Optical fiber-typed spectral confocal coherence tomography optical system and application thereof

An optical fiber spectral confocal coherence tomography optical system, comprising:

• an optical fiber coupler,
• a broadband light source, connected to an input end of the optical fiber coupler, for providing a light source signal,
• a reference component, connected to a first output end of the optical fiber coupler, for receiving the light source signal emitted by the optical fiber coupler and controllably forming the light source signal into an interference signal,
• a sample component, connected to a second output end of the optical fiber coupler, for receiving the light source signal emitted by the optical fiber coupler and forming a spectral confocal signal after the light source signal passes through a sample to be tested, and
• a spectrometer, connected to a third output end of the optical fiber coupler, for firstly receiving the spectral confocal signal, then receiving a total output signal obtained from the superposition of the interference signal and the spectral confocal signal, and achieving signal separation according to the spectral confocal signal and the total output signal to enhance a signal-to-noise ratio and resolution of signals, wherein
• the spectrometer, connected to a third output end of the optical fiber coupler, for firstly receiving the spectral confocal signal, then receiving a total output signal obtained from the superposition of the interference signal and the spectral confocal signal, wherein for achieving signal separation according to the spectral confocal signal and the total output signal, the spectrometer is for:
• broadband light emitted by the broadband light source entering the reference component and the sample component;
• closing a light shutter in the reference component, preventing the broadband light from entering the reference component while allowing the broadband light to only enter the sample component to form the spectral confocal signal;
• opening the light shutter in the reference component, allowing the broadband light to enter the reference component to obtain the interference signal;
• and
• superimposing the interference signal and the spectral confocal signal to obtain the total output signal, and outputting the total output signal to the spectrometer;
• the total output signal being expressed as:
• I
• o
• (
• λ
• )
• =
• ∑
• j
• =
• 1
• M
• [
• π
• ⁢
• a
• 2
• λ
• ⁡
• (
• d
• conf
• ⁢
• 0
• +
• b
• ⁢
• λ
• j
• )
• ⁢
• sin
• ⁢
• c
• ⁡
• (
• π
• ⁢
• a
• 2
• ⁢
• b
• ⁡
• (
• λ
• -
• λ
• j
• )
• 2
• ⁢
• λ
• ⁡
• (
• d
• conf
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• 0
• +
• b
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• λ
• j
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• 2
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• ]
• 4
• ×
• 2
• ⁢
• ∑
• j
• =
• 1
• M
• ⁢
• I
• R
• ⁢
• I
• j
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• cos
• ⁡
• (
• ϕ
• j
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• 0
• +
• 4
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• π
• λ
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• d
• int
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• j
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• where Io represents the total output signal;
• λ represents a wavelength;
• M represents the number of surfaces of the sample to be tested;
• j represents a jth surface of the sample to be tested;
• dconf0, a, and b represent parameters of a dispersing lens;
• λj represents a wavelength corresponding to the jth surface of the sample to be tested;
• IR and Ij represent intensities of light reflected from a reference surface and a surface of the sample to be tested, respectively;
• ϕj0 represents an initial phase of the interference signal;
• and dintj represents an optical depth corresponding to a jth surface of the dispersing lens;
• and
• wherein for achieving signal separation according to the spectral confocal signal and the total output signal, the spectrometer is for:
• using the opening/closing of the light shutter in the reference component to obtain the total output signal/the spectral confocal signal, respectively;
• and
• obtaining the interference signal by dividing the total output signal by the spectral confocal signal, and using a covariance method to perform signal model fitting and autocorrelation calculation to achieve high-resolution estimation and signal separation.