Device and method for measuring ultrashort pulse time overlap degree in cars microscopic imaging system

Abstract

The invention provides an ultrashort pulse time overlap degree measurement device and a method in a CARS microscopic imaging system. The ultrashort pulse time overlap degree measurement device in theCARS microscopic imaging system comprises a femtosecond laser (1), a Stokes light pulse optical path, a pump light pulse optical path, a spectrum analyzer (12), a focusing objective lens (15), a three-dimensional electronic control object stage (16), a collection objective lens (17), a short pass filter (18) and a signal detection and data processing system ( 19). The ultrashort pulse time overlapdegree measurement method in the CARS microscopic imaging system comprises the following steps: calculating the relative time delay, namely the same path delay between the residual pump light pulse and a light soliton used as the Stokes light; according to the interference spectrum oscillation intensity of the residual pump light pulse and the pump light pulse, determining the time delay of the adjustable space optical time delay line, namely the asynchronous time delay, required when the residual pump light pulse and the pump light pulse overlap; and estimating the time overlap degree of ultrashort pulses in the CARS microscopic imaging system when the adjustable space optical time delay line is adjusted according to the same path delay and the asynchronous time delay. According to the ultrashort pulse time overlap degree measurement device and method in the CARS microscopic imaging system, closed-loop feedback control of ultrashort pulse time overlap in the CARS microscopic imagingsystem is facilitated, and the measurement efficiency is improved.

Description

technical field [0001] The invention relates to the fields of nonlinear fiber optics, pulse time delay control and non-contact spectral microscopic imaging, in particular to a device and method for measuring ultrashort pulse time overlap in a CARS microscopic imaging system. Background technique [0002] Coherent Anti-Stokes Raman Scattering (CARS) microscopic imaging technology is a non-contact and label-free microscopic technology that utilizes the resonance energy level information of molecules in substances for imaging. The essence of CARS microscopic imaging technology is the four-wave mixing effect of pump light, probe light, and the resonance energy level of the sample to be tested, where the frequency difference between the pump light and the Stokes light is equal to the target chemical bond resonance energy of the sample to be tested When the pump light and the Stokes light are focused on the sample to be tested at the same time, and the three meet the phase matchin...

AI Technical Summary

Problems solved by technology

In CARS microscopic imaging technology, the time overlap between the pump light pulse and the Stokes light pulse is crucial, and an optical delay line or a stepping motor stage is usually used to achieve the time overlap between the two, but Since the time width of the pump light pulse and the Stokes light pulse is very narrow, only a few hundred femtoseconds to several picoseconds, the time of the pump light pulse and the Stokes light pulse is directly detected by a photodetector and an oscilloscope Overlap is very difficult

At the same time, due to the wavelength dependence of the propagation delay in the CARS microscopic imaging system based on the soliton self-frequency shift effect, when measuring the complete Raman resonance line of the sample to be tested, it is necessary to use the pump light pulse and the Stokes The frequency difference of the optical pulse constantly adjusts the relative delay between the two to ensure the overlap between them. Therefore, the time overlap between the pump optical pulse and the Stokes optical pulse has the disadvantages of difficult tuning and long adjustment time.

[0004] However, there are few literatures discussing the time overlap of ultrashort pulses in the CARS microscopic imaging system. The existing optical delay line tuning is still a large-scale scanning and is used as the pump light pulse and Stokes light according to whether the CARS signal appears. Basis for Pulse Time Overlap

Therefore, the existing delay adjustment method is not conducive to the closed-loop feedback control of pulse time overlap in the CARS microscopic imaging system and the automatic measurement of the system, which reduces its use value in practical applications.

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