JP2555726Y2 - Air refractive index measuring device - Google Patents
Air refractive index measuring deviceInfo
- Publication number
- JP2555726Y2 JP2555726Y2 JP9254091U JP9254091U JP2555726Y2 JP 2555726 Y2 JP2555726 Y2 JP 2555726Y2 JP 9254091 U JP9254091 U JP 9254091U JP 9254091 U JP9254091 U JP 9254091U JP 2555726 Y2 JP2555726 Y2 JP 2555726Y2
- Authority
- JP
- Japan
- Prior art keywords
- light
- vacuum
- air
- polarized light
- mirror
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Description
【０００１】[0001]
【産業上の利用分野】本考案は、空気中でのレーザ測長
における波長補正のための空気屈折率測定装置に関し、
特に温度による誤差を光学的に低減できるようにした装
置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air refractive index measuring device for wavelength correction in laser measurement in air.
In particular, the present invention relates to an apparatus capable of optically reducing errors due to temperature.
【０００２】[0002]
【従来の技術】空気中でのレーザ光の干渉を利用した測
長において、空気屈折率の変化による波長の変化を補正
することは、その測長精度を向上させる上で重要であ
る。空気屈折率を光学的に測定しようとする場合、基準
間隔を用いて、空気屈折率の変化によって生じる光路長
変化を干渉法で求めると高精度な測定が可能である。そ
の際に、基準間隔として真空の基準間隔部を有する構造
のものを用いると、温度による基準間隔の膨張や気圧に
よる圧縮などによる長さの変化の影響を受け難く、安定
な測定が可能である。2. Description of the Related Art In length measurement using laser light interference in air, it is important to correct a change in wavelength due to a change in air refractive index in order to improve the length measurement accuracy. In the case where the air refractive index is to be measured optically, high precision measurement is possible if the optical path length change caused by the change in the air refractive index is obtained by the interferometry using the reference interval. At this time, if a structure having a vacuum reference interval portion is used as the reference interval, it is hardly affected by a change in length due to expansion of the reference interval due to temperature or compression due to atmospheric pressure, and stable measurement is possible. .
【０００３】図２はこのような真空の基準間隔部を備え
た空気屈折率測定装置の従来例である。図２において、
ゼーマン効果を利用したＨｅ−Ｎｅレーザ光源１から、
僅かに周波数が異なり回転方向が逆の円偏光が出射され
る。このレーザ光は、ハーフミラー２で一部が透過し、
１／４波長板３を通ることにより、回転方向が逆の円偏
光から直交した直線偏光に変換される。偏光ビームスプ
リッタ（以下、単にＰＢＳという）４により直交した２
つの直線偏光の内のｐ成分は、ＰＢＳ４を透過して、１
／４波長板５を通る。１／４波長板５は、ｐ偏光が透過
すると、右回り円偏光となるように、その主軸方向を調
整されている。この右回り円偏光は、基準間隔部６の窓
６１を通って、真空部６ａに入る。真空部６ａは、筒状
の部材６２の内部に設けられている。右回りの円偏光
は、真空部６ａの他方の端面にあるミラー６３で反射さ
れ、左回りの円偏光になり、真空部６ａ，窓６１を通っ
て、１／４波長板５を透過することにより、ｐ偏光とな
る。このｐ偏光は、ＰＢＳ４で反射され、１／４波長板
７を通って円偏光となり、光検出器８ａに入射する。FIG. 2 shows a conventional example of an air refractive index measuring device having such a vacuum reference interval. In FIG.
From the He-Ne laser light source 1 utilizing the Zeeman effect,
Circularly polarized light having a slightly different frequency and a reverse rotation direction is emitted. This laser light is partially transmitted by the half mirror 2,
By passing through the quarter-wave plate 3, the light is converted from circularly polarized light whose rotation direction is opposite to linearly polarized light that is orthogonal. 2 orthogonal by a polarizing beam splitter (hereinafter simply referred to as PBS) 4
The p component of the two linearly polarized lights passes through the PBS 4 and
It passes through the wavelength plate 5. The principal axis direction of the quarter-wave plate 5 is adjusted so that, when p-polarized light is transmitted, it becomes clockwise circularly polarized light. The clockwise circularly polarized light passes through the window 61 of the reference interval 6 and enters the vacuum section 6a. The vacuum part 6a is provided inside the cylindrical member 62. The clockwise circularly polarized light is reflected by the mirror 63 on the other end face of the vacuum part 6a, becomes a counterclockwise circularly polarized light, passes through the vacuum part 6a and the window 61, and transmits through the quarter-wave plate 5. As a result, the light becomes p-polarized light. This p-polarized light is reflected by the PBS 4, passes through the quarter-wave plate 7, becomes circularly polarized light, and enters the photodetector 8 a.
【０００４】一方、ＰＢＳ４により直交した２つの直線
偏光の内のｓ成分は、ＰＢＳ４で反射され、ミラー９を
介して１／４波長板５を通る。そこで、ｓ偏光は左回り
円偏光となる。さらに基準間隔部６の窓６１を通って空
気部６ｂに入る。この空気部６ｂは、真空部６ａと同一
長さ基準を持つように設計されている。円偏光は、空気
部６ｂの他方の端面にあるミラー６３で反射され、右回
りの円偏光になり、空気部６ｂ，窓６１を通って、１／
４波長板５を透過することにより、ｐ偏光となる。この
ｐ偏光は、ミラー９を介してＰＢＳ４を透過して、１／
４波長板７を通って円偏光となり、光検出器８ａに入射
し、真空部６ａを通った光と干渉する。また、ハーフミ
ラー２で反射された周波数が異なり回転方向が逆の円偏
光は、光検出器８ｂに入射して干渉する。光検出器８
ａ，８ｂでは、それぞれ干渉信号が電気信号に変換され
て、信号処理部１０に出力される。信号処理部１０で
は、光検出器８ａ，８ｂから得られる電気信号を位相信
号に変換して、空気の屈折率の絶対値が求められる。On the other hand, the s component of the two linearly polarized lights orthogonal to each other by the PBS 4 is reflected by the PBS 4 and passes through the ミ ラ ー wavelength plate 5 via the mirror 9. Thus, the s-polarized light becomes left-handed circularly polarized light. Further, the air enters the air portion 6b through the window 61 of the reference interval portion 6. The air section 6b is designed to have the same length standard as the vacuum section 6a. The circularly polarized light is reflected by the mirror 63 on the other end face of the air part 6b, becomes clockwise circularly polarized light, passes through the air part 6b and the window 61, and becomes 1 /
By transmitting through the four-wavelength plate 5, the light becomes p-polarized light. This p-polarized light passes through the PBS 4 via the mirror 9 and
The light becomes circularly polarized light through the four-wavelength plate 7, enters the photodetector 8a, and interferes with light that has passed through the vacuum section 6a. The circularly polarized light having a different frequency and a different rotation direction reflected by the half mirror 2 is incident on the photodetector 8b and interferes therewith. Photodetector 8
In a and 8b, the interference signal is converted into an electric signal and output to the signal processing unit 10. The signal processing unit 10 converts the electric signal obtained from the photodetectors 8a and 8b into a phase signal, and obtains the absolute value of the refractive index of air.
【０００５】この上記従来技術に示す空気屈折率測定装
置によれば、基準間隔部６に形成した真空部６ｂによ
り、温度や圧力や材料の経年変化などの基準間隔部６の
長さ基準の変動による影響を補正できるため、高精度な
空気の屈折率の絶対値を測定することができる。[0005] According to the air refractive index measuring device shown in the above-mentioned prior art, the variation of the reference length of the reference gap 6 such as temperature, pressure and aging of the material is caused by the vacuum section 6b formed in the reference gap 6. Can correct the absolute value of the refractive index of air with high accuracy.
【０００６】[0006]
【考案が解決しようとする課題】しかしながら、真空部
６ａに光を導入する際に通過する窓６１に温度分布が存
在すると、窓６１での光路長変化が生じ、空気屈折率に
誤差が生じてしまう。つまり、上記光学系では、ＰＢＳ
４で、光が各偏光成分に分離されてから、窓６１を透過
するまでに生じる光路長の変化、特にＰＢＳ４の温度分
布の変化と窓６１の温度分布によって生じる光路長変化
を空気部６ｂにおける屈折率の変化と一緒に検出するた
め、その分離ができず、屈折率測定精度を低下させる要
因となっていた。However, if there is a temperature distribution in the window 61 through which light is introduced into the vacuum section 6a when the light is introduced into the vacuum section 6a, a change in the optical path length at the window 61 occurs and an error occurs in the air refractive index. I will. That is, in the above optical system, PBS
4, the change in the optical path length that occurs from the time when the light is separated into the respective polarization components to the time when the light passes through the window 61, particularly the change in the temperature distribution of the PBS 4 and the change in the optical path length caused by the temperature distribution of the window 61, Since the detection is performed together with the change in the refractive index, the separation cannot be performed, and this has been a factor that lowers the accuracy of the refractive index measurement.
【０００７】本考案は、上記従来技術の課題を踏まえて
成されたものであり、位相信号の基準となる干渉光を、
レーザ光源から出射された直後ではなく、真空部の直前
の窓の光路長変化を含めた状態で得ることによって、窓
の温度変化による影響を除去して、高精度の空気屈折率
測定装置を提供することを目的としたものである。[0007] The present invention has been made in view of the above-mentioned problems of the prior art.
Providing a high-precision air refractive index measurement device by removing the effects of window temperature changes by obtaining the window including the change in the optical path length of the window just before the vacuum section, not just immediately after emission from the laser light source It is intended to do so.
【０００８】[0008]
【課題を解決するための手段】上記課題を解決するため
の本考案の構成は、周波数が異なり直交した直線偏光を
出射するレーザ光源と、このレーザ光源の出射光を２本
の平行光に分岐する光学系と、この光学系により分岐さ
れた２本の平行光の各直線偏光成分を分離する偏光ビー
ムスプリッタと、この偏光ビームスプリッタで反射され
た成分を反射して前記偏光ビームスプリッタを透過した
成分と平行にするミラーと、筒状部材とこの筒状部材の
光軸に対して垂直な両端面に配置され光を入射させる窓
および光を反射させるミラーで形成され真空に保持され
た真空部と、この真空部と平行に配置され前記窓および
ミラーにより前記真空部とは同一長さの測定空間が形成
された空気部を有し、前記窓の真空部および空気部側に
それぞれ前記レーザ光源から出射され平行に分岐された
一方のレーザ光の各偏光成分が反射されるように配置さ
れた反射部を有する基準間隔部と、この基準間隔部の反
射部およびミラーからの反射光をそれぞれ検出する２つ
の光検出器と、この両光検出器で得られる干渉信号の位
相差から空気屈折率を求める信号処理部とを備えた構成
としたことを特徴とするものである。In order to solve the above-mentioned problems, the configuration of the present invention comprises a laser light source that emits orthogonal linearly polarized lights having different frequencies, and splits the light emitted from the laser light source into two parallel lights. An optical system, a polarizing beam splitter for separating linearly polarized light components of two parallel lights split by the optical system, and a component reflected by the polarizing beam splitter to be reflected and transmitted through the polarizing beam splitter. A vacuum section formed by a mirror for parallelizing the components, a cylindrical member, windows arranged on both end surfaces perpendicular to the optical axis of the cylindrical member for receiving light, and a mirror for reflecting light, and maintained in vacuum And an air portion arranged in parallel with the vacuum portion and having a measurement space of the same length as the vacuum portion formed by the window and the mirror, and the laser beams are provided on the vacuum portion and the air portion side of the window, respectively. A reference interval having a reflection portion disposed so as to reflect each polarization component of one of the laser beams emitted from the light source and branched in parallel, and the reflection light from the reflection portion and the mirror of the reference interval, It is characterized by comprising two photodetectors to be detected and a signal processing unit for obtaining an air refractive index from a phase difference between interference signals obtained by the two photodetectors.
【０００９】[0009]
【作用】本考案によれば、ＰＢＳで基準となる真空部に
入る光と空気部に入る光を分岐してから、各空間に入る
までに受ける光路長変化を近接した光路で測定して、そ
の影響を引くことで、真空部および空気部のみで受ける
光路長変化を測定することができ、高精度な屈折率測定
を行うことができる。According to the present invention, the light entering the vacuum part and the light entering the air part, which are the reference in the PBS, are branched, and the change in the optical path length received before entering each space is measured in the close optical path. By subtracting the influence, it is possible to measure the change in the optical path length received only in the vacuum section and the air section, and it is possible to perform a highly accurate refractive index measurement.
【００１０】[0010]
【実施例】以下、本考案を図面に基づいて説明する。図
１は本考案の空気屈折率測定装置の一実施例を示す構成
図である。図１において、１１はゼーマン効果を利用し
た僅かに周波数が異なり回転方向が逆向きの円偏光を出
射するレーザ光源である。１２は１／４波長板、１３は
レーザ光源１１から出射されたレーザ光を２本の平行光
に分岐するビームスプリッタ（以下、単にＢＳとい
う）、１４はＢＳ１３により分岐された２本の平行光の
各直線偏光成分を分離するＰＢＳ、１５はＰＢＳ１４で
反射された成分を反射してＰＢＳ１４を透過した成分と
平行にするミラー、１６は１／４波長板である。１７は
真空部１７ａと空気部１７ｂから成る基準間隔部であ
り、この基準間隔部１７は入射光を透過させ、その片側
面に反射部１７１ａ，１７１ｂが蒸着によって形成され
た窓１７１とミラー１７２および光軸方向での長さの変
化（即ち、温度による膨張や圧力による収縮、および材
料の持つ経年変化など）が光軸と垂直な面内では均一な
材料で形成された筒状部材１７３から成り、この筒状部
材１７３の両側に窓１７１とミラー１７２が密着されて
おり、真空に保持された真空部１７ａが形成されてい
る。空気部１７ｂは実際の空気屈折率の測定空間であ
り、窓１７１とミラー１７２の間に真空部１７ａと平行
に配置され、窓１７１とミラー１７２の間隔は真空部１
７ａと空気部１７ｂは等しくされている。１８は１／４
波長板、１９ａ，１９ｂは光検出器、２０は光検出器１
９ａ，１９ｂで得られた干渉信号から位相差を測定し、
空気屈折率を求める信号処理回路である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the air refractive index measuring device of the present invention. In FIG. 1, reference numeral 11 denotes a laser light source which emits circularly polarized light having a slightly different frequency and a reverse rotation direction by utilizing the Zeeman effect. Reference numeral 12 denotes a quarter-wave plate, 13 denotes a beam splitter (hereinafter simply referred to as BS) for splitting a laser beam emitted from the laser light source 11 into two parallel beams, and 14 denotes two parallel beams split by the BS 13. A mirror 15 for reflecting the component reflected by the PBS 14 to make it parallel to the component transmitted by the PBS 14, and 16 a quarter-wave plate. Reference numeral 17 denotes a reference interval portion composed of a vacuum portion 17a and an air portion 17b. The reference interval portion 17 allows incident light to pass therethrough, and has a window 171 and a mirror 172 on one side of which reflection portions 171a and 171b are formed by vapor deposition. A change in length in the direction of the optical axis (ie, expansion due to temperature, contraction due to pressure, and aging of the material) consists of a cylindrical member 173 made of a uniform material in a plane perpendicular to the optical axis. A window 171 and a mirror 172 are in close contact with each other on both sides of the cylindrical member 173, and a vacuum portion 17a maintained in a vacuum is formed. The air portion 17b is a space for measuring the actual air refractive index, and is disposed between the window 171 and the mirror 172 in parallel with the vacuum portion 17a.
7a and the air part 17b are made equal. 18 is 1/4
Wave plates, 19a and 19b are photodetectors, 20 is photodetector 1.
The phase difference is measured from the interference signals obtained in 9a and 19b,
This is a signal processing circuit for calculating the air refractive index.
