Showing papers on "Parabolic reflector published in 2007"

Lighting device and projector

Abstract: An illuminating device includes a first light source unit emitting illumination beams with a first optical axis; a second light source unit; and two reflecting elements arranged on both sides of an optical path of the first light source unit. The reflecting element arranged on the side of the second light source unit reflects the illumination beams emitted from a substantially half region on one side in an aperture plane of the parabolic reflector of the second light source unit, towards the direction along the first optical axis. The reflecting element arranged opposite to the second light source unit reflects the illumination beams emitted from a substantially half region on the other side in the aperture plane of the parabolic reflector of the second light source unit, towards the direction along the first optical axis.

Led assembly for rear lamps in an automobile

Abstract: Various techniques are described herein for combining two or more LEDs in a single reflective cavity for a rear lamp in an automobile. The LEDs may be two or more different colors for performing different functions, such as a stop light, a turn signal, and a tail light. In one embodiment, the LEDs have side emitting lenses and are coaxially aligned in a parabolic reflector. The LEDs may be mounted facing each other or mounted in the same direction, or a combination of both. The LEDs may share a common heat sink. A second reflector may be positioned inside a larger reflector, where a first LED is mounted near the focal point of the larger reflector, and a second LED is mounted near the focal point of the inner reflector. Additional LEDs may also be mounted in either reflector and separately controlled.

Optimization of multiphoton excitation microscopy by total emission detection using a parabolic light reflector.

Abstract: Summary We have constructed a device that maximizes the probability of collecting all of the scattered and ballistic light isotropically generated at the focal spot of multiphoton excited emissions (MPE) to optimize the signal-to-noise ratio (SNR) for micro-imaging. This was accomplished by optically coupling a parabolic reflector (that surrounds the sample and top of the objective) to a pair of collimating lenses (above the sample) that redirects emitted light to a separate detector. These additional optics, combined with the objective, allow the total emission detection (TED) condition to be approached. Numerical simulations suggest an approximately 10-fold improvement in SNR with TED. Comparisons between the objective detection and TED reveal an enhancement of 8.9 in SNR (77% of predicted) for GFP-labelled brain slices and similar results for fluorescent beads. This increase in SNR can be used to improve time resolution, reduce laser power requirements/photodynamic damage, and, in certain cases, detection depth, for MPE imaging techniques.

Practical Field Alignment of Parabolic Trough Solar Concentrators

Abstract: In this paper a new technique for parabolic trough mirror alignment based on the use of an innovative theoretical overlay photographic (TOP) approach is described. The technique is a variation on methods used to align mirrors on parabolic dish systems. It involves overlaying theoretical images of the heat collection element (HCE) in the mirrors onto carefully surveyed photographic images and adjustment of mirror alignment until they match. From basic geometric principles, for any given viewer location the theoretical shape and location of the reflected HCE image in the aligned mirrors can be predicted. The TOP approach promises to be practical and straightforward, and inherently aligns the mirrors to the HCE. Alignment of an LS-2 mirror module on the rotating platform at the National Solar Thermal Test Facility (NSTTF) with the TOP technique along with how it might be implemented in a large solar field is described. Comparison of the TOP alignment to the distant observer approach on the NSTTF LS-2 is presented and the governing equations used to draw the theoretical overlays are developed. Alignment uncertainty associated with this technique is predicted to be less than the mirror slope error.

Single light source uniform parallel light curtain

Abstract: A continuous high resolution fluid level monitoring system is provided by embodiments of the present invention. This continuous high resolution fluid level monitoring system includes a unique fluid level sensor having a point light source, parabolic reflector, sensor array, and detection, processing and control system. The point light source illumines a parabolic reflector wherein the point light source is located at the focus of the parabolic reflector. The parabolic reflector reflects light from the point light source to produce a parallel light curtain. This parallel light curtain is parallel to an axis of symmetry of the parabolic reflector. The parallel light curtain illumines a chamber such as a chamber in an ophthalmic surgical device used to contain surgical fluid. The sensor array coupled to the chamber detects the parallel light curtain illuminating the chamber. The sensor array provides an output to a detection/processing/control system in order to determine the fluid level within the chamber. This optical method of determining the surgical fluid levels may be advantageous in that it prevents physical contamination of the surgical fluids.

Retro-Axial VOA Using Parabolic Mirror Pair

Abstract: This letter presents a design of a microelectromechanical systems variable optical attenuator (VOA) that employs a pair of parabolic mirrors as the retro-reflector, which has obtained a linear relationship over a 62-dB range between the attenuation (in decibels) and the mirror rotation angle (in degrees). The insertion loss measures 0.6 dB thanks to the three-dimentional optical coupling design. The linearity comes from the simultaneous shift and defocus of the laser beam. Compared with the conventional coaxial and cross-axial VOAs, such retro-axial design has the two fibers arranged on the same side and thus facilitates the use of standard packaging formats

Two-stage solar concentrating system

Abstract: An improved solar concentrating system (100) uses a two-stage arrangement of mirrors wherein the rays of the sun are reflected and concentrated to a point focus. The solar concentrator ( 100) may be used to increase the temperature of a substance such as metal, for use in a variety of applications including the melting of metals in a foundry furnace. The solar concentrating system (100) comprises at least two single-curved parabolic mirrors (10, 20) connected in an operable arrangement. The rays of the sun are reflected from a first single-curved parabolic mirror ( 10) to a second single-curved parabolic mirror (20). The plane of symmetry of the second single-curved parabolic mirror is arranged substantially orthogonal to the plane of symmetry of the first single-curved parabolic mirror thereby concentrating the rays of the sun to a point focus.

Phosphor light source, its manufacturing method, light source device, and lighting system

Abstract: PROBLEM TO BE SOLVED: To materialize a small phosphor light source having high light intensity without increasing light intensity of exciting light. SOLUTION: This phosphor light source is disposed in the vicinity of the focus of a rotating parabolic mirror. The phosphor light source emits fluorescence with the exciting light radiated from the rotation axis direction of the rotating parabolic mirror, and has a base substance 70 and a phosphor part 80. The exciting light irradiated surface of the phosphor part 80 is formed into a non-planar shape having microscopic projecting and recessed parts. COPYRIGHT: (C)2007,JPO&INPIT

Off-axis mirror based optical system design for circularization, collimation, and expansion of elliptical laser beams

Abstract: In this paper, we present two optical system design methods for beam circularization, collimation, and expansion of semiconductor laser output beam for possible application in LIDAR systems. Two different optical mirror systems are investigated: an off-axis hyperbolic/parabolic mirror system and an off-axis parabolic mirror system. Equations specific to these mirror systems are derived and computer package programs such as ZEMAX and MATLAB are used to simulate the optical designs. The beam reshaping results are presented.

Multi-reflector mechanism for a led light source

Abstract: A multi-reflector mechanism for a LED light source which comprises a LED light source, an outer parabolic reflector, an inner parabolic reflector and a sliding switch, wherein the inner reflector is disposed within the outer reflector with the focuses of both reflectors being different points on a common axis, and the focus of the outer reflector being the highest one nearest to the plane of the opening of the outer reflector; and the LED light source is disposed within the inner reflector and protrudes out from the vertex of the inner reflector and is coaxially and adjustably disposed at or near the focus of the inner reflector or of the outer reflector, and the light emitting angle of the LED light source is larger than the angle formed by the two points on the edge of the opening forming the diameter thereof and the focus of the inner reflector. The present invention can emit a bright, sharp and wide spot of light at a shorter distance and, as an alternative by means of a sliding switch, a bright, sharp and small spot of light at a farther distance.

Ray-space acquisition system of all-around convergent views using a rotation mirror

Abstract: In this paper, we introduce a new Ray-Space acquisition system that we developed. The Ray-Space method records the position and direction of rays that are transmitted in the space as ray data. The composition of arbitrary viewpoint images using the Ray-Space method enables the generation of realistic arbitrary viewpoint picture. However, acquisition of a dense Ray-Space is necessary to apply the Ray-Space method. The conventional method of acquiring the ray data uses a camera array. This method enables capturing a dynamic scene. To acquire a dense Ray-Space by this method, however, interpolation is necessary. There is another common method for ray data acquisition, which uses a rotating stage. This method enables capturing images without requiring interpolation. However, only static scenes can be captured by this method. Therefore, we developed a new Ray-Space acquisition system. This system uses two parabolic mirrors. Incident rays that are parallel to the axis of a parabolic mirror gather at the focus of the parabolic mirror. Hence, rays that come out of an object that is placed at the focus of the lower parabolic mirror gather at the focus of the upper parabolic mirror. Then, the real image of the object is generated at the focus of the upper parabolic mirror, and a rotating aslope mirror scans rays at the focus of the upper parabolic mirror. Finally, the image from the aslope mirror is captured by a camera. By using this system, we were able to acquire an all-around image of an object.

Optimization of 200-800 MHZ eleven feed for GMRT

Abstract: This paper discusses in brief the electrical design of the Eleven feed for the parabolic reflector antennas of Giant Meterwave Radio Telescope (GMRT-India) optimized for 200 to 800 MHz bandwidth. Paper also gives the comparison between the simulated and measured antenna input reflection coefficient and radiation patterns. The measured S11 of the feed is less than -8 dB and the computed total aperture efficiency including the mismatch losses, is better than -3.2 dB over desired bandwidth for the reflector antennas of GMRT having 62.5° of half subtended angle. (6 pages)

Development of micro mirror solar concentrator

Abstract: The low cost micro facet solar concentrator is proposed. Large number of small flat mirrors is situated at parabolic surface to approximate large parabolic mirror. Low cost commercial flat mirrors can be used for manufacturing of such concentrator. Geometrical analysis show that this concentrator will have concentration rate of some hundreds suns. Rough estimations show that the cost of the concentrator should be approximately $ 55 per square meter of concentrator surface.

Circle of Least Confusion of a Spherical Reflector

Abstract: A simple, tractable equation is provided for determining the size and location of the circle of least confusion of a concave spherical reflector. This method is exact for the object at infinity and with wave effects neglected. Designers of large radius Arecibo-like telescopes, both radio and optical, with symmetrical, spherical primaries should find the method useful. The mathematical results are valid for apertures with an angle of incidence up to 45°. Comparisons of the location of the disk of least confusion with longitudinal spherical aberration and the radius of the disk with transverse spherical aberration are presented.

Grating monochromator/spectrograph

Abstract: A monochromator for use in a spectrograph admits light from an aperture to a primary reflector (preferably an off-axis parabolic mirror) which collimates the input light with low aberration and directs it to a diffraction grating. The component wavelengths of the input light are then directed to first and second secondary reflectors (preferably spherical or toroidal mirrors), which are chosen to cooperatively focus the component wavelengths in ordered bands across an array detector while each at least substantially cancels the effects of any aberrations introduced by the other. By choosing optical elements which supply the grating with input light with low aberration, and then choosing optical elements which receive the component wavelengths from the grating and which offset any aberrations introduced by the other receiving optical elements, wavelength resolution at the detector can be enhanced.

High resolution x-ray microscope

Abstract: The authors present x-ray images of grid meshes and biological material obtained using a microspot x-ray tube with a multilayer optic and a 92-element parabolic compound refractive lens (CRL) made of a plastic containing only hydrogen and carbon. Images obtained using this apparatus are compared with those using an area source with a spherical lens and a spherical lens with multilayer condenser. The authors found the best image quality using the multilayer condenser with a parabolic lens, compared to images with a spherical lens and without the multilayer optics. The resolution was measured using a 155-element parabolic CRL and a multilayer condenser with the microspot tube. The experiment demonstrates about 1.1μm resolution.

Condensing and collecting optical system using parabolic reflectors or a corresponding ellipsoid/hyperboloid pair of reflectors

Abstract: not available for EP1196717Abstract of corresponding document: WO0102774A condensing and collecting optical system includes a collimating reflector (30) and focusing reflector (40). The collimating reflector (30) includes a portion of a paraboloid of revolution having a focal point (36) and a optical axis (38). The focusing reflector (40) includes a paraboloid of revolution having a focal point (46) and an optical axis (48). A source of the electromagnetic radiation (20) placed at the focal point (36) of the collimating reflector (30) produces a collimated beam of radiation. The focusing reflector (40) is positioned so as to receive the collimated beam and focus it toward a target (60) positioned at the focal point (46) of the focusing reflector (40).

Nonlinear Structural Analysis Methodology and Dynamics Scaling of Inflatable Parabolic Reflector Antenna Concepts

Abstract: Ultra-light weight and ultra-thin membrane inflatable antenna concepts are fast evolving to become the state-of-the-art antenna concepts for deep-space applications. NASA Langley Research Center has been involved in the structural dynamics research on antenna structures. One of the goals of the research is to develop structural analysis methodology for prediction of the static and dynamic response characteristics of the inflatable antenna concepts. This research is focused on the computational studies to use nonlinear large deformation finite element analysis to characterize the ultra-thin membrane responses of the antennas. Recently, structural analyses have been performed on a few parabolic reflector antennas of varying size and shape, which are referred in the paper as 0.3 meters subscale, 2 meters half-scale, and 4 meters full-scale antenna. The various aspects studied included nonlinear analysis methodology and solution techniques, ways to speed convergence in iterative methods, the sensitivities of responses with respect to structural loads, such as inflation pressure, gravity, and pretension loads in the ground and in-space conditions, and the ultra-thin membrane wrinkling characteristics. Several such intrinsic aspects studied have provided valuable insight into evaluation of structural characteristics of such antennas. While analyzing these structural characteristics, a quick study was also made to assess the applicability of dynamics scaling of the half-scale antenna. This paper presents the details of the nonlinear structural analysis results, and discusses the insight gained from the studies on the various intrinsic aspects of the analysis methodology. The predicted reflector surface characteristics of the three inflatable ultra-thin membrane parabolic reflector antenna concepts are presented as easily observable displacement fringe patterns with associated maximum values, and normal mode shapes and associated frequencies. Wrinkling patterns are presented to show how surface wrinkle progress with increasing tension loads. Antenna reflector surface accuracies were found to be very much dependent on the type and size of the antenna, the reflector surface curvature, reflector membrane supports in terms of spacing of catenaries, as well as the amount of applied load.

High-resolution, flat-field, plane-grating, f/10 spectrograph with off-axis parabolic mirrors.

Abstract: A high-resolution, flat-field, plane-grating, f/10 spectrometer based on the novel design proposed by Gil and Simon [Appl. Opt. 22, 152 (1983)] is demonstrated. The spectrometer design employs off-axis parabolic collimation and camera mirrors in a configuration that eliminates spherical aberrations and minimizes astigmatism, coma, and field curvature in the image plane. In accordance with theoretical analysis, the performance of this spectrometer achieves a high spatial resolution over the large detection area, which is shown to be limited only by the quality of its optics and their proper alignment within the spatial resolution of a 13 μm×13 μm pixelated CCD detector. With a 1500 lines/mm grating in first order, the measured spectral resolving power of λ/Δλ=2.5(+/-0.5)×104 allows the clear resolution of the violet Ar(I) doublet at 419.07 and 419.10 nm.

Illuminating device and projector

Abstract: An illuminating device includes a first light source unit emitting illumination beams with a first optical axis; a second light source unit; and two reflecting elements arranged on both sides of an optical path of the first light source unit. The reflecting element arranged on the side of the second light source unit reflects the illumination beams emitted from a substantially half region on one side in an aperture plane of the parabolic reflector of, the second light source unit, towards the direction along the first optical axis. The reflecting element arranged opposite to the second light source unit reflects the illumination beams emitted from a substantially half region on the other side in the aperture plane of the parabolic reflector of the second light source unit, towards the direction along the first optical axis.

Spherical aberration correction decelerating lens, spherical aberration correction lens system, electron spectrometer, and photoelectron microscope

Abstract: A spherical aberration correction decelerating lens corrects a spherical aberration occurring in an electron beam or an ion beam (hereinafter, referred to as “beam”) emitted from a predetermined object plane position with a certain divergence angle, and said spherical aberration correction decelerating lens comprises at least two electrodes, each of which is constituted of a surface of a solid of revolution whose central axis coincides with an optical axis and each of which receives an intentionally set voltage applied by an external power supply, wherein at least one of the electrodes includes one or more meshes (M) which has a concaved shape opposite to an object plane (P0) and which is constituted of a surface of a solid of revolution so that a central axis of the concaved shape coincides with the optical axis, and a voltage applied to each of the electrodes causes the beam to be decelerated and causes formation of a decelerating convergence field for correcting the spherical aberration occurring in the beam. This makes it possible to provide a spherical aberration correction decelerating lens which converges a beam, emitted from the sample and having high energy and a large divergence angle, onto an image plane.

Raman probe configured for low-concentration measurements

Abstract: Raman measurement apparatus optimized for gaseous and other low-concentration samples includes a focusing objective that uses only first-surface mirrors instead of lenses, thereby dramatically reducing background noise. In the preferred embodiment, the focusing and collimation functions performed by the objective section are performed by an off-axis parabolic mirror. A spherical first-surface mirror opposing the parabolic mirror re-images the counter-propagating beam back through the same focus for re-collimation by the parabolic mirror. A probe-head section operative to generate the counter-propagating beam has substrates and surfaces arranged such that the excitation beam does not pass through any substrates after it is filtered by the bandpass coating, thereby further decreasing background signals. Additionally, when the objective section includes the opposing spherical mirror, the excitation beam is collected substantially in its entirety and neutralized out of the collection path by the probe-head section.

A closed parabolic trough solar collector

Abstract: Parabolic trough[1] is the most mature technology for large scale exploitation of solar energy. Several power plants based on this technology have been operational for years, and more are being built. However, the current technology suffers from a too high installation cost. This high cost makes it very hard to compete economically with fossil energy without government subsidies, compromising the perspective of using this technology to solve the problem of CO2 emissions. In this article, we study a design of closed-box parabolic trough concentrated solar collector. By accepting an optical loss of a few percentages due to reflections by the cover, this design offers several advantages over the current open model, in particular a potential of significant cost reduction. In Section 1, we first make a rapid study of the actually dominant open parabolic trough design, to locate its main sources of cost, the problems facing it, and the potential of improvement. The basic design of the closed collector is given in Section 2. It is a hermetic box with a transparent cover and the parabolic reflector forming the back. And the tracking of the sun is done by rotating (swinging) the box around the receiver tube which is fixed with respect to the ground. The advantages include a geometrically rigid structure leading to a considerable simplification of the construction (hence a reduced cost), and the protection of almost all optic surfaces, in particular the reflecting mirror (hence a lower mirror cost without durability problems). Moreover, we can now adopt a tilted installation that reduces the seasonal variation of the output and improves the capacity factor of the whole system. The closed-box model and the subsequent size reduction bring about several technical issues that must be dealt with. The most important one is the receiver tube that absorbs the solar energy and transforms it to heat to be carried out by a fluid. The current permanently sealed Dewar construction is not suitable for the smaller collectors, due to probable high price and high thermal losses that

Non-dispersive infrared gas sensor with light concentration means

Abstract: A non-dispersive infrared gas sensor with a light concentration unit is provided to improve the accuracy of a device by detecting a small amount of gas by maximally concentrating lights using a light concentration unit. A non-dispersive infrared gas sensor with a light concentration unit includes an optical cavity(20) and a reflecting mirror(11). The reflecting mirror has a main reflecting mirror(21) in a shape of a parabola, a sub-reflecting mirror(31) in a shape of parabola, and a parabolic mirror(22). The sub-reflecting mirror is formed on one end portion of the main reflecting mirror in a long axis direction as one body. The parabolic mirror is formed on the other end side as one body to encompass a light source(12). The light source is formed on a focus of the parabolic mirror. An optical barrel(33) is formed on the other end of the main reflecting mirror.

