6 research outputs found
Electron emission from deep level defects EL2 and EL6 in semi-insulating GaAs observed by positron drift velocity transient measurements
A ±100 V square wave applied to a Au/semi-insulating SI-GaAs interface was used to bring about electron emission from and capture into deep level defects in the region adjacent to the interface. The electric field transient resulting from deep level emission was studied by monitoring the positron drift velocity in the region. A deep level transient spectrum was obtained by computing the trap emission rate as a function of temperature and two peaks corresponding to EL2 (E a=0.81±0.15 eV) and EL6 (E a=0.30±0.12 eV) have been identified. © 2002 American Institute of Physics.published_or_final_versio
All-passive pixel super-resolution of time-stretch imaging
Based on image encoding in a serial-temporal format, optical time-stretch
imaging entails a stringent requirement of state-of-the- art fast data
acquisition unit in order to preserve high image resolution at an ultrahigh
frame rate --- hampering the widespread utilities of such technology. Here, we
propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch
imaging that preserves pixel resolution at a relaxed sampling rate. It
harnesses the subpixel shifts between image frames inherently introduced by
asynchronous digital sampling of the continuous time-stretch imaging process.
Precise pixel registration is thus accomplished without any active
opto-mechanical subpixel-shift control or other additional hardware. Here, we
present the experimental pixel-SR image reconstruction pipeline that restores
high-resolution time-stretch images of microparticles and biological cells
(phytoplankton) at a relaxed sampling rate (approx. 2--5 GSa/s) --- more than
four times lower than the originally required readout rate (20 GSa/s) --- is
thus effective for high-throughput label-free, morphology-based cellular
classification down to single-cell precision. Upon integration with the
high-throughput image processing technology, this pixel-SR time- stretch
imaging technique represents a cost-effective and practical solution for large
scale cell-based phenotypic screening in biomedical diagnosis and machine
vision for quality control in manufacturing.Comment: 17 pages, 8 figure