【００１１】このような構成において、レーザ光源１１
から出射されるレーザ光の周波数をｆ1 ，ｆ2 とする。
この互いに異なる周波数で逆向きの回転方向である円偏
光が１／４波長板１２を通ると、直交した直線偏光に変
換される。ここで、ｓ偏光の周波数をｆ1 ，ｐ偏光の周
波数をｆ2 とする。直交した直線偏光はＢＳ１３によっ
て、ｐ，ｓ偏光共にパワーが２分された平行な２本のビ
ーム（ビームＲ，ビームＭとする）に分けられる。ビー
ムＲのｐ偏光分は、ＰＢＳ１４を透過し、１／４波長板
１６で右回り円偏光となり、窓１７１を通って反射部１
７１ａによって反射され、左回り円偏光となる。この左
回り円偏光は、再び窓１７１を通り、１／４波長板１６
を通るとｓ偏光となる。このｓ偏光は、ＰＢＳ１４で反
射されて、１／４波長板１８により左回り円偏光となっ
て、光検出器１９ｂに入射する。また、ビームＲのｓ偏
光分は、ＰＢＳ１４で反射され、ミラー１５を介して１
／４波長板１６に入射され、左回り円偏光となる。この
左回り円偏光は、窓１７１を通って、反射部１７１ｂに
よって反射され、右回り円偏光となる。この右回り円偏
光は、再び窓１７１を通り、１／４波長板１６を通ると
ｐ偏光となる。このｐ偏光は、ＰＢＳ１４を透過し、１
／４波長板１８により右回り円偏光となって、光検出器
１９ｂに入射する。In such a configuration, the laser light source 11
Let f 1 and f 2 be the frequencies of the laser light emitted from.
When the circularly polarized light having the opposite rotation direction at different frequencies passes through the quarter-wave plate 12, it is converted into orthogonal linearly polarized light. Here, the frequency of the s-polarized light is f 1 , and the frequency of the p-polarized light is f 2 . The orthogonal linearly polarized light is divided by the BS 13 into two parallel beams (hereinafter, referred to as a beam R and a beam M) whose power is divided into two for both the p and s polarizations. The p-polarized light component of the beam R is transmitted through the PBS 14, becomes clockwise circularly polarized light by the 波長 wavelength plate 16, passes through the window 171, and is reflected by the reflecting portion 1.
The light is reflected by the light 71a and becomes left-handed circularly polarized light. The left-handed circularly polarized light again passes through the window 171 and passes through the quarter-wave plate 16.
S-polarized light. The s-polarized light is reflected by the PBS 14, becomes a left-handed circularly polarized light by the quarter-wave plate 18, and enters the photodetector 19b. Further, the s-polarized light component of the beam R is reflected by the PBS 14,
The light is incident on the 波長 wavelength plate 16 and becomes left-handed circularly polarized light. The left-handed circularly polarized light passes through the window 171 and is reflected by the reflection unit 171b to become right-handed circularly polarized light. This clockwise circularly polarized light again passes through the window 171 and becomes p-polarized light when passing through the quarter-wave plate 16. This p-polarized light passes through the PBS 14 and
The light becomes right-handed circularly polarized light by the に よ り wavelength plate 18 and enters the photodetector 19b.
【００１２】ここで、ＰＢＳ１４で分岐されてから、基
準間隔部１７の反射部１７１ａ，１７１ｂで反射され、
再びＰＢＳ１４で合波されるまでの両光路長の初期値か
らの変化量をそれぞれ とすると、その時間変化 によって、ｓ偏光，ｐ偏光の周波数ｆ1 ，ｆ2 は、ドッ
プラー効果によって周波数変調され、 となる。光検出器１９ｂでは、両周波数のビート成分 が得られる。ただし、λは波長である。Here, after being branched by the PBS 14, the light is reflected by the reflecting portions 171a and 171b of the reference interval portion 17, and
The amount of change from the initial value of both optical path lengths until they are multiplexed by the PBS 14 again Then, its time change Thus, the frequencies f 1 and f 2 of the s-polarized light and the p-polarized light are frequency-modulated by the Doppler effect, Becomes In the photodetector 19b, beat components of both frequencies Is obtained. Here, λ is a wavelength.
【００１３】一方、ＢＳ３によって分岐されたビームＭ
は、ビームＲと基準間隔部１７の窓１７１までは、ほぼ
同じような光路で伝わる。ビームＭのｐ偏光分は、窓１
７１を通って、真空部１７ａを伝わり、ミラー１７２で
反射されて、再び真空部１７ａ，窓１７１，１／４波長
板１６を通ってｓ偏光となり、ＰＢＳ１４で反射され
て、１／４波長板１４を通って、光検出器１９ａに入射
する。ビームＭのｓ偏光分は、窓１７１を通って、空気
部１７ｂを伝わり、ミラー１７２で反射されて、再び空
気部１７ｂ，窓１７１，１／４波長板１６を通ってｐ偏
光となり、ミラー１５で反射後、ＰＢＳ１４を透過し
て、１／４波長板１４を通って、光検出器１９ａに入射
する。On the other hand, beam M split by BS3
Travels along the beam R and the window 171 of the reference interval 17 in substantially the same optical path. The p-polarized light component of the beam M is given by window 1
The light passes through the vacuum section 17a, passes through the vacuum section 17a, is reflected by the mirror 172, passes again through the vacuum section 17a, the window 171, the quarter-wave plate 16, becomes s-polarized light, is reflected by the PBS 14, and is reflected by the PBS 14 14 and enters the photodetector 19a. The s-polarized light component of the beam M passes through the window 171, propagates through the air portion 17b, is reflected by the mirror 172, passes through the air portion 17b, the window 171, the quarter-wave plate 16 again, and becomes p-polarized light. After passing through the PBS 14, the light passes through the PBS 14, passes through the quarter-wave plate 14, and enters the photodetector 19a.
【００１４】ここで、ビームＭがＰＢＳ１４で分岐され
てから真空部１７ａ，空気部１７ｂを通って、ミラー１
７２で反射されて、再びＰＢＳ１４で合波されるまでの
両光路長の初期値からの変化量は、真空部１７ａおよび
空気部１７ｂの長さ基準をＬ、空気部１７ｂの空気屈折
率をＮ（真空部１７ａの屈折率は１）とすると、 となる。なお、△（ｎｌ）a ，△（ｎｌ）b の項は、ビ
ームＭとビームＲとで隣り合った光路を通っているた
め、同じ変化を受けると見做すことができる。次に、変
化量の時間変化 によって、ｓ偏光，ｐ偏光の周波数ｆ1 ，ｆ2 はドップ
ラー効果によって周波数変調され、 となる。光検出器１９ｂでは、両周波数のビート成分 ｆM ＝｛△（ｎＬ）＋△（ｎｌ）a ｝／△ｔ／λ −｛△Ｌ＋△（ｎｌ）b ｝／△ｔ／λ が得られる。Here, the beam M is split by the PBS 14 and then passes through the vacuum section 17a and the air section 17b to pass through the mirror 1
The amount of change from the initial value of both optical path lengths before being reflected at 72 and recombined by the PBS 14 is L based on the length reference of the vacuum section 17a and the air section 17b, and N based on the air refractive index of the air section 17b. (The refractive index of the vacuum part 17a is 1) Becomes Note that the terms △ (nl) a and △ (nl) b can be regarded as undergoing the same change because the beams M and R pass through adjacent optical paths. Next, the change over time Thus, the frequencies f 1 and f 2 of the s-polarized light and the p-polarized light are frequency-modulated by the Doppler effect, Becomes In the photodetector 19b, beat components f M = ｛△ (nL) + △ (nl) a ｝ / △ t / λ− ｛△ L + △ (nl) b ｝ / △ t / λ of both frequencies are obtained.
【００１５】これら光検出器１９ａ，１９ｂで得られた
両周波数のビート成分ｆM ，ｆR は、信号処理回路２０
に入力され、信号処理回路２０にて、その差が求められ
る。 この式から、ＰＢＳ１４から基準間隔部１７の窓１７
１までの光路長差の変動を含まない信号を取り出すこと
ができ、空気屈折率ｎを正確に求めることができる。つ
まり、上記式は、 ｛△（ｎＬ）−△Ｌ｝＝（ｆM −ｆR ）・△ｔ・λ より、 △ｎＬ−ｎ△Ｌ−△Ｌ＝（ｆM −ｆR ）・△ｔ・λ ∴ △ｎ＝（ｆM −ｆR ）・△ｔ・λ／Ｌ＋（ｎ−１）△Ｌ／Ｌ となる。The beat components f M and f R of both frequencies obtained by the photodetectors 19 a and 19 b are combined with the signal processing circuit 20.
And the difference is obtained in the signal processing circuit 20. From this equation, the window 17 of the reference interval 17 is
A signal that does not include the variation of the optical path length difference up to 1 can be extracted, and the air refractive index n can be accurately obtained. That is, the expression, {△ (nL) - △ L} = from (f M -f R) · △ t · λ, △ nL-n △ L- △ L = (f M -f R) · △ t · λ ∴ △ n = a (f M -f R) · △ t · λ / L + (n-1) △ L / L.
