scholarly journals Low spatial coherence electrically pumped semiconductor laser for speckle-free full-field imaging

2015 ◽  
Vol 112 (5) ◽  
pp. 1304-1309 ◽  
Author(s):  
Brandon Redding ◽  
Alexander Cerjan ◽  
Xue Huang ◽  
Minjoo Larry Lee ◽  
A. Douglas Stone ◽  
...  
Keyword(s):  
Semiconductor Laser ◽  
High Speed ◽  
Spatial Coherence ◽  
Spectral Radiance ◽  
Laser Resonator ◽  
Full Field ◽  
Wide Range ◽  
Electrically Pumped ◽  
Laser Sources ◽  
Field Imaging

The spatial coherence of laser sources has limited their application to parallel imaging and projection due to coherent artifacts, such as speckle. In contrast, traditional incoherent light sources, such as thermal sources or light emitting diodes (LEDs), provide relatively low power per independent spatial mode. Here, we present a chip-scale, electrically pumped semiconductor laser based on a novel design, demonstrating high power per mode with much lower spatial coherence than conventional laser sources. The laser resonator was fabricated with a chaotic, D-shaped cavity optimized to achieve highly multimode lasing. Lasing occurs simultaneously and independently in ∼1,000 modes, and hence the total emission exhibits very low spatial coherence. Speckle-free full-field imaging is demonstrated using the chaotic cavity laser as the illumination source. The power per mode of the sample illumination is several orders of magnitude higher than that of a LED or thermal light source. Such a compact, low-cost source, which combines the low spatial coherence of a LED with the high spectral radiance of a laser, could enable a wide range of high-speed, full-field imaging and projection applications.

scholarly journals Electrically pumped semiconductor laser with low spatial coherence and directional emission

2019 ◽  
Vol 115 (7) ◽  
pp. 071101 ◽  
Author(s):  
Kyungduk Kim ◽  
Stefan Bittner ◽  
Yongquan Zeng ◽  
Seng Fatt Liew ◽  
Qijie Wang ◽  
...  
Keyword(s):  
Semiconductor Laser ◽  
Spatial Coherence ◽  
Directional Emission ◽  
Electrically Pumped

Low-spatial coherence electrically pumped red-emitting semiconductor laser

2018 ◽  
Author(s):  
Wanhua Zheng ◽  
Yufei Jia ◽  
Yufei Wang ◽  
Shao Yu Zhao ◽  
Linhai Xu ◽  
...  
Keyword(s):  
Semiconductor Laser ◽  
Spatial Coherence ◽  
Electrically Pumped

Low-Spatial Coherence Chaotic Cavity Laser for Speckle-Free Full-Field Imaging

2014 ◽  
Author(s):  
B. Redding ◽  
A. Cerjan ◽  
X. Huang ◽  
A. D. Stone ◽  
M. L. Lee ◽  
...  
Keyword(s):  
Spatial Coherence ◽  
Full Field ◽  
Cavity Laser ◽  
Field Imaging

Combustion in High-Speed Direct Injection Diesel Engines—A Comprehensive Study

1994 ◽  
Vol 208 (4) ◽  
pp. 223-240 ◽  
Author(s):  
D E Winterbone ◽  
D A Yates ◽  
E Clough ◽  
K K Rao ◽  
P Gomes ◽  
...  
Keyword(s):  
High Speed ◽  
Direct Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Correlation Technique ◽  
Full Field ◽  
Combustion Gases ◽  
Carbon Particles ◽  
Wide Range ◽  
Cross Correlation Technique

This paper reports the latest results of a comprehensive project investigating the performance of a Ricardo Hydra direct injection diesel engine. Early work covered a number of aspects of research into the gross behaviour of this engine: this paper concentrates on techniques for obtaining quantitative data from photographs of the combustion process. High-speed photographs, at framing rates up to 20 000 frames/s, were taken using a piston with a quartz bowl, at engine speeds up to 3000 r/min. The pre-combustion period was illuminated using a synchronized copper vapour laser. After the initiation of combustion, the process is self-illuminating and information on the combustion process was obtained by analysing the radiation emitted by the carbon particles. The two-colour method was used to evaluate the temperature of the combustion gases over the full field of view. The images have also been analysed by a cross-correlation technique to obtain velocity information. Tests have been performed on the engine over a wide range of operating conditions, but this paper concentrates on the effect of swirl ratio on combustion. It will be shown that too much swirl increases the ignition delay period and results in an increase in the NOx emissions but a decrease in the soot. It will also be shown that the velocity pattern after combustion is in good agreement with that evaluated by Arcoumanis et al. at the end of compression, which implies that swirl persists through the combustion period despite significant decay.

