A high-precision multi-dimensional microspectroscopic technique for morphological and properties analysis of cancer cell

Femtosecond Laser-Induced Phase Transformation on Single-Crystal 6H-SiC

Silicon carbide (SiC) is widely used in many research fields because of its excellent properties. The femtosecond laser has been proven to be an effective method for achieving high-quality and high-efficiency SiC micromachining. In this article, the ablation mechanism irradiated on different surfaces of 6H-SiC by a single pulse under different energies was investigated. The changes in material elements and the geometric spatial distribution of the ablation pit were analyzed using micro-Raman spectroscopy, Energy Dispersive Spectrum (EDS), and an optical microscope, respectively. Moreover, the thresholds for structural transformation and modification zones of 6H-SiC on different surfaces were calculated based on the diameter of the ablation pits created by a femtosecond laser at different single-pulse energies. Experimental results show that the transformation thresholds of the Si surface and the C surface are 5.60 J/cm2 and 6.40 J/cm2, corresponding to the modification thresholds of 2.26 J/cm2 and 2.42 J/cm2, respectively. The Raman and EDS results reveal that there are no phase transformations or material changes on different surfaces of 6H-SiC at low energy, however, decomposition and oxidation occur and then accumulate into dense new phase material under high-energy laser irradiation. We found that the distribution of structural phase transformation is uneven from the center of the spot to the edge. The content of this research reveals the internal evolution mechanism of high-quality laser processing of hard material 6H-SiC. We expect that this research will contribute to the further development of SiC-based MEMS devices.

Auto-focusing femtosecond laser manufacturing system via acoustic emission technology

Auto-focusing technology in ultrafast laser processing, especially for non-planar structures, holds paramount importance. The existing methodologies predominantly rely on optical mechanisms, thereby being limited by the original system and material reflectivity. This work proposes an approach that utilizes laser-induced sound as a feedback signal for system control, thereby circumventing the need for optical system adjustments and facilitating almost real-time tracking. We established an ultrafast laser processing system augmented by acoustic emission technology, allowing for focus tracking on inclined planes. This system also exhibits the capability to generate diverse microscopic morphologies, including grooves and differently oriented laser-induced periodic surface structures (LIPSS), through the manipulation of the acoustic signal threshold. This method can be easily integrated into existing laser processing systems, offering new capabilities for curved surface processing, microstructure manufacturing, and transparent material processing.

Measurement of thickness and refractive index of transparent material synchronously based on chromatic confocal sensor

A defined refractive index is essential to measure the thickness of transparent materials with a chromatic confocal sensor (CCS). To overcome this limitation, a new measuring model is proposed by configuring a motor to drive the CCS for movement and placing a reflector behind the sample. This innovative approach enables the measurement of thickness and refractive index of transparent material synchronously through geometric calculations based on peak signals from different surfaces. Experimental results show that the model can achieve an average thickness measurement deviation of ±0.4µm and an average refractive index measurement deviation of ±0.005, making it highly suitable for industrial applications in thin film manufacturing sectors such as new energy vehicles, flexible displays, biomedicine, and more.

MEMS-based portable confocal Raman spectroscopy rapid imaging system

Aiming at the miniaturization and rapid imaging requirements of a portable confocal Raman system, a MEMS-based portable confocal Raman spectroscopy rapid imaging method is proposed in this study. This method combines the dual 2D MEMS mirror scanning method and the grid-by-grid scanning method. The dual 2D MEMS mirror scanning method is used for the miniaturization design of the system, and the grid-by-grid scanning method is used for rapid imaging of Raman spectroscopy. Finally, the rapid imaging and miniaturization design of a portable confocal Raman spectroscopy system are realized. Based on this method, a portable confocal Raman spectroscopy rapid imaging system with an optical probe size of just 98m m×70m m×40m m is constructed. The experimental results show that the imaging speed of the system is 45 times higher than that of the traditional point-scan confocal Raman system, and the imaging speed can be further improved according to the requirements. In addition, the system is used to swiftly identify agate ore, and the material composition distribution image over a 126µm 2×126µm 2 region is obtained in just 16 min. This method provides a new solution for the rapid imaging and miniaturization design of the confocal Raman system, as well as a new technical means for rapid detection in deep space exploration, geological exploration, and field detection.