【００１６】ただし、通常の空気では、屈折率は１．０
００２７程度であり、 ｎ−１＝２７０×１０-6 である。したがって 、低膨張材料（石英など）によっ
て、△Ｌ／Ｌを０．５×１０-6×１０℃程度に抑えれ
ば、屈折率測定に対する誤差は、１．３５×１０-9と非
常に小さい値となり、上記式における（ｎ−１）△Ｌ
／Ｌの項は無視できる。However, in ordinary air, the refractive index is 1.0
0027, and n−1 = 270 × 10 −6 . Therefore, if ΔL / L is suppressed to about 0.5 × 10 −6 × 10 ° C. by using a low expansion material (eg, quartz), the error in the refractive index measurement is very small, 1.35 × 10 −9. (N-1) △ L in the above equation.
The term / L can be ignored.
【００１７】[0017]
【考案の効果】以上、実施例と共に具体的に説明したよ
うに、本考案によれば、ＰＢＳで基準となる真空部に入
る光と空気部に入る光を分岐してから、各空間に入るま
でに受ける光路長変化を近接した光路で測定して、その
影響を引くことで、真空部および空気部のみで受ける光
路長変化を測定することができ、高精度な屈折率測定を
行うことができる空気屈折率測定装置を実現できる。As described above in detail with the embodiment, according to the present invention, the light entering the vacuum part and the light entering the air part, which are the reference in the PBS, are branched and then entered into each space. By measuring the change in the optical path length received up to the adjacent optical path and subtracting the influence, the change in the optical path length received only in the vacuum section and the air section can be measured, and high-precision refractive index measurement can be performed. An air refractive index measuring device that can be realized.
【図面の簡単な説明】[Brief description of the drawings]
【図１】本考案の空気屈折率測定装置の一実施例を示す
構成図である。FIG. 1 is a configuration diagram showing an embodiment of an air refractive index measuring device of the present invention.
【図２】空気屈折率測定装置の従来例である。FIG. 2 is a conventional example of an air refractive index measuring device.
１１ レーザ光源 １２、１６、１８ １／４波長板 １３ ビームスプリッタ １４ 偏光ビームスプリッタ １５ ミラー １７ 基準間隔部 １７ａ 真空部 １７ｂ 空気部 １９ａ、１９ｂ 光検出器 ２０ 信号処理回路 １７１ 窓 １７１ａ、１７１ｂ 反射部 １７２ ミラー １７３ 筒状部材 DESCRIPTION OF SYMBOLS 11 Laser light source 12, 16, 18 Quarter-wave plate 13 Beam splitter 14 Polarization beam splitter 15 Mirror 17 Reference interval part 17a Vacuum part 17b Air part 19a, 19b Photodetector 20 Signal processing circuit 171 Window 171a, 171b Reflection part 172 Mirror 173 cylindrical member
Claims (1)
するレーザ光源と、 このレーザ光源の出射光を２本の平行光に分岐する光学
系と、 この光学系により分岐された２本の平行光の各直線偏光
成分を分離する偏光ビームスプリッタと、 この偏光ビームスプリッタで反射された成分を反射して
前記偏光ビームスプリッタを透過した成分と平行にする
ミラーと、 筒状部材とこの筒状部材の光軸に対して垂直な両端面に
配置され光を入射させる窓および光を反射させるミラー
で形成され真空に保持された真空部と、この真空部と平
行に配置され前記窓およびミラーにより前記真空部とは
同一長さの測定空間が形成された空気部を有し、前記窓
の真空部および空気部側にそれぞれ前記レーザ光源から
出射され平行に分岐された一方のレーザ光の各偏光成分
が反射されるように配置された反射部を有する基準間隔
部と、 この基準間隔部の反射部およびミラーからの反射光をそ
れぞれ検出する２つの光検出器と、 この両光検出器で得られる干渉信号の位相差から空気屈
折率を求める信号処理部とを備えた構成としたことを特
徴とする空気屈折率測定装置。1. A laser light source that emits linearly polarized light having different frequencies and orthogonal to each other, an optical system that splits light emitted from the laser light source into two parallel light beams, and two parallel light beams that are split by the optical system. A polarizing beam splitter that separates each linearly polarized light component, a mirror that reflects the component reflected by the polarizing beam splitter and makes the component transmitted through the polarizing beam splitter parallel to the cylindrical member, and a cylindrical member and a cylindrical member. A vacuum section formed on windows provided at both end surfaces perpendicular to the optical axis and receiving light and a mirror for reflecting light and held in a vacuum, and the vacuum provided by the window and the mirror arranged in parallel with the vacuum section. The portion has an air portion in which a measurement space of the same length is formed, and each of one of the laser beams emitted from the laser light source and branched in parallel to the vacuum portion and the air portion side of the window, respectively. A reference interval having a reflection portion arranged to reflect a light component; two photodetectors for detecting reflected light from the reflection portion and the mirror of the reference interval, respectively; A signal processing unit for calculating an air refractive index from a phase difference of an obtained interference signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9254091U JP2555726Y2 (en) | 1991-11-13 | 1991-11-13 | Air refractive index measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9254091U JP2555726Y2 (en) | 1991-11-13 | 1991-11-13 | Air refractive index measuring device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0543058U JPH0543058U (en) | 1993-06-11 |
