Explore the vast range of titles available.

Detection and analysis of volatile compounds in exhaled breath represents an attractive tool for monitoring the metabolic status of a patient and disease diagnosis, since it is non-invasive and fast. Numerous studies have already demonstrated the benefit of breath analysis in clinical settings/applications and encouraged multidisciplinary research to reveal new insights regarding the origins, pathways, and pathophysiological roles of breath components. Many breath analysis methods are currently available to help explore these directions, ranging from mass spectrometry to laser-based spectroscopy and sensor arrays. This review presents an update of the current status of optical methods, using near and mid-infrared sources, for clinical breath gas analysis over the last decade and describes recent technological developments and their applications. The review includes: tunable diode laser absorption spectroscopy, cavity ring-down spectroscopy, integrated cavity output spectroscopy, cavity-enhanced absorption spectroscopy, photoacoustic spectroscopy, quartz-enhanced photoacoustic spectroscopy, and optical frequency comb spectroscopy. A SWOT analysis (strengths, weaknesses, opportunities, and threats) is presented that describes the laser-based techniques within the clinical framework of breath research and their appealing features for clinical use.

The central 0.1 parsecs of the Milky Way host a supermassive black hole identified with the position of the radio and infrared source Sagittarius A* (refs. 1 , 2 ), a cluster of young, massive stars (the S stars 3 ) and various gaseous features 4 , 5 . Recently, two unusual objects have been found to be closely orbiting Sagittarius A*: the so-called G sources, G1 and G2. These objects are unresolved (having a size of the order of 100 astronomical units, except at periapse, where the tidal interaction with the black hole stretches them along the orbit) and they show both thermal dust emission and line emission from ionized gas 6 – 10 . G1 and G2 have generated attention because they appear to be tidally interacting with the supermassive Galactic black hole, possibly enhancing its accretion activity. No broad consensus has yet been reached concerning their nature: the G objects show the characteristics of gas and dust clouds but display the dynamical properties of stellar-mass objects. Here we report observations of four additional G objects, all lying within 0.04 parsecs of the black hole and forming a class that is probably unique to this environment. The widely varying orbits derived for the six G objects demonstrate that they were commonly but separately formed. The Galactic Centre is orbited by two objects that look like gas and dust clouds but behave more like stars, and now four additional similar objects are reported.

Multispectral camouflage, especially for the infrared-microwave range, is an essential technology for the safety of facilities, vehicles, and humans. So far, it has been realized mainly by high infrared specular reflection and high microwave absorption. However, external infrared sources can expose the target through specular reflection; also, the heat production from microwave absorption can increase the infrared radiation. This work proposes a multispectral camouflage scheme based on hierarchical visible-infrared-microwave scattering surfaces to address these issues. The proposed device exhibits: (1) low infrared emissivity (  = 0.17) and low infrared specular reflectivity (  = 0.13), maintaining low infrared radiation and capability to overcome the presence of an external infrared source simultaneously; (2) high scattering in microwave range, with −10 dB radar cross section reduction bandwidth of 8–13 GHz, simultaneously achieving microwave camouflage and reducing the heat production; (3) tunability of color for visible camouflage. This work proposes a method to control scattering over visible-infrared-microwave bands, thereby introducing a new design paradigm for modern camouflage technology.

Availability of relativistically intense, single-cycle, tunable infrared sources will open up new areas of relativistic nonlinear optics of plasmas, impulse IR spectroscopy and pump-probe experiments in the molecular fingerprint region. However, generation of such pulses is still a challenge by current methods. Recently, it has been proposed that time dependent refractive index associated with laser-produced nonlinear wakes in a suitably designed plasma density structure rapidly frequency down-converts photons. The longest wavelength photons slip backwards relative to the evolving laser pulse to form a single-cycle pulse within the nearly evacuated wake cavity. This process is called photon deceleration. Here, we demonstrate this scheme for generating high-power (~100 GW), near single-cycle, wavelength tunable (3–20 µm), infrared pulses using an 810 nm drive laser by tuning the density profile of the plasma. We also demonstrate that these pulses can be used to in-situ probe the transient and nonlinear wakes themselves. Plasma can act as strong nonlinear refractive index medium that can be exploited to downshift the frequency of a laser pulse. Here, the authors show the generation of single-cycle tunable infrared pulses using strong density gradients associated with laser-produced wakes in plasmas.

