第１の実施の形態によるテラヘルツ光供給光学系
が採用されている。すなわち、図３中のテラヘルツ光発
生部１７として図１中のテラヘルツ光発生部２が用いら
れ、図３中の軸外し放物面鏡２３として図１中の軸外し
放物面鏡１が用いられ、両者の位置関係が前述した図１
に示す位置関係に設定されている。In this embodiment, the terahertz light supply optical system according to the first embodiment described above is adopted as the terahertz light generating section 17 and the off-axis parabolic mirror 23 in FIG. That is, the terahertz light generator 2 in FIG. 1 is used as the terahertz light generator 17 in FIG. 3, and the off-axis parabolic mirror 1 in FIG. 1 is used as the off-axis parabolic mirror 23 in FIG. The positional relationship between the two is shown in FIG.
The positional relationship shown in is set.
【００６４】したがって、本実施の形態によれば、テラ
ヘルツ光発生部１７で発生したテラヘルツ光が、軸外し
放物面鏡２３により利用効率良く平行光束のテラヘルツ
光に変換される。このため、試料４０を透過するテラヘ
ルツ光の強度が高まり、ひいては、ＳＮ比の高い測定を
行うことができる。Therefore, according to the present embodiment, the terahertz light generated by the terahertz light generating section 17 is converted by the off-axis parabolic mirror 23 into a parallel light beam of terahertz light with high utilization efficiency. For this reason, the intensity of the terahertz light that passes through the sample 40 is increased, and as a result, measurement with a high SN ratio can be performed.
【００６５】また、本実施の形態では、図３中のテラヘ
ルツ光検出部２１及び軸外し放物面鏡２６として、前述
した第２の実施の形態によるテラヘルツ光検出光学系が
採用されている。すなわち、図３中のテラヘルツ光検出
部２１として図２中のテラヘルツ光検出部５が用いら
れ、図３中の軸外し放物面鏡２６として図２中の軸外し
放物面鏡１が用いられ、両者の位置関係が前述した図２
に示す位置関係に設定されている。Further, in the present embodiment, the terahertz light detecting optical system according to the second embodiment described above is adopted as the terahertz light detecting portion 21 and the off-axis parabolic mirror 26 in FIG. That is, the terahertz light detecting unit 5 in FIG. 2 is used as the terahertz light detecting unit 21 in FIG. 3, and the off-axis parabolic mirror 1 in FIG. 2 is used as the off-axis parabolic mirror 26 in FIG. The positional relationship between the two is shown in FIG.
The positional relationship shown in is set.
【００６６】したがって、本実施の形態によれば、軸外
し放物面鏡２５から軸外し放物面鏡２６に入射される平
行光束のテラヘルツ光が、利用効率良く高感度で、テラ
ヘルツ光発生部１７により検出される。このため、この
点からも、よりＳＮ比の高い測定を行うことができる。Therefore, according to the present embodiment, the terahertz light of the parallel light flux incident on the off-axis parabolic mirror 25 to the off-axis parabolic mirror 26 is used efficiently and with high sensitivity, and the terahertz light generating section is used. Detected by 17. Therefore, also from this point, it is possible to perform measurement with a higher SN ratio.
【００６７】なお、本実施の形態では、前述した第１の
実施の形態によるテラヘルツ光供給光学系、及び、前述
した第２の実施の形態によるテラヘルツ光検出光学系
の、両方が採用されている。しかしながら、本発明によ
るテラヘルツ光装置では、それらのいずれか一方のみを
採用するだけでもよい。すなわち、図３中のテラヘルツ
光発生部１７及び軸外し放物面鏡２３として図６に示す
従来のテラヘルツ光供給光学系を採用してもよいし、あ
るいは、図３中のテラヘルツ光検出部２１及び軸外し放
物面鏡２６として図７に示す従来のテラヘルツ光検出光
学系を採用してもよい。In this embodiment, both the terahertz light supply optical system according to the first embodiment described above and the terahertz light detection optical system according to the second embodiment described above are adopted. . However, the terahertz optical device according to the present invention may employ only one of them. That is, the conventional terahertz light supply optical system shown in FIG. 6 may be adopted as the terahertz light generation unit 17 and the off-axis parabolic mirror 23 in FIG. 3, or the terahertz light detection unit 21 in FIG. Alternatively, a conventional terahertz light detection optical system shown in FIG. 7 may be adopted as the off-axis parabolic mirror 26.
【００６８】以上、本発明の各実施の形態について説明
したが、本発明はこれらの実施の形態に限定されるもの
ではない。Although the respective embodiments of the present invention have been described above, the present invention is not limited to these embodiments.
