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Defense Information, Communication, and Space Technology
Published in Anna M. Doro-on, Handbook of Systems Engineering and Risk Management in Control Systems, Communication, Space Technology, Missile, Security and Defense Operations, 2023
The basic configuration of a fiber laser, as shown in Figure 5.18b, comprises a gain medium in the form of a long optical fiber of suitable material doped with lasing ions (also refer to Section 5.1.5.3.3). The high efficiency associated with the fiber laser also has a major impact on the overall cost of the laser. The laser is typically pumped by diodes operating around 800 nm, and the laser emission is at 1064 nm, with conversion efficiencies typically exceeding 60% in many high-power systems (Dong and Samson 2016). In the case of the fiber laser, the pump diodes are typically at around 940 nm and the lasing wavelength is also around 1064 nm, with conversion efficiencies typically exceeding 60% in many high-power systems, and the required pump power is less than half for the fiber laser compared with that for the diode-pumped solid-state laser (DPSSL). Based on this simple comparison, the required pump power is less than half for the fiber laser compared with that for the DPSSL, and assuming similar costs for both laser diodes, we would expect much lower-cost fiber for pumps in the case of the fiber laser (Dong and Samson 2016). Historically, the pump laser diodes for fiber lasers have been more expensive than 800-nm pumps for DPSSL, but the price has been dropping dramatically over the past 10 years as the volume increases and the technology matures (Dong and Samson 2016).
Image-Based Photonic Techniques for Microfluidics
Published in Sushanta K. Mitra, Suman Chakraborty, Fabrication, Implementation, and Applications, 2016
David S. Nobes, Mona Abdolrazaghi, Sushanta K. Mitra
As an example, argon ion CW lasers (Bridges, 1964) have many experimental applications. They can emit 13 individual wavelengths at the ultraviolet, visible, and near-infrared spectra. These lasers can operated in a multimode, that is, with all lines together or in a single mode so that only a single wavelength is available. Useful wavelengths in the visible spectrum are 488.0 and 514.5 nm because they produce maximum power. These laser units are commercially available in a range up to 20 W. With the advent of solid-state technology, diode-pumped solid-state lasers are available in various wavelengths and have the advantage of being compact. Depending on the laser configuration, they can be operated either as CW lasers or as pulsed lasers. For example, pulsed laser technology often used in measurement systems uses neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal as the lazing medium (Geusic et al., 1964). These lasers have a fundamental wavelength of 1064 nm in the infrared spectrum and are often frequency doubled to 532 nm in the green part of the visible spectrum. These lasers are characterized by the amount of energy per pulse (joules/pulse) and typically have a low repetition rate in the range of 0-30 Hz, although high rates are available. The main characteristic of this style of laser is the short pulse duration, ~10 ns, and the high energy density per pulse (up to 400 mJ/pulse). This allows for bright illumination over a significantly shorter time scale than the majority of time scales found in typical microscale flows.
Zinc-containing precursor dependence of hydrothermal method for the synthesis of N-doped ZnO photocatalysts
Published in Chemical Engineering Communications, 2021
Minh Chau Ta Xuan, Tuan Ngoc Tran, Claire Botto, Tram Anh Ha, The Luan Nguyen, Tien Khoa Le
The structural properties of our photocatalysts were studied by powder X-ray diffraction (XRD) (BRUKER-Binary V3 X-ray diffractometer) using Cu Kα radiation (λ = 1.5406 Å) with the accelerating voltage of 40 kV and the applied current of 40 mA. Field emission scanning electron microscopy (FESEM) studies of these samples were carried out on a HITACHI S-4800 with an acceleration voltage at 10 kV. Their Brunauer-Emmet-Teller surface area (SBET) was measured via the nitrogen adsorption-desorption experiments on a NOVA 1000e analyzer (Quantachrome Instruments). The band gap energy (Eg) values of our catalysts were determined from room temperature UV-Visible diffuse reflectance spectra (DRS) using a Perkin-Elmer Lambda 850 Spectrophotometer equipped with a 15 cm diameter integrating sphere bearing the holder in the bottom horizontal position. The elemental composition of samples was also determined by an energy-dispersive X-ray (EDX) analyzer coupled to a scanning electron microscopy (HITACHI S-4800). In order to investigate the surface functional groups of N-doped ZnO samples, their infrared spectra were recorded with a Fourier transform infrared (FTIR) spectrometer (Bruker VERTEX 70). The powder samples were embedded in KBr matrix for the recording. Raman scattering was performed on a HORIBA Jobin-Yvon spectrophotometer consisting of diode pumped solid state laser with 532 nm wavelength.
Multicolor upconversion luminescence of dye-coordinated Er3+ at the interface of Er2O3 and CaF2 nanoparticles
Published in Science and Technology of Advanced Materials, 2019
Ayumi Ishii, Yuya Adachi, Ayaka Hasegawa, Miyu Komaba, Shuhei Ogata, Miki Hasegawa
Scanning electron microscopy (SEM) images were obtained using an Ultra-55 microscope (Carl Zeiss AG, Germany) equipped with a secondary in-lens electron detector, together with a QUANTAX detector (Bruker Corporation, Germany) for energy-dispersive X-ray spectrometry (EDS). Synchrotron X-ray powder diffraction (XRPD) patterns were obtained with a large Debye–Scherrer camera installed at the BL02B2 beamline (SPring-8), using an imaging plate as the detector and an incident X-ray wavelength of 0.9988Å. Fourier transform infrared (FTIR) spectra were measured in attenuated total reflection (ATR) mode with a diamond crystal using the Nicolet iS5 infrared spectrometer (Thermo Fisher Scientific K. K., Japan). Optical absorption and luminescence spectra were recorded on a UV-3100 spectrophotometer (Shimadzu Corporation, Japan) with an absolute specular reflectance attachment and a Jobin Yvon Fluorolog 3–22 (Horiba Scientific, Japan), respectively. A 980 nm semiconductor laser and a 671 nm diode-pumped solid-state laser with an adjustable power supplies were used as CW excitation light sources (CivilLaser, China). A 450 W Xe lamp equipped in the luminescence spectrometer (Fluorolog 3–22, Horiba Scientific, Japan) was also used as a low-intensity light source. The full width at half maximum (FWHM) at 750 nm is 350 cm−1. The excitation light intensity and wavelength were adjusted using neutral-density (ND) and color filters (OMG Co., Ltd., Japan). The light intensity was measured by a Si photodetector connected with a power meter (Ophir Japan Ltd., Japan).
Simultaneous transmission and absorption photometry of carbon-black absorption from drop-cast particle-laden filters
Published in Aerosol Science and Technology, 2019
Cary Presser, James G. Radney, Matthew L. Jordan, Ashot Nazarian
Ultimately, a CW diode-pumped solid-state laser was used, which operated at a wavelength of 532 nm. The maximum increase in temperature for the incident beam (without any filter) was 11 K to 12 K above the ambient air temperature. The change in temperature with the blank filter reached a maximum of about 1 K above the ambient, while the coated filter temperature rose about 9 K for the heaviest-coated filter and about 1.5 K for the lightest-coated filter. The maximum temperature achieved for the coated filters decreased as the filter loading decreased, approaching that of the blank filter measurements. As expected, absorption of the laser energy by the carbon black resulted in higher detected temperatures. Also observed was that the transmission always increased as the particle loading on the filter decreased, approaching that of the blank filter (which remained essentially unchanged).