| JP2555726Y2 true JP2555726Y2 (en) | 1997-11-26 |
Family
ID=14057213
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9254091U Expired - Fee Related JP2555726Y2 (en) | 1991-11-13 | 1991-11-13 | Air refractive index measuring device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2555726Y2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006258739A (en) * | 2005-03-18 | 2006-09-28 | Fujinon Corp | Output device of branched light flux and measuring devices of a plurality of light flux output type |
| JP5180594B2 (en) * | 2008-01-08 | 2013-04-10 | 新東エスプレシジョン株式会社 | Interferometer |
| KR101321409B1 (en) * | 2012-01-12 | 2013-10-23 | (주)미토스 | Refractive index measuring method for plastic lens with curvature |
| KR101504061B1 (en) * | 2014-02-17 | 2015-03-19 | 한국기술교육대학교 산학협력단 | System for measuring light absorption coefficient of sample and measuring method thereof |
| KR101602068B1 (en) * | 2014-12-02 | 2016-03-09 | 한국기술교육대학교 산학협력단 | System for measuring light absorption coefficient using polarization and interference |
-
1991
- 1991-11-13 JP JP9254091U patent/JP2555726Y2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0543058U (en) | 1993-06-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10890487B2 (en) | Integrated polarization interferometer and snapshot specro-polarimeter applying same | |
| JPH0198902A (en) | Light wave interference length measuring instrument | |
| US10024647B2 (en) | Method of air refractive index correction for absolute long distance measurement | |
| JPH10500767A (en) | Interferometer | |
| WO2012062096A1 (en) | Method and device for measuring air refractive index based on laser synthetic wavelength interference | |
| US5757489A (en) | Interferometric apparatus for measuring a physical value | |
| JP2555726Y2 (en) | Air refractive index measuring device | |
| JPS61219803A (en) | Apparatus for measuring physical quantity | |
| JPH11183116A (en) | Method and device for light wave interference measurement | |
| US6483593B1 (en) | Hetrodyne interferometer and associated interferometric method | |
| JPH09280822A (en) | Light wave interference measuring device | |
| CN110966939B (en) | Interferometric measuring device, measuring method and photoetching equipment | |
| JP2990309B2 (en) | Optical member for measuring correction coefficient of differential interferometer | |
| JPS60104236A (en) | Method and device for measuring mode double refractive index of polarized wave maintaining optical fiber | |
| JPH1144503A (en) | Light wave interference measuring device | |
| JPH0755571A (en) | Plarization dispersion measuring instrument | |
| JP3036951B2 (en) | Light wave interference measurement device | |
| JPH11344303A (en) | Laser interference length measuring apparatus | |
| RU2742694C1 (en) | Two-wave laser displacement meter | |
| JPH11108614A (en) | Light-wave interference measuring instrument | |
| JPH0617851B2 (en) | Method and apparatus for measuring mode birefringence of birefringent fiber | |
| RU2303237C2 (en) | Interferometer device for measuring optical thickness of a transparent layer or a gap | |
| JPS60173429A (en) | Method and device for measuring dispersion of polarized wave | |
| JPH11211417A (en) | Method and device for measuring light wave interference | |
| JP2000121322A (en) | Laser length measuring machine |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R323115 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |