Showing papers on "Beam splitter published in 1999"

The Fermionic Hanbury Brown and Twiss Experiment

Abstract: A Hanbury Brown and Twiss experiment for a beam of electrons has been realized in a two-dimensional electron gas in the quantum Hall regime. A metallic split gate serves as a tunable beam splitter to partition the incident beam into transmitted and reflected partial beams. In the nonequilibrium case the fluctuations in the partial beams are shown to be fully anticorrelated, demonstrating that fermions exclude each other. In equilibrium, the cross-correlation of current fluctuations at two different contacts is also found to be negative and nonzero, provided that a direct transmission exists between the contacts.

Hanbury brown and twiss-type experiment with electrons

Abstract: Fermion anti-bunching was directly observed by measuring the cross-covariance of the current fluctuations of partitioned electrons. A quantum point contact was used to inject single-mode electrons into a mesoscopic electron beam splitter device. The beam splitter output currents showed negative cross-covariance, indicating that the electrons arrived individually at the beam splitter and were randomly partitioned into two output channels. As the relative time delay between the outputs was changed, the observed ringing in the cross-covariance was consistent with the bandwidths used to monitor the fluctuations. The result demonstrates a fermion complement to the Hanbury Brown and Twiss experiment for photons.

Optical head device

Abstract: It is provided an optical head device which includes: a light source; an objective lens, configured to converge light emitted from the light source to an information recording surface of an optical disk; a beam splitter, configured to deflect returned light reflected by the optical disk into an optical path which is different from an optical path of the light emitted from the light source; a photo detector, configured to detect the returned light deflected by the beam splitter; and a depolarizing element, disposed on an optical path between the beam splitter and the photo detector, and configured to cause the returned light to transmit through while reducing a degree of polarization of the returned light.

Projection display system for reflective light valves

Abstract: A projection display system for reflective light valves includes a light source for generating a light beam having RGB light components, wherein the red light component is p-polarized and the green and blue light components are s-polarized; a reflector structure having plural polarizing beam splitter and dichroic filters therein, wherein each PBS and DF reflects a preselected light component and transmits a different preselected light component, and a LCD panel for generating a light-component-specific image associated with each light component; and a projection lens for projecting an image combined from the light-component-specific images from the LCDs; wherein a light-component-specific image passes through one and only one PBS and through one and only one DF between the LCD and the projection lens.

Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter

Abstract: An optical imaging system including a wide-angle Cartesian polarizing beam splitter, light valve illumination optics having an f/# <= 25, and at least one reflective light valve The Cartesian polarizing beam splitter (PBS) has a structural orientation defining fixed polarization axes The use of a Cartesian PBS allows the development of systems using curved PBS that provide higher light output and/or replace or augment other optical components By recognizing and advantageously applying properties of wide-angle Cartesian polarizers, the present invention discloses a high-efficiency optical imaging system capable of functioning at f/#'s equal to or below f/25 while maintaining a contrast ratio of at least 1200 to 1, or, more preferably, 150 to 1 in a projection system configuration

Instrument for monitoring polymerase chain reaction of DNA

Abstract: An optical instrument monitors PCR replication of DNA in a reaction apparatus having a temperature cycled block with vials of reaction ingredients including dye that fluoresces in presence of double-stranded DNA. A beam splitter passes an excitation beam to the vials to fluoresce the dye. An emission beam from the dye is passed by the beam splitter to a CCD detector from which a processor computes DNA concentration. A reference strip with a plurality of reference emitters emit reference beams of different intensity, from which the processor selects an optimum emitter for compensating for drift. Exposure time is automatically adjusted for keeping within optimum dynamic ranges of the CCD and processor. A module of the beam splitter and associated optical filters is associated with selected dye, and is replaceable for different dyes.

Broad band wire grid polarizing beam splitter for use in the visible wavelength region

Abstract: A wire grid polarizing beam splitter has a generally parallel arrangement of thin, elongated elements which interact with electromagnetic waves of a source light beam to generally transmit or pass light of one polarization, and reflect light of the other polarization. The arrangement of elements has a throughput greater than approximately 50%, and an extinction greater than approximately 100. In addition, the arrangement of elements has a period less than approximately 0.21 μm, and a width to period ratio of between approximately 0.25 to 0.76. The elements have a thickness of between approximately 0.05 to 0.5 μm.

Broadband form birefringent quarter-wave plate for the mid-infrared wavelength region.

Abstract: We discuss the design, fabrication and optical performance of a broadband form-birefringent quarter-wave plate for the 3.5 to 5 aem wave-length region. Rigorous coupled wave analysis (RCWA) was used to design the requisite subwavelength grating for silicon substrates in ambient air. Fabricated samples yield a measured phase retardation of 89o to 102o over the desired wavelength range.

Micromachined free-space integrated micro-optics

Abstract: The surface-micromachining technique has been employed to fabricate novel three-dimensional micro-optical elements for free-space integrated optics. The optical axes of these optical elements are parallel to the substrate, which enables the entire free-space optical system to be integrated on a single substrate. Microscale Fresnel lenses, mirrors, beam splitters, gratings, and precision optical mounts have been successfully fabricated and characterized. In addition, micropositioners such as rotary stages and linear translational stages are monolithically integrated with the optical components using the same surface-micromachining process to provide on-chip optical alignment or optomechanical switching. Self-aligned hybrid integration with semiconductor edge-emitting lasers and vertical cavity surface-emitting lasers are also demonstrated for the first time. This new free-space micro-optical bench (FSMOB) technology could significantly reduce the size, weight, and cost of most optical systems, and could have a significant impact on optical switching, optical sensing and optical data-storage systems as well as on the packaging of optoelectronic components.

Efficient two-panel projection system employing complementary illumination

Abstract: An imaging system, comprising a broadband unpolarized white light source ( 81 ), a polarization converter system for converting polarization axes of unpolarized white light into a substantially single polarization axis, to produce a beam of polarized light, a selective polarization filter ( 82 ), adapted to selectively rotate a polarization axis of a selected spectral band of light of the with respect to remaining polarized light based on a control signal ( 119 ), a polarized beam splitter ( 84 ), for separating light having a the substantially single polarization axis from light having a rotated polarization axis, a pair of electro-optic spatial light modulators ( 86, 89 ), disposed along a path of light within the spectral band and a path of remaining light outside the spectral band, respectively, and being adapted to modulate an image therein, and a polarized beam splitter ( 88 ), for recombining modulated light from the pair of light modulators. In a preferred embodiment, the selective polarization filter ( 82, 72 ) is divided into a plurality of regions ( 70, 71 ), each adapted to independently and selectively rotate a polarization axis of a selected spectral band of light of the with respect to remaining polarized light.

Observation of Four-Photon Interference with a Beam Splitter by Pulsed Parametric Down-Conversion

Abstract: When four photons arrive at a beam splitter, two from each side, a four-photon, six-path interference effect occurs to yield a sixfold enhancement of the probability for all four photons to exit together from the beam splitter. We produce the four-photon state by using the stimulated emission process in a pulsed parametric down-conversion and measure the probability for all four photons to exit from one side of the beam splitter. The observed enhancement factor is in good agreement with a multimode treatment of pulsed down-conversion.

Observation of quantum accelerator modes

Abstract: We have realized a quantum accelerator mode using a system consisting of ultracold cesium atoms falling through a pulsed standing wave of off resonant light. We present a picture of this system based on diffraction and show that the effect arises from the application of blazed matter wave diffraction gratings. The implications of our results for quantum chaos and the prospect of constructing a large angular separation matter wave beam splitter are discussed.

Optical tomography based on spectrum interference and optical surface profile measuring apparatus

Abstract: PROBLEM TO BE SOLVED: To enable optical surface profile measurement and optical section image photographing to transparent, translucent and opaque objects, by using an interferometer analyzing the intensity of a light appearing by interference of a luminous flux from a measuring arm and a reference arm, with a spectroscope. SOLUTION: A light outputted from a light source 1 is divided into a measurement light 3 and a reference light 4 by a beam splitter 2. The measurement light 3 is turned toward a lens 6 by a rotary mirror 5 and converged in an object 7 to be measured. A reflected light returns to the beam splitter 2, and travels toward an interferometer outlet where a spectrophotometer constituted of a dispersion prism 3, a spectroscope 9 and a detection array 10 is installed. The spectrophotometer records the intensity of a light reflected from the whole irradiation body deep part at a light position X, with a function of wavelength excluding the reference light. By moving a reference mirror 11 along the optical axis with a piezoelectric adjusting unit 12, phase measurement is enabled while using discontinuous adjusting function of the reference mirror 11. COPYRIGHT: (C)1999,JPO

A transmission polarizing beam splitter grating

Abstract: We present the design, fabrication, and test of a polarizing beam splitter grating for operation at 633 nm under a angle of incidence. This component is compact and its fabrication is reproducible enough to be integrated in optical reconfigurable interconnect systems. For TE polarization, the incident beam is undeflected whereas TM beams exhibit a deviation. We used electromagnetic theory to optimize the performance of the polarizing beam splitter grating. We employed direct electron beam writing and reactive ion etching to fabricate a polarizing beam splitter etched in a layer deposited on a glass substrate. Experimental results show that diffraction efficiencies more than 80% and extinction ratios above 100 are manufacturable with present technology.

Optical system for a scanning fluorometer

Abstract: A method and apparatus for determining the fluorescence, luminescence, or absorption of a sample is provided. The sample may either be contained within a cuvette or within one or more sample wells within a multi-assay plate. A combination of a broadband source, a monochromator, and a series of optical filters are used to tune the excitation wavelength to a predetermined value within a relatively wide wavelength band. A similar optical configuration is used to tune the detection wavelength. An optical scanning head assembly is used that includes mirrored optics for coupling the excitation source to the sample and the emitted light to the detector. An elliptical focussing mirror is used to magnify and focus the light projected from an optical fiber coupled to the source subassembly onto the sample. A portion of the source light is reflected by a beamsplitter onto a reference detector used to monitor the output of the source. The light from the elliptical mirror passes through an aperture in a second elliptical mirror prior to impinging upon the sample. The light emitted by the sample within the sample well is reflected by the second elliptical mirror and imaged onto the entrance aperture of an optical fiber coupled to the detector subassembly. The optical axes of both mirrors are slightly offset from the sample well normal. The mirror offset minimizes the amount of light reflected from the meniscus of the sample or the bottom surface of the sample well that enters the detection subassembly.

Luminaire having beam splitters for mixing light from different color ' LEDs

Abstract: Apparatus for mixing light from discrete LED light sources utilizes beam splitters which each have a semi-reflective layer which partially transmits and partially reflects light of any wavelength incident thereon. Each semi-reflective layer is situated in a transparent prismatic black between reflective surfaces on parallel outside faces of the block so that two parallel input beams are mixed and transmitted as two parallel mixed beams of like color. For a square array of light sources, a first mixing stage consists of two such prismatic blocks arranged side-by-side, and a second mixing stage consists of two such prismatic blocks arranged side-by-side and rotated 90 degrees to the first stage. The second stage is arranged to receive a square array of mixed beams and produces four identical output beams. The colors of the light sources are chosen so that all output beams are white.

Grazing incidence interferometer and method

Abstract: A two-beam interferometer illuminates a sample surface with light at grazing incidence angles for the purpose of analyzing a surface characteristic such as surface topography. The interferometer includes a diffractive-optic beam splitter, which separates an incoming light beam into measurement and reference beams and a diffractive-optic beam combiner, which produces an output beam by interfering portions of the reference beam with reflected portions of the measurement beam. Those portions of the reference wavefront and the measurement wavefront that interfere originate from substantially the same portion of the initial illumination wavefront.

Novel laser controlled variable matter wave beamsplitter.

Abstract: We demonstrate a novel variable beam splitter using a tripod-linkage of atomic states, the physics of which is based on the laser control of the non-adiabatic coupling between two degenerate dark states. This coupling and the splitting ratio is determined by the time delay of the interaction induced by two of the laser beams.

Modeling the responsivity and self-emission of a double-beam Fourier-transform infrared interferometer

Abstract: A modeling study aimed at characterizing the radiometric properties of a double-beam Fourier-transform infrared interferometer is presented. Measurements showed that the two responsivities associated with each interferometer channel are different in certain spectral regions. This anomaly was attributed to a dissymmetry between the optical transmissions of the two plates that form the beam splitter. This dissymmetry is primarily responsible for the instrument residual emission. A secondary cause of residual emission is attributed to the relative alignment of the two input optics. Both effects were taken into account in a model that gives the instrument residual emission in terms of the beam splitter temperature. Actual results indicate that in the 7-14-microm window the instrument residual emission can be modeled with an absolute radiometric error smaller than 0.5 K (blackbody at 290 K). The model was used to develop an automatic calibration procedure that yields radiance errors smaller than 0.05 microW/cm(2) sr cm(-1) in the 7-14-microm band. The radiometric stability of the interferometer was analyzed.

Solid state based illumination source utilizing dichroic reflectors

Abstract: A light source having emissions in a plurality of spectral bands. The simplest light source according to the present invention is constructed from first and second light sources and a dichroic beam splitter. The first and second solid state light sources emit light in first and second bands of non or only partially-overlapping wavelengths. The dichroic beam splitter combines light from the first and second solid state light sources by passing light in the first band while reflecting light in the second band to generate light having a spectral content in the first and second bands. The solid state light sources are preferably arrays of LEDs, VCSELs, or edge emitting semiconductor lasers. A light source having improved radiance in the green region of the spectrum can be constructed by utilizing first and second solid state light sources that emit in different bands in the green portion of the spectrum. A white light source can be constructed by utilizing a third solid state light source and a second dichroic beam splitter and by choosing the emission bands of the light sources such that light leaving the second dichroic beam splitter is perceived as white by an observer when all three solid state light sources are emitting light. This light source has a radiance that is higher than the radiance of each individual solid state light source.

Display and camera device for videophone and videophone apparatus

Abstract: A display and camera device for a videophone comprises a liquid crystal display for displaying a picture, a camera such as a CCD sensor or a CMOS sensor, a free-form surface prism, and a prism for guiding light to the camera. The free-form surface prism has a concave reflector for optically enlarging a picture displayed on the display. A beam splitter is provided on a bonded surface between the free-form surface prism and the prism. The beam splitter is designed to reflect some of light beams from the display toward the reflector and transmit some of light beams from the reflector. A camera-system optical path extending from the camera is aligned with a display-system optical path extending from the display within the free-form surface prism and the outside space.

Quantum cryptographic communication channel based on quantum coherence

Abstract: A quantum cryptographic communication channel having: a light source; a reflector; first and second sources each capable of generating a pair of photons emitted in the form of signal and idler light beams when energized by the light source, the first and second sources being arranged relative to each other such that the idler beam from the first source is incident upon the second source and aligned into the idler beam of the second source and the signal beams are directed by the reflector to converge upon a common point; a light modulator for changing the phase of the idler beam from the first source between first and second phase settings before being incident upon the second source; a controller for controlling the timing of the phase change from the first phase setting to the second phase setting; first and second detectors for detecting the incidence of the signal beams from the first and second sources; and a beam splitter disposed at the common point for directing the signal beams to the first detector when the phase of the idler beam from the first source has the first phase setting and to the second detector when the phase of the idler beam from the first source has the second phase setting.

Polarization dynamics in vertical-cavity surface-emitting lasers with optical feedback: experiment and model

Abstract: We study the polarization-resolved dynamics of a vertical-cavity surface-emitting laser with mode-matched and polarization-preserving optical feedback. The total power can display low-frequency fluctuations, which are associated with drops in power of the dominant linearly polarized mode and with bursts of power of the depressed mode. However, for most parameter values the vertical-cavity surface-emitting laser output does not display low-frequency fluctuations, although antiphase dynamics between the two linear polarization components has been found. A theoretical model that includes all reflections in the external cavity with a minimum computational cost is developed.

Soft-x-ray laser interferometry of a plasma with a tabletop laser and a Lloyd's mirror.

Abstract: Interferometry using optical lasers is a powerful technique for the diagnostics of plasmas that provides time-resolved two-dimensional maps of the electron density. However, free‐free absorption and refraction of the probe beam limit the maximum electron density, plasma size, and plasma density gradients that can be probed with optical wavelengths. The development of soft-x-ray lasers has opened the possibility of extending plasma interferometry to shorter wavelengths, significantly expanding the range of plasma parameters that can be probed. Recently, a 15.5-nm Ne-like Y laser pumped by the Nova laser at Lawrence Livermore National Laboratories was used in combination with a skewed Mach‐Zehnder interferometer to probe very high-density laser-created plasmas. 1,2 The amplitude-division interferometer used in those pioneering experiments was implemented by use of thin multilayer beam splitters and multilayer-coated mirrors developed for that wavelength. The advent of gain-saturated discharge-pumped tabletop soft-x-ray lasers 3,4 and the development of several saturated 5 or nearly saturated 6,7 soft-x-ray lasers pumped by relatively compact optical lasers will allow the probing of a great variety of dense plasmas. However, multilayer beam splitters cannot be developed for the wavelengths corresponding to some of these lasers at present, owing to the lack of materials with adequate optical constants. Alternatively, amplitude-division interferometers based on diffraction gratings 8 and wavefront-division interferometers 9,10 have been discussed.

Optical polarization sensing apparatus and method

Abstract: An integrated polarization sensing apparatus and method uses a self-homodyne detection scheme to provide required sensitivity for numerous applications, such as glucose concentration monitoring, without the need for expensive, bulky components. The detection scheme is implemented by splitting a polarized laser beam with a polarization beam splitter into a P wave component and an S wave component, phase modulating the P wave component and recombining the two components. The polarization of the combined optical beam is then rotated slightly by the variable to be monitored, such as by passing the beam through a glucose solution. Finally, the beam is passed onto a photodetector that generates a signal that is proportional to the polarization rotation angle. This device has the advantage of employing optical components, including polarizing beam splitters, phase modulators and lenses, that can all be fabricated on a single silicon chip using MEMS technology so that the device can be made compact and inexpensive.

High average power fiber laser system with high-speed, parallel wavefront sensor

Abstract: A high average power fiber-laser system comprises a master oscillator for generating a primary laser signal; a beam splitter array for splitting the primary laser signal into N secondary laser signals; an optical frequency shifter for shifting the frequency of the primary laser signal; a phase modulator array for providing phase compensation of the N secondary laser signals; N single-mode dual clad fiber amplifiers for amplifying the N secondary laser signals and generating an output beam; a beam sampler for sampling the wavefront of the output beam, defining an array of sampled signals; means responsive to the array of sampled signals for interferometrically combining the array of said sampled signals and the shifted primary laser signal into an array of heterodyne optical signals, each having a phase that corresponds to the state of phase of the array of sampled signals; and means responsive to the array of heterodyne optical signals for providing a plurality of feedback signals to the phase modulator array that are linearly proportioned to the state of phase over at least one wave to provide phase compensation of the secondary laser signals. This includes digital dividers for dividing electrical signals by a selected integer and an exclusive OR gate for providing a pulse train having a duty cycle that reflects the phase to be compensated.

Method and system for imaging an object with a plurality of optical beams

Abstract: A diffracting beam splitter splits an optical beam. The resulting beams are swept over an object by a beam deflector. The beams are mechanically scanned transverse to the beam deflection direction. A position sensitive device receives light reflected from the incident beams and a three dimensional profile of the object is produced.

Projection display apparatus

Abstract: A projection display apparatus has at least two dichroic reflecting surfaces, a wavelength plate, a polarizing beam splitter, and two reflection-type liquid crystal display devices. The first dichroic reflecting surface separates a polarized light beam into light beams of two different wavelength ranges. The wavelength plate rotates the polarization plane of the light beam of the first wavelength range. The second dichroic reflecting surface integrates together the light beam of the first wavelength range after the rotation of its polarization plane and the light beam of the second wavelength range. The polarizing beam splitter reflects one and transmits the other of the light beams of the first and second wavelength ranges after the integration by the second dichroic reflecting surface. The reflection-type liquid crystal display devices modulate and reflect the light beams reflected from and transmitted through the polarizing beam splitter, respectively. The polarizing beam splitter transmits the light beam coming from the first reflection-type liquid crystal display device and reflects the light beam coming from the second reflection-type liquid crystal display device so as to integrate together those two light beams.

Variable gratings for optical switching: rigorous electromagnetic simulation and design

Abstract: Ben-Gurion University of the NegevDepartment of Electrical andComputer EngineeringP.O. Box 653Beer-Sheva 84105IsraelE-mail: hava@bguee.bgu.ac.ilAbstract. This paper is devoted to rigorous electromagnetic diffractionanalysis, in the near infrared, for micromechanical silicon interdigitatedbeam gratings with both lateral and vertical displacement of movablebeams. In the wavelength-to-period ratio domain where the gratings sup-port three diffraction orders, the specific designs of high-efficiencyswitches for polarized radiation, such as switches from a transmitter to a133 transmission beamsplitter and from a retroreflector to an 1 32 re-flection beam divider, are presented. The possibility of light modulation,which follows from these designs, is discussed. The analysis with re-spect to wavelength, beam-width, beam-height, and incidence-anglevariations shows a good tolerance of the devices’ performance to spec-tral shifts and to fabrication and mounting errors. In addition, with the useof our software we simulated the diffraction efficiency versus displace-ment at a visible wavelength for a micromechanical grating reported inthe literature. There is good agreement between theory and experiment.

Laser optical density measurement system

Abstract: An apparatus for measuring optical density of highly absorptive materials in which a beam splitter divides light from a laser source into a reference beam, which is directed to a reference detector, and a sample beam, which is reflected off a diffusing plate, through a light limiting aperture, and to a sample The emanations from the sample are directed to a sample detector An instrumentation amplifier compares the intensities of the two detectors The aperture and reference detector are positioned so that the measured intensities are equal, and the optical density of the sample is calculated