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Homodyne laser interferometer probe and displacement measurement system using the same

Foreign code F110004069
File No. N021-09WO
Posted date Jul 8, 2011
Country EPO
Application number 06715045
Gazette No. 1860396
Gazette No. 1860396
Date of filing Mar 2, 2006
Gazette Date Nov 28, 2007
Gazette Date Apr 23, 2014
International application number JP2006303935
International publication number WO2006093210
Date of international filing Mar 2, 2006
Date of international publication Sep 8, 2006
Priority data
  • 2006JP303935 (Mar 2, 2006) WO
  • P2005-056753 (Mar 2, 2005) JP
Title Homodyne laser interferometer probe and displacement measurement system using the same
Abstract A low-cost homodyne laser interferometer probe of simple structure is provided which allows predetermined performance to be easily obtained by a simple adjustment, and a displacement measurement system using the same is also disclosed.
The homodyne laser interferometer probe includes an optical fiber (1) for guiding light, a collimator lens (2) that receives the light from the optical fiber (1), a 1/4 wavelength plate (3) that receives light from the collimator lens (2) and that converts the light from linearly polarized light into circularly polarized light, a beam splitter (4) for dividing light from the 1/4 wavelength plate (3) into reference light and measurement light, a first focal lens (5) that receives the reference light from the beam splitter (4), a reflection mirror (6) for reflecting the reference light from the first focal lens (5), and a second focal lens (7) that receives the measurement light from the beam splitter (4).
H ere, the reference light from the reflection mirror (6) is returned to measurement means along the same route.
The measurement light from the second focal lens (7) is applied to a measurement object (8), and the measurement light (signal light) from the measurement object (8) is returned to the measurement means along the same route.
Scope of claims [claim1]
1. A homodyne laser interferometer probe (1), comprising: (a) an optical fibre (2) for guiding light; (b) a collimator lens (3) that receives the light from the optical fibre (2); (c) a 1/4 wavelength plate (4) that receives the light from the collimator lens (3) and converts the light from linearly polarized light to circularly polarized light; (d) a beam splitter (5) for dividing the light from the 1/4 wavelength plate (4) into reference light and measurement light; (e) a first focal lens (6) that receives the reference light from the beam splitter (5); (f) a reflection mirror (7) for reflecting the reference light from the first focal lens(6); (g) an adjustment mechanism between the first focal lens (6) and the beam splitter (5) that adjusts a distance between the first focal lens (6) and the beam splitter (5) while keeping constant a distance between the first focal lens (6) and the reflection mirror (7); (h) a second focal lens(8) that receives the measurement light from the beam splitter (5), wherein the reference light from the reflection mirror (7) is returned to a measurement means along the same route, and wherein the measurement light from the second focal lens (8) is applied to a measurement object and the measurement light from the measurement object is returned to the measurement means along the same route.
[claim2]
2. A homodyne laser interferometer probe (20,30), comprising: (a) an optical fibre (21,31) for guiding light; (b) a collimator lens (22,32) that receives the light from the optical fibre (21); (c) a beam splitter (23,33) that receives the light from the collimator lens (22,32) and that divides the light into reference light and measurement light; (d) a first focal lens (24,34) that receives the reference light from the beam splitter (23,33); (e) a reflection mirror (25,35) for reflecting the reference light from the first focal lens (24,34); (f) an adjustment mechanism between the first focal lens (24,34) and the beam splitter (23,33) that adjusts a distance between the first focal lens (24,34) and the beam splitter (23,33) while keeping constant a distance between the first focal lens (24,34) and the reflection mirror (25,35); (g) a second focal lens (26,36) that receives the measurement light from the beam splitter (23,33); and (h) a photodetector that applies the measurement light from the second focal lens (26,36) to a measurement object, that returns the measurement light reflected by the measurement object to the beam splitter (23,33), and that measures the measurement light from the beam splitter (23,33) via a third focal lens (27,37), as well as measures the reference light from the reflection mirror (25,35) along the same route.
[claim3]
3. The homodyne laser interferometer probe (21,31) according to claim 2, wherein the photodetector is a photodiode (28).
[claim4]
4. The homodyne laser interferometer probe (21,31) according to claim 2, wherein the photodetector is a photodiode (28) connected to the focus part of the third focal lens (27,37), via an optical fibre (38).
[claim5]
5. The homodyne laser interferometer probe (1,20,30) according to any preceding claim, wherein the adjustment mechanism is a shear piezo element.
[claim6]
6. The homodyne laser interferometer probe (1,20,30) according to any preceding claim, wherein the adjustment mechanism consists of a shear piezo element and wedges.
[claim7]
7. A displacement measurement system that, using the homodyne laser interferometer probe according to claim 1, introduces the reference light and the measurement light that have been returned to the optical fibre (2), into an element for detecting the intensity of light that mutually interferes through the intermediary of a beam splitter, and that performs homodyne interferometer measurement using the optical path difference between the measurement light and the reference light.
[claim8]
8. A displacement measurement system using the homodyne laser interferometer probe according to claim 2, 3 or 4 which performs a homodyne laser interferometer measurement by the optical path difference between the reference light and the measurement light, based on the reference light and the measurement light obtained by the photodetector.
  • Applicant
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
  • Inventor
  • KAWAKATSU HIDEKI
IPC(International Patent Classification)
Reference ( R and D project ) CREST Nano Factory and Process Monitoring for Advanced Information Processing and Communication AREA
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