A new reflector surface and geometry using low-concentration mirror boosting of flat-plate photo voltaic
devices is described. The overheating effects that have previously been seen using non-uniform, high
reflectivity side mirrors have been reduced. The new high-stability reflector material has lower UV
reflectivity that reduces panel ageing and over heating. A moderate reflectivity in the violet wavelength
further cuts the level of overheating while sacrificing only minimally in electrical power output efficiency.
The new surface maintains high, uniform reflectivity at green, yellow, red, and IR wavelengths. Mass-produced
panels are undergoing tests, and some preliminary results are presented. Surface self-cleaning of
hydrophilic and hydrophobic coating over the reflecting surface is also discussed. Other applications of the
same mirror in the solar thermal field are briefly discussed. Some improved tracking PV geometry versions
using the new material are presented.
The present security environment has created a need for robust, sensitive, portable gas-phase chemical sensors. The
ready availability of high performance quantum cascade lasers, which can operate at ambient temperatures with only
thermoelectric cooling, has made the possibility of such sensors quite realistic. A compact, sensitive, cost-effective
photo-acoustic sensor capable of sub-part-per-million sensitivity is described. The sensor can be entirely selfcontained
in a small volume weighing only a few pounds. The quantum cascade laser is enclosed in a sealed
package incorporating a collimating lens and thermoelectric cooler. The package sits on an external thermoelectric
cooler. Both the laser and thermoelectric coolers are driven by a self-contained power supply and controller
specifically designed for the purpose. The photo-acoustic gas cell contains input and output ports and anti-reflection
coated optical windows. Details of the sensor's configuration and performance will be described as it relates to
explosive detection using thermal fragmentation.
The first successful photon-counting airborne laser altimeter was demonstrated in 2001 under NASA's
Instrument Incubator Program (IIP). This "micro-altimeter" flew at altitudes up to 22,000 ft (6.7 km)
and, using single photon returns in daylight, successfully recorded high resolution images of the
underlying topography including soil, low-lying vegetation, tree canopies, water surfaces, man-made
structures, ocean waves, and moving vehicles. The lidar, which operated at a wavelength of 532 nm
near the peak of the solar irradiance curve, was also able to see the underlying terrain through trees
and thick atmospheric haze and performed shallow water bathymetry to depths of a few meters over
the Atlantic Ocean and Assawoman Bay off the Virginia coast.
Sigma Space Corporation has recently developed second generation systems suitable for use in a small
aircraft or mini UAV. A frequency-doubled Nd:YAG microchip laser generates few microjoule,
subnanosecond pulses at fire rates up to 22 kHz. A Diffractive Optical Element (DOE) breaks the
transmit beam into a 10x10 array of quasi-uniform spots which are imaged by the receive optics onto
individual anodes of a high efficiency 10x10 GaAsP segmented anode microchannel plate
photomultiplier. Each anode is input to one channel of a 100 channel, multistop timer demonstrated to
have a 100 picosecond timing (1.5 cm range) resolution and an event recovery time less than 2 nsec.
The pattern and frequency of a dual wedge optical scanner, synchronized to the laser fire rate, are
tailored to provide contiguous coverage of a ground scene in a single overflight.
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