Raman spectroscopic detection method

Patent metadata

Field	Value
Publication number	US-10267678-B2
Application number	US-201414577748-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Dec 27, 2013
Publication date	Apr 23, 2019
Grant date	Apr 23, 2019

Abstract

Embodiments of the present invention provide a Raman spectroscopic inspection method, comprising the steps of: measuring a Raman spectrum of an object to be inspected successively to collect a plurality of Raman spectroscopic signals; superposing the plurality of Raman spectroscopic signals to form a superposition signal; filtering out a florescence interfering signal from the superposition signal; and identifying the object to be inspected on basis of the superposition signal from which the florescence interfering signal has been filtered out. By means of the above method, a desired Raman spectroscopic signal may be acquired by removing the interference caused by a florescence signal from a Raman spectroscopic inspection signal of the object. It may inspect correctly the characteristics of the Raman spectrum of the object so as to identify the object effectively.

First claim

What is claimed is:

1. A Raman spectroscopic inspection method, comprising the steps of:
(a-1) irradiating an object to be inspected by a laser at a fixed wavelength, such that a spectrum is generated from the irradiated object under a Raman scattering effect;
(a) performing a plurality of successive measurements of the spectrum generated from the object to collect a plurality of spectroscopic signals comprising Raman and florescence signals of the object respectively by a Raman spectroscopic instrument;
(b) adding up the plurality of spectroscopic signals comprising Raman and florescence signals to form a superposition signal, for enhancing the intensity of signal;
(c) filtering out the florescence signal from the superposition signal; and
(d) identifying the object to be inspected on basis of the superposition signal from which the florescence signal has been filtered out,
wherein the step (c) comprises:
(c1) acquiring a plurality of numerical sample points of the superposition signal, a number of the numerical sample points meeting a requirement of a sampling theorem;
(c2) calculating the florescence signal by iteration on basis of the plurality of numerical sample points of the superposition signal; and
(c3) subtracting the florescence signal from the superposition signal, and
wherein in the step (c2), the florescence signal is calculated by iteration as follow:
assuming that {y n } is a sequence of numerical sample points of the superposition signal, y n (i) is a value of the i th numerical sample point in {y n }, and {y n+1 } is a sequence which is calculated out after one iteration and y n+1 (i) is a value of the i th numerical sample point in {y n+1 }, then

y

n
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⁡

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n

⁡

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)

,

y
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⁡

(

i
-
m

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+

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(

i
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m

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]

where m is a positive integer and has an initial value of 1, wherein the above iteration is performed repeatedly until m meets a predetermined threshold, where m is added by 1 per iteration.

2. The Raman spectroscopic inspection method according to claim 1 , wherein the method, before the step (a), further comprises:
(a00) measuring the spectrum of the object to be inspected in advance to collect a single spectroscopic signal; and
(a01) judging a Raman characterizing intensity in the collected single spectroscopic signal, and if the Raman characterizing intensity is enough to recognize a Raman characteristic, then identifying the object to be inspected directly on basis of the collected single spectroscopic signal without performing the subsequent steps, otherwise, if the Raman characterizing intensity is not enough to recognize the Raman characteristic, then continuing to perform the step (a).

3. The Raman spectroscopic inspection method according to claim 2 , wherein in the step (a01), the judgment of the Raman characterizing intensity is done by searching a Raman characterizing peak in the single spectroscopic signal; and if the Raman characterizing peak is found, then determining the Raman characterizing intensity is enough to recognize the Raman characteristic, otherwise, if the Raman characterizing peak is not found, then determining the Raman characterizing intensity is not enough to recognize the Raman characteristic.

4. The Raman spectroscopic inspection method according to claim 2 , wherein in the step (a01), the judgment of the Raman characterizing intensity is done by searching a Raman characterizing peak in the single spectroscopic signal; and if the Raman characterizing peak is found and a ratio of an intensity of the Raman characterizing peak to an average intensity of the single spectroscopic signal is greater than a predetermined first threshold, then determining the Raman characterizing intensity is enough to recognize the Raman characteristic, otherwise, if the Raman characterizing peak is not found, or the ratio of the intensity of the Raman characterizing peak to the average intensity of the single spectroscopic signal is not greater than the predetermined first threshold although it is found, then determining the Raman characterizing intensity is not enough to recognize the Raman characteristic.

5. The Raman spectroscopic inspection method according to claim 1 , wherein the method, between the step (b) and the step (c), further comprises:
(b1) judging a Raman characterizing intensity in the superposition signal, and if the Raman characterizing intensity is enough to recognize a Raman characteristic, then identifying the object to be inspected directly on basis of the superposition signal without performing the subsequent steps, otherwise, if the Raman characterizing intensity is not enough to recognize the Raman characteristic, then continuing to perform the step (a).

6. The Raman spectroscopic inspection method according to claim 5 , wherein in the step (b1), the judgment of the Raman characterizing intensity is done by searching a Raman characterizing peak in the superposition signal; and if the Raman characterizing peak is found, then determining the Raman characterizing intensity is enough to recognize the Raman characteristic, otherwise, if the Raman characterizing peak is not found, then determining the Raman characterizing intensity is not enough to recognize the Raman characteristic.

7. The Raman spectroscopic inspection method according to claim 5 , wherein in the step (b1), the judgment of the Raman characterizing intensity is done by searching a Raman characterizing peak in the superposition signal; and if the Raman characterizing peak is found and a ratio of an intensity of the Raman characterizing peak to an average intensity of the superposition signal is greater than a predetermined second threshold, then determining the Raman characterizing intensity is enough to recognize the Raman characteristic, otherwise, if the Raman characterizing peak

Assignees

• Nuctech Co Ltd

Inventors

• Zhao Ziran
• Zhang Jianhong
• Wang Hongqiu
• Wang Weiwei
• Wang Zhiming
• Yi Yumin

Classifications

• G01J3/44 Primary

  Raman spectrometry; Scattering spectrometry {; Fluorescence spectrometry} · CPC title

• G01N21/65

  Raman scattering · CPC title

• G01J2003/4424

  Fluorescence correction for Raman spectrometry · CPC title

• G01N2201/06113

  Coherent sources; lasers · CPC title

• G01J3/0297 Primary

  Constructional arrangements for removing other types of optical noise or for performing calibration · CPC title