laser produced plasma; spatial confinement; laser induced breakdown spectroscopy;PLASMA FORMATION; CENTRAL SCHEMES; ABLATION; PARTICLES; PULSES; LIBS

The spatial confinement of plasma produced by a nanosecond laser is investigated using time resolved spectroscopy, fast imaging, interferometry, and numerical computation. The dynamics of the plasma, depending on shock waves, laser power, and wall distances, are studied. Experimental results confirm that the plasma is constricted by the reflected shock associated with a temperature and density gradient. The peak laser power determines the initial plasma parameters which affect the spectral intensities and the velocity of the reflective shock waves. The wall distance determines the reflection time of the shocks, which in turn influences the time delay of the collision between the two reflective shocks. The numerical results reveal a fast propagation process surrounding the reflective shocks, which indicates that the velocity of the reflective shock wave is influenced by the density of the plasma. The maximum enhancement factor similar to 5.2 is realized at a delay time of 11.7 mu s under a pulse laser energy of 180 mJ and a wall distance of 9 mm.

Laser-induced breakdown spectroscopy; tissue ablation; soft tissue; classification; principal component analysis; k nearest neighbors; confusion matrix; pork;BIOMEDICAL APPLICATIONS

Classification of pork soft tissues, including skin, fat, loin, tenderloin and ham muscles, was achieved using combination of laser-induced breakdownspectroscopy, principal component analysis and k nearest neighbors classification.

LIBS instrument design; Liquid steel analysis; On-line process monitoring; Vacuum alloys production; Laser-induced breakdownspectroscopy;LIBS; STEEL

Laser-induced breakdown spectroscopy (LIBS) utilizing an echelle spectrograph-ICCD system is employed for online analysis of elements concentration in a vacuum induction melting workshop. Active temperature stabilization of echelle spectrometer is implemented specially for industrial environment applications. The measurement precision is further improved by monitoring laser parameters, such as pulse energy, spatial and temporal profiles, in real time, and post-selecting laser pulses with specific pulse energies. Experimental results show that major components of nickel-based alloys are stable, and can be well detected. By using internal standard method, calibration curves for chromium and aluminum are obtained for quantitative determination, with determination coefficient (relative standard deviation) to be 0.9559 (<22%) and 0.9723 (<2.8%), respectively. (C) 2017 Elsevier B.V. All rights reserved.

IN-SITU; LIBS; STEELS; CLASSIFICATION; EXPLORATION; ELEMENTS; SPECTRA; SAMPLES; SOIL; MN

Stand-off laser-induced breakdown spectroscopy (ST-LIBS) has attracted increasing attention as a valuable method for the remote analysis of materials. In this work, a multi-collector (MC) system combining low cost small lenses imitating the structure and shape of an artificial optical compound eye (AOCE) is presented to enhance the spectral intensity of ST-LIBS. The volume of the MC system is one eighteenth smaller than that of a telescope system and the number of collectors can be flexibly changed according to the requirements. The mechanisms of spectral enhancement are also discussed. In order to illustrate the performance of the MC system, the spectral intensities and the limits of detection (LoDs) of Mn and Cr elements acquired by the telescope system and the MC system were compared at a distance of 2 meters. The results showed that the spectral intensity acquired from the MC system was enhanced by 2.2 times, and the LoDs of Mn and Cr were decreased to 294 mu g g(-1) and 49 mu g g(-1). These results indicate that the MC system has great potential in providing a portable, flexible and effective collection method for remote detection.

Biosignature suites; Caves; Mars; Life detection;INDUCED BREAKDOWN SPECTROSCOPY; PHOENIX LANDING SITE; GALE CRATER; MULTIVARIATE-ANALYSIS; CALCIUM-CARBONATE; LIFE DETECTION; MARS; SUBSURFACE; PRECIPITATION; ASTROBIOLOGY

The search for life and habitable environments on other Solar System bodies is a major motivator for planetary exploration. Due to the difficulty and significance of detecting extant or extinct extraterrestrial life in situ, several independent measurements from multiple instrument techniques will bolster the community's confidence in making any such claim. We demonstrate the detection of subsurface biosignatures using a suite of instrument techniques including IR reflectance spectroscopy, laser-induced breakdown spectroscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy. We focus our measurements on subterranean calcium carbonate field samples, whose biosignatures are analogous to those that might be expected on some high-interest astrobiology targets. In this work, we discuss the feasibility and advantages of using each of the aforementioned instrument techniques for the in situ search for biosignatures and present results on the autonomous characterization of biosignatures using multivariate statistical analysis techniques.

Acoustic Radiation Force Elasticity Microscope(ARFEM); Laser induced breakdown spectroscopy (LIBS); Ultrasonic transducer; Femtosecond laser; Corneal elasticity;STRENGTH

The unique spatial distribution of corneal elasticity is shown by the nonhomogeneous structure of the cornea. It is critical to understanding how biomechanics control corneal stability and refraction and one way to do this job is non-invasive measurement of this distribution. Femtosecond laser pulses have the ability to induce optical breakdown and produced cavitation in the anterior and posterior cornea. A confocal ultrasonic transducer applied 6.5 ms acoustic radiation force-chirp bursts to the bubble at 1.5 MHz while monitoring bubble position using pulse-echoes at 20 MHz. The laser induced breakdown spectroscopy(LIBS) were measured in the anterior and posterior cornea with the plasmas that induced by the same femtosecond laser to see whether the laser inducedplasmas signals will show relationship to Young's modulus.

laser induced breakdown spectroscopy (LIBS); Acoustic Radiation Force Elasticity Microscope(ARFEM); ultrasonic transducer; Femtosecond laser; corneal elasticity;STRENGTH

The nonhomogeneous structure of the cornea suggests a unique spatial distribution of corneal elasticity. Non-invasive measurement of this distribution is critical to understanding how biomechanics control corneal stability and refraction. Femtosecond laser pulses induced optical breakdown and produced cavitation in the anterior and posterior cornea. A confocal ultrasonic transducer applied 6.5 ms acoustic radiation force-chirp bursts to the bubble at 1.5 MHz while monitoring bubble position using pulse-echoes at 20 MHz. The laser induced breakdown spectroscopy (LIBS) were measured in the anterior and posterior cornea to see whether the laser induced plasmas signals will show relationship to Young's modulus.