Showing papers by "Michael Bass published in 2009"

Temperature-dependent stimulated emission cross section in Nd 3+ :YVO 4 crystals

Abstract: Spectroscopic properties of neodymium-doped yttrium orthovanadate crystals were measured in the temperature range between 5 and 350 K. Crystals fabricated by different suppliers, with 0.3 and 1 at% Nd3+, were compared. For each temperature, the stimulated emission cross sections of the Nd3+ 4F3/2 decay to the 4I9/2, 4I11/2, and 4I13/2 states were obtained using the Fuchtbauer-Ladenburg and the reciprocity techniques. Nd:YVO4 shows higher absorption at room temperature and higher stimulated emission cross section with similar variation with temperature when compared with Nd:YAG. The anomalous dependence on temperature of the Nd3+ 4F3/2 excited-state lifetime is discussed and an explanation is suggested.

New variants in the Enpp1 and Ptpn6 genes cause low BMD, crystal-related arthropathy, and vascular calcification.

Abstract: A large genome-wide, recessive, N-ethyl-N-nitrosourea (ENU)-induced mutagenesis screen was performed on a mixed C57BL/6J and C3H.SW-H2/SnJ mouse background to identify genes regulating bone mass. Approximately 6500 male and female G(3) hybrid mice were phenotyped at 8 and 10 wk of age by DXA analysis for evidence of changes in unadjusted or body weight-adjusted BMD or BMC. Phenodeviant lines were identified based on statistical criteria that included a false discovery rate (FDR) 2.8. Genome-wide mapping scans were initiated on 22 lines, with evidence of high or low BMD or BMC that deviated by approximately -30% to +50% from the means. Several lines were discontinued as showing lack of heritability, but two heritable lines were identified with narrow chromosomal regions that allowed sequencing of potential mutant candidate genes. Novel mutations were identified in the Enpp1 (C397S) gene on chromosome 10 (line 4482) and the Ptpn6 (I482F) gene on chromosome 6 (line 4489) that were both associated with low bone mass. In addition, the phenotype of the Enpp1 mice showed a striking joint disease and calcification of blood vessels including the aorta, myocardium, and renal arteries and capillaries. These results support a role for the Enpp1 gene in the pathogenesis associated with mineralization of articular cartilage and vascular calcification. This work confirms the utility of the chemical mutagenesis approach for identification of potential disease genes and confirms the role of Enpp1 and Ptpn6 in regulating mineralization and skeletal bone mass.

More on analyzing the reflection of a laser beam by a deformed highly reflective volume Bragg grating using iteration of the beam propagation method

Abstract: A further extension of the iteration method for beam propagation calculation is presented that can be applied for volume Bragg gratings (VBGs) with extremely large grating strength. A reformulation of the beam propagation formulation is presented for analyzing the reflection of a laser beam by a deformed VBG. These methods will be shown to be very accurate and efficient. A VBG with generic z-dependent distortion has been analyzed using these methods.

Volume Bragg Grating assisted broadband tunability and spectral narrowing of Ti:Sapphire oscillators

Abstract: A widely tunable, narrow band Ti:Sapphire oscillator is reported. Tunability and spectral narrowing were achieved by use of a volume Bragg grating in the cavity. Tunability was observed from 785 nm to 852 nm while maintaining a spectral linewidth less than 10 pm with essentially no spectral jitter. Oscillation on only 2 longitudinal modes is also reported at 852 nm with the grating at normal incidence providing ~200 mW output power.

Evolution of Luminescence from Doped Gallium Phosphide over 40 Years

Abstract: The results of luminescence studies conducted on the same samples of GaP over a 40-year period are discussed. The results strongly imply that periodic ordering of impurities improved the overall optical and mechanical properties of the material over time. Forty years after preparation, “hot” luminescence spectra in gallium phosphide (GaP) are similar to those for nanocrystals. The aged pure and N-doped crystals exhibit stimulated emission at 300 K. The aged GaP:N:Sm at room temperature generates bright green or yellow and red tunable luminescence. These results correlate with Raman light scattering and microhardness data obtained from the same crystals.

Time‐dependent evolution of crystal lattice, defects and impurities in CdIn2S4 and GaP

Abstract: We demonstrate that in III-V and ternary compounds the natural stimuli for ordered distribution of impurities along crystal nodes and interstitials, host atoms and inherent vacancies in right lattice positions prevail over the others which could lead to a heterogenic distribution. The result is obtained in the crystals, prepared in 1963-1977, due to each 10-15 years monitoring of their optical and mechanical properties. Here we have summarized the results of the 2005-2008 monitoring and compare them with the earlier obtained data. We show that the partly inverse spinel CdIn2S4 turns into the perfect normal spinel, while in GaP the impurity ordering leads to the formation of a new type of crystal lattices. Periodically disposed impurities and inherent structural defects modify, improve and stabilize properties of the crystals. New luminescent phenomena of these crystals, including stimulated emission and “hot” luminescence have been discovered. The existing technologies help us to reproduce these naturally ordered structures and to apply them for new generation of optoelectronic devices. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Handbook of Optics, Third Edition Volume III: Vision and Vision Optics(set)

