Showing papers on "Waveplate published in 1998"

Optical torque controlled by elliptical polarization.

Abstract: We show theoretically and demonstrate experimentally that highly absorbing particles can be trapped and manipulated in a single highly focused Gaussian beam. Our studies of the effects of polarized light on such particles show that they can be set into rotation by elliptically polarized light and that both the sense and the speed of their rotation can be smoothly controlled.

Wave-plate polarizing beam splitter based on a form-birefringent multilayer grating.

Abstract: We have fabricated a novel device that acts as a quarter-wave plate at normal incidence and as a polarizing beam splitter at an angle of incidence of ?40 deg. The device is made from a multilayer SiO2/Si3N4 surface-relief zeroth-order one-dimensional grating with a period of 0.3 µm. The device is designed for an operating wavelength of 632.8??nm. We designed the device by using rigorous coupled-wave analysis and fabricated it by direct-write electron-beam lithography and reactive ion etching. Measurements confirmed the performance of the device as a wave plate and as a polarizing beam splitter.

Imperfect quarter-waveplate compensation in Sagnac interferometer-type current sensors

Abstract: We analyze scale factor errors associated with integrating imperfect quarter-waveplates into loop and in-line Sagnac interferometer fiber-optic current sensors. We show that relatively large imperfections in the quarter-waveplates can be tolerated in the loop version when the birefringence axes of the two quarter-waveplates are oriented 45/spl deg/ with respect to each other. For the in-line version, we demonstrate an electronic signal processing scheme that desensitizes the scale factor to imperfections in the quarter-waveplate.

Folded optical system having improved image isolation

Abstract: An optical collimating assembly for imaging light from a display. The optical assembly includes first and second linear polarization filters having polarization directions that are orthogonal to one another. A folded imaging assembly that includes a first beam splitter, a first ¼ wave plate, and a second beam splitter is located between the polarization filters. A second ¼ wave plate is also located between the polarization filters. The first ¼ wave plate has a birefringence axis that is orthogonal to the birefringence axis of the second ¼ wave plate. In the preferred embodiment of the present invention, the ¼ wave plates are constructed from the same birefringent material. One of the reflectors is preferably constructed from a material having a reflectivity that depends on the direction of linear polarization of light striking the beam splitter.

Display devices, electronic apparatus using the same, and polarized light separator

Abstract: A light-scattering layer 1150, a polarized light separator 1160, and a polarized light separator 1180 are provided in this order below a TN liquid crystal 1140. The polarized light separators 1160 and 1180 are polarized light separators for reflecting light of a linearly polarized light of a wavelength region (Δλ) in the X direction, and transmitting light of an other wavelength region (-Δλ). Since the wavelength region (Δλ) of the polarized light separator 1160 and 1180 are different from each other, as viewed from the light incident side, in a voltage non-application section 1120, light that is reflected by the polarized light separator 1160 becomes emitted light 1122 of a color of the wavelength region (Δλ1), and in a voltage application section 1110, light that is transmitted through the polarized light separator 1160 is reflected by the polarized light separator 1180 to become emitted light 1112 of a color of the wavelength region (Δλ2). Therefore, as viewed from the light incident side, two-color display of the color of the wavelength region (Δλ2) can be obtained on a color background of the wavelength region (Δλ1).

Measurement of waveplate retardation using a photoelastic modulator

Abstract: A practical system and method for measuring waveplate retardation. The system employs a photoelastic modulator (22) in an optical setup and provides high sensitivity. The analysis is particularly appropriate for quality-control testing of waveplates (26). The system is also adaptable for slightly varying the retardation provided by a waveplate (26) (or any other retarder device) in a given optical setup. To this end, the waveplate (26) position may be precisely altered to introduce correspondingly precise adjustments of the retardation values that the waveplate (26) provides. The system is further refined to permit one to compensate for errors in the retardation measurements just mentioned. Such errors may be attributable to static birefringence present in the optical element of the photoelastic modulator (22) that is incorporated in the system.

