Showing papers on "Beam splitter published in 2001"

Highly simplified device for ultrashort-pulse measurement

Abstract: We show that a frequency-resolved optical gating device using (1) a thick nonlinear crystal to replace the usual thin crystal and spectrometer and (2) a Fresnel biprism to replace the beam splitter and delay line yields a remarkably simple single-shot ultrashort-pulse intensity-and-phase measurement device with no sensitive alignment parameters and significantly greater sensitivity.

Generation of Continuous Variable Einstein-Podolsky-Rosen Entanglement via the Kerr Nonlinearity in an Optical Fiber

Abstract: We report on the generation of a continuous variable Einstein-Podolsky-Rosen (EPR) entanglement using an optical fiber interferometer. The Kerr nonlinearity in the fiber is exploited for the generation of two independent squeezed beams. These interfere at a beam splitter and EPR entanglement is obtained between the output beams. The correlation of the amplitude (phase) quadratures is measured to be 4.0+/-0.2 (4.0+/-0.4) dB below the quantum noise limit. The sum criterion for these squeezing variances 0.80+/-0.03<2 verifies the nonseparability of the state. The product of the inferred uncertainties for one beam (0.64+/-0.08) is well below the EPR limit of unity.

Single panel color video projection display using reflective banded color falling-raster illumination

Abstract: A projection display system. The projection system includes a light source, illumination optics that are capable of splitting the light from the source into individual color bands, and folding mirrors. The folding mirrors operate to direct the color bands to a reflective element that has a contoured surface. The contoured surface of the reflective element causes the light to form into scanning rasters that are recombined and sent to a spatial light modulator. The spatial light modulator is typically made up of a panel of individually addressable elements. If the spatial light modulator requires polarized light, a polarizing beam splitter and quarter-wave plate are included as part of the illumination optics.

Jamin-type interferometers and components therefor

Abstract: A retroreflector (32) has three mutually-orthogonal reflective surfaces arranged around an optical axis (12). The reflective surfaces stop short of the optical axis to provide a central region of the retroreflector which transmits incident light (M,N) and a peripheral region of the retroreflector which retroreflects incident light (C,D). When the reflector is used in a Jamin-type interferometer (10) with another reflector (34), this enables the interferometer to be used for measuring displacement between the reflectors. In the interferometer, a projected beam (M) is disposed between a pair of return beams (D,N) and/or one of the return beams (N) is disposed between a pair of the projected beams (C,M). This enables a first contiguous area of a face of a beam splitter (22) to be provided with a phase-shifting coating (28) to produce a phase quadrature relationship between a pair of interferogram beams (G,I). This simplifies the masking required when applying the coating (28). In manufacture of the beam splitting member (22), a thin-film, beam-splitting, metal coating is applied to the member, and the member and coating are baked so as to modify the phase shift produced by the coating to enable the phase quadrature relationship. During baking a beam of light is projected at the coating with an angle of incidence of substantially π/4 radians so that the beam is split into a transmitted component and a reflected component. The intensities or phases of the transmitted and reflected components are monitored during baking, and the baking is terminated when the monitored intensities or phases have a predetermined relationship. This improves the reliability and/or accuracy of the resulting phase shift.

High efficiency beam splitter for multifocal multiphoton microscopy

Abstract: In this article we present the development of a multibeam two-photon laser scanning microscope. A new type of beam splitter to create the multitude of laser beams is described. This type of beam splitter has higher transmission and generates more uniform beams than can be achieved with the microlens approach used by other groups. No crosstalk exists between the different foci due to small temporal delays between the individual beams. The importance of dispersion compensation to obtain maximum efficiency of the microscope is discussed. With optimum compensation the fluorescence signal was raised by a factor of 14. Different modes of detecting the fluorescence signals and their effect on imaging speed and resolution are discussed.

The Extended Virtual Table: An Optical Extension for Table-Like Projection Systems

Abstract: A prototype of an optical extension for table-like rear-projection systems is described. A large, half-silvered mirror beam splitter is used as the optical combiner to unify a virtual and a real workbench. The virtual workbench has been enabled to display computer graphics beyond its projection boundaries and to combine virtual environments with the adjacent real world. A variety of techniques are described and referred to that allow indirect interaction with virtual objects through the mirror. Furthermore, the optical distortion that is caused by the half-silvered mirror combiner is analyzed, and techniques are presented to compensate for this distortion.

Interferometric measuring device

Abstract: The invention relates to an apparatus for an interferometric measuring device comprising a first interferometer and a second interferometer, wherein short-coherent radiation is fed to the first interferometer by means of a radiation source, which radiation is split into two partial beams by means of a first beam splitter, and wherein the optical path length is longer in one partial beam than in the other partial beam to the effect that the optical path difference is greater than the coherence length of the radiation, wherein the two partial beams are recombined prior to exit from the first interferometer and are fed to the second interferometer, which splits the radiation into two further partial beams, wherein the optical path lengths of the two partial beams are different to the effect that the optical path difference written in the first interferometer is compensated again, wherein the optical path length for a respective partial beam in the first and second interferometer can be set by means of at least one moveable optical component and the moveable optical components are mechanically coupled to one another. The invention furthermore relates to a method for compensating for an optical path difference in such an interferometric measuring device, wherein the optical path differences between the partial beams in the two interferometers are altered simultaneously and by the same magnitude by means of mechanically coupled moveable optical components. It is thereby possible to vary path differences in the partial beams of the interferometers in one work step, the conditions for forming interference still being complied with.

Optimal cloning of coherent states with a linear amplifier and beam splitters.

Abstract: A transformation achieving the optimal symmetric N-->M cloning of coherent states is presented. Its implementation requires only a phase-insensitive linear amplifier and a network of beam splitters. An experimental demonstration of this continuous-variable cloner should therefore be in the scope of current technology. The link between optimal quantum cloning and optimal amplification of quantum states is also pointed out.

Method and apparatus for real-time detection, control and recording of sub-clinical therapeutic laser lesions during ocular laser photocoagulation

Abstract: An optical system is provided for use with a target site and includes a laser source (12) producing an output beam and a reflector. A beam splitter is positioned to receive the output beam and splits the output beam into a first beam incident on the reflector and a second beam incident on at least one point of the target site. The reflector is adjustably positioned and moveable along the reference optical path moveable along the reference optical path to change a length of the reference optical path.

Digital cinema projector

Abstract: A digital cinema projector ( 100 ) for projection of color images onto a display surface comprises a light source ( 116 ), which produces a beam of light. Beam-shaping optics ( 130 ) homogenize and focus the beam of light and color splitting optics ( 132 ) separate focus beam of light into separate color beams. A first modulation optics system comprises a prepolarizer ( 212 ), which prepolarizes a first color beam; a wire grid polarization beamsplitter ( 224 ), which transmits a first predetermined polarization state of the prepolarized beam; a reflective spatial light modulator ( 204 ), which alters the transmitted prepolarized beam with information and reflects the image bearing first color beam through the wire grid polarization beamsplitter ( 224 ); and a wire grid polarization analyzer ( 228 ), which transmits the image bearing first color beam and attenuates unwanted polarization components. A recombination prism ( 232 ) combines the first color beam from the first modulation optical system with other image bearing color beams to create a full color image bearing beam. A projection lens system ( 150 ) projects the full color image bearing beam onto the display surface ( 140 ).

Fully symmetric nulling beam combiners

Abstract: A simple method of nulling broadband light is presented. A mirror-symmetric pair of right-angle periscopes is first used to introduce a geometric field flip between two incident light beams, after which the light is combined by means of one of a number of constructive two-beam interferometers. A reciprocal pair of beam-splitter passages provides for complete symmetry. Such an approach greatly eases beam-splitter design requirements and should find use both in initial ground-based nulling experiments and ultimately in space-borne interferometers targeted at direct extrasolar planet detection.

Performing selected optical measurements with optical coherence domain reflectometry

Abstract: A system and method for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating. A broad band light source produces light having a short coherence length. A beamsplitter splits the light into a signal beam and a reference beam. A reference mirror is disposed to receive the reference beam. A lens brings the signal beam to focus on the sample. A diffraction grating receives reflections from the sample and from the reference mirror, the reflections being incident on the diffraction grating with respect to said diffraction grating normal such that a positive diffraction order from one of the reflections and a negative diffraction order from the other one of the reflections and a negative diffraction order from the other one of the reflections propagate along a common path. A lens collects the diffracted order from the diffraction grating directed along the common path and brings the diffracted orders to focus on a detector, the detector producing an output of said positive and negative diffracted orders received. A computer processes the output from the detector. In other versions of the invention, reflections from the sample are not directed onto the diffraction grating but instead are combined with a diffracted order from reflections from the reference mirror.

Method and apparatus for reducing laser speckle using polarization averaging

Abstract: A method and apparatus for reducing speckle uses polarization averaging. A polarizing beam splitter divides a first polarized laser output into a second polarized laser output and a third polarized laser output. A plurality of mirrors creates an optical path difference between the second and third polarized laser outputs. The optical path difference is at least about a coherence length for the first polarized laser output. The second and third polarized laser outputs are combined into a fourth laser output, which illuminates an depolarizing screen. If a human eye or an optical system having a intensity detector views the depolarizing screen, the eye or the intensity detector will detect reduced speckle, which results from uncorrelated speckle patterns created by the second polarized laser output and the third polarized laser output.

Use of multiple laser sources for rapid, flexible machining and production of vias in multi-layered substrates

Abstract: A laser via drilling system, and a method of use thereof, is provided. The apparatus uses two or more laser systems to achieve processing parameter flexibility. The output beams from the independently controlled laser systems are combined using a beam splitter that combines the beams into single or multiple processing beams. The operational flexibility of the system can be further enhanced through the use of multiple EO modulators and a polarization sensitive beam splitter.

Polarization beam splitters using polarization diffraction gratings.

Abstract: We report a polarization beam splitter that uses polarization gratings written onto a zero-twist nematic liquid-crystal display. We show three configurations. The first two separate the diffracted light into two orthogonally polarized orders that are either linearly or circularly polarized. In the third configuration, we demonstrate a novel case for which the output is separated into two nonorthonormal polarization states. One component is linearly polarized and the second is circularly polarized.

Method and apparatus for free-space quantum key distribution in daylight

Abstract: A quantum cryptography apparatus securely generates a key to be used for secure transmission between a sender and a receiver connected by an atmospheric transmission link. A first laser outputs a timing bright light pulse; other lasers output polarized optical data pulses after having been enabled by a random bit generator. Output optics transmit output light from the lasers that is received by receiving optics. A first beam splitter receives light from the receiving optics, where a received timing bright light pulse is directed to a delay circuit for establishing a timing window for receiving light from the lasers and where an optical data pulse from one of the lasers has a probability of being either transmitted by the beam splitter or reflected by the beam splitter. A first polarizer receives transmitted optical data pulses to output one data bit value and a second polarizer receives reflected optical data pulses to output a second data bit value. A computer receives pulses representing receipt of a timing bright timing pulse and the first and second data bit values, where receipt of the first and second data bit values is indexed by the bright timing pulse.

Compact near-eye illumination system

Abstract: An enhanced illumination system for a micro-display comprises an illuminator for a reflective display panel having a light source and a prism. The prism has a first substantially planar face proximate to the light source and to the display panel, so that light propagates from the light source into the prism through the first face and is redirected to the display panel through the first face. A second face of the prism is positioned opposite the light source so that light reflected from the display panel impinges on the second face and propagates to imaging optics. The illuminator may also include an auxiliary prism optically coupled to the second face of the first prism to correct for astigmatism of the reflected light from the display panel and a beam splitter between the first prism and the auxiliary prism.

Interferometers with coated polarizing beam splitters that are rotated to optimize extinction ratios

Abstract: An interferometer includes a two-frequency laser and a polarizing beam splitter (PBS) that separates a heterodyne beam from the laser into separate beams having different the frequencies and orthogonal polarizations. Optical fibers conduct the separate beams to a beam combiner for interferometer optics. The PBS and/or the beam combiner can use a coating to reflect one linear polarization and transmit an orthogonal linear polarization. To improve extinction ratios in the PBS or the beam combiner, a yaw angle for an input beam is non-zero and corresponds to a peak in the extinction ratio of a reflected beam.

Image display apparatus

Abstract: The image display apparatus of this invention includes: an illumination optical system for outputting a light beam of red, green, and blue three primary color light components in the state where two of the three color light components are different in polarization direction from the other color light component; a beam splitter for splitting the light beam output from the illumination optical system according to the polarization direction; a color separator for separating the two color light components having the same polarization direction: a plurality of reflection image display elements for modulating the light beams separated by the beam splitter and the color separator; and a projection optical system for projecting the light beams modulated by the plurality of reflection image display elements.

Catadioptric reduction projection optical system and exposure apparatus having the same

Abstract: A catadioptric projection optical system is provided, which can use a beam splitting optical system smaller in size than a conventional polarizing beam splitter, can set a long optical path from a concave reflecting mirror to an image plane, allows easy adjustment of the optical system, and has excellent imaging performance. A light beam from an object surface forms a first intermediate image through a refracting lens group. A light beam from the first intermediate image passes through a polarizing beam splitter and is reflected by a concave reflecting mirror to form a second intermediate image in the polarizing beam splitter. A light beam from the second intermediate image is reflected by the polarizing beam splitter means to form a final image on the image plane via a refracting lens group. The polarizing beam splitter means is arranged near the positions at which the intermediate images are formed.

Material irradiation apparatus with a beam source that produces a processing beam for a workpiece, and a process for operation thereof

Abstract: A material irradiation apparatus with a beam source produces a processing beam The apparatus has a beam splitting device following the beam source, by which the processing beam is divided into several partial beams Each partial beam can be deflected by a deflecting device discretely associated with it to different places on at least one workpiece to be processed, independently of the other partial beams The workpiece to be processed is situated on a workpiece movement device that is movable in at least one axis The machining beam is successively incident on a plurality of beam splitter devices that are movably arranged in the axis of the machining beam that is incident on them The partial beams emerging from the beam splitter devices are simultaneously incident on the workpiece movement device The workpiece movement device is arranged to be movable in at least one coordinate direction that deviates from the movement axis of the beam splitter devices In a process for the operation of the material irradiation apparatus, the deflecting devices of the partial beams can deflect at least two, preferably at least four, partial beams simultaneously to at least one point on the surface of the workpiece

Polarization recovery system for projection displays

Abstract: A waveguide polarization recovery system both polarizes the input light energy for use with an LCD imager and converts the polarity of unusable light energy to add to the illumination of the LCD imager. The compact polarization recovery waveguide system generally includes: (1) an input waveguide that provides non-polarized light energy into the system; (2) an output waveguide that receives polarized light energy from the system; (3) a polarized beam splitter that received the light energy from the input waveguide and transmits lights energy of a first polarization type and reflects light energy of a second polarization type, and (4) a wave plate that modifies the polarization of either the transmitted or reflected light energy. The polarization recovery system also generally includes one or more mirrors that are positioned as need to direct the transmitted and the reflected light energy to the output waveguide.

A simple air wedge shearing interferometer for studying exploding wires

Abstract: A new type of shearing interferometer using an air wedge is described. This interferometer is based on a beam splitter constructed using two 90-degree prisms. A small air gap, which varies in spacing from top-to-bottom, separates the second prism from the first and forms the air wedge. The single incident laser beam is focused near the gap, and the two primary reflections from the long sides of each prism form the two coherent virtual sources necessary for interferometry. The shift between the two images of the object at the detector, as well as the orientation and frequency of the fringes, can be independently adjusted by altering the air gap thickness and angle, as well as the position of the laser focus in the gap. This interferometry scheme is inexpensive and easily aligned, and has been successfully and reliably used in exploding wire experiments.

Green phosphor converted light emitting diode

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.

Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter and color separation and recombination prisms

Abstract: An optical imaging system including an illumination system, a Cartesian PBS, and a prism assembly. The illumination system provides a beam of light, the illumination system having an f/# less than or equal to 2.5. The Cartesian polarizing beam-splitter has a first tilt axis, oriented to receive the beam of light. A first polarized beam of light having one polarization direction is folded by the Cartesian polarizing beam splitter and a second polarized beam of light having a second polarization direction is transmitted by the Cartesian polarizing beam splitter. The Cartesian polarizing beam splitter nominally polarizes the beam of light with respect to the Cartesian beam-splitter to yield the first polarized beam in the first polarization direction. The color separation and recombination prism is optically aligned to receive the first polarized beam. The prism has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces. The second tilt axis may be oriented perpendicularly to the first tilt axis of the Cartesian polarizing beam-splitter so that the polarized beam is nominally polarization rotated into the second polarization direction with respect to the color separating surfaces and a respective beam of colored light exits through each of the exit surfaces. Each imager is placed at one of the exit surface of the color separating and recombining prism to receive one of the respective beams of colored light, wherein each imager can separately modulate the polarization state of the beam of colored light.

Coherent detecting receiver using a time delay interferometer and adaptive beam combiner

Abstract: An optical apparatus for coherent detection of an input optical beam. The apparatus includes a beam splitter for splitting the input optical beam into a first component and a second component; an optical delay device arranged to receive the second component, the optical delay device imposing an intentional delay in the second component of the input optical beam; and an adaptive beam combiner coupled to receive the second component with a delay imposed thereon by the optical delay device; and the first component from the beam splitter. The adaptive beam combiner has two exiting components having the same wavefronts and propagating directions as the first and second components and being in quadrature. A detector arrangement is provided for receiving and detecting the first and second exiting components from the adaptive beam combiner.

Design of a Binary Grating with Subwavelength Features that Acts as a Polarizing Beam Splitter.

Abstract: A binary diffractive optical element, acting as a polarizing beam splitter, is proposed and analyzed. It behaves like a transmissive blazed grating, working on the first or the second diffraction order, depending on the polarization state of the incident radiation. The grating-phase profile required for both polarization states is obtained by means of suitably sized subwavelength groups etched in an isotropic dielectric medium. A rigorous electromagnetic analysis of the grating is presented, and numerical results concerning its performances in terms of diffraction efficiency as well as frequency and angular bandwidths are provided.

Fourier gratings as submillimeter beam splitters

Abstract: Over the past years, a number of groups have developed phase gratings as local oscillator beam multiplexers for array receivers in the submillimeter wavelength domain. The most popular type of grating is the Dammann (1977) grating, a simple and versatile binary phase grating. We introduce a new type of grating, the Fourier grating, which, in contrast to the binary structure of Dammann gratings, uses a smooth grating structure. Due to the lack of sharp edges these gratings can be manufactured with high precision as reflection gratings even for two-dimensional (2-D) dispersion. Fourier gratings are designed using a simple optimization procedure that only involves a small number of parameters. Their diffraction efficiency is very high. We have produced a number of gratings and tested them at a frequency of 490 GHz, verifying the theoretical results.

Integrated polarisation beam splitter using waveguide birefringence dependence on waveguide core width

Abstract: A novel integrated polarisation beam splitter on a silica-based planar lightwave circuit that utilises the waveguide birefringence dependence on waveguide core width is proposed. It was successfully confirmed that the fabricated splitter has a polarisation extinction ratio of >21 dB over a wide wavelength range of 1530 to 1620 nm.