On-line measuring system using optical fiber grating synthetic wave for interfering step height

A fiber grating and step height technology, which is applied in the field of optical measurement, can solve the problems of inability to measure the step height and not suitable for online measurement, and achieve the effect of expanding the range.

Inactive Publication Date: 2008-02-20
BEIJING JIAOTONG UNIV
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  • Abstract
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Problems solved by technology

[0009] 1. The measurement system is sensitive to interference such as environmental vibration and temperature drift, and is not suitable for online measurement
[0010] 2. The measured step height is limited b

Method used

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  • On-line measuring system using optical fiber grating synthetic wave for interfering step height
  • On-line measuring system using optical fiber grating synthetic wave for interfering step height
  • On-line measuring system using optical fiber grating synthetic wave for interfering step height

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Embodiment Construction

[0021] The present invention will be further described below in conjunction with FIG. 3 and specific embodiments.

[0022] As shown in Figure 3, the parameters of fiber gratings FBG1, FBG2 and FBG3 are the same, and the reflected Bragg wavelengths are the same, all of which are λ 1 ; The reflection spectrum of the chirped fiber grating CFBG4 contains λ 2 , Λ 3 , But not including λ 1 . The fiber gratings FBG1 and FBG2 are respectively written at the ends of the two interference arms of the measuring fiber Michelson interferometer. In this way, the fiber gratings FBG1 and FBG2 are used as mirrors to form a stable fiber Michelson interferometer, and the stable fiber Michelson interferometer and The optical paths of the measuring fiber Michelson interferometer almost coincide. The wavelengths are all in the 1550nm band but the wavelengths are different, respectively λ 1 , Λ 2 , Λ 3 The light emitted by the three DFB lasers is coupled into the measurement system through the 3X1 couple...

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Abstract

The utility model discloses an on-line measuring system for interference step height in composite wave from optical fiber raster. A composite optical fiber interferometer is built by making use of the Bragg wavelength reflective property in the optical fiber raster. The composite interferometer comprises two optical fiber Michelson interferometers with almost coincident light paths. A Michelson interferometer is used for measuring, and the other is used for stabilizing the system. The impact on the measuring system brought by the environmental interference is corrected through the feedback control compensation, so that the system is applicable to online measuring. Three lasers emit lights of slightly different wavelength but within 1550nm waveband. Because of the effects of the optical fiber raster reflecting Bragg wavelength and self-chirped optical fiber raster reflecting the specific spectrum, a wavelength acts on the stabilizing interferometer for stabilizing the measuring system, and the other two wavelengths act on the measuring interferometer to produce composite wave interference for actual measurement. Different composite wavelengths can be gained by regulating the two wavelengths acting on the measuring interferometer; and the measurement of different step heights can be carried out.

Description

Technical field [0001] The invention relates to a synthetic wave interference step height measurement system using a fiber grating, in particular to a step height measurement system suitable for online measurement, and belongs to the technical field of optical measurement. Background technique [0002] [1] D.P. Hand, T.A. Carolan, J.S. Barton, and J.D.C. Jones, Optics Letters, 1993, Vol. 18, No. 16, pages 1361-1363. The working principle of the prior art document [1] is shown in Figure 1. The light emitted by the semiconductor laser passes through the Faraday isolator and the optical fiber 50:50 coupler before reaching the measuring head. The measuring head is a Fizeau interferometer, and part of the light is The fiber end surface is reflected as the reference light, and the other part of the light is focused by the self-focusing lens and projected on the measured surface, reflected by the measured surface and then returned to the system and interfered with the reference light. T...

Claims

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Application Information

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IPC IPC(8): G01B11/02G01B9/02G01D5/353G01D5/38
Inventor 谢芳张琳
Owner BEIJING JIAOTONG UNIV
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