The commercial rooftop environment poses difficult challenges for concentrating photovoltaic (CPV) systems. Rooftop
CPV must not only meet low cost and high energy production targets common to ground mounted systems but also must
solve safety, wind loading, and area usage requirements in ways that are compatible with the rooftop environment. To
meet these requirements we have developed a low-profile carousel-mounted array of Fresnel concentrators using triple
junction solar cells. In this paper we describe the key features of the opto-mechanical and thermal design for
manufacturability and reliability. These features include the concentration level, the mechanical drive scheme, the
configuration of the lens with secondary optical element, and passive cooling. Also described are elements of the optical
component testing and assembly methods. We present exemplary results of environmental testing and measurements of
We describe a novel optical architecture for a LCoS binocular virtual display which, for the first time, meets or exceeds market leading pSi headset performance. A key component of the optical system is the frontlight illumination, which affords system specifications such a 36 degree field of view, a contrast of 80:1, and no IPD adjustment necessary (12 mm pupil). We detail the frontlight design and development, and its interaction with the complete electro-optical module.
End-to-end modeling of the photometric performance of LCD projection system using Monte Carlo geometrical ray tracing methods is an accurate and precise tool for predicting and improving the performance of these deices before, during and after product development. However, an accurate simulation first requires considering which physical properties contribute most to the system's photometric performance. Second, these properties must be characterized by physical measurements and translated into the tangible modeling parameters of a ray tracing program. Third, the implications of using a Monte Carlo ray tracing algorithm, and in general any other optical transformation algorithm, on radiometric accuracy must be well understood. These considerations as well as a generalized approach to the characterization and simulation of an LCD projector are described. A commercially available ray tracing program, the Advanced Systems Analysis Program, is used to demonstrate this approach. The irradiance uniformity, CIE color performance and screen brightness of an arc source LCD projector system are computed as an example.
The total internal reflection lens is a multi-faceted non-imaging device that was introduced in a paper we presented at the SPIE Non-Imaging Optics conference two years ago, with emphasis on solar-energy concentration. This paper will discuss the concentration on a target of the light emitted omnidirectionally from a compact source, such as an incandescent filament, a light- emitting diode, or an arc lamp. The converging type of TIR lens can efficiently concentrate this light into the relatively restricted range of acceptance angles typical of optical fibers and image illumination subsystems. It can replace the conventional ellipsoidal reflector and is superior to it in two ways: (1) its interception efficiency is considerably higher, when used with a back mirror; (2) its aberrations are lower in magnitude, because of the additional degrees of design freedom possible in the three-faced facets of the TIR lens. However, it is more sensitive to lens optical quality, so that theoretically possible results are best achieved with diamond-turning of lenses or molds. Also, TIR lenses are sensitive to errors in source position.
Angular momentum conservation and phase space are used for an exact calculation of bend loss in rectangular light pipes without rayiracing. It is found that the loss fraction ofrays in the bend plane is greater than that of the full 3-D distribution for any bend radius. There is excellent agreement between the calculated and measured loss.
Diode-pumped slab lasers require concentrators for high-average power operation. We detail the properties of diode lasers and slab lasers which set the concentration requirements and the concentrator design methodologies that are used, and describe some concentrator designs used in high-average power slab lasers at Lincoln Laboratory.
We have demonstrated the feasibility of a high temperature cool-wall optical furnace that harnesses the unique power of concentrated solar heating for advanced materials processing and testing. Out small-scale test furnace achieved temperatures as high as 2400 C within a 10 mm X 0.44 mm cylindrical hot-zone. Optimum performance and efficiency resulted from an innovative two-stage optical design using a long-focal length, point-focus, conventional primary concentrator and a non-imaging secondary concentrator specifically designed for the cylindrical geometry of the target fiber. A scale-up analysis suggests that even higher temperatures can be achieved over hot zones large enough for practical commercial fiber post- processing and testing.