The torus of dust surrounding a quasar — a very luminous supermassive black hole that accretes matter from its surroundings — has now been captured with high-resolution infrared imaging. Images of an active galactic nucleus.

Mid-Infrared imaging is vital for the study of a wide variety of astronomical phenomena, including evolved stars, exoplanets, and dust enshrouded processes such as star formation in galaxies. However, infrared detectors have traditionally been expensive and it is difficult to achieve the sensitivity needed to see beyond the overwhelming mid-infrared background. Here we describe the upgrade and commissioning of a simple prototype, low-cost 10 μ m imaging instrument. The system was built using commercially available components including an uncooled microbolometer focal plane array and chopping system. The system was deployed for a week on the 1.52 m Carlos Sanchez Telescope and used to observe several very bright mid-infrared sources with catalogue fluxes down to ∼600 Jy. We report a sensitivity improvement of ∼4 mag over our previous unchopped observations, in line with our earlier predictions.

Because the galloping of iced conductors is one of the main disasters in the State Grid, resulting in huge economic and property losses every year, the research on relevant monitoring methods is of great significance. The existing galloping monitoring technology is mainly based on the contact detection method, which presents potential electrical hazards and power supply problems. In this paper, a conductor galloping monitoring method based on the target detection of infrared sources is put forward to overcome the shortcomings of existing methods. In other words, an infrared source label is installed on the conductor spacer, high-definition night vision infrared cameras are installed on electric power towers to take video of the infrared source labels, and the characteristic amplitude of conductor galloping is calculated by an image recognition and tracking algorithm. The practical application results indicate that the method has the advantages of non-contact detection, safety and reliability, and high detection accuracy.

Microscale infrared thermal emitters are highly demanded in a variety of applications such as micro-molecular thermal sensing and micro-thermal imaging. In this paper, we propose a micro-meta-cavity array through combining nanohole metasurfaces and Fabry–Pérot (FP) cavity. Based on this design, integrated multiband micro-thermal emitters covering 7 − 9 μm and 10 − 14 μm wavelength ranges with high spatial resolution near wavelength scale has been theoretically and experimentally demonstrated simultaneously, providing the possibility for microscale infrared sources. In addition, narrow thermal emission bandwidth is enabled by the interaction between the resonant modes of metasurface and the FP cavity mode in meta-cavity. The emission features of each meta-cavity are investigated and analyzed through thermal imaging. Furthermore, polarization, wavelength and spatial multiplexing thermal emission with high spatial resolution is also experimentally demonstrated utilizing nanohole patterns. We anticipate that this thermal emission microchip can be possibly employed in micro-molecular sensing and micro-thermal imaging in the future.

A narrow-band survey of star-formation regions is under way with the 1-m Schmidt telescope at the Byurakan Observatory (the Byurakan Narrow Band Imaging Survey, BNBIS). One of the goals of the survey is a search for Herbig-Haro (HH) type outflows in the neighborhoods of bright infrared sources in dark clouds. One of the first discoveries in this program was an extended bipolar outflow from the optically invisible IRAS 06212-1049 source associated with a previously unknown biconical reflecting nebula. This bipolar outflow (HH 1216) consist of several optically bright HH-knots and a small emission jet along the axis of the nebula. The overall length of the observable part of the HH 1216 outflow is estimated at about 1 pc and its distance at ~950 pc. The bolometric luminosity of the source IRAS 06212-1049 is at least 13 L⨀. Yet another HH-knot, HH 1217, has been observed near the source IRAS 06216-1044 with a luminosity of at least 13 L⨀ and located in the same dark cloud. Yet another isolated emission object has been found in this region; it is probably a distant planetary nebula.

Reconfigurable freeform optical systems greatly enhance imaging performance within non-symmetric, compact, and ergonomic form factors. In this paper, several advances improve design, testing, and monitoring of these systems. Specific enhancements include definition of polynomials for fast and efficient parameterizations of vector distributions in non-circular apertures and merit based function optimization. Deflectometry system improvements enable metrology for almost any conceivable optic shape and guide deterministic optical figuring process during the coarse grinding phase by including modulated infrared sources. As a demonstration of these improvements, parametric optimization is tested with the tomographic ionized-carbon mapping experiment, a reconfigurable optical system. Other case studies and demonstrations include metrology of a fast, f/1.26 convex optic, an Alvarez lens, and real-time monitoring of an array of independently-steerable hexagonal mirror segments as well as an induction formed surface and inflatable Mylar mirror.