【００６９】[0069]
【発明の効果】以上説明したように、本発明によれば、
平行光束として供給するテラヘルツ光の利用効率を高め
ることができるテラヘルツ光供給光学系及びこれを用い
たテラヘルツ光装置を提供することができる。As described above, according to the present invention,
It is possible to provide a terahertz light supply optical system that can improve the utilization efficiency of terahertz light supplied as a parallel light flux, and a terahertz light device using the same.
【００７０】また、本発明によれば、検出するテラヘル
ツ光の利用効率を高めることができるテラヘルツ光検出
光学系及びこれを用いたテラヘルツ光装置を提供するこ
とができる。Further, according to the present invention, it is possible to provide a terahertz light detection optical system capable of enhancing the utilization efficiency of the terahertz light to be detected, and a terahertz light device using the same.
【図１】本発明の第１の実施の形態によるテラヘルツ光
供給光学系を示す概略断面図である。FIG. 1 is a schematic sectional view showing a terahertz light supply optical system according to a first embodiment of the present invention.
【図２】本発明の第２の実施の形態によるテラヘルツ光
検出光学系を示す概略断面図である。FIG. 2 is a schematic sectional view showing a terahertz light detection optical system according to a second embodiment of the present invention.
【図３】本発明の第３の実施の形態によるテラヘルツ光
装置を模式的に示す概略構成図である。FIG. 3 is a schematic configuration diagram schematically showing a terahertz optical device according to a third embodiment of the present invention.
【図４】軸外し放物面鏡の一例を示す概略斜視図であ
る。FIG. 4 is a schematic perspective view showing an example of an off-axis parabolic mirror.
【図５】図４中のＷ−Ｗ’線に沿った概略断面図であ
る。5 is a schematic cross-sectional view taken along the line WW 'in FIG.
【図６】従来のテラヘルツ光供給光学系を示す概略断面
図である。FIG. 6 is a schematic sectional view showing a conventional terahertz light supply optical system.
【図７】従来のテラヘルツ光検出光学系を示す概略断面
図である。FIG. 7 is a schematic sectional view showing a conventional terahertz light detection optical system.
１，２３，２６ 軸外し放物面鏡 １ａ 反射面 ２，１７ テラヘルツ光発生部 ３ 光スイッチ素子 ４ 超半球レンズ ５，２１ テラヘルツ光検出部 １１ フェムト秒パルス光源 ３０ 制御・演算処理部 ４０ 被測定物 1,23,26 Off-axis parabolic mirror 1a Reflective surface 2,17 Terahertz light generator 3 Optical switch element 4 super hemisphere lens 5,21 Terahertz light detector 11 Femtosecond pulse light source 30 Control / arithmetic processing unit 40 DUT
───────────────────────────────────────────────────── フロントページの続き (72)発明者 岩本 敏志 栃木県大田原市実取770番地 株式会社栃 木ニコン内 Ｆターム(参考） 2H041 AA23 AB14 AZ00 AZ05 2H087 KA12 NA04 NA05 RA04 TA01 TA03 TA04 TA06 5F072 JJ20 RR10 SS08 YY20 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Toshishi Iwamoto Tochi Co., Ltd. 770, Mitsutori, Otawara City, Tochigi Prefecture Inside the Nikon F-term (reference) 2H041 AA23 AB14 AZ00 AZ05 2H087 KA12 NA04 NA05 RA04 TA01 TA03 TA04 TA06 5F072 JJ20 RR10 SS08 YY20
Claims (3)
ラヘルツ光を発生するテラヘルツ光発生部と、軸外し放
物面鏡とを備え、前記テラヘルツ光発生部から発生した
テラヘルツ光を実質的に平行光束にして供給するテラヘ
ルツ光供給光学系において、 （ａ）前記発散光束の発散中心点が、前記軸外し放物面
鏡の焦点の付近又は前記焦点と光学的に等価な位置の付
近に位置すること、 （ｂ）前記発散光束のうち前記放射強度の最も高い方向
に向かう基準光線が、少なくとも前記軸外し放物面鏡の
回転放物面をなす反射面の付近で、前記反射面を規定す
る回転軸を含む所定の基準面内に実質的に含まれるこ
と、及び、 （ｃ）前記反射面のテラヘルツ光入射領域の周縁と前記
基準面とが交わる２つの点にそれぞれ到達する前記発散
光束に含まれる２本の光線のうちの一方の光線と前記基
準光線とが、少なくとも前記反射面の付近で、前記基準
面内においてなす角度の絶対値と、前記２本の光線のう
ちの他方の光線と前記基準光線とが、少なくとも前記反
射面の付近で、前記基準面内においてなす角度の絶対値
とが、略等しいこと、 の各条件を満たすように、前記テラヘルツ光発生部と前
記軸外し放物面鏡との光学的な位置関係が設定されたこ