Optics arrangement including a compensator cell and static wave plate for use in a continuously viewable, reflection mode, ferroelectric liquid crystal spatial light modulating system

Abstract: A reflection mode, ferroelectric liquid crystal spatial light modulating system, includes a light reflecting type spatial light modulator. The spatial light modulator has a light reflecting surface cooperating with a layer of ferroelectric liquid crystal light modulating medium switchable between first and second states so as to act on light in different first and second ways, respectively. A switching arrangement switches the liquid crystal light modulating medium between the first and second states and an illumination arrangement produces a source of light. An optics arrangement is optically coupled the spatial light modulator and the illumination arrangement such that light is directed from the source of light into the spatial light modulator for reflection back out of the modulator and such that reflected light is directed from the spatial light modulator into a predetermined viewing area The optics arrangement includes a passive quarter wave plate positioned in the optical path between the light source and the spatial light modulator and in the optical path between the spatial light modulator and the viewing area. A compensator cell is also positioned in the optical path between the light source and the spatial light modulator and in the optical path between the spatial light modulator and the viewing area. The compensator cell has a layer of ferroelectric liquid crystal light modulating medium switchable between a primary and a secondary state so as to act on light in different primary and secondary ways, respectively.

Broadband optical retardation device

Abstract: A broadband optical retardation device, such as may be used for polarisation encoding of display information or in diffractive optical systems, includes a patterned uniform half wave plate retarder in combination with a non-patterned uniform quarter wave plate retarder having an optic axis orientated at 90° to the xz plane. The patterned retarder consists of alternating first and second regions having first and second optic axes at different orientations to a reference axis, for example at + 22.5° and - 22.5° to the xz plane. Considering light of wavelength μ° incident on the retarder and linearly polarised in the xy plane, such light is differently polarised by the regions, and the light output by the device includes regions in which the light is right circularly polarised and regions in which the light is left circularly polarised. In the case of incident light of wavelenths greater or less than μ°, the output light becomes progressively more linearly polarised as the wavelengths departs to a greater extent from the ideal value, but not to the same extent as would be the case if the device consisted simply of a patterned single layer acting as a quarter plate retarder.

Through silicon modulator and method using polarized light

Abstract: Through silicon optical modulators (TSOM) formed in a silicon integrated circuit comprise an array of MOSFET elements which cause optical phase shifts of reflected light to identify a state of a signal. A polarization of the reflected light is modified by the phase shift and transmits the signal. The polarization of reflected light can be controlled by the angle of the incident light, by polarizing optical slits fabricated in the modulator, or by using a polarized mirror. Either embodiment allows the polarized reflected light to be nulled out. As such, a polarization of the reflected light is altered when the signal is applied to the modulator. The altered polarization can then be detected.

Polarization properties of light emitted by a bent optical fiber probe and polarization contrast in scanning near-field optical microscopy

Abstract: This article describes the polarization properties of light emitted by a bent optical fiber probe which is used for scanning near-field optical microscopy operated in atomic force mode (SNOM/AFM). SNOM/AFM can be applied to the observation of magnetic domains by imaging polarization contrast in transmission mode. A bent optical fiber probe with a subwavelength aperture is vibrated vertically as a cantilever for atomic force microscopy. Plane polarized light with an extinction ratio of better than 70:1 was emitted by the aperture by controlling the polarization state of incident light to the probe. A particular transverse polarization component of light transmitting a sample is selected by a polarization analyzer and detected. We obtained clear polarization contrast images of 0.7 μm length bits written with a conventional method using a focused laser beam on a bismuth-substituted dysprosium-iron-garnet film.

