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51.
K. Zimmer R. Böhme B. Rauschenbach 《Applied Physics A: Materials Science & Processing》2007,86(3):409-414
Laser-induced backside etching of fused silica with gallium as highly absorbing liquid is demonstrated using pulsed infrared
laser radiation. The influences of the laser fluence, the pulse number, and the pulse length on the etch rate and the etched
surface topography were studied and the results are compared with these of excimer laser etching. The high reflectivity of
the fused silica-gallium interface at IR wavelengths results in the measured high threshold fluences for etching of about
3 J/cm2 and 7 J/cm2 for 18 ns and 73 ns pulses, respectively. For both pulse lengths the etch rate rises almost linearly with laser fluence and
reaches a value of 350 and 300 nm/pulse at a laser fluence of about 12 and 28 J/cm2, respectively. The etching process is almost free from incubation processes because etching with the first laser pulse and
a constant etch rate were observed. The etched surfaces are well-defined with clear edges and a Gaussian-curved, smooth bottom.
A roughness of about 1.5 nm rms was measured by AFM at an etch depth of 0.95 μm.
The normalization of the etch rates with respect to the reflectivity and the pulse length results in similar etch rates and
threshold fluence for the different pulse widths and wavelengths. It is concluded that etching is a thermal process including
the laser heating, the materials melting, and the materials etching by mechanical forces. The backside etching of fused silica
with IR-Nd:YAG laser can be a promising approach for the industrial usage of the backside etching of a wide range of materials.
PACS 81.65.C; 81.05.J; 79.20.D; 61.80.B; 42.55.L 相似文献
52.
E. Frster K. Goetz D. Zimmer P. Glas A. Goetsch R. Koch M. Naumann P. V. Nickles M. Schnürer I. Will 《Annalen der Physik》1987,499(1):61-73
This paper reports details on the design of the Nd: glass laser facility NIXE at the Central Institute of Optics and Spectroscopy, including the target chamber and the x-ray diagnostics, spatial and temporal behaviour of the 1.06 μm radiation generated are given. Plane, massive targets of aluminium and silicon have been irradiated with 6-nsec FWHM laser pulses. Investigations of laser produced Al- and Si-plasmas have been performed with spectral and spatial high resolution diagnostics, consisting of a 3 channel crystal-spectrometer, 2 crystal-microscopes, and 2 pinhole cameras and the results are presented. Line spectra have been interpreted within the hypothesis of a steady state coronal equilibrium. He-like lines of the Al-plasma indicate temperatures up to 400 eV and densities up to 2 · 1020 cm?3. Total x-ray photon flux in the He-like resonance line has been calculated giving 1013 phot/ster. 相似文献
53.
54.
James Mc Laughlin Peter Zimmer 《Journal of Mathematical Analysis and Applications》2008,345(2):670-677
We prove a new Bailey-type transformation relating WP-Bailey pairs. We then use this transformation to derive a number of new 3- and 4-term transformation formulae between basic hypergeometric series. 相似文献
55.
Robert J. Zimmer 《Mathematische Annalen》1990,287(1):697-701
Research partially supported by NSF Grant 相似文献
56.
Ultracold neutrons (UCNs) play an important role for precise measurements of the properties of the neutron and its interactions. During the past 25 years, a neutron turbine coupled to a liquid deuterium cold neutron source at a high-flux reactor has defined the state of the art for UCN production, despite a long history of efforts towards a new generation of UCN sources. This Letter reports a world-best UCN density available for users, achieved with a new source based on conversion of cold neutrons in superfluid helium. A conversion volume of 5 liters provides at least 274,000 UCN in a single accumulation run. Cyclically repeated operation of the source has been demonstrated, as well. 相似文献
57.
The configurational distribution of all the cobalt(III) complexes containing a 14-membered tetra-aza macrocyclic backbone in the Cambridge Structural Database was determined by cluster analysis, and the reason for some of the complexes adopting their configuration was established by molecular mechanics. 相似文献
58.
K. Zimmer R. Böhme D. Ruthe B. Rauschenbach 《Applied Physics A: Materials Science & Processing》2006,84(4):455-458
Laser-induced backside wet etching (LIBWE) that is regularly performed with hydrocarbon solutions is demonstrated with the liquid metal gallium as a new class of absorbers for the first time. Well-contoured square etch pits in fused silica with smooth bottoms and well-defined edges were achieved already with the first pulse from a 248 nm excimer laser. The etching is characterized by a threshold fluence of 1.3 J/cm2 and a straight proportional etch rate growth with the fluence up to 8.2 J/cm2. In addition, the etch depth increases linearly for onward pulsed laser irradiation and gives evidence for an only marginal incubation effect. The high fluences necessary for etching originate from the high reflection losses as well as the high thermal conductivity of the metallic absorber. The suggested etch mechanism comprises the heating of the fused silica up to or beyond the fused silica melting point by the laser heated gallium and the removing of the softened or molten fraction of the material by mechanical forces from shock waves, bubbles, high pressures, or stress fields. PACS 81.65.C; 81.05.J; 79.20.D; 61.80.B; 42.55.L 相似文献
59.
We present a detailed analysis of the recently demonstrated technique to generate quasi-stationary pulses of light [M. Bajcsy, A.S. Zibrov, M.D. Lukin, Nature (London) 426 (2003) 638] based on electromagnetically induced transparency. We show that the use of counter-propagating control fields to retrieve a light pulse, previously stored in a collective atomic Raman excitation, leads to quasi-stationary light field that undergoes a slow diffusive spread. The underlying physics of this process is identified as pulse matching of probe and control fields. We then show that spatially modulated control-field amplitudes allow us to coherently manipulate and compress the spatial shape of the stationary light pulse. These techniques can provide valuable tools for quantum nonlinear optics and quantum information processing. 相似文献
60.