JPS6338091B2 - - Google Patents
Info
- Publication number
- JPS6338091B2 JPS6338091B2 JP18659981A JP18659981A JPS6338091B2 JP S6338091 B2 JPS6338091 B2 JP S6338091B2 JP 18659981 A JP18659981 A JP 18659981A JP 18659981 A JP18659981 A JP 18659981A JP S6338091 B2 JPS6338091 B2 JP S6338091B2
- Authority
- JP
- Japan
- Prior art keywords
- refractive index
- wavelength
- group refractive
- vacuum
- interferometer
- 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
Links
- 230000003287 optical effect Effects 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims 1
- 238000000691 measurement method Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- 238000005305 interferometry Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
Classifications
-
- 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
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Description
【発明の詳細な説明】
本発明は、群屈折率を高精度に測定する方法に
関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring group refractive index with high precision.
高精度な干渉計測の場合、一般に空気の位相屈
折率が必要であるが、２波長の合成波長による干
渉計測の場合、以下に詳述するように群屈折率が
必要である。この群屈折率は、現在、測距儀など
においても不可欠なものであり、従つて、この群
屈折率の値を高精度に測定可能とすることには技
術的に大きな意義がある。 In the case of high-precision interferometry, the phase refractive index of air is generally required, but in the case of interferometry using a composite wavelength of two wavelengths, the group refractive index is required as described in detail below. This group refractive index is currently indispensable in rangefinders and the like, and therefore, it is of great technical significance to be able to measure the value of this group refractive index with high precision.
本発明は、このような群屈折率を極めて簡単な
手段により高精度に測定する方法を提供しようと
するものであり、波長λ1とそれより少し小さい波
長λ2の光束をそれらの光軸をそろえて光路に真空
部を有する干渉計に入射し、両光束による干渉縞
を検出部で同時に検出し、媒質と真空に関する検
出器出力信号の位相差を測定することによつて群
屈折率を求めることを特徴とするものである。 The present invention aims to provide a method for measuring such a group refractive index with high precision using extremely simple means, in which light beams with a wavelength λ 1 and a slightly smaller wavelength λ 2 are aligned with their optical axes. The light beams are aligned and incident on an interferometer that has a vacuum section in the optical path, and the detection section simultaneously detects the interference fringes caused by both light beams.The group refractive index is determined by measuring the phase difference between the detector output signals regarding the medium and the vacuum. It is characterized by this.
以下に本発明の方法についてさらに詳細に説明
する。 The method of the present invention will be explained in more detail below.
２光束干渉計において、波長λ1とそれよりも少
し小さい波長λ2の光束の強度干渉による干渉縞を
同じ検出器で同時に検出すると、モアレ縞的にλ1
とλ2との合成波長
λs＝λ1λ2／（λ1−λ2）
に対応する正弦状の干渉縞信号が生じる。 In a two-beam interferometer, when interference fringes due to the intensity interference of a light beam with a wavelength λ 1 and a slightly smaller wavelength λ 2 are simultaneously detected by the same detector, λ 1 appears in the form of Moiré fringes.
A sinusoidal interference fringe signal corresponding to the combined wavelength λ s =λ 1 λ 2 /(λ 1 −λ 2 ) of λ 2 and λ 2 is generated.
この合成波長λsによる干渉縞は、分散特性を持
つた透過媒質中において、位相屈折率ではなく、
群屈折率によつて規定される。 The interference fringes due to this combined wavelength λ s are not determined by the phase refractive index in a transmission medium with dispersion characteristics, but by
It is defined by the group refractive index.
即ち、媒質中における合成波長λsoは、n1，n2
及びnsをそれぞれ波長λ1，λ2、及び合成波長λsに
ついての屈折率としたとき、
λso＝λs／ns＝λ1／n1＋λ2／n2／λ1／n1−λ2／n
2＝λ1λ2／n2λ1−n1λ2
によつて与えられ、ここでλ2がλ1より少しだけ小
さいことから、
λ1＝λ2＋δλ
n1＝n2−δn
と置くと、
λso＝λs／ns＝λ1λ2／n2（λ2＋δλ）−（n2−δn
）λ2
＝λ1λ2／n2δλ＋δnλ2＝λ1λ2／δλ／n2
＋λ2（δn／δλ）
＝λs／n2＋λ2（δn／δλ）
となり、従つて前記屈折率nsは、
ns＝n2＋λ2（δn／δλ）
によつて与えられ、この式の右辺は群屈折率その
ものである。従つて合成波長λsについての媒質中
における屈折率が（λ1＋λ2）／２の波長における
群屈折率によつて規定されることがわかる。従つ
て、２波長の同時干渉によつて発生する合成波長
の位相を真空セルの外と中に関して測定すれば、
これらの位相差から真空セルの外の媒質の群屈折
率が求められる。 That is, the combined wavelength λ so in the medium is n 1 , n 2
and n s are the refractive indices for the wavelengths λ 1 , λ 2 , and the combined wavelength λs, respectively, λ so = λ s /n s = λ 1 /n 1 +λ 2 /n 2 /λ 1 /n 1 − λ 2 /n
2 = λ 1 λ 2 /n 2 λ 1 −n 1 λ 2 , where λ 2 is slightly smaller than λ 1 , so λ 1 = λ 2 + δλ n 1 = n 2 − δn. Then, λ so = λ s /n s = λ 1 λ 2 /n 2 (λ 2 + δλ) − (n 2 − δn
) λ 2 = λ 1 λ 2 /n 2 δλ+δnλ 2 = λ 1 λ 2 /δλ/n 2
+λ 2 (δn/δλ) = λ s /n 2 +λ 2 (δn/δλ) Therefore, the refractive index n s is given by n s = n 2 +λ 2 (δn/δλ), and this The right side of the equation is the group index itself. Therefore, it can be seen that the refractive index in the medium for the synthetic wavelength λ s is defined by the group refractive index at the wavelength of (λ 1 +λ 2 )/2. Therefore, if we measure the phase of the composite wavelength generated by simultaneous interference of two wavelengths with respect to the outside and inside of the vacuum cell, we get:
From these phase differences, the group refractive index of the medium outside the vacuum cell can be determined.
第１図は上述した原理に基づいて空気の群屈折
率を測定する干渉計の構成を示すもので、波長λ1
のレーザ光源１及び波長λ2のレーザ光源２を備
え、これらの光源からのレーザ光はハーフミラー
等からなるビーム混合器３において混合される。
上記レーザ光源１，２としては、例えば
0.63μmHe―Neレーザと0.61μmHe―Heレーザを
用い、あるいは0.51μmArイオンレーザと
0.49μmArイオンレーザを用いることができ、さ
らに色素レーザなどの２波長同時発振レーザを用
いることもできる。 Figure 1 shows the configuration of an interferometer that measures the group refractive index of air based on the principle described above.
A laser light source 1 having a wavelength of λ 2 and a laser light source 2 having a wavelength of λ 2 are provided, and the laser lights from these light sources are mixed in a beam mixer 3 consisting of a half mirror or the like.
As the laser light sources 1 and 2, for example,
Using 0.63 μm He-Ne laser and 0.61 μm He-He laser, or with 0.51 μm Ar ion laser.
A 0.49 μm Ar ion laser can be used, and a dual wavelength simultaneous oscillation laser such as a dye laser can also be used.
これらの光源からのレーザ光は、光軸をそろえ
て干渉計に入射され、即ちコリメータ４を経てハ
ーフミラー等からなるビーム分割器５に投射さ
れ、ここで参照鏡６に向う反射光と反射鏡７に至
る透過光に分割される。分割された一方の光路即
ちビーム分割器５と反射鏡７との間には、空気に
ついての測定を行うために真空ポンプ８に接続し
た真空セル９等の真空部を配設しているが、一般
的には測定しようとする試料が配設され、光束の
一部がこの試料中を透過する。参照鏡６及び反射
鏡７からの反射光はそれぞれもとの光路を戻つて
ビーム分割器５に入り、このビーム分割器５を透
過または反射して光軸が一致し、集光レンズ１０
で集光される。 The laser beams from these light sources are incident on the interferometer with their optical axes aligned, and are projected through a collimator 4 to a beam splitter 5 consisting of a half mirror or the like, where the reflected beams directed toward a reference mirror 6 and the reflecting mirror are projected. The transmitted light is divided into 7 parts. A vacuum section such as a vacuum cell 9 connected to a vacuum pump 8 is disposed between one of the divided optical paths, that is, between the beam splitter 5 and the reflecting mirror 7, in order to measure air. Generally, a sample to be measured is placed, and a portion of the light beam is transmitted through the sample. The reflected lights from the reference mirror 6 and the reflecting mirror 7 each return to their original optical paths and enter the beam splitter 5, and are transmitted or reflected through the beam splitter 5 so that their optical axes coincide with each other, and the condenser lens 10
The light is focused.
このようにして、波長λ1とλ2の光束による各干
渉が生じ、真空セル９を透過した光束による干渉
縞は真空セルの管径に対応した大きさの反射鏡１
１で反射して検出器１２により検出され、真空セ
ル９を透過しない光束による干渉縞は反射鏡１１
のまわりを通つて検出器１３により検出される。 In this way, interference occurs between the light beams of wavelengths λ 1 and λ 2 , and interference fringes due to the light beams transmitted through the vacuum cell 9 are formed by the reflecting mirror 1 whose size corresponds to the tube diameter of the vacuum cell 9.
Interference fringes due to the light beam reflected by the detector 12 and not transmitted through the vacuum cell 9 are reflected by the reflector 11.
is detected by the detector 13.
