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Optical refractometry measuring method and device

A measurement method and a technology of a measurement device, which are applied in the direction of a measurement device, an optical instrument test, a reflectometer for detecting backscattered light in the frequency domain, etc., can solve the problems of inability to perform measurement, broadening of the spectrum width of beat frequency signals, and resolution Deterioration and other issues

Active Publication Date: 2009-12-23
NIPPON TELEGRAPH & TELEPHONE CORP
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0005] However, in the prior art, it is known that the resolution deteriorates at measurement distances exceeding 1 / 2 of the coherence length of the frequency-sweeping light source, and in the worst case the measurement becomes impossible
This is because the interference between the backscattered light from the circuit under test and the local light disappears at a measurement distance exceeding 1 / 2 of the coherence length of the frequency-sweeping light source, and as a result, the spectral width of the beat signal becomes wider.

Method used

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  • Optical refractometry measuring method and device
  • Optical refractometry measuring method and device
  • Optical refractometry measuring method and device

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no. 1 approach

[0076] image 3 It is a functional block diagram showing an embodiment of the light reflection measurement device of the present invention. This optical reflectance measurement device performs OFDR measurement of the distribution of reflectance with respect to the propagation direction in a circuit to be measured. exist image 3 Among them, the output light 9 from the frequency-sweeping light source 1 is branched by the optical directional coupler C, one of which enters the measurement unit 11 as the measurement light 2 , and the other enters the coherence monitoring unit 12 as the monitor light 10 . The results measured by the measurement unit 11 and the results monitored by the coherence monitoring unit 12 are input to the analysis unit 13, and the backscattered light intensity distribution in the measured circuit (inside the measurement unit 11) is obtained through arithmetic processing.

[0077] The measurement unit 11 detects the interference beat signal of the output l...

no. 2 approach

[0118] In the first embodiment, it is possible to optimally correct the c The beat frequency signal generated by the backscattered signal light at the point / 2. However, as the assay point changes from NL c / 2 distance, the correction accuracy deteriorates. In the second embodiment, a processing method capable of avoiding deterioration of correction accuracy will be described. In this embodiment, the basic structure of the device is the same as Figure 4 Similarly, the processing by the data processing unit 18a is different.

[0119] As described in the first embodiment, the correction process using equation (11) is at distance NL c / 2 is best. After correction, the beat frequency F corresponding to this distance N becomes a constant and is represented by the following formula (14).

[0120] f N = f N (t) β(t) (14)

[0121] In formula (14), f N (t) is the time differential X' of formula (11) N (t)(=dX N (t) / dt), represents the instantaneous beat frequency. β(t) i...

no. 3 approach

[0162] Figure 13 It is a figure which shows an example of the basic structure of the optical reflectance measurement apparatus by OFDR. exist Figure 13 In the above, the output light from the frequency-sweeping light source 1 is branched through the optical directional coupler A, one is used as the reference light 3 , and the other is injected into the optical circuit 4 to be measured. The signal light 5 backscattered inside the optical circuit 4 to be measured is taken out by the optical directional coupler A, combined with the reference light 3 by the optical directional coupler B, and then detected by the receiver 6 . At this time, the interference beat signal generated due to the interference of the two light waves is sampled by the sampling device 7, and the measured data is analyzed by the frequency analysis device 8, thereby measuring the signal from each position in the optical circuit 4 to be measured. The backscattered light intensity distribution at .

[0163] ...

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Abstract

It is an object to provide an optical refractometry measuring method and an optical refractometry measuring device for making it possible to obtain high precision regardless of a measuring distance. The optical refractometry measuring method and the optical refractometry measuring device, which measures a rear scattering light intensity distribution of a measuring subject in a light propagating direction by using an optical frequency domain refractometry method (OFDR), is characterized in that a coherence monitor (12) is prepared to monitor a coherence characteristic of a frequency sweeping light source (1) and a measured result in a measuring unit (11) is corrected in accordance with the monitored result.

Description

technical field [0001] The present invention relates to a reflection measurement method for measuring the distribution of reflectance with respect to a propagation direction in a circuit to be measured such as an optical circuit, and an apparatus for implementing the method. Background technique [0002] Optical Frequency Domain Reflectometry (OFDR, Optical Frequency Domain Reflectometry) is known as one of optical reflection measurement methods used for measurement of transmission loss in optical circuits and diagnosis of faulty parts (for example, refer to Non-Patent Document 1). In this method, the output light from the frequency-sweeping light source is divided into two branches, and the interference beat signal (beat) signal generated by the interference of the reflected light from the measurement object and one branch light is analyzed. The distribution of backscattered light intensity with respect to the direction of light propagation is measured. [0003] That is, i...

Claims

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Application Information

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IPC IPC(8): G01M11/02G01M11/00
CPCG01M11/3172
Inventor 樊昕昱伊藤文彦古敷谷优介
Owner NIPPON TELEGRAPH & TELEPHONE CORP
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