Method and system for calibrating spectrum based on interference spectrum phase information

Abstract

The invention discloses a method and a system for calibrating a spectrum based on interference spectrum phase information. In a sweep frequency optical coherence chromatography imaging system, a Mach Zehnder interferometer interference spectrum signal is generated by a Mach Zehnder interferometer, and an unwrapping phase of the Mach Zehnder interferometer interference spectrum signal is acquired in a computer based on digital Hilbert transform; the unwrapping phase and the wave number of a sweep frequency light source form a linear relation; equiphase interval interpolation is performed on an optical coherence chromatography signal by using unequal interval phase distribution; and optical coherence chromatography signal sampling points in equal wave number interval distribution are acquired so as to perform an image reconstruction algorithm based on fast Fourier transformation. In the invention, all the acquired sampling points are used for interpolation, so the interpolation precision is enhanced greatly, and the signal to noise ratio of the reconstructed signal is improved; actual axial resolution approximating to the ideal resolution can be obtained; moreover, the algorithm is simple, and real-time and high-sensitivity calibrated data processing and image reconstruction can be implemented.

Description

technical field [0001] The invention relates to an optical coherence tomography technique and a frequency-sweeping optical coherence tomography technique, in particular to a spectrum calibration method and system based on interference spectrum phase information. Background technique [0002] Optical coherence tomography (OCT) imaging technology is a new type of optical imaging technology that can perform non-invasive, non-contact, high-resolution in vivo imaging of the tissue structure and physiological functions of the tested living sample. It has broad application prospects in the field of early diagnosis of diseases and in vivo biopsy. [0003] The Fourier domain optical coherence tomography system includes two types: the spectral domain optical coherence tomography system and the frequency-swept optical coherence tomography system. The spectral domain OCT system adopts the structure of broadband light source and fast multi-channel spectrometer, and the swept frequency O...

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Problems solved by technology

[0005] The above-mentioned methods all have their inherent shortcomings. For example, the method of using a narrow-band fixed-wavelength filter (such as a fiber Bragg grating) to calibrate the frequency-sweeping output light can only calibrate the wavelength of the starting point at one point, and cannot correct the change of the frequency-sweeping output spectrum. The impact on the resolution; the method of using the comb signal generated by the fiber optic Fabry-Perot interferometer to calibrate the interference signal requires the introduction of more complex devices, and can only generate a limited number of sampling points for the interference signal Interpolation reduces the interpolation accuracy and system sensitivity; using the Mach-Zehnder interferometer to synchronously detect the OCT interference signal combined with the nearest neighbor comparison algorithm for calibration, although it does not need to introduce additional complex devices, the effect of improving the resolution is better. , but still can only generate a limited number of sampling points with equal wavenumber intervals, which reduces the interpolation accuracy and sensitivity, and due to the limitation of the Nyquist sampling theorem, it is necessary to generate a larger optical path for calibrating the interference signal at a large optical path difference Poor Mach-Zehnder interference signal reduces the calibration accuracy of the algorithm and increases the burden on the acquisition card

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