Calculation of the illuminance distribution in the focal spot of a focusing system taking into account aberrations in this system and divergence of a focused laser beam

Abstract: The dependence of the focal-spot size of a 'deep' parabolic mirror reflector on the laser-beam divergence is analysed by the method of elementary reflections. The dependence of the focal-beam diameter of an ideal focusing optical system on the laser-beam parameters is described. The expression is obtained for calculating the illumination distribution in the focal spot of a 'deep' mirror reflector which takes into account both aberrations and light-gathering power of the reflector and the divergence of a focused laser beam.

Surface gradient integrated profiler for x-ray and EUV optics: self calibration method of measured position for an off-axis parabolic mirror (f=150mm) measurement

Abstract: A new ultra-precision profiler has been developed in order to measure such as asymmetric and aspheric profiles. In the present study, the normal vectors at each points on the surface are determined by the reflected light beam goes back exactly on the same path as the incident beam. The surface gradients at each point are calculated from the normal vector and the surface profile is obtained by integrating the gradient. The measuring instrument was designed according to the above principle of the measuring method. In the design, four ultra-precision goniometers were applied to the adjustment of the light axis for the normal vector measurement. In the measuring instrument, the angle-positioning resolution and accuracy of each goniometer are respectively 1.8x10 -8 rad and 2x10 -7 rad. A coaxial with an off-axis parabolic mirror has been developing for applying as an optical cavity. The most important engineering technique is to measure the profile of the reflective surface with sub nanometer. The present measuring instrument is evaluating to have capability to the surface measuring accuracy with nanometer for such parabolic mirror profile measurement. A coaxial off-axis parabolic mirror with 150 mm focal length has been polished. The outside and inside diameter of the mirror is 360 mm and 258 mm respectively. The thickness of the coaxial direction is 50 mm. The focal point is located on the center of the coaxial and the center of the coaxial direction of the mirror. The profile measurement such a mirror has been demonstrated. Specially, self calibration method for increasing the measured position accuracy from measured data is discussed.

WIDE RANGE DETECTOR USING PARABOLIC CYLINDRICAL MIRROR FOR THz APPLICATIONS

Abstract: A new, wide-band, high-speed and high-sensitivity THz detector has been developed. The prototype detector consists of a parabolic cylindrical mirror, a long wire antenna and a Schottky barrier diode. Direct detection measurements have shown a stable sensitivity of 150 ± 50 V/W for 1–2 THz without any adjustments. The long wire antenna was fixed at the focus of parabolic cylindrical mirror then it has been realized less operation steps, easy coupling to the external THz signals and a dramatic enhancement in the practicality of this system. The optically polished mirror and frosted surface one showed comparable sensitivities, thus easy polishing and less cost mirror fabrication can be applied for this system. The radiation pattern showed a maximum radiation angle of approximately 23° with its dominant main lobe, which was attributed to the wire antenna character and confirmed good agreements with classical antenna theory.

Illumination system with compound parabolic retro-reflector for single LCOS panel projection display

Abstract: In this paper, a new illumination system with ultra high performance (UHP) lamp is proposed for projection display. Parabolic reflector (PR) and compound parabolic retro-reflector (CPR) were jointly used to collect and collimate the light generated from UHP lamp. A polarization converter system (PCS) was used to increase the light efficiency of the projection display system. A beam transformer between PCS and 2f imaging systems was directly used to make the illumination meet the requirement of projection display system. With the consideration of the loss of reflection, the light efficiency in this projection display system was estimated to be 15.6%.

Solar collecting plate and truss for trough-focus solar collector

Abstract: A heat collection plate and a quilting frame for groove focusing heat collector are disclosed. The heat collection plate is composed of a parabolic mirror face plate and a heat collector pipe arranged on the focal point of the parabolic mirror face, wherein the parabolic mirror face plate is fixed on the quilting frame through a support, and the support is bended to parabolic type. The quilting frame is composed of a main bar and a small bar which are connected to a triangle. The utility model has the advantages of rotational, reasonable structure, high strength, good performance of wind resistance, bending resistance and torsion resistance, high heat-collecting efficiency, large power and following the solar, which satisfies the demanding heat temperature of the absorbing air conditioner.