波長λ1及びλ2の光束による干渉縞をそれぞれ同
時に検出した各検出器１２，１３の出力は、増幅
器１４，１５、２乗算器１６，１７、ローパスフ
イルタ１８，１９を通すことによりコントラスト
を強めてレコーダ２０に送られ、参照鏡を掃引装
置２１で掃引することによつて生じる干渉縞信号
Ｓがレコーダ２０に記録される。そして、これら
の正弦状の干渉縞信号は群屈折率で規定されるの
で、これらの位相差φを測定すると、真空セルの
長さをＬとして、空気の群屈折率nsが、
ns＝１＋（ｍ＋φ）／2L
によつて高精度に求められる。なぜなら、ｍは自
然数であり、従来の精度の悪い方法からでも一義
的に決定されるからである。 The outputs of the detectors 12 and 13, which simultaneously detected the interference fringes caused by the light beams of wavelengths λ 1 and λ 2 , are passed through amplifiers 14 and 15, 2 multipliers 16 and 17, and low-pass filters 18 and 19 to enhance the contrast. The interference fringe signal S generated by sweeping the reference mirror with the sweep device 21 is recorded on the recorder 20. Since these sinusoidal interference fringe signals are defined by the group refractive index, when these phase differences φ are measured, the group refractive index n s of air is determined as n s = where the length of the vacuum cell is L. It can be determined with high accuracy by 1+(m+φ)/2L. This is because m is a natural number and can be uniquely determined even by conventional methods with low precision.
以上に詳述したところから明らかなように、本
発明によれば、極めて簡単な手段によつて容易に
群屈折率を測定することができ、しかも光波干渉
を利用しているのでその群屈折率を極めて高精度
に求めることができる。 As is clear from the detailed description above, according to the present invention, the group refractive index can be easily measured by extremely simple means, and since light wave interference is used, the group refractive index can be easily measured. can be determined with extremely high precision.
第１図は本発明の実施に用いる装置の構成図で
ある。
１２，１３……検出器。
FIG. 1 is a block diagram of an apparatus used to implement the present invention. 12, 13...detector.
Claims (1)
をそれらの光軸をそろえて二光束形干渉計の一方
の光路の視野の一部に真空部を有する干渉計に入
射し、両光束による干渉縞を検出器で検出した後
２乗・フイルタリングの処理を行い、真空部とそ
れ以外の２種類の信号の位相差を測定することに
よつて群屈折率を求めることを特徴とする群屈折
率の高精度測定法。1. Light beams of wavelength λ 1 and a slightly smaller wavelength λ 2 are aligned with their optical axes and are incident on an interferometer that has a vacuum section in a part of the field of view of one optical path of a two-beam interferometer. A detector detects the interference fringes caused by the waveform, then performs squaring and filtering processing, and then determines the group refractive index by measuring the phase difference between two types of signals, one in the vacuum and the other. High-precision measurement method for group refractive index.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18659981A JPS5887447A (en) | 1981-11-20 | 1981-11-20 | High-precise measuring method for group refractive index |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18659981A JPS5887447A (en) | 1981-11-20 | 1981-11-20 | High-precise measuring method for group refractive index |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5887447A JPS5887447A (en) | 1983-05-25 |
| JPS6338091B2 true JPS6338091B2 (en) | 1988-07-28 |
Family
ID=16191372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18659981A Granted JPS5887447A (en) | 1981-11-20 | 1981-11-20 | High-precise measuring method for group refractive index |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5887447A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004286575A (en) * | 2003-03-20 | 2004-10-14 | National Institute Of Advanced Industrial & Technology | Method and system for precisely measuring group refractive index of optical material |
| JP2007114206A (en) * | 2006-11-30 | 2007-05-10 | National Institute Of Advanced Industrial & Technology | Method for precision measurement of group refractive index of optical material |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2694201B2 (en) * | 1988-11-16 | 1997-12-24 | 日本電信電話株式会社 | Dispersion measuring method and apparatus |
| JP2017003434A (en) * | 2015-06-10 | 2017-01-05 | キヤノン株式会社 | Method of measuring refractive index, measuring device, and method of manufacturing optical element |
| CN108318420A (en) * | 2017-12-22 | 2018-07-24 | 北京航天计量测试技术研究所 | A kind of light channel structure for high-precision gas refractometry |
-
1981
- 1981-11-20 JP JP18659981A patent/JPS5887447A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004286575A (en) * | 2003-03-20 | 2004-10-14 | National Institute Of Advanced Industrial & Technology | Method and system for precisely measuring group refractive index of optical material |
| JP2007114206A (en) * | 2006-11-30 | 2007-05-10 | National Institute Of Advanced Industrial & Technology | Method for precision measurement of group refractive index of optical material |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5887447A (en) | 1983-05-25 |
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