Laminated phase plate and liquid crystal display comprising the plate

Abstract: A laminated phase plate composed of first and second optical phase difference compensation plates (1 and 2). The retardation of the first optical phase difference compensation plate (1) for a transmitted light with a wavelength of 550 nm is 100 - 180 nm. The retardation of the second optical phase difference compensation plate (2) for a transmitted light with a wavelength of 550 nm is 200 - 360 nm. The plates (1 and 2) are so arranged that the value of |υ1 - 2 X υ2| will range from 80 to 100 degrees wherein υ1 denotes an angle between the vibration direction (4) of a linearly polarized light (3) which is visible light and has the same plane of vibration and the slow axis direction of the first optical phase difference compensation plate (1) when the linearly polarized light (3) enters the second optical phase difference compensation plate (2), and υ2 denotes an angle between the vibration direction of the linearly polarized light (3) entering the second optical phase compensation plate (2) and the slow axis direction of the second optical phase difference compensation plate (2). Thus a laminated phase plate with an improved function is provided realizing a reflection liquid crystal display which has an excellent visibility or a projection liquid crystal display which has a high efficiency.

Polarized light illuminator and projecting type image display

Abstract: A polarized light illuminator wherein the light from a light source (106) the polarization direction of which is random is made to enter a polarized light separating section (103) via an integrator optical system (102) including a second lens plate (110) which is subjected to deformed aperture designing, the polarized light separating section (103) being adapted to separate the incident light into two polarized light beams the polarization directions of which cross each other at right angles, the polarization directions of the polarized light beams being then set properly by a polarized light conversion section (104), whereby the light the polarization direction of which is random is converted into light of an arbitrary polarization direction, this enabling a polarized light illuminator in which the expanse of the illuminating light is minimized to be obtained, such a polarized light illuminator being able to be suitably utilized as an illuminator for a projecting type image display using a liquid crystal light bulb which carries out modulation by utilizing polarized light, whereby the reduction of the cost of the illuminator and the improving of the illuminance thereof can be compatible with each other.

Optical information storage unit

Abstract: An optical information storage unit for reproducing information recorded on a magneto-optic recording medium having a land and a groove as recording tracks, is provided with at least one of first and second systems, where the first system includes a 1/2 wave plate which is arranged so that a crystal optical axis of the 1/2 wave plate and an electrical vector of a light beam emitted from a light source forms approximately 45 degrees, where the 1/2 wave plate being removable from a position of the light beam, and the second system is arranged with the 1/2 wave plate so that the crystal optical axis of the 1/2 wave plate and the electrical vector of the light beam emitted from the light source forms approximately 45 degrees, where the 1/2 wave plate is movable so that another 1/2 wave plate can move to the position of the light beam so that a crystal optical axis of the other 1/2 wave plate is parallel to or perpendicular to the electrical vector. An electrical vector of the light beam irradiated on the magneto-optic recording medium is set so that the electrical vector is perpendicular to a direction in which a recorded signal flows when reproducing the signal from the land and is parallel to the direction in which the recorded signal flows when reproducing the signal from the groove.

A three-intensity technique for polarizer-sample-analyser photometric ellipsometry and polarimetry

Abstract: This work presents a novel three-intensity-measurement technique to determine the ellipsometric parameters and in a polarizer-sample-analyser photometric ellipsometer. This technique can be employed to correct the azimuthal misalignment of the analyser with respect to the plane of incidence. By performing two sets of measurements with this technique with the polarizer's azimuth at and , respectively, we can simultaneously determine the azimuthal deviation of the polarizer and further improve the ellipsometric measurements. Applying this technique in the transmission mode allows us to obtain the phase retardation and the optical axis of a waveplate at the same time.

Display and electronic device comprising the same

Abstract: Over a liquid crystal cell (10), there are disposed a phase difference film (30) and an upper polarized light separator (20). Below the liquid crystal cell (10), there are disposed a diffuser (40), a lower polarized light separator (50), a color filter (60), a PET film (70) and an Al evaporation film (80). The upper and lower polarized light separators (20 and 50) are polarized light separators (reflecting polarizers) for reflecting a linearly polarized light in one direction as a linearly polarized light in the one direction and for transmitting a linearly polarized light in another direction perpendicular to the one direction as the linearly polarized light in the other direction. The light from an LED (120) is guided by a light guide (110) into a light guide plate (130) interposed between the upper polarized light separator (20) and the phase difference film (30). The light from the lower face of the light guide plate (130) is emitted toward the liquid crystal cell (10).

Reflective array multiplexer with polarization compensation

Abstract: An optical multiplexer is formed that overcomes the polarization dependence of conventional DWDM routers and is also significantly smaller than prior art routers. A reflective router is formed that utilizes one-half of a star coupler, with a reflective surface formed along the planar face of the coupler so as to form a "folded" arrangement. First and second waveguide arrays are coupled to opposing quadrants of the folded coupler, with the reflective surface providing the coupling therebetween. A quarter wave plate (or Faraday rotator) and reflective surface are disposed at the output of the second waveguide array and are used to provide a TE/TM mode conversion to the optical signals exiting the second array (thereby canceling out any polarization-dependent effects). The reflective surface beyond the quarter wave plate re-directs the optical signal back through the second waveguide array. The signal will then again reflect through the folded coupler and exit the multiplexer through the first waveguide array. The pair of reflective surfaces function to "fold" the router along two axes, thereby reducing the overall size of the router by 75% when compared with prior art arrangements.

Circular dichroism detector for hplc

Abstract: A circular dichroism detector includes a light source having a large emission intensity in the ultraviolet region such as an HgXe lamp or Hg lamp, a diffraction grating for wavelength dispersing the light emitted from the light source, a polarizer for linearly polarizing the light emitted from the light source, a PEM for modulating wavelength dispersed linearly polarized light to alternately produce left-handed circularly polarized light and right-handed circularly polarized light, a flow cell through which the circularly polarized light will be passed, and a photodiode for detecting the circularly polarized light passing through the flow cell.

Polarized light illuminator and projection type image display apparatus

Abstract: The polarized light illuminator of this invention includes: a light source; a first fly's eye lens and a second fly's eye lens disposed in this order from the light source; a polarization separation element disposed between the light source and the second fly's eye lens for separating unpolarized light into a first polarized light component and a second polarized light component having polarization directions perpendicular to each other, to output the first polarized light component and the second polarized light component in different directions from each other; and a polarization conversion element disposed near the second fly's eye lens for converting the first polarized light component and the second polarized light component output from the polarization separation element into unidirectionally polarized light, wherein the polarization separation element has a first flat plate and a second flat plate, the first flat plate having a polarization separation surface for reflecting the first polarized light component and transmitting the second polarized light component, while the second flat plate having a reflection surface for reflecting the second polarized light component which has passed through the first flat plate, the polarization separation surface and the reflection surface being disposed at different angles from each other with respect to the optical axis of the light source.

Polarization surface light source device and liquid crystal display device

Abstract: PROBLEM TO BE SOLVED: To obtain a polarization surface light source device which is excellent in luminance balance at a front surface and in diagonal view while effectively utilizing the advantage of the higher luminance based on an improvement in light utilization efficiency by the utilization of a polarized light separating layer and is advantageously usable for formation of a large-screen liquid crystal display device, etc. SOLUTION: This device has the polarized light separating layer 3 which separates natural light to the reflected light and transmitted light consisting of polarized light at least via one or >=2 layers of prism sheets 2 of 92 to 112 deg. in apex angle on a surface light source 1. As a result, even the polarized light, such as circularly polarized light or linearly polarized light, reflected by the polarized light separating layer may be utilized as the polarized light transmitted through the polarized light separating layer via the reflection and the inversion, by which the luminance is improved. The luminance in a diagonal view direction may be improved and the luminance balance at the front surface and in diagonal view advantageous for the large screen may be obtained while the degradation in the luminance in the front surface direction in optical path control by the prism sheet 2 is suppressed as far as possible.

High-efficiency polarizing arrangement and projection apparatus using the same

Abstract: In the present projection apparatus, R, G and B lights in the form of a S polarized light emitted from a fly-eye lens and a field lens are separated and the S polarized light is converted to a P polarized light so that it is illuminated onto a light valve. The S polarized light separated by the polarization beam splitter is illuminated onto the light valve converted to the P polarized light without being discarded, illuminance of the light onto the light valve is uniform and its polarization azimuth is arranged in the form of the P polarized light.

Polarization based differential receiver for reduction of background in free-space optical links

Abstract: An optical link includes a transmitter and a receiver for sending and receiving data across a free-space link or any other link in which a high level of background light may be present. The transmitter includes a source of circularly polarized light having a predetermined wavelength. The source is modulated to transmit data. The receiver includes a circuit for generating a signal indicative of the difference in intensity of left-handed circularly polarized light and right-handed circularly polarized light incident on the receiver. In one embodiment of the invention, the receiver includes a first polarization filter for blocking left-handed circularly polarized light of the predetermined wavelength and a second polarization filter for blocking right-handed circularly polarized light of the predetermined wavelength, the filters being displaced from one another. A first detector measures the intensity of light leaving the first polarization filter, and a second detector measures the intensity of light leaving the second polarization filter. The circularly polarized light source may be generated from a linearly polarized light source by passing the linearly polarized light through a ¼ waveplate. Similarly, a polarization filter for blocking light of a predetermined circular polarization may be constructed by passing the light through a ¼ waveplate and a linear polarization filter. In one embodiment of the present invention, the transmitter modulates the source of circularly polarized light by changing the direction of polarization of the source of circularly polarized light.

Reflection-type liquid crystal displaying apparatus

Abstract: A liquid crystal displaying apparatus has a reflection-type liquid crystal display with vertical orientation-mode liquid crystals, to modulate linearly polarized light. Also provided is a polarization and diffracting section to convert read light beams obliquely incident thereto to the linearly polarized light, to allow the linearly polarized light to be incident to the liquid crystal display, allow first polarized light components of the linearly polarized light modulated by the liquid crystal display to pass therethrough, the first polarized light components vibrating in a first direction perpendicular to a second direction in which the linearly polarized light vibrates, and diffract second polarized light components of the linearly polarized light to a third direction from which the read light beams be incident to the liquid crystal display, the second polarized light components vibrating in the second direction. Further provided are a quarter wavelength plate to allow elliptically polarized light which includes the first polarized light components and a small quantity of the second polarized light components to pass therethrough when the liquid crystal display is active for modulation, and a polarizer to allow polarized light components of the elliptically polarized light to pass therethrough, the polarized light components matching a transmission axis of the polarizer.

Laminated phase plate and liquid crystal display comprising the laminated phase plate

Abstract: A laminated phase plate is formed by laminating a first optical phase difference compensation plate, having a retardation between 100 and 180 nm for transmitted light, with a wavelength of 550 nm and a second optical phase difference compensation plate having a retardation between 200 and 360 nm for transmitted light with a wavelength of 550 nm. The optical phase difference compensation plates are arranged so that |θ1−(2×θ2)| is between 80 and 100 degrees. The term θ1 is an angle between a vibration direction of linearly polarized light and a slow axis direction of the first optical phase difference compensation plate when the linearly polarized light, which is visible light and has a fixed plane of vibration, is incident on the second optical phase difference compensation plate. The term θ2 is an angle between the vibration direction of linearly polarized light incident on the second optical phase difference compensation plate and a slow axis direction of the second optical phase difference compensation plate.

