L. Maxey, T. Ally, A. Brunson, F. Garcia, K. Goetz, K. Hasse, T. McManamy, M. Mitchell, M. Simpson, T. Shea, J. Kumler, D. Brown, T. Lindsey, T. Victorio
A fiber-coupled imaging system for monitoring the proton beam profile on the target of the Spallation Neutron Source
was developed using reflective, refractive and diffractive optics to focus an image onto a fiber optic imaging bundle. The
imaging system monitors the light output from a chromium-doped aluminum oxide (Al203:Cr) scintillator on the nose of
the target. Metal optics are used to relay the image to the lenses that focus the image onto the fiber. The material choices
for the lenses and fiber were limited to high-purity fused silica, due to the anticipated radiation dose of 108 R. In the first
generation system (which had no diffractive elements), radiation damage to the scintillator on the nose of the target
significantly broadened the normally monochromatic (694 nm) spectrum. This created the need for an achromatic design
in the second generation system. This was achieved through the addition of a diffractive optic for chromatic correction.
An overview of the target imaging system and its performance, with particular emphasis on the design and testing of a
hybrid refractive/diffractive high-purity fused silica imaging triplet, is presented.
Commercial buildings represent a near term market for cost competitive solar electric power provided installation costs and solar photovoltaic module costs can be reduced. JX Crystals has developed a carousel sun tracker that is prefabricated and can easily be deployed on building flat roof tops without roof penetration. JX Crystals is also developing 3-sun PV mirror modules where less expensive mirrors are substituted for two-thirds of the expensive single crystal silicon solar cell surface area. Carousels each with four 3-sun modules have been set up at two sites, specifically at Oak Ridge National Lab and at the University of Nevada in Las Vegas. The test results for these systems are presented.
Oak Ridge National Laboratory (ORNL) has begun the development of a program for the manufacturing and characterizing fuel pellets for use in advanced nuclear reactors. To achieve high reliability it is necessary to characterize the pellets during production runs. In this paper we present a simple TRISO Particle Counting And Sizing Tool (TP-CAST) that performs dual measurements of counting and size estimation for particles at rates up to 200 per second. The TP-CAST is based on a laser with line-generation optics and a PC-based data acquisition and analysis system. The instrument can measure 1000 micron pellets with a standard deviation of approximately 11 microns and with counting errors less than 0.075%. Our paper discusses the signal modeling, algorithms for size estimation, system design, and experimental results of the prototype TP-CAST system assembled at ORNL.
Efficient hybrid luminaire development is an integral part of the Hybrid Solar Lighting Program at Oak Ridge National Laboratory. Hybrid luminaires are necessary to blend light from a fiber optic solar source with electric fluorescent lamps. The luminaire designs studied involve a commercially available fluorescent luminaire that has been modified to include optical elements for efficiently dispersing fiber optic solar light sources. Quantitative measurements of optical efficiency and spatial intensity distribution for two luminaire designs are compared.
Research is underway at Oak Ridge National Laboratory (ORNL) that could lead to entirely new, highly energy-efficient ways of lighting buildings using the power of sunlight. In addition to providing light, the hybrid lighting system will convert sunlight to electricity much more efficiently than conventional solar technologies using thermo-photovoltaic cells. In commercial buildings today, lighting consumes more electric energy than any other building end-use. It accounts for more than a third of all electricity consumed for commercial use in the United States. Typically, less than 25% of that energy actually produces light; the rest generates heat that increases the need for air-conditioning. ORNL is developing a system to reduce the energy required for lighting and the air-conditioning loads associated with it, while generating power for other uses.
The system uses roof-mounted concentrators to collect and separate the visible and infrared portions of sunlight. The visible portion is distributed through large-diameter optical fibers to hybrid luminaires. (Hybrid luminaires are lighting fixtures that contain both electric lamps and fiber optics for direct sunlight distribution.) When sunlight is plentiful, the fiber optics in the luminaries, provide all or most of the light needed in an area. Unlike conventional electric lamps, they produce little heat. During times of little or no sunlight, sensor-controlled electric lamps will operate to maintain the
desired illumination level.
A second use of the hybrid lighting collector system is to provide sunlight for enhanced practical photosynthesis carbon dioxide mitigation. In this project the hybrid lighting collector system is
being used to provide sunlight to a lab-scale photobioreactor for growing algae that is being used for CO2 mitigation. The end goal of this project is to provide a photobioreactor that can be used to mitigate CO2 in fossil fuel fire power plants.
This paper will discuss the development and operating
experience to date of two hybrid lighting solar collectors installed at ORNL and at Ohio University. The first hybrid lighting collector system was tested at ORNL and then installed at Ohio University in June of 2002. A second collector of the same design was installed at ORNL in September of 2002. The Ohio University collector system has been running continually since its installation while the ORNL unit has been operated in a research mode on most sunny days. They have operated with very little human interaction and this paper will summarize the development, operating experience, collection efficiency, as well as providing information on additional data being collected as part of the system operation.
We describe a practical method for precisely aligning the optical components of a low-cost solar concentrator developed for fiber optic solar lighting applications. A two-stage alignment process, involving both mechanical and optical alignment techniques, is described which allows the tilt, centering, and focal alignment of a large parabolic primary reflector relative to a segmented planar secondary mirror to be accurately determined. The alignment strategy is well suited to optical systems utilizing large reflectors with non-referenced optical axes and non-precision surface characteristics, as is typical of many inexpensive reflectors.
A design for an optical seeker optimized for spin-stabilized projectiles is presented. Using the spin of the bullet to scan a linear photodetector array across the target field, a relatively wide field-of-regard seeker may be constructed with an adequate SNR for homing applications. The linear photodetector array is based on room-temperature quantum-well infrared photodetectors (QWIP) optimized for a wavelength of 10.6 microns. The entire seeker containing the 1 × 64-element linear photodetector array, amplifiers and signal processor/flight computer can be constructed on a single 1-cm square bonded chip-on-chip. A compact folded telescope has been designed to collect light from a CO2 laser designator to guide the projectile to the target. Details of the seeker design as well as laboratory measurements of the concept using a visible light prototype seeker will be presented.
The Spallation Neutron Source (SNS) under construction at the Oak Ridge National Laboratory (ORNL) will be the most important new neutron scattering facility in the United States. Neutron scattering instruments for the SNS will require large area detectors with fast response (< 1 microsecond), high efficiency over a wide range of neutron energies (0.1 to 10 eV), and low gamma ray sensitivity. We are currently developing area neutron detectors based on a combination of a 6LiF/ZnS(Ag) scintillator screen coupled to a wavelength-shifting fiber optic readout array. A 25 x 25 cm prototype detector is currently under development. Initial tests at the Intense Pulsed Neutron Source at the Argonne National Laboratory have demonstrated good imaging properties coupled with very low gamma ray sensitivity. The response time of this detector is approximately 1 microsecond. Details of the design and test results of the detector will be presented.
We present a simple and general method of aspheric figure metrology using a CGH null mounted in the test beam of a conventional Fizeau or Twyman-Green interferometer. A 'standard' reflective CGH is used to establish optical alignment with respect to the interferometer's spherical test beam. This alignment is then mechanically trnaferred to a custom CGH null. The accuaracy of the alignment transfer is readily verified. The test method has been modeled by raytracing and verified experimentally by testing a perforated 8 inch F/1.5 on-axis paraboloid and a 50 mm off-axis paraboloid from their centers of curvature.
Recent combinations of diffractive and refractive functions in the same optical component allow designers additional opportunities to make systems more compact and enhance performance. This paper describes a research program for fabricating hybrid refractive/diffractive components from diamond-turned molds using the bulk casting of sol-gel silica glass. We use the complementary dispersive nature of refractive and diffractive optics to render two-color correction in a single hybrid optical element. Since diamond turning has matured as a deterministic manufacturing technology, techniques previoulsy suitable only in the infrared are now being applied to components used at visible wavelengths. Thus, the marriage of diamond turning and sol-gel processes offers a cost-effective method for producing highly customized and specialized optical components in high quality silica glass. With the sol-gel casting method of replication, diamond-turned mold costs can be shared over many pieces. Diamond turning takes advantage of all of the available degrees of freedom in a single hybrid optical element: aspheric surface to elimiate spherical aberration, kinoform surface for control of primary chromatic aberration, and the flexibility to place the kinoform on nonplanar surfaces for maximum design flexibility. We will discuss the critical issues involved in designing the hybrid element, single point diamond-turning the mold, and fabrication in glass using the sol-gel process.
This paper describes measurement algorithms and control procedures that can be effectively applied to the automation of an alignment procedure for paraboloidal optical mirrors. Interferometric alignment of an off-axis paraboloidal optical mirror can be a tedious and labor- intensive process. We review a previous solution to the alignment problem that employs a corner-cube retroreflector and present a method of automating this process using an imaging interferometer coupled to a processing system that controls a set of actuators. The relevant image-processing algorithms are described, and the actuator-control system is discussed. Methods of extending this solution to the automatic alignment of other aspheric optics are explored.
A technique is described for aligning an autocollimating test of an off-axis paraboloidal segment. A corner reflector (corner-cube retroreflector) is incorporated as an alignment aid to interferometrically align a paraboloidal segment to a spherical wavefront. This alignment task is typically quite challenging and time consuming because the interferograms obtained from a partially aligned autocollimating test cannot be easily interpreted for alignment correction. The normal alignment process requires iterative cycles of adjustment, realignment, and evaluation to achieve results. The use of a corner reflector significantly reduces the time required for the alignment of a n autocollimating test because it provides images and interferograms that can easily be interpreted for alignment correction. The wide dynamic range of this alignment technique makes it applicable to a variety of alignment tasks involving paraboloidal mirrors.
Beryllium mirrors, approximately 19.8 cm x 8.8 cm in size, were designed, procured, and evaluated. The mirrors are off-axis rectangular segments of an f/1 paraboloid. These segments, which are the primary mirrors in a Cassegrainian telescope design, are lightweighted and incorporate a stress-free mounting technique which minimizes post-assembly alignment. Upon delivery, the mirrors were characterized to determine their compliance with the figure, scatter, reflectance, and dimensional specifications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.