Active and passive UV filters for solid-state lasers are developed on the basis of Ce-doped silica gel glass. It is concluded that there are two types of optical center. It is assumed that they represent Ce(III) oxygen complexes whose nearest surrounding includes quadruply- charged (the first type) and triply-charged (the second type) ions of cerium.
Monitoring of stratospherical ozone depletion by filter radiometers calls for narrowband filters with outstanding parameters. At filter wavelengths down to 300 nm narrow bandwidth, high peak transmittance together with high out- of-band blocking especially at longer wavelength are demanded. Furthermore, filters have to be completely free of wavelength shift caused by humidity. Conventional interference filters suffer from such shift because of the water sorption of the evaporated layers. By using plasma ion assisted deposition of zirconia and silica layers we succeeded in manufacturing blocked two-cavity filters with full width at half maximum of 1.7 nm and peak transmittance of 17 percent to NIR optical density is at least 6. There was no decrease in wavelength of such filters by changing relative humidity from 100 percent to 0 percent. Corresponding conventional filters shifted 4.5 nm under the same conditions. The filter performance achieved allows use for the development of sensitive and specific instrumentation for environmental, climate, and meteorological research.
The AXAF CCD imaging spectrometer (ACIS) consists of ten CCDs arranged in two arrays, one for imaging astronomical fields and one to be used in conjunction with transmission gratings for spectroscopy of astrophysical sources. ACIS uses Lexan/aluminum meshless films placed above these two CCD arrays to filter by mapping their soft x-ray transmission on fine spatial scales, so that the filter response can be removed from the CCD data and a more accurate estimate of the true sky recovered. We measured engineering and flight versions of these filters at the University of Wisconsin Synchrotron Radiation Center between June 1995 and April 1996. For all data, better than one percent accuracy in transmission as a function of energy was maintained over the entire filter area. The resulting transmission maps reveal spatial non-uniformities in the filters of about 0.5 percent to 2 percent. These transmission maps provide the finest spatial calibration ever achieved on such filters.
Purpose. In order to improve our knowledge on the efficacy and safety of sunscreen products, we measured the skin penetration profiles of ultra-violet (UV) filters in vitro and in vivo, and the corresponding sun protection factors (SPF) from two vehicles (an O/W emulsion-gel and petroleum jelly). Methods. The UV filters tested were oxybenzone (5%, A), 2-ethylhexyl 4-methoxycinnamate (7.5%, B), and 2-ethylhexylsalicylate (3%, C). Two mg/cm(2) were applied for 2 min to 6 h. In vitro penetration measurements were performed with static diffusion cells. In vivo, horny layer concentrations were measured after stripping and the SPF evaluated as recommended by the COLIPA-guidelines. Results. Significant differences between vehicles were noticed in vitro as well as in vivo. In vitro, the emulsion-gel generated higher epidermal concentrations than petroleum jelly. Values at 6 h, expressed as percent of the applied dose for A, B, and C were 4, 9, and 7% for the emulsion-gel and 2, 1, and 2% for petroleum jelly. An opposite trend was noticed, mainly for A, in the deeper skin layers with concentrations of 2% in the dermis and 5% in the receptor fluid for petroleum jelly and 0.6% and 1% for the emulsion-gel respectively. In vive, for each UV filter, maximal stratum corneum levels (15 strips) were obtained at 0.5 h with percentages of the applied doses of 50% for the emulsion-gel and 15% for petroleum jelly. SPFs, measured 0.5 h after application amounted to 14 for the emulsion-gel and 5 for petroleum jelly and decreased in both cases by a factor 2.2 after removal of non penetrated product. Conclusions. These preliminary results demonstrated that UV filters penetration and retention as well as expected SPF could be optimized by a suitable vehicle.
Solutions of organic compounds are proposed as viable high-pass, Rayleigh rejection filters for ultraviolet resonance Raman spectroscopy. The steep transmittance curves of these solutions effectively reject elastically scattered light in this region while passing Raman-shifted frequencies. The materials used in the filters are readily available and inexpensive, and the solutions are easily prepared. Filters for four lines in the range of 288 nm to 342 nm from a Raman-shifted 3rd and 4th harmonic of a Nd:YAG laser are presented, although the principle of preparing similar liquid filters can be applied to virtually any near-UV wavelength. The use of these filter solutions in conjunction with a single monochromator was found to significantly reduce levels of elastically scattered light without sacrifice of optical throughput; Raman scattering at frequency shifts within 200 cm-1 of the Rayleigh line could be observed, and the transmittance at shifts >1000 cm-1 was ≥80%. The Rayleigh-line rejection efficiencies for the filters in this study are modest (102-103) compared with those for filters employed in the visible region; but they can be easily boosted by increasing the chromophore concentration or filter pathlength with a trade-off of throughput for Raman scattering at small wavenumber shifts.
Measurements of the transmission properties of the AXAF CCD imaging spectrometer (ACIS) UV/optical blocking filters were performed at the National Synchrotron Light Source at Brookhaven Laboratories. The X-ray transmissions of two Al:Si/LEXAN/Al:Si three layer filters were measured between 260 and 3000 eV. The main purpose of the calibration was to determine a model transmission function with an accuracy of better than 1 percent. We present results from fits of model transmission functions to the measured x-ray transmission data. Detailed fine energy scans above the Al-K and C-K absorption edges revealed the presence of fine oscillations of the x-ray transmission. These features are most likely extended x-ray absorption fine structures (EXAFS). The amplitude of the EXAFS oscillations above the Al absorption edge is about 5 percent of the mean value of the x-ray transmission. EXAFS theory predicts a temperature dependence on the amplitude of the EXAFS oscillations. This dependence arises from the fact that thermal vibrations of the atoms in a solid produce a phase mismatch of the backscattered electron wave function. Since the ACIS filters will be at a much lower temperature on orbit we provide a prediction of the EXAFS component for the expected on orbit temperature of the ACIS filters.
A comparative conformational and dynamical study of a series of structurally related molecules with UV-filtering properties, i.e. N,N-dimethyl-N-[2-(4-benzoyl-2-hydroxyphenoxy)ethyl]-N-dodecyl ammonium bromide 2, N,N-dimethyl-N-[6-(4-benzoylphenoxy)hexyl]-N-dodecyl ammonium bromide 3 and N,N-dimethyl-N-[3-(salicyloylamino)propyl]-N-dodecyl ammonium bromide 5, has been performed in CDCl3 and [H-2(6)]DMSO solutions, The main conformers of 2 and 3 (extensively folded conformations) and 5 ('linear' conformations) were determined by means of selective spin-lattice proton relaxation rates, carbon spin-lattice relaxation rates and 1D nuclear Overhauser effects, On the basis of these results a possible correlation between conformation and antibacterial activity is discussed.
The performance of an add-drop filter fabricated in P-doped silica-on-silicon waveguides with UV induced Bragg gratings is reported. Sidelobe levels and transmitted channel isolation of-40dB are achieved using double filtering.
We present the first realization of a notch filter using a long-period grating UV-written in an adiabatically tapered fibre. As a result of the high coupling efficiency of the taper, 23 dB extinction and 60 nm -3 dB bandwidth were obtained.
The authors report the realisation of a new UV written fibre bandpass filter composed of two quarter-wave shifts inserted in a short Bragg grating. This new resonator presents a wider transmission band than classical singly phase-shifted grating of equal lengths and equivalent rejection bandwidths.