Application of High Speed Image Correlation for Measurement of Mode Shapes of a Car Bonnet

2011 ◽  
Vol 70 ◽  
pp. 45-50
Author(s):  
Thorsten Siebert ◽  
Wei Zhuo Wang ◽  
John E. Mottershead ◽  
Andrea Pipino
Keyword(s):  
High Speed ◽  
Speckle Pattern ◽  
Measurement Techniques ◽  
Image Correlation ◽  
Mode Shapes ◽  
Analysis Tool ◽  
Full Field ◽  
Digital Speckle Pattern Interferometry ◽  
Full Field Measurement ◽  
Wide Range

For the analysis of vibrations and mode shape extraction in particular the use of optical full-field measurement techniques has grown during the last years. Beside techniques like Digital Speckle Pattern Interferometry, Moiré, Thermography or Photoelasticity the Digital Image Correlation techniques have already been successfully proven to be an accurate displacement analysis tool for a wide range of applications.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

Assessment of Commercial Off-the-Shelf Tissue Adhesives for Sealing Military-Relevant Corneal Perforation Injuries

2021 ◽  
Author(s):  
Eric J Snider ◽  
Lauren E Cornell ◽  
Brandon M Gross ◽  
David O Zamora ◽  
Emily N Boice
Keyword(s):  
Intraocular Pressure ◽  
High Speed ◽  
Anterior Segment ◽  
Ocular Tissue ◽  
Corneal Tissue ◽  
Corneal Perforation ◽  
Tissue Adhesives ◽  
Open Globe ◽  
Wide Range ◽  
Commercial Off The Shelf

ABSTRACT Introduction Open-globe ocular injuries have increased in frequency in recent combat operations due to increased use of explosive weaponry. Unfortunately, open-globe injuries have one of the worst visual outcomes for the injured warfighter, often resulting in permanent loss of vision. To improve visual recovery, injuries need to be stabilized quickly following trauma, in order to restore intraocular pressure and create a watertight seal. Here, we assess four off-the-shelf (OTS), commercially available tissue adhesives for their ability to seal military-relevant corneal perforation injuries (CPIs). Materials and Methods Adhesives were assessed using an anterior segment inflation platform and a previously developed high-speed benchtop corneal puncture model, to create injuries in porcine eyes. After injury, adhesives were applied and injury stabilization was assessed by measuring outflow rate, ocular compliance, and burst pressure, followed by histological analysis. Results Tegaderm dressings and Dermabond skin adhesive most successfully sealed injuries in preliminary testing. Across a range of injury sizes and shapes, Tegaderm performed well in smaller injury sizes, less than 2 mm in diameter, but inadequately sealed large or complex injuries. Dermabond created a watertight seal capable of maintaining ocular tissue at physiological intraocular pressure for almost all injury shapes and sizes. However, application of the adhesive was inconsistent. Histologically, after removal of the Dermabond skin adhesive, the corneal epithelium was removed and oftentimes the epithelium surface penetrated into the wound and was adhered to inner stromal tissue. Conclusions Dermabond can stabilize a wide range of CPIs; however, application is variable, which may adversely impact the corneal tissue. Without addressing these limitations, no OTS adhesive tested herein can be directly translated to CPIs. This highlights the need for development of a biomaterial product to stabilize these injuries without causing ocular damage upon removal, thus improving the poor vision prognosis for the injured warfighter.

scholarly journals Vibration of Rotating and Revolving Planet Rings with Discrete and Partially Distributed Stiffnesses

2020 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Fuchun Yang ◽  
Dianrui Wang
Keyword(s):  
High Speed ◽  
Differential Operators ◽  
Natural Frequencies ◽  
Rotation Speed ◽  
Distribution Area ◽  
Vibration Modes ◽  
Governing Equations ◽  
Vibration Properties ◽  
Wide Range ◽  
Forced Responses

Vibration properties of high-speed rotating and revolving planet rings with discrete and partially distributed stiffnesses were studied. The governing equations were obtained by Hamilton’s principle based on a rotating frame on the ring. The governing equations were cast in matrix differential operators and discretized, using Galerkin’s method. The eigenvalue problem was dealt with state space matrix, and the natural frequencies and vibration modes were computed in a wide range of rotation speed. The properties of natural frequencies and vibration modes with rotation speed were studied for free planet rings and planet rings with discrete and partially distributed stiffnesses. The influences of several parameters on the vibration properties of planet rings were also investigated. Finally, the forced responses of planet rings resulted from the excitation of rotating and revolving movement were studied. The results show that the revolving movement not only affects the free vibration of planet rings but results in excitation to the rings. Partially distributed stiffness changes the vibration modes heavily compared to the free planet ring. Each vibration mode comprises several nodal diameter components instead of a single component for a free planet ring. The distribution area and the number of partially distributed stiffnesses mainly affect the high-order frequencies. The forced responses caused by revolving movement are nonlinear and vary with a quasi-period of rotating speed, and the responses in the regions supported by partially distributed stiffnesses are suppressed.

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