Abstract: The most comprehensive and up-to-date optics resource available Prepared under the auspices of the Optical Society of America, the five carefully architected and cross-referenced volumes of the Handbook of Optics, Third Edition, contain everything a student, scientist, or engineer requires to actively work in the field. From the design of complex optical systems to world-class research and development methods, this definitive publication provides unparalleled access to the fundamentals of the discipline and its greatest minds. Individual chapters are written by the world's most renowned experts who explain, illustrate, and solve the entire field of optics. Each volume contains a complete chapter listing for the entire Handbook, extensive chapter glossaries, and a wealth of references. This pioneering work offers unprecedented coverage of optics data, techniques, and applications. Volume III, all in full color, covers vision and vision optics. Table of contents Vision Ch1. Optics of the Eye Ch2. Visual Performance by Wilson Geisler and Martin Banks Ch3. Psychophysical Methods by Dennis Pelli and Bart Farell Ch4. Visual Acuity and Hyperacuity by Gerald Westheimer Ch5. Optical Generation of the Visual Stimulus by Stephen A. Burns and Robert H. Webb Ch6. The Maxwellian View Combined with an Addendum on Apodization by Gerald Westheimer Ch7. Ocular Radiation Hazards by David Sliney Ch8. Biological Waveguides by Vasudevan Lakshminarayanan and Jay M. Enoch Ch9. The Problem of Correction for the Stiles-Crawford effect in Radiometry and Photometry by Jay M. Enoch and Vasudevan Lakshminarayanan Ch10. Colorimetry by David Brainard and Andrew Stockman Ch11. Color Vision by Andrew Stockman and David Brainard Ch12. Assessment of Refraction and Refractive Errors and Their Influence on Optical Design by Ralph Chou Ch13. Binocular Vision Factors That Influence Optical Design by Clifton Schor Ch14. Optics of Vision in the Aging Eye by John Werner and Brooke Schefrin Ch15. Adaptive Optics (AO) in Retinal Microscopy and Vision by Donald Miller and Austin Roorda Ch16. Refractive Surgery, Correction of Vision, PRK and LASIK by Harilaos and Luis Diaz-Santana Ch17. Corneal Confocal Imaging by Barry Masters Ch18. Diagnostic Use of Optical Coherence Tomography (OCT) in the Eye by Johanes de Boer Ch19. Graded Index of Refraction (GRIN) Profiling of the Eye Lens by B. Pierscionek Ch20. Optics of Contact Lenses by E. Bennett Ch21. Inter-Ocular Lenses (IOL's), Accommodative and Multifocal IOL's by James Schweigerling Ch22. Displays for Vision Research by William Cowan Ch23. Visual Problems at Computers by Jeffrey Anshel and James Sheedy Ch24. Human Vision and Electronic Imaging by Bernice Rogowitz, T.N. Pappas, Jan P. Allerback Ch25. Visual Factors Associated with Head-Mounted Displays by Brian H. Tsou and Martin Shenker

Diode-Pumped Very Large Core, Gain Guided, Index Antiguided Single Mode Fiber Laser

Abstract: Single-mode laser action, up to 4-times the threshold power, in a diode-pumped Nd-doped phosphate glass fiber having a 300-μm core is demonstrated. Subtle differences associated with the effectiveness of diode-pumping gain-guided, index-antiguided fibers are discussed.

Up converters and GaAs based semiconductor light source system for large color gamut display and projection displays

Abstract: Method and system for an up conversion lighting system for use with displays. The system includes an up converter-semiconductor light source for emitting an up conversion emission and a spectrally selective optical element in the path of the emission for selectively passing selected wavelengths. The optical element has a coating selected to pass selected wavelengths. The up converter-semiconductor light source includes an up converter for emitting the up conversion emission, a semiconductor light source coupled with the up converter to excite an up conversion material within the up converter to emit an up conversion emission and a spatial light modulator for modulating the up conversion emission. For a full color display, the up converter includes a red, green and blue up converter and a separate a light source coupled with the red, green and blue up converters. The spectrally selectively optical element can be a spectrally selectively beam splitter having a film coating that is selected to transmit selected wavelengths.

Biocompatible nano rare earth oxide upconverters for imaging and therapeutics

Abstract: Methods and systems biomedical application of up conversion nanoparticles. Co-doped cerium oxide nanoparticles were synthesized by precipitation technique. Up conversion nano cerias are biocompatible as a biomarker with antioxidant properties. Up conversion nano cerias interact in a cell specific manner showing catalase mimetic activity. With suitable surface targeting ligands, up conversion nano cerias can be used for site selective drug delivery for the treatment of diseases like cancer.

Low voltage display or indicator system employing combinations of up converters and semiconductor light sources

Abstract: Methods and systems for a combination of up converters and semiconductor light sources in low voltage display or indicator system that can be battery powered. The display or indicator system includes one or more spatial light modulators and one or more up converters in combination with one or more semiconductor light sources. The spatial light modulator can be a liquid crystal display or a micro electro mechanical system or other spatial light modulator and can use direct modulation of the semiconductor light sources to modulate the visible emission from the up converters. The spatial light modulator can be placed between the up converting light source and the viewer or behind the up converting light source depending on the type of spatial light modulator, or modulation may be applied directly to one or more semiconductor light sources or arrays of semiconductor light sources that excite the up converters.