Metal nanoparticles fabricated from chemical methods exhibit various excellent properties with their unique physicochemical properties and structures. To address the problems of the complicated manufacturing process and the side products generation, laser ablation in aqueous environment is proposed as a facile and environment friendly method to fabricate nanoparticles, producing very limited impurities. Ag, TiO2 and Ag/TiO2 composite nanoparticles are fabricated under the irradiation of pulsed laser with surfactant dodecyl trimethyl ammonium bromide (DTAB) as the stabilizer. Assembly shape of surfactants could be tuned by controllable concentrations, resulting in different nanostructures of nanoparticles. The laser processing parameters and the stabilizer showed collaborative effect on the morphology design of metal colloid nanoparticles. SEM images showed different morphologies of Ag nanoparticles and evenly distributed TiO2 nanoparticles are obtained. Typical silver crystals and rutile titanium dioxide crystals was characterized by XRD patterns. The UV-visible spectrum reflected the effects of Ag nanoparticles synthesized under different concentrations of DTAB on the absorption wavelengths of silver and titanium dioxide composites.
It is difficult to process quartz to get a large aperture ratio micropore(Φ127μm) by the mechanical tools, but it is possible processed by MEMS technology. The fluorine etching technology is used in experiments. The etching rate of quartz is proportional to the concentration of the HF acid. The etching rate of the mixtures of different proportions of the HF acid (49%) and the NH4F solution (35%) can be acquired, and the etching rate is lower if NH4F solution (35%) replace by the saturated NH4F solution. The experimental results conform to the chemical equation of Judge J S. In the experiment of the micropore etch, the wafers are respectively put in the mixtures of 1:1 and 3:2 ratio of the hydrofluoric acid (49%) and the ammonium fluoride solution (40%), and the morphology of micropore can be observed by the scanning electron microscopy and the confocal microscopy, and then the deepest depth of the micropore is tested by the confocal microscopy, the relationship between etching rate and the proportional of mixed solution can be got.
Photoacoustic imaging is attracting increasing interests in biomedical imaging. The comparing between the traditional
piezoelectric detections and optical detections is described. Three kinds of all-optical detection photoacoustic imaging
systems, including system based on optical reflectance at a glass-liquid interface, system based on FP polymer film and
the system based on POISe, are introduced and compared in this paper. Because these methods are difficult to realize
measuring the photoacoustic signal on a 2D plane with the backward detection mode, a new kind of photoacoustic
imaging system based on Electronic Speckle Pattern Interferometry (ESPI) is proposed. An ESPI outside displacement
measurement system is adopted to detect the surface displacement of sample. Since the exposure time of a standard CCD
which is of the order of tens of milliseconds, the temporal resolution to sample an acoustic field at MHz frequencies is
achieved by interrogating the sensor with a short laser pulse whose bandwidth is about 20ns. After measuring and
disposing the displacement data of the sample at a series detecting time, the photoacoustic image will be reconstructed
by a delay and sum beam-forming algorithm or by a reconstruction algorithm based on the decomposition. In principle,
the system will realize noncontact and backward-mode inspection and smaller element sizes of the receiver in the
photoacoustic imaging application.
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