Ultrasound Signal Detection with Multi-bounce Laser Microphone.

The multi-bounce laser microphone utilizes optical methods to detect the displacement of a gold-covered thin film diaphragm caused by ultrasound signal pressure waves. This sensitive all-optical sensing technique provides new opportunities for advanced ultrasound imaging as it is expected to achieve a higher detection signal-to-noise ratio (SNR) in a broader spectrum, as compared to conventional ultrasonic transducers. The technique does not involve signal time-averaging and the real-time enhancement in detection SNR stems from the amplification of signal strength due to multiple bouncing off the diaphragm.

Comprehensive study of solid pharmaceutical tablets in visible, near infrared (NIR), and longwave infrared (LWIR) spectral regions using a rapid simultaneous ultraviolet/visible/NIR (UVN) + LWIR laser-induced breakdown spectroscopy linear arrays detection system and a fast acousto-optic tunable filter NIR spectrometer.

This is the first report of a simultaneous ultraviolet/visible/NIR and longwave infrared laser-induced breakdown spectroscopy (UVN + LWIR LIBS) measurement. In our attempt to study the feasibility of combining the newly developed rapid LWIR LIBS linear array detection system to existing rapid analytical techniques for a wide range of chemical analysis applications, two different solid pharmaceutical tablets, Tylenol arthritis pain and Bufferin, were studied using both a recently designed simultaneous UVN + LWIR LIBS detection system and a fast AOTF NIR (1200 to 2200 nm) spectrometer. Every simultaneous UVN + LWIR LIBS emission spectrum in this work was initiated by one single laser pulse-induced micro-plasma in the ambient air atmosphere.

Comparative studies of long-wave laser-induced breakdown spectroscopy emissions excited at 1.064 µm and eye-safe 1.574 µm.

In this work, comparative long-wave infrared (LWIR) laser-induced breakdown spectroscopy (LIBS) emission studies of two excitation sources: conventional 1.064 μm and eye-safe laser wavelength at 1.574 μm were performed to analyze several widely-used inorganic energetic materials such as ammonium and potassium compounds as well as the organic liquid chemical warfare agent simulant, dimethyl methylphosphate (DMMP).

Long-Wave Infrared (LWIR) Molecular Laser-Induced Breakdown Spectroscopy (LIBS) Emissions of Thin Solid Explosive Powder Films Deposited on Aluminum Substrates.

Thin solid films made of high nitro (NO)/nitrate (NO) content explosives were deposited on sand-blasted aluminum substrates and then studied using a mercury-cadmium-telluride (MCT) linear array detection system that is capable of rapidly capturing a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared region (LWIR; ∼5.6-10 µm). Despite the similarities of their chemical compositions and structures, thin films of three commonly used explosives (RDX, HMX, and PETN) studied in this work can be rapidly identified in the ambient air by their molecular LIBS emission signatures in the LWIR region.

Mid-infrared, long wave infrared (4-12 μm) molecular emission signatures from pharmaceuticals using laser-induced breakdown spectroscopy (LIBS).

In an effort to augment the atomic emission spectra of conventional laser-induced breakdown spectroscopy (LIBS) and to provide an increase in selectivity, mid-wave to long-wave infrared (IR), LIBS studies were performed on several organic pharmaceuticals. Laser-induced breakdown spectroscopy signature molecular emissions of target organic compounds are observed for the first time in the IR fingerprint spectral region between 4-12 μm. The IR emission spectra of select organic pharmaceuticals closely correlate with their respective standard Fourier transform infrared spectra.

Long-wave, infrared laser-induced breakdown (LIBS) spectroscopy emissions from energetic materials.

Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives sensing and has significant potential for real-time standoff detection and analysis. In this study, LIBS emissions were obtained in the mid-infrared (MIR) and long-wave infrared (LWIR) spectral regions for potential applications in explosive material sensing. The IR spectroscopy region revealed vibrational and rotational signatures of functional groups in molecules and fragments thereof.

Mid-infrared emission from laser-induced breakdown spectroscopy.

Laser-induced breakdown spectroscopy (LIBS) is a powerful analytical technique for detecting and identifying trace elemental contaminants by monitoring the visible atomic emission from small plasmas. However, mid-infrared (MIR), generally referring to the wavelength range between 2.5 to 25 microm, molecular vibrational and rotational emissions generated by a sample during a LIBS event has not been reported.