32results about How to "Diffraction efficiency" patented technology

Lightwave diffraction device formed of a dielectric layer (4), a mirror (12) arranged at the lower face (10) of said layer, a semi-reflective structure (13) arranged at the upper face (100) of said layer, and a diffractive structure (8) arranged in said layer or on its faces. The height (H) of the layer is chosen so as to substantially satisfy the resonance condition for at least one leaky mode propagating in said layer for at least one given incident wave having a determined wavelengthλ and a determined incidence angle θ_c. Next, the diffractive structure is arranged so that there is no propagating positive diffracted order, and so that all negative orders other than the −1^st propagating order have zero or a relatively small diffraction efficiency, the reflected −1^st order propagating in a direction non-parallel to the incident wave. This diffraction device allows a high diffraction efficiency of up to 100% for the −1^st order.

The present invention concerns a method for constructing a light coupling system wherein a grating is manufactured on the surface of a multimode waveguide and defines the entrance of the waveguide for an incident light beam, said grating comprising a repetition of patterns. The grating is defined by a set of parameters comprising: •grating period (P), separating two adjacent patterns, •grating depth (d) between the highest and the lowest point of the pattern, •incident angle mean value (θ) of the incident light with respect to the waveguide. The method comprises a step of optimization of the set of parameters to obtain an optimized second set of parameters, in order to obtain a transmission efficiency (Ce) of the incident light into said waveguide for the first or the second diffractive order exceeding 35% for unpolarized light, or exceeding 50% for polarized light, at a given wavelength of the incident light.

A display device has a plurality of light emitting elements for emitting lights, a display element for modulating the light emitting from the plurality of light emitting elements so as to convert it to an image light showing an optical image, a reflection type hologram element, having a positive optical power with respect to the lights from the plural light emitting elements, for diffracting and reflecting the lights from the plural light emitting elements to approximately one direction so as to guide the diffracted and reflected lights to the display element; and an enlarging optical system for forming an enlarged image of the optical image converted by the lights from the image display element. The plural light emitting elements are positioned in a plane approximately vertical to an optical path of the lights diffracted and reflected by the hologram element. The hologram element is tilted to a direction facing the plural light emitting elements with respect to the optical path of the lights diffracted and reflected by the hologram element.

An updateable system and method of recording a hologram on a media simultaneously reduces the writing time and increases persistence without sacrificing diffraction efficiency. A voltage kick-off technique controls the bias electric field applied to a photorefractive polymer media in conjunction with the application of the writing beams and dark decay. Essentially the voltage kick-off technique applies a high electric field above the optimal field while the writing beams are on and reduces the electric field when the writing beams are off during dark decay. The voltage kick-off technique produced two separate unexpected results. First, when the writing beams are turned off and the electric field is lowered the diffraction efficiency continues to increase until it reaches a maximum efficiency that is within a few percent of that achieved by writing at the optimal field until steady-state is achieved. Second, the decay time constant is much larger than expected producing a much longer persistence without sacrificing diffraction efficiency or writing time.

An external cavity laser apparatus and method wherein wavelength or channel selection is carried independently from adjustment of external cavity optical path length. The apparatus comprises a wavelength or channel selector tuner and an external cavity tuner, wherein the wavelength tuner is uncoupled from the external cavity tuner. The tuning mechanisms for wavelength selection and cavity optical path length are configured to operate independently or orthogonally with respect to each other. The wavelength tuner may operate according to a first, channel selection signal, while the external cavity tuner operates according to a second, external cavity adjustment signal. The wavelength tuner and external cavity tuner may operate under the control of the same, or of separate controllers. The channel selection signal may be derived from a look-up table of adjustment parameter data accessed by a controller, and the external cavity adjustment signal may be derived from an error signal from a detector configured to measure external cavity loss.

Incoming light is spectrally analyzed by diffracting the incoming light with a grating. At least a part of the incoming light is split off so that this part contains mainly one polarization component of the incoming light. It is ensured that this split-off part and a remaining part of the incoming light reach the grating with their polarized component mainly parallel to a main direction of polarization which is diffracted with maximal efficiency by the grating. For this purpose, at least the split-off part is diffracted after being passed through a polarization rotating element.

Provided is an optically addressable spatial light modulator (OASLM)-based holographic display and a method of operating the same. The display includes an addressing unit including a light source unit emitting a plurality of recording beams, a driving mirror array including driving mirrors that each reflect a recording beam incident thereon, and a mirror member array including mirror members that each obliquely reflect a recording beam incident thereon, in which each of the driving mirrors corresponds to one of the mirror members. The recording beams, which are transmitted by the addressing unit, are focused onto the OASLM by micro lenses of a lenslet array. The OASLM is optically addressed by the recording beams focused by the micro lenses of the lenslet array and thus modulates and diffracts a reproduction beam, incident thereon from a reproduction beam providing unit, and thus a holographic image is reproduced.

Area: Optics

Optical element with Braggs phase grating that consists of electro-optical material or is embedded in an additional layer. The Braggs phase grating is designed as a series of periodically applied elevations and indentations of the waveguide's surface, coated with one layer of the compensating material and one layer of the electrically isolating material, along the propagation of light. The phase grating is equipped with a means of generating a spatially inhomogeneous, aperiodic, external electrical field.

Area of the Invention

The invention belongs to the physical area of optics and, in fact, to the optics methods and facilities for spectral filtering of optical radiation. This is based on electro-optical crystals and is to be used to produce narrow-band filters with a broad wave spectrum of changeover to wavelength, and for production of selective optical attenuators and modulators of light and optical equalisers.

Description of the Invention

The object of the invention is, on the one hand, the production of optical elements in an integral optical design that have a multifunctional use (tuneable optical filters, selective optical attenuators and modulators, optical switches and optical equalisers), and which possess a high spectral selectivity, a broad wavelength band of tuneability, great dynamics, and a low tendency toward cross-talk. A further aim of this invention was to develop a process for control of the aforementioned filters that makes it possible to electrically control the profile of the transfer function, the location of the transfer function's maximum, the number of channels to be selected, and compensation of phase distortion, while using a relatively low control voltage, and with a high tuneability and switching speed.

The task in hand is resolved by a large number of inventions that are related by one joint intention.

A diffraction grating having multiple holographic optical elements (HOEs), including a Dickson grating and at least one other volume phase grating (VPG). In typical embodiments, the multi-HOE grating is implemented to provide high dispersion, at least substantially uniform diffraction efficiency and at least substantially equal diffraction efficiencies for all polarizations across a wide range of wavelengths. The refractive index modulations of the Dickson grating's volume phase medium preferably have significantly greater spatial frequency than those of each other VPG of the multi-HOE grating. Typical embodiments of the multi-HOE grating can be manufactured at low cost with sufficiently small size and high dispersion (for both S-polarized and P-polarized radiation) to be useful in Dense Wavelength Division Multiplexing (DWDM) applications and other applications requiring high dispersion. The multi-HOE grating can be implemented as a transmissive or reflective grating.

The present invention is an optical pick-up system for use in an optical disk device including more efficient beam diffraction for tracking purposes. The system may be used for one or more types of optical disks (e.g., DVDs, CDs, CD-ROMs). The invention includes a system for use in a DVD