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This work describes the phase equilibrium measurements of acoustically levitated binary mixtures with concentration measurements using Raman spectroscopy without sample extraction of the autoclave. The levitator design is implemented in a Single-Droplet Optical Cell for levitation processes under varying atmospheres. The advantages of acoustic levitation of small droplets under increased temperatures and pressure combined with spectroscopic applications like Raman spectroscopy enable novel experiments possibly relevant to the fields of chemical engineering. To the author's knowledge, this is the first use of Raman spectroscopy for phase equilibria investigations on acoustically levitated droplets under high pressure and temperature. The results show very good agreements with literature data. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Over the last decade many papers dedicated to the generation of nanoparticles in liquids using laser ablation have been published. They have shown that the nanoparticles size distribution is dependent of the laser fluence and shifts towards smaller sizes when the surfactant concentration is increased. In this paper an alternative approach is presented that permits the control of the size distribution of gold nanoparticles during laser ablation in aqueous solutions containing different surfactant molecules with different shapes and size [ABSTRACT FROM AUTHOR]

We present a novel laser microfabrication method to generate structures on the basis of a new class of functional photosensitive composites. In particular, the focus lies on the development of conductive composites by incorporating SWNTs into the matrix of polymers thus forming highly conductive nanocomposites. Conductive microstructures have been produced with the ultra-high resolution technology based on laser direct writing (e.g. single-, two-photon polymerization) using polymer/SWNTs nanocomposites. This technology opens new prospects for the realization of novel MEMS and MOEMS with increased functionality, integration, and higher level of miniaturization. [ABSTRACT FROM AUTHOR]

Laser selective micro patterning of thin film of Poly (3,4-ethylenedioxythiophene):Poly (styrene sulfonate) (PEDOT:PSS) blend is investigated. Picosecond pulsed laser with 355 nm and 1064 nm wavelengths are used to study the ablation behavior of PEDOT:PSS thin film coated on glass. We present and discuss ablation thresholds for different film thicknesses as well as ablation lines with different overlapping rates. The results observed by SEM and white-light interference microscopy reveal that PEDOT:PSS film on glass substrates can be selectively patterned by optimized laser parameters. [ABSTRACT FROM AUTHOR]

The authors recorded the elastic light-scattering pattern of pollen over a large spatial angle range to investigate the potential light scattering for pollen identification. The scattering from elm, hazel, birch, chestnut, willow, sunflower, ragweed and pine was measured. The scattering patterns show distinct differences that can be used for the classification of pollen with simple algorithms. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A correction to the article "Comparison of in Situ and ex Situ Methods for Synthesis of Two-Photon Polymerization Polymer Nanocomposites" by Guo, Q. et al. that was published in the 2014 issue is presented

We demonstrate and discuss the integration of Bragg gratings in aerosol-jetted polymer optical waveguides, produced in the optical assembly and connection technology for component-integrated bus systems (OPTAVER) process. By using a femtosecond laser and adaptive beam shaping, an elliptical focal voxel generates different types of single pulse modification by nonlinear absorption in the waveguide material, which are arranged periodically to form Bragg gratings. Integration of a single grating structure or, alternatively, an array of Bragg grating structures in the multimode waveguide yields a pronounced reflection signal with typical multimodal properties, i.e., a number of reflection peaks with non-Gaussian shapes. However, the main wavelength of reflection, located around 1555 nm, is evaluable by means of an appropriate smoothing algorithm. When loaded by mechanical bending, a pronounced Bragg wavelength shift of this reflected peak up to 160 pm is detected. This demonstrates that the additively manufactured waveguides can be used not only for signal transmission but also as a sensor.

We report on the fabrication of rectangular microchannels with vertical sidewalls in fused silica by laser backside ablation. A 515 nm femtosecond laser is focused by an objective with a NA of 0.5 through the sample on the glass/air interface, allowing processing from the backside into the bulk material. Experimental investigations reveal a logarithmically increasing depth of the channels with an increasing number of scans, while keeping the focal position fixed. A certain number of scans has to be applied to generate rectangular shaped channels while their depth can be controlled by the applied fluence from 2.64 µm to 13.46 µm and a corresponding ablation roughness R a between 0.20 µm and 0.33 µm. The channel width can be set directly via the number of parallel ablated lines demonstrated in a range from 10 µm to 50 µm. By adjusting the focal position after each scan the channel depth can be extended to 49.77 µm while maintaining a rectangular channel geometry. Finally, concentric rings are ablated to demonstrate the flexibility of the direct writing process.

We report on the fabrication of an axicon by applying a two-step manufacturing process including a 1030 nm femtosecond and a 10.6 µm CO 2 laser. First, the pre-defined axicon geometry is generated by high-precision femtosecond layer-by-layer ablation. In order to meet high surface quality requirements, inevitable stipulated for optical use, the surface of the thus structured axicon is smoothened by a subsequent CO 2 laser polishing process. The finalized axicon fulfills optical quality as the surface roughness Ra is significantly reduced from 0.56 µm to 34 nm. For the evaluation of the optical quality, the axicon is placed in a measurement setup including the femtosecond laser. Comparison between the calculated Bessel beam for an ideal axicon and the quasi-Bessel beam generated and measured by the fabricated axicon reveals excellent agreement, verifying our precise manufacturing method.