A CCD-based polarization interferometric technique for testing waveplates

Abstract: A CCD-based polarization interferometric technique is developed to test waveplates. A Babinet compensator is used to produce interference fringes for polarized input and the retardance introduced by the waveplate when inserted in the optical beam is calculated from the fringe shifts using the phase matching technique. A theoretical model is fitted with the observed fringe shifts to get an accuracy of 0.5° in the retardance calculation. The experimental set-up and the measurement of retardance for zero-order and high-order quarter waveplates are discussed. The retardance calculation for a zero-order waveplate is found to be more accurate than the high-order waveplate. This technique can also be used to measure an arbitrary amount of retardance produced by any birefringent waveplate and also to determine its optic axis direction.

Optical device usable as optical isolator as well as optical amplifier and system including this optical device

Abstract: PROBLEM TO BE SOLVED: To provide an optical isolator having wavelength selectivity relating to an optical device usable as the optical isolator as well as an optical amplifier and system including the optical device. SOLUTION: This optical isolator comprises polarizers P1 and P2 which have transmission axes to determine the polarization axes of the polarized light rays respectively transmitted therethrough and a double refractive element BE and Faraday rotator FR which are disposed between these polarizers P1 and P2. The double refractive element BE is set in its thickness in such a manner that the element is a wavelength plate to a first wavelength and is a half wave plate to a second wavelength different from the first wavelength. The Faraday rotating angle is set at π/4, the angle formed by the transmission axes of the polarizers P1 and P2 at π/4 and the angle formed by the transmission axis of the polarizer P1 and the optical axis of the double refractive element BE at π/4.

Birefringence in rapidly rotating glass disks

Abstract: Centripetal forces modify the optical properties of a rotating glass disk, thus creating a circularly symmetric distortion in the refractive index. This centripetal birefringence has a strong radial dependency and increases with the square of the spin speed. The effect on a polarized beam transmitted through the glass may be reduced mathematically to that of an effective wave plate whose retardance and orientation may be calculated from knowledge of the stress distribution in the disk. Alternatively, one can directly measure the Jones-matrix elements that correspond to the effective wave plate by use of polarization phase measurements at two or more locations on the disk. This direct measurement compensates the centripetal birefringence in the instrumentation employed by the data-storage industry to measure the flying height of read–write heads.

Polarization plane light source device and liquid crystal display device

Abstract: PROBLEM TO BE SOLVED: To provide a polarization plane light source device capable of effectively utilizing >=50% of light made to exit from a light transmission plate by utilizing a linearly polarized light separating element and forming a liquid crystal display(LCD) device or the like having high light utilization efficiency and high luminance. SOLUTION: The polarization plane light source device consists of a superposed body having at least a light transmission plate 1 capable of allowing incident light from a side face to exit from an upper face and having a reflection layer on the lower face side, a 1/4 wavelength plate 2 and a linearly polarized light separating layer 3 for separating natural light into reflected light consisting of linearly polarized light and transmitted light and an LCD device is composed of arranging a liquid crystal(LC) cell on the light exit side of the light source device. Since the reflected light separated by the separation layer 3 is made incident again upon the layer 3 as transmissive linearly polarized light through the reflection layer 11 of the plate 1 and the 1/4 wavelength plate 2 and transmitted and exit light is obtained by adding the transmitted light obtained by reincidence of the reflected light to the original transmitted light, the application efficiency of light can be improved and an LCD device having high luminance and high visibility can be formed.

Birefringence imaging with illumination-mode near-field scanning optical microscope

Abstract: A new optical configuration for a near field scanning optical polarized microscope with an illumination mode is reported. It uses two circularly polarized laser beams with different frequencies which are generated by an axial Zeeman laser. A laser beam is incident on an optical fiber and is launched form the apex of a sharpened fiber probe in order to illuminate the sample. The scattered light on the surface of the sample is collected with an objective lens and goes through the optical elements of the quarter wave plate and the linear polarizer. The light from polarization devices is converted to an electric signal with a photomultiplier and fed into a lock-in amplifier. The quarature components and intensity signal are acquired to computer, and the retardation and the azimuth angle of the birefringence are then calculated via computer. The measurement characteristic of the developed system and image of birefringence material are shown.