Nanosecond resolution photography system for laser-induced cavitation based on PIV dual-head laser and industrial camera

The detailed study of the initial and collapse processes of the laser-induced cavitation requires nanosecond resolution (both nanoseconds exposure and nanoseconds interframe time) of the photography measurement system. The high-speed video cameras are difficult to achieve nanoseconds interval time. The framing and streak cameras are able to reach the nanosecond resolution, but their complex technology and expensive prices make them far from being commercially available. The present study builds a nanosecond resolution photography system based on PIV dual-head laser and conventional industrial camera. The exposure time of the photography system is controlled by the laser pulse width, which is 5 ns. The two heads of the PIV laser are operated independently thus the smallest time interval between two laser pulses can be set to less than 10 ns. A double-pulse per-exposure imaging technique is used to record the information from two laser pulses on single frame on a low-speed industrial camera. The nanosecond resolution photography system was applied to the laser-induced cavitation experiments to verify the reliability of the measurement results. The measurement of the shock wave velocity demonstrates the ability of the system to capture ultrafast phenomena, which reduces from 3611 m/s to approximately 1483 m/s within 400 ns. The experimental results also reveal the asymmetric evolution of laser-induced cavitation bubbles. The major axis of the ellipsoidal bubble has twice reversals along the laser propagation and perpendicular direction from the laser-induced breakdown to the first collapse.     

聚能射流高速光学测试技术

本文介绍了用正文同步扫描测量技术对聚能射流的动态参数进行测试,拍摄到非常清晰的射流头部在空气中飞行所产生的空气冲击波。运用计算机图象处理技术对拍摄的底片进行处理以后,获得了较为理想的射流图象。对底片进行测量,获得了射流在X平面内和Y平面内的离轴偏差,以及射流在X、Y平面内的飞行姿态,射流的累积长度作为速度的函数,射流的速度分布,射流的质量分布和动能分布,射流的断裂时间和断裂位置。     

Some aspects of colloids in photography

The principles of colloid and interface science underlie the successful formulation and manufacture of photographic products. The colour-forming components are usually delivered in colloidal form. Rapid and stable manufacture depends on the dynamic surface properties and the rheology of the coated fluids.     

Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD).     

Nanoparticles and Nanotechnology in Silver Halide Imaging

Abstract

The future prospect of silver halide imaging materials was outlined and proceeded to the elucidation of the nanoparticles and nanotechnology, which would contribute to it. They include silver halide grains, J‐aggregates of sensitizing dyes, dispersions of dyes and couplers, silver nanoparticles and nanowires. A focus is placed on the combination of silver clusters and nanoparticles with silver halide grains, which makes greatest contribution to high performance of silver halide imaging materials.     

Digital photography

Digital photography was discovered by Sony in 1981. The technology struggled for many years, mainly because the electronics of the day were inadequate. Nowadays, digital photography is the mainstream photographic technology, having overtaken the mature silver halide technology. This paper describes the chemistry and technology of silver halide and digital photography. Particular emphasis is given to producing high-quality images by ink jet printing, the technology of choice to produce photographic prints from digital cameras.     

Micro- and macro deformation measurement by extension of correlation technique

In this work, we present the implementation of Electronic Speckle Pattern Interferometry (ESPI), Digital Speckle Photography (DSP) and Digital Image Correlation (DIC) as complementary techniques to measure in-plane micro and macro displacement. The main advantage of ESPI is its great sensitivity to small displacements (smaller than the size of the speckle). However, the contrast of fringes in this technique is severely affected by de-correlation effects when the in-plane displacement exceeds the size of the speckle. To eliminate the de-correlation effects, we use the DSP technique. It is possible to generate artificial speckles, usually bigger than those generated by means of illumination of the sample with laser light. By combining DSP and DIC the displacement field can be obtained when the ESPI method cannot be applied due to image de-correlation. The experimental results show that the combination of these techniques is useful to analyze deformations over a wider range.     

A general strategy to quantify analytes through fluorescence chromaticity and luminosity

To realize a fast, easy-operation and precise way using fluorescence probes to quantify analytes is a goal to facilitate detection, especially in situ. Herein, we are reporting an approach which can be generally employed for the differentiation and quantitation of analytes through fluorescence chromaticity and luminosity. Seven representative fluorescent probes, targeting pH, cysteine, hydrogen sulfide, hydrogen peroxide, palladium and hydrazine, were synthesized and tested. Without utilizing costly instrumentations, portable devices were employed to collect data of photographs from the fluorescence samples in responses to different analytes. Subsequently, the photographic images were digitally processed to generate calibration curves between chromaticity/luminosity verse concentrations after mapping to the CIE 1931 xyY standard color space. Good linear calibration curves and quantitative analysis of unknown samples with low errors through the spectral technology demonstrated the reliability of this method. Thus, we showed the analytical method with a simple and on-site constructible/portable device which is promising for applications in more fluorescence probes.     

测量温度场分布的激光散斑照相计量术

本文讨论了激光散斑照相术在测量密度(或温度)扬中的应用。提出了激光散斑——纹影干涉仪的光学系统,可在同一瞬时得到一张散斑图和一张差分干涉图。对沿竖直加热平板自然对流的温度边界层进行了定量地测量。从散斑图和从干涉图中获得的实验结果符合极好。为了说明本方法的应用范围,对一个非稳定的波动甚大的本申灯火焰进行了测量。实验结果表示,激光散斑照相术更适于研究湍流场,因为干涉术在这种情况下已失去其定量计量的作用。     

Controlled Chemical and Drug Delivery via the Internal and External Surfaces of Layered Compounds

Abstract

We demonstrate, and review the very small, but growing body of literature regarding a recently discovered application of layered compounds, which involves the ability of layered materials to sequester and later release molecules of chemical and biological significance. The application relies upon intercalation chemistry; a reversible process whereby atoms, molecules, macromolecules, and polymers may be inserted into the interstices of a layered matrix. We demonstrate that layered materials are able to effectively getter water‐soluble atoms and molecules from aqueous dispersions, and further demonstrate that the absorbed molecules can be later released from the interlayer region to perform a desired chemical function. Work in our laboratory involving the application of layered hybrid materials in photographic media is described in detail and we establish two general release mechanisms whereby intercalated functional chemistry can be first sequestrated and later delivered via a chemical switch to perform a desired function. The process has enormous potential as a general method for the controlled, temporal release of materials of chemical and biological significance.