JP2748198B2 - High extinction ratio orthogonal dual frequency light source for heterodyne interferometer - Google Patents
High extinction ratio orthogonal dual frequency light source for heterodyne interferometerInfo
- Publication number
- JP2748198B2 JP2748198B2 JP3238587A JP23858791A JP2748198B2 JP 2748198 B2 JP2748198 B2 JP 2748198B2 JP 3238587 A JP3238587 A JP 3238587A JP 23858791 A JP23858791 A JP 23858791A JP 2748198 B2 JP2748198 B2 JP 2748198B2
- Authority
- JP
- Japan
- Prior art keywords
- light source
- extinction ratio
- high extinction
- frequency light
- dual frequency
- 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
Landscapes
- Instruments For Measurement Of Length By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
Description
【発明の詳細な説明】
これまで，音響光学素子を用いた直交２周波数光源は，
ヘテロダイン干渉計において，共通光路を構成し易いこ
とから，用いられてきた。しかし，これまでの直交２周
波数光源では，最終の合波に用いた偏光ビームスプリッ
タの反射面に楕円偏光を入射すると反射光は主成分は垂
直成分であるが，平行成分が若干漏れてくるため，消光
比が悪くなり干渉ビートに余分な成分が現れてくる。こ
のため，位相計出力が非線形性誤差を生じる。本発明
は，このような非線形性誤差を生じないように偏光漏れ
成分のない，直交２周波数光源に関するものである。本
特許の光学系略図を図１に示す。レーザ光源Ｌ，１／２
波長板ＨＷをとおった光は偏光ビームスプリッタＰＢＳ
１の偏光軸に４５度に入射し，２ビームに分割される。
音響光学素子Ａ１，Ａ２でそれぞれ周波数偏移をうけ
る。各ビームは偏光ビームスプリッタＰＢＳ１の不完全
性および音響光学素子中の歪みなどにより楕円偏光にな
る。これらのビームを，従来の光源と異なり消光比の高
いグラムトムソンプリズムＧＰ１，ＧＰ２を通して，完
全な直線偏光にして合波用偏光ビームスプリッタＰＢＳ
２に入射して，高消光比の直交２周波数光をえる。これ
により，従来の光源の消光比が約３０ｄＢにくらべ，本
方法では５０ｄＢ以上が得られ，約２０ｄＢ向上でき
る。この光源を光ヘテロダイン干渉計に用いると非線形
誤差のない高精度な位相測定が可能になる。DETAILED DESCRIPTION OF THE INVENTION Until now, orthogonal two-frequency light sources using acousto-optic devices have been
In a heterodyne interferometer, it has been used because it is easy to configure a common optical path. However, in the conventional orthogonal two-frequency light source, when elliptically polarized light is incident on the reflection surface of the polarization beam splitter used for the final multiplexing, the reflected light has a vertical component as a main component, but a small amount of a parallel component leaks. As a result, the extinction ratio deteriorates and an extra component appears in the interference beat. For this reason, the output of the phase meter causes a non-linearity error. The present invention relates to a quadrature two-frequency light source having no polarization leakage component so as not to cause such a nonlinearity error. A schematic diagram of the optical system of this patent is shown in FIG. Laser light source L, 1/2
The light passing through the wave plate HW is a polarizing beam splitter PBS
It is incident on one polarization axis at 45 degrees and split into two beams.
Each of the acousto-optic devices A1 and A2 undergoes frequency shift. Each beam becomes elliptically polarized light due to imperfections of the polarizing beam splitter PBS1 and distortion in the acousto-optic device. These beams are converted into perfect linearly polarized light through Gram-Thompson prisms GP1 and GP2, which have a high extinction ratio unlike the conventional light source, and are combined into a polarizing beam splitter PBS for multiplexing.
2 to obtain orthogonal two-frequency light having a high extinction ratio. As a result, compared to the extinction ratio of the conventional light source of about 30 dB, the present method can obtain 50 dB or more, and can improve about 20 dB. When this light source is used in an optical heterodyne interferometer, highly accurate phase measurement without a non-linear error can be performed.
【図面の簡単な説明】 図１は，高消光比直交２周波数光源の光学系。[Brief description of the drawings] FIG. 1 shows an optical system of a high extinction ratio orthogonal two-frequency light source.
Claims (1)
前に高消光比の偏光素子を挿入することにより，漏れ成
分をなくし，高消光比化した直交２周波数光源。(57) [Claims] An orthogonal two-frequency light source having a high extinction ratio by eliminating a leakage component by inserting a polarizing element having a high extinction ratio in front of a polarizing beam splitter for combining two laser beams.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3238587A JP2748198B2 (en) | 1991-06-11 | 1991-06-11 | High extinction ratio orthogonal dual frequency light source for heterodyne interferometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3238587A JP2748198B2 (en) | 1991-06-11 | 1991-06-11 | High extinction ratio orthogonal dual frequency light source for heterodyne interferometer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0666513A JPH0666513A (en) | 1994-03-08 |
| JP2748198B2 true JP2748198B2 (en) | 1998-05-06 |
Family
ID=17032422
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3238587A Expired - Fee Related JP2748198B2 (en) | 1991-06-11 | 1991-06-11 | High extinction ratio orthogonal dual frequency light source for heterodyne interferometer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2748198B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101893448B (en) * | 2010-07-16 | 2011-08-17 | 中国科学院长春光学精密机械与物理研究所 | Method for eliminating or reducing nonlinearity errors in laser heterodyne interferometry |
| CN101936747B (en) * | 2010-07-28 | 2011-09-28 | 中国科学院长春光学精密机械与物理研究所 | Method for eliminating fundamental waves and odd harmonics of nonlinear errors in wave detection method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS647679A (en) * | 1987-06-30 | 1989-01-11 | Hoya Corp | Laser device |
-
1991
- 1991-06-11 JP JP3238587A patent/JP2748198B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0666513A (en) | 1994-03-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |