Showing papers on "Waveplate published in 2002"

Quarter wave plate comprising two optically anisotropic layers

Abstract: A circularly polarizing plate comprises a linearly polarizing membrane and a quarter wave plate. The quarter wave plate comprises an optically anisotropic layer A and an optically anisotropic layer B. The quarter wave plate has such an optical characteristic that a retardation value essentially is a quarter of a wavelength when the retardation value is measured at the wavelength of 450 nm, 550 nm and 650 nm. One of the optically anisotropic layers A and B is a layer made from liquid crystal molecules, and the other is a polymer film or a layer made from liquid crystal molecules.

Polarizer and microlithography projection system with a polarizer

Abstract: A polarizer suitable for transforming incident linearly polarized or circularly polarized light into exiting radially or tangentially polarized light with virtually no transmission losses has, in one of its embodiments, a plate fabricated from birefringent material on whose entrance and exit faces small zones ( 11, 12 ) with deflecting structures ( 8, 9 ) in the form of gratings or Fresnel surfaces have been created. The crystal axis ( 5 ) of said birefringent material is aligned parallel to the incident light beam. Said deflecting structures deflect light along a transmission direction ( 13 ) that is inclined with respect to said crystal axis ( 5 ), causing a phase shift between the field components of the transmitted light. Suitable choices of the angle of inclination (NW) of said transmission direction with respect to said crystal axis and the thickness (D) of said plate will allow transforming incident linearly polarized or circularly polarized light into an exiting light beam with an axisymmetric (tangential or radial) polarization distribution.

Towards atomic force microscopy up to 100 MHz

Abstract: An atomic force microscope for nanocantilevers measuring from a few 100 nm to a few μm in length was implemented. The natural frequencies of the nanocantilevers lie in the range of 1 MHz to 1 GHz, and optical detection schemes adapted to their size and frequency range was selected. A helium neon laser with a beat frequency of 890 MHz was used as the laser source. The beat was shifted to 1090 MHz by an acousto-optical-modulator, and used as the carrier for heterodyne laser Doppler measurement. This enabled velocity measurement up to around 100 MHz. The probe beam of the Doppler interferometer was guided to the nanocantilever by a single mode polarization-maintaining optical fiber terminated by a collimating lens, a quarter wave plate, and a focusing lens. Reflected light was collected by the same optics and mixed with the reference beam. Self-excitation of the nanocantilever at its lowest natural frequency was implemented for an amplitude of 1 nmp-p at 36 MHz. The Q factor of the cantilever was 8000. Noise...

Polarization-sensitive optical spectral interferometric coherence tomography apparatus and measuring method for polarization information inside sample by the same

Abstract: PROBLEM TO BE SOLVED: To verify fine structures including birefringence distribution which has not been acquired by a conventional OCT (optical coherence tomography) measurement in the measurement of cross-sectional structures of biosamples including the birefringence distribution such as fish bones and human skin. SOLUTION: The sate of reference light and the state of object light are each selectively regulated into any one of the four ways of horizontal linear polarized light, vertical linearly polarized light, 45° linearly polarized light, and right-handed circularly polarized light. Each state of polarized light is combined by a beam splitter 10 into sixteen-way combinations of four by four, and is passed through a spectroscope having a diffraction grating 20 and lenses. Its interference fringes are photographed by a CCD camera 22 to acquire sixteen coherence tomographic images. By determining each element of the Mueller matrix capable of displaying the polarization characteristics of the sample from the sixteen coherence tomographic images, the polarization information inside the sample is measured. COPYRIGHT: (C)2004,JPO

Reconfigurable multilevel phase holograms for optical switches

Abstract: A way of dynamically encoding polarization-insensitive multilevel phase holograms using nematic liquid crystals is presented. The method, using a quarter wave plate and a mirror, allows the optical efficiency of a free space single-mode fiber-to-fiber switch to be greatly enhanced. The validity of the approach has been verified experimentally by observing the power diffracted in the /spl plusmn/1 orders of a nematic liquid crystal grating as a function of input polarization and applied voltage.

Analysis of the spatial distribution of polarized light backscattered from layered scattering media.

Abstract: The scattering of polarized light from a two layer scattering medium is investigated using Monte Carlo simulations. First order and normalized second order moments are used to analyze the spatial properties of the emerging light in different polarization states. Linearly and circularly polarized illumination is used to probe different depths. Absorption and layer thickness are varied and it is demonstrated that the determination of these values is aided by the inclusion of polarization information. The lateral and depth localization of light by polarization subtraction is also quantified. Potential applications of these techniques are burn depth and melanoma thickness measurements.

Inscription of holographic gratings using circularly polarized light: influence of the optical set-up on the birefringence and surface relief grating properties

Abstract: The polarization properties of the optical set-up used for holographic recording of diffraction gratings on azopolymer thin films are analyzed. The state of polarization of circularly polarized light is fully analyzed after reflection on a mirror at various incidences (Lloyd-mirror set-up). The Stokes analysis is performed using a photopolarimeter and the phase shift, the ellipticity and the azimuth orientation are compared with those calculated from Fresnel formulae. At large angles of incidence, an initially right circularly polarized (RCP) beam becomes elliptically polarized with an azimuth of nearly +45°. From these results, holographic diffraction gratings are recorded on an azobenzene-containing polymer thin film using (i) co- and contra-circularly polarized beams and (ii) a right circularly polarized beam interfering with a +45° linearly polarized light beam. Using Jones-matrix formalism, the polarization states of the diffracted orders from the birefringence (Δn) and the surface-relief (2Δd) gratings are derived and compared with experimental measurements. Finally, the induced local birefringences and surface-relief amplitudes are discussed in connection with atomic force microscopy measurements. The diffraction efficiencies obtained under the (+45°+RCP) and (LCP + RCP) (where LCP = left circularly polarized) configurations are thus compared and discussed.

Laminated quarter-wave plate or circularly polarizing plate, liquid-crystal display device using the same and method for producing the same

Abstract: A laminated quarter-wave plate having: a laminate of a quarter-wave plate and a half-wave plate, wherein: the quarter-wave plate and the half-wave plate are laminated on each other so that directions of in-plane slow axes intersect each other; and each of the quarter-wave plate and the half-wave plate satisfies a relation Nz=(nx−nz)/(nx−ny)>1.05 in which nx and ny are in-plane main refractive indices, and nz is a thickness wise refractive index; and a circularly polarizing plate having: a laminate of a laminated quarter-wave plate defined above and a polarizer.

Optical devices comprising high performance polarizer package

Abstract: Disclosed is a polarizer package comprising an integrated combination of an absorbing layer and a compensator. Two of the identical polarizer packages can be crossed and used in a transmissive optical device. This polarizer package can also be used in combination with a reflective plate and a quarter wave plate in a reflective optical device. Such polarizer packages exhibit an improved viewing angle characteristic across all wavelengths of interest, has a large tolerance for compensators to be aligned relative to their preferred directions, and can be used within an LCD or emissive display system.

In-fiber nematic liquid crystal optical modulator based on in-plane switching with microsecond response time

Abstract: We describe a simple method and device design that enables fast in-plane electro-optic modulation in conventional nematic liquid crystal (NLC) devices. When combined with optimized NLC materials, this approach yields rotational speeds of 1°/μs (independent of rotation angle, over a wide range) at a moderately low voltage. The observed rotational dynamics indicate that even these high speeds may not represent fundamental physical limits. We demonstrate these ideas in a compact tunable NLC waveplate that uses microelectrodes patterned directly on the tips of optical fibers. These devices offer fast, continuously tunable optic axis with low insertion loss and good performance in the near infrared. Modulators that use this design have promising potential applications for polarization control and analysis in optical communication systems.

Optical properties of skin

Abstract: This paper describes the light intensity and polarization characteristics of the regular reflectance and the backscattered light, which were generated by putting the linear polarized light into the surface of skin. We come to the following conclusions: (1) when incidence light is linear polarized light, its regular reflectance is polarized light with the same polarization state of the incident light, while the backscattered light will lose almost all its polarization; (2) when the incidence light, whose optical vector's direction is parallel with the incidence plane, enters the skin with the Brewster's angle, the regular reflectance almost vanishes. At the same time, receive the light energy where the regular reflectance occurs. The backscattered light, which enters the tissue, covers 97% ofthe received total energy.

Real-time analysis of partially polarized light with a space-variant subwavelength dielectric grating

Abstract: A novel method for real-time polarization measurement is presented. The method is based on a space-variant wave plate that we realized as a computer-generated space-variant subwavelength dielectric grating. The Stokes parameters of the incident beam are determined by Fourier analysis of the space-variant intensity transmitted through the grating and an analyzer. We discuss the design and realization of such wave plates and demonstrate our technique with polarization measurements of both polarized and partially polarized CO2-laser radiation at a wavelength of 10.6 µm.

Generation of a phase-flipped Gaussian mode for optical measurements

Abstract: We propose optical techniques for the generation of a TEM00 Gaussian beam which has a π phase flip in the electric field amplitudes between the two halves of the beam profile. The methods make use of a special waveplate and a masked Sagnac interferometer. The produced phase-flipped mode is the ideal light mode for optical measurements requiring high precision in one spatial dimension. Two examples of such applications are discussed.

Fibre-polarimeter based on grating taps

Abstract: The fabrication of novel tilted fibre Bragg gratings coupling light out of the fibre core into two different directions is demonstrated. These gratings in combination with a fibre based quarter waveplate are used to form a high-speed fibre polarimeter for real-time polarisation monitoring.

Polarized light source system with mirror and polarization converter

Abstract: A polarized light source for a display system includes an optical system to image light from a light source onto a display along a first optical path, a reflective polarizer to receive the light from the optical system along a first optical path, direct light of a first polarization of the display, and reflect light of a second polarization along a second optical path separate from the first optical path toward the optical system, a mirror in the second optical path to receive light having the second polarization from the reflective polarizer, and reflect it back to the reflective polarizer, and a polarization conversion system in the second optical path between the reflective polarizer and the mirror to convert the polarization of the reflected light of the second polarization to the first polarization.

Variable polarization plane rotator and optical device using same

Abstract: An optical device includes a small and low-cost variable polarization plane rotator that can control a rotation angle of the polarization plane easily. A variable polarization plane rotator is provided with a λ/4 phase plate having an optical axis in the same direction as, or at a 90 degree angle relative to, a polarization direction of an input light beam. A phase difference variable element has an optical axis at a ±45 degree angle relative to the optical axis of the λ/4 phase plate, to apply a variable phase difference between the polarization components parallel to and perpendicular to the optical axis thereof. A phase difference adjustment section adjusts the variable phase difference of the phase difference variable element, wherein the input light beam after being transmitted through the phase difference variable element to form elliptically polarized light or circularly polarized light, is transmitted through the λ/4 phase plate to form linearly polarized light. The polarization plane of the input light beam is rotated by an angle corresponding to the phase difference applied by the phase difference variable element.

Vertically aligned liquid crystal display device

Abstract: PROBLEM TO BE SOLVED: To provide a vertically aligned liquid crystal display device having an excellent visual angle characteristic. SOLUTION: The vertically aligned liquid crystal display device has a circular polarizer including a vertically aligned liquid crystal cell including liquid crystal molecules vertically aligned to substrate surfaces during non-impression of a voltage between a pair of the substrate and a first optical element which is arranged outside a vertically aligned liquid crystal cell 13 and formed of linear polarizing plates 11 and 15 and biaxially optically anisotropic materials 12 and 14 and exhibits retardation of a quarter wavelength within a plane and a second optical element which is arranged between the circular polarizer and the vertically aligned liquid crystal cell and between first optical elements 16 and 17 having negative optical anisotropy and between the linear polarizing plate of the circular polarizer and the quarter wave plate, exhibits, retardation of the half wavelength or quarter wavelength within a plane and has positive optical anisotropy. COPYRIGHT: (C)2003,JPO

Dual projector lamps

Abstract: A dual lamp light source utilizes a polarizing beam splitter to provide an output beam from one or the other or both sources. One lamp is positioned adjacent a face whose plane is parallel to the optical axis of the beam splitter and whose output is internally reflected. The other lamp is positioned adjacent a rear face of the beam splitter so that its output is the output of the beam splitter. Each of the beams is polarized in a unique orientation. A polarizer is placed in the exit path and is aligned to pass one of the orientations. A polarization rotation device is interposed between the beam splitter and polarizer and, by its orientation, determines which of the lamp inputs is transmitted by the polarizer. The rotation device can be mechanical, including a rotatable half wave plate or electronic, utilizing a liquid crystal retarder device that is controlled by an applied electrical signal. The present device can also be used as a “day-night” illumination source if one lamp is a bright day lamp and the other is a less bright night lamp equipped with an IR filter. The lamps are then used alternatively.

High speed fiber-optic attenuation modules

Abstract: Unique multi-diffraction structures using electronically controlled Bragg diffraction devices such as acousto-optic (AO) devices to accomplish optical beam attenuation control functions. These variable optical attenuator (VOA) modules can be fully inertialess as they can use electronically programmable sub-microsecond speed AO devices to implement optical gain controls. These VOAs deliver desirable capabilities in one optically reversible unit, making high dynamic range, low loss, high power handling, ultra-fast, high optical isolation, broadband operation, self-aligning robust modules. These VOAs can be made essentially independent of the optical polarization of the incident light by the use of a unique fixed waveplate compensation technique within the VOA configuration that suppresses polarization dependent loss. Broadband gain control operation over several wavelengths can be achieved by controlling the frequency and electrical drive power of the chosen frequencies feeding the acousto-optic devices. Interleaver devices can be cascaded with the acousto-optic modules to improve wavelength selectivity of the overall VOA modules. Alternative embodiments can use electrically programmable Bragg gratings in polymer dispersed liquid crystal and acousto-optic tunable filter devices as Bragg grating devices. Embodiments are proposed using independently controlled Bragg diffractions using multiple drive signals connected to multiple device transducers. Drive signal formats can be digital, analog, or a combination for simultaneously driving the VOA modules. Dual-mode VOA module designs are also described using mirror positioning.

Interferometric filter wavelength meter and controller

Abstract: A wavelength measurement system uses birefringent material waveplate, thereby producing a substantially sinusoidal spectral response. As a result, the responses of multiple birefringent filters can be combined to yield a filter system with a periodic frequency response that has an additive wavelength resolution that is spectrally stable. That is, the wavelength measurement system (100) does not have regions where wavelength resolution is degraded. In one implementation, a waveplate system (112) is used, placed between two blocks of birefringent material (110) and (114). A quadrant detector (116) is used to detect the intensities of the resulting four beams.

Device and method for plasma processing, and slow-wave plate

Abstract: A micro wave plasma processing device using a radial line slot antenna, wherein a slot plate (16) is formed with a material having a coefficient of thermal expansion near the coefficient of thermal expansion of a slow-wave plate (18) or by depositing a metal on a dielectric plate forming the slow-wave plate (18), and an adhesion between the slow-wave plate and the slot plate forming a micro wave radiation surface in the antenna is increased to prevent an abnormal discharge.

Broad-band apochromatic retarders: choice of materials

Abstract: Apochromatic retarders can be constructed by using a combination of three plates of different birefringent materials with properly chosen thicknesses. However, when dealing with a broad wavelength range, their performance depends very much on the materials chosen. A procedure is presented for optimizing the choice of materials for such a broad-band retarder.

Hybrid component and method for combining two pumping lights and depolarizing them simultaneously and optical amplifier therefor

Abstract: The present invention relates to a hybrid component and method capable of simultaneously combining and depolarizing two pump laser diodes of different wavelengths with linear polarized output. The beam combiner is a Wellstone prism which is used to combine two linear-polarized pumping beams, and the depolarizer has three different embodiments: a single stage high birefringent waveplate; two stages high birefringent waveplates; a quarter waveplate or a three-quarter waveplate plus a single stage high birefringent waveplate. The Polarization Beam Combiner (PBC) and the depolarizer are integrated into one single hybrid component, in which two orthogonal pumping lights with different wavelengths are combined and depolarized simultaneously. Therefore, the hybrid component and method makes it simpler and cheaper to design a Raman amplifier and will propel Raman amplifier market penetration in optical communication systems.

Waveplate and optical circuit formed from mesogen-containing polymer

Abstract: Waveplates formed of mesogen-containing polymers and planar lightwave circuits containing such waveplates. Polymers have sidechains containing mesogens such as biphenyl-containing groups. Polymers may have a glass transition temperature between 100 °C and 300 °C, and polymers may be stretched in excess of 150% to increase birefringence of polymer and provide thin films. Waveplates formed of stretched polymer films may have high biaxial birefringence.

Tumble angle measuring method and measurer

Abstract: The present invention belongs to the field of optical angle measuring technology, and includes setting half-reflecting mirror in the output light axis of Zeeman laser, setting half wave plate perpendicularly in the transmission light path of the half-reflecting mirror, and setting half wave plate, analyzer, one first photoelectronic detector successively and perpendicular second photoelectronic detector in the reflection light path; and one phase meter with input connected to the output of the first and the second photoelectronic detectors and output to the computer. The present invention hasstrengthened non-linearity and 4 times raised sensitivity, and the close measuring detectors and light source results in compact structure and ever high practicability.

Interference of circularly polarized light: contrast and application in fabrication of three-dimensional periodic microstructures

Abstract: The contrast of interference pattern formed by two circularly polarized waves and by a linearly polarized wave and a circularly polarized one is discussed. The results are compared with that by two linear beams. It shows that the use of circular light in holographic fabrication of three-dimensional periodic microstructures may remove the necessity of beam ratio and polarization optimization needed in the interference of three linear noncoplanar beams and improve the uniform contrast of resultant pattern simultaneously.

Optical shifter and optical display system

Abstract: An optical shifter includes at least one shifting section that periodically displaces the optical axis of incoming linearly polarized light. The shifting section includes first and second liquid crystal cells and a birefringent element. Each of the liquid crystal cells changes the polarization direction of the incoming light from a first direction into a second direction, or vice versa, responsive to a voltage being applied to the cell. The first and second directions are perpendicular to each other. The birefringent element changes its refractive indices with the polarization direction of the light incident thereon. The first and second cells and the birefringent element are arranged to transmit the incoming light in this order. The liquid crystal layer of the second cell compensates for a disturbance in polarization that was caused while the incoming linearly polarized light was transmitted through the liquid crystal layer of the first cell.