とを特徴とするテラヘルツ光供給光学系。1. A terahertz light generating section for generating terahertz light of a divergent luminous flux having directivity in radiation intensity and an off-axis parabolic mirror are provided, and the terahertz light generated from the terahertz light generating section is substantially generated. In a terahertz light supply optical system that supplies a parallel light flux, (a) the divergence center point of the divergent light flux is located near the focal point of the off-axis parabolic mirror or near a position optically equivalent to the focal point. (B) Among the divergent light fluxes, the reference light beam directed in the direction of the highest radiant intensity defines the reflecting surface at least near the reflecting surface forming the paraboloid of rotation of the off-axis parabolic mirror. Substantially within a predetermined reference plane including the rotation axis, and (c) the divergent light flux reaching each of two points where the peripheral edge of the terahertz light incident region of the reflection surface and the reference plane intersect. include One of the two light rays and the reference light ray has an absolute value of an angle formed in the reference surface at least near the reflection surface, and the other ray of the two light rays and the The reference ray and the absolute value of the angle formed in the reference plane at least near the reflecting surface are substantially equal to each other, and the terahertz light generating section and the off-axis parabolic surface are satisfied. A terahertz light supplying optical system characterized in that an optical positional relationship with a mirror is set.
のテラヘルツ光を前記収束中心点に対応するテラヘルツ
光検出点で受光し検出感度に指向性を有するテラヘルツ
光検出部と、軸外し放物面鏡とを備え、前記軸外し放物
面鏡の回転放物面をなす反射面に該反射面を規定する回
転軸と実質的に平行に入射される、実質的に平行光束の
テラヘルツ光を検出するテラヘルツ光検出光学系におい
て、 （ａ）前記収束中心点が、前記軸外し放物面鏡の焦点の
付近又は前記焦点と光学的に等価な位置の付近に位置す
ること、 （ｂ）前記収束光束のうち前記検出感度の最も高い方向
から前記収束中心点に向かう基準光線が、少なくとも前
記反射面の付近で、前記回転軸を含む所定の基準面内に
実質的に含まれること、及び、 （ｃ）前記反射面のテラヘルツ光入射領域の周縁と前記
基準面とが交わる２つの点からそれぞれ前記テラヘルツ
光検出点に到達する前記収束光束に含まれる２本の光線
のうちの一方の光線と前記基準光線とが、少なくとも前
記反射面の付近で、前記基準面内においてなす角度の絶
対値と、前記２本の光線のうちの他方の光線と前記基準
光線とが、少なくとも前記反射面の付近で、前記基準面
内においてなす角度の絶対値とが、略等しいこと、 の各条件を満たすように、前記テラヘルツ光検出部と前
記軸外し放物面鏡との光学的な位置関係が設定されたこ
とを特徴とするテラヘルツ光検出光学系。2. A terahertz light detection unit that receives a terahertz light of a converged light flux that is about to converge at a convergence center point at a terahertz light detection point corresponding to the convergence center point and has directivity in detection sensitivity, and an off-axis parabola. A terahertz light of a substantially parallel luminous flux, which is incident on a reflecting surface forming a paraboloid of rotation of the off-axis parabolic mirror substantially parallel to a rotation axis defining the reflecting surface. In the terahertz light detection optical system for detecting, (a) the convergence center point is located near the focal point of the off-axis parabolic mirror or near a position optically equivalent to the focal point; A reference light beam from the direction of the highest detection sensitivity of the convergent light flux toward the convergence center point is substantially included in a predetermined reference surface including the rotation axis at least near the reflection surface, and (C) Teraher of the reflecting surface At least one of the two light rays included in the convergent light flux reaching the terahertz light detection point from two points where the peripheral edge of the light incident area and the reference surface intersect, and the reference light ray, In the vicinity of the reflecting surface, the absolute value of the angle formed in the reference surface, and the other light ray of the two light rays and the reference light ray are at least near the reflecting surface, in the reference surface. The absolute value of the angle formed is substantially equal, and the optical positional relationship between the terahertz light detection unit and the off-axis parabolic mirror is set so as to satisfy the following conditions. Optical detection optics.
発生部から発生し所定の光路を経て到達するテラヘルツ
光を検出するテラヘルツ光検出部と、を備えたテラヘル
ツ光装置において、 請求項１記載のテラヘルツ光供給光学系及び請求項２記
載のテラヘルツ光検出光学系のうちの両方又はいずれか
一方を備えたことを特徴とするテラヘルツ光装置。3. A terahertz optical device comprising: a terahertz light generating section; and a terahertz light detecting section for detecting terahertz light generated from the terahertz light generating section and arriving via a predetermined optical path. A terahertz light device comprising both or one of the terahertz light supply optical system and the terahertz light detection optical system according to claim 2.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001327025A JP2003131137A (en) | 2001-10-24 | 2001-10-24 | Terahertz light supplying optical system, terahertz light detection optical system and terahertz optical device using them |
| PCT/JP2002/011024 WO2003036362A1 (en) | 2001-10-24 | 2002-10-24 | Terahertz light supplying optical system, terahertz light detecting optical system, and terahertz optical device using this |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001327025A JP2003131137A (en) | 2001-10-24 | 2001-10-24 | Terahertz light supplying optical system, terahertz light detection optical system and terahertz optical device using them |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2003131137A true JP2003131137A (en) | 2003-05-08 |
Family
ID=19143307
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001327025A Pending JP2003131137A (en) | 2001-10-24 | 2001-10-24 | Terahertz light supplying optical system, terahertz light detection optical system and terahertz optical device using them |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2003131137A (en) |
| WO (1) | WO2003036362A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005019809A1 (en) | 2003-08-22 | 2005-03-03 | Japan Science And Technology Agency | Optical path difference compensation mechanism for acquiring time-series signal of time-series conversion pulse spectrometer |
| JP2006086227A (en) * | 2004-09-14 | 2006-03-30 | Osaka Univ | Optical switch |
| CN103364417A (en) * | 2012-04-01 | 2013-10-23 | 中国科学院深圳先进技术研究院 | Terahertz wave detection device |
| US8872330B2 (en) | 2006-08-04 | 2014-10-28 | Osram Opto Semiconductors Gmbh | Thin-film semiconductor component and component assembly |
| US9142720B2 (en) | 2007-01-29 | 2015-09-22 | Osram Opto Semiconductors Gmbh | Thin-film light emitting diode chip and method for producing a thin-film light emitting diode chip |
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|---|---|---|---|---|
| JP2022028468A (en) * | 2020-08-03 | 2022-02-16 | 株式会社日本マイクロニクス | Measurement system and measurement method |
| CN114280770B (en) * | 2021-11-29 | 2023-08-11 | 上海微波技术研究所（中国电子科技集团公司第五十研究所） | Terahertz full-silicon off-axis super lens and design method thereof |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000079248A1 (en) * | 1999-06-21 | 2000-12-28 | Hamamatsu Photonics K.K. | Terahertz wave spectrometer |
| JP3896532B2 (en) * | 1999-07-09 | 2007-03-22 | 独立行政法人科学技術振興機構 | Terahertz complex permittivity measurement system |
| JP4237363B2 (en) * | 1999-11-10 | 2009-03-11 | 日本分光株式会社 | Infrared spectrometer |
-
2001
- 2001-10-24 JP JP2001327025A patent/JP2003131137A/en active Pending
-
2002
- 2002-10-24 WO PCT/JP2002/011024 patent/WO2003036362A1/en active Application Filing
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005019809A1 (en) | 2003-08-22 | 2005-03-03 | Japan Science And Technology Agency | Optical path difference compensation mechanism for acquiring time-series signal of time-series conversion pulse spectrometer |
| US7507966B2 (en) | 2003-08-22 | 2009-03-24 | Japan Science And Technology Agency | Optical-path-difference compensation mechanism for acquiring wave form signal of time-domain pulsed spectroscopy apparatus |
| US7705311B2 (en) | 2003-08-22 | 2010-04-27 | Japan Science And Technology Agency | Optical-path-difference compensation mechanism for acquiring wave from signal of time-domain pulsed spectroscopy apparatus |
| EP2442093A2 (en) | 2003-08-22 | 2012-04-18 | Japan Science and Technology Agency | Optical-path-difference compensation mechanism for acquiring wave form signal of time-domain pulsed spectroscopy apparatus |
| JP2006086227A (en) * | 2004-09-14 | 2006-03-30 | Osaka Univ | Optical switch |
| US8872330B2 (en) | 2006-08-04 | 2014-10-28 | Osram Opto Semiconductors Gmbh | Thin-film semiconductor component and component assembly |
| US9142720B2 (en) | 2007-01-29 | 2015-09-22 | Osram Opto Semiconductors Gmbh | Thin-film light emitting diode chip and method for producing a thin-film light emitting diode chip |
| CN103364417A (en) * | 2012-04-01 | 2013-10-23 | 中国科学院深圳先进技术研究院 | Terahertz wave detection device |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2003036362A1 (en) | 2003-05-01 |
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