Surveillance, detection, and tracking of multiple high-speed projectiles, particularly bullets, RPGs, and
artillery shells, can help military forces immediately locate sources of enemy fire and trigger countermeasures. The
traditional techniques for detection and tracing of fast moving objects typically employ various types of radar, which has
inherently low resolution for such small objects. Fast moving projectiles are aerodynamically heated up to several
hundred degree Kelvin temperatures depending on the speed of a projectile. Thereby, such projectiles radiate in the Mid-
Infrared (MWIR) region, where electro-optical resolution is far superior, even to microwave radars. A new passive
electro-optical tracker (or PET) uses a two-band IR intensity ratio to obtain a time-varying speed estimate from their
time-varying temperatures. Based on an array of time-varying speed data and an array of azimuth/ elevation angles, PET
can determines the 3D projectile trajectory and back track it to the source of fire. Various methods are given to
determine the vector and range of a projectile, both for clear and for non-homogeneous atmospheric conditions. One
approach uses the relative intensity of the image of the projectile on the pixels of a CCD camera to determine the
azimuthal angle of trajectory with respect to the ground, and its range. Then by using directions to the tracked projectile
(azimuth and elevation angles of the trajectory) and the array of instant projectile speeds, PET determines the distance to
the projectile at any point on its tracked trajectory or its predicted trajectory backwards or forwards in time. A second
approach uses a least-squares optimization technique over multiple frames based on a triangular representation of the
smeared image to yield a real-time trajectory estimate. PET's estimated range accuracy is 0.2 m and the azimuth of the
trajectory can be estimated within 0.2°.
The Boeing Company Phantom Works has
developed three different prototype photovoltaic
concentrator arrays since March 2007. Identified as
Prototype A, B and C, the experimentally proven technical
characteristics of each design are presented. The
concentrator designs utilize a 1 cm2 multi-junction solar
cell assembly in conjunction with SMS non-imaging optical
designs [1, 2] manufactured with low-cost mass-producible
technologies. Prototype A is an on-axis XR optical
concentrator with a 733x geometrical concentration
demonstrating a ± 1.73° acceptance angle and 23.7%
conversion efficiency. Prototype B is an off-axis free-form
XR optical concentrator with a 810x geometrical
concentration demonstrating a ± 1.32° acceptance angle
and 25.3% conversion efficiency. Prototype C is the most
recent off-axis free-form XR optical concentrator with a
801x geometrical concentration and a theoretical ±1.80°
acceptance angle demonstrating a conversion efficiency
greater than 27.0%. Prototype C is also the basis for the
Boeing Proof of Design (POD) module, demonstrating an
acceptance angle of ±1.48° and a conversion efficiency of
29.4% (as of May 8, 2009). Manufacturability has been
paramount during the design process, resulting in high
performance concentrating photovoltaic modules using
production quality components.
The performance of the XR solar concentrator, using a high efficiency multi-junction solar cell developed
recently by Spectrolab, is presented. The XR concentrator is an ultra-compact Nonimaging optical design
composed of a primary mirror and a secondary lens, which can perform close to the thermodynamic limit
of concentration (maximum acceptance angle for a given geometrical concentration). The expected
acceptance angle of the concentrator is about ±2 deg for a geometrical concentration of 800x (a Fresnel
lens and secondary system typically has ±0.6 deg of acceptance for 300x of geometrical concentration).
This concentrator is optimized to improve the irradiance distribution on the solar cell keeping it under the
maximum values the cell can accept.
The XR concentrator has high manufacturing tolerance to errors and can be produced using low cost
manufacturing techniques. The XR is designed with the Simultaneous Multiple Surface (SMS) design
method of Nonimaging Optics. Its application to high-concentration photovoltaics is now being
developed in a consortium led by The Boeing Company, which has recently been awarded a project by
the US DOE in the framework of the Solar America Initiative.
The performance of the XR solar concentrator, using a high efficiency multi-junction solar cell developed
recently by Spectrolab, is presented. The XR concentrator is an ultra-compact Nonimaging optical design
composed of a primary mirror and a secondary lens, which can perform close to the thermodynamic limit
of concentration (maximum acceptance angle for a given geometrical concentration). The expected
acceptance angle of the concentrator is about ±2 deg for a geometrical concentration of 800x (a Fresnel
lens and secondary system typically has ±0.6 deg of acceptance for 300x of geometrical concentration).
This concentrator is optimized to improve the irradiance distribution on the solar cell keeping it under the
maximum values the cell can accept.
The XR concentrator has high manufacturing tolerance to errors and can be produced using low cost
manufacturing techniques. The XR is designed with the Simultaneous Multiple Surface (SMS) design
method of Nonimaging Optics. Its application to high-concentration photovoltaics is now being
developed in a consortium led by The Boeing Company, which has recently been awarded a project by
the US DOE in the framework of the Solar America Initiative.
Brightness enhancement of backlighting for displays is typically achieved via crossed micro prismatic films that are introduced between a backlight unit and a transmissive (LCD) display. Prismatic films let pass light only into a restricted angular range, while, in conjunction with other reflective elements below the backlight, all other light is recycled within the backlight unit, thereby increasing the backlight luminance. This design offers no free parameters to influence the resulting light distribution and suffers from insufficient stray light control. A novel strategy of light recycling is introduced, using a microlens array in conjunction with a hole array in a reflective surface, that can provide higher luminance, superior stray light control, and can be designed to meet almost any desired emission pattern. Similar strategies can be applied to mix light from different colored LEDs being mounted upside down to shine into a backlight unit.
A novel luminaire utilizes repeated Fresnel reflections by angled surfaces to transform a small collimated input beam into a controlled output pattern with a high degree of polarization, either linear or radial. Applications to backlighting, front-lighting, optical communications and automotive lighting will be discussed.
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