Light-spectrum phase calibration system and method based on cascade Mach-Zehnder interferometer

Abstract

The invention discloses a light-spectrum phase calibration system and a light-spectrum phase calibration method based on a cascade Mach-Zehnder interferometer. A first reference interference signal with optical path difference d1 close to maximum imaging depth of the system and a second reference interference signal with optical path difference d2 close to zero optical path are separated from a cascade MZI (Mach Zehnder Interferometer) interference spectrum signal through Fourier transform, filtering and inverse Fourier transform; the first reference interference signal is used for demarcating and calibrating a fractional part of a light spectrum phase jump at the maximum imaging depth part in real time during a wave-number sampling process; the second reference interference signal is used for determining 2pi integer multiples of the light spectrum phase jump at the maximum imaging depth part, wherein the phase jump caused by an initial wave-number jumping is in linear relation with the depth; and the practical phase jump at any depth can be calibrated by combining the two reference interference signals. According to the light-spectrum phase calibration system and the light-spectrum phase calibration method disclosed by the invention, not only is real-time linear calibration realized, but also calibration precision of the light-spectrum phase jump is ensured, so that a 2pi confusion problem of the light-spectrum phase jump calibration is solved, and the real-time high-flexibility phase detection and the reconstruction of phase images can be realized.

Description

technical field [0001] The invention relates to optical coherence tomography (OCT) technology and phase-sensitive frequency-sweeping optical coherence tomography technology, in particular to a spectral phase calibration system and method based on cascaded Mach-Zehnder interferometers. 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] Phase-sensitive OCT technology can simultaneously measure the amplitude and phase of backscattered light. By measuring the nm-level displacement of tissue in response to external stimuli, compared with traditional OCT technology, it can provide phase-related functional contrast information. In quantitative ph...

AI Technical Summary

Problems solved by technology

This method has complex hardware structure and high requirements for data acquisition cards. The synchronization error of data acquisition between different data acquisition cards may cause phase noise, and the calibration interference signal cannot eliminate the 2π confusion of phase jumps.

[0012] E.D.Moore et al. from the University of Colorado proposed a self-referenced frequency-sweeping phase-sensitive interferometer to measure absolute distances. The absolute distance measurement is achieved through accurate calibration of the interferometer sampling interval, and an additional interferometer is used to monitor the instantaneous frequency of the frequency-sweeping light source. In this way, the sampling distance is calibrated in real time, but the frequency monitoring accuracy of the additional interferometer needs to be calibrated by a wavelength reference device with high spectral accuracy (0.1pm order of magnitude)

[0013] All of the above methods have inherent shortcomings, need to introduce more complex devices, and cannot solve the 2π confusion problem of spectral phase jump, therefore, it is necessary to study a wide range of spectral Phase Calibration Method

Images