Aberration-free Harmonic Microscopic Measurement Method Based on Long-distance Focusing

Abstract

The aberration-eliminating harmonic microscopic measurement method based on long-distance focusing belongs to the field of nonlinear optical microscopic imaging; in the harmonic signal detection module, a reference mirror is introduced to reverse the optical path, and the focusing objective lens can be used repeatedly to compensate for imaging Systematic aberrations in the process. By moving the reference mirror axially, refocusing of harmonic signals is achieved. The pulse emitted by the femtosecond laser is shaped and reflected by the scanning galvanometer. After passing through the optical system, it is converged by the microscope objective lens inside the sample to form the excitation spot required for harmonic signal generation. The harmonic signal excited by the sample is collected by the detection objective lens, passes through the transfer system, and is focused on the reference mirror surface by the transfer objective lens. The reflected light returns symmetrically, passes through the relay objective lens again, is reflected by the beam splitter, passes through the narrow-band filter, and finally is detected by the photomultiplier tube. This method effectively compensates for system aberrations, and can realize large-scale and fast axial scanning of harmonic microscopic imaging, and the sample remains stationary without being disturbed by focusing.

Description

technical field [0001] The invention belongs to the field of optical microscopic measurement, and mainly relates to an ultra-precise non-contact measurement method for measuring three-dimensional fine structures in nano devices and biological samples. Background technique [0002] By using the nonlinear optical effects of the sample itself, such as second harmonic generation and third harmonic generation, microscopic imaging of biological samples without fluorescent labels, microstructure detection of nano-devices, and diagnosis of disease mechanisms can be performed. But in most harmonic microscopy imaging systems, focusing to different depths of the sample is achieved by the relative mechanical displacement of the sample and objective lens. Disadvantages of this mode are the slow imaging speed and the potential disturbance of the imaged sample due to scanning movement during imaging. In addition, the system aberrations of this detection mode are relatively large. [0003...

AI Technical Summary

Problems solved by technology

Disadvantages of this mode are slow imaging speeds and possible disturbance of the imaged sample by scanning movement during imaging

In addition, the system aberrations of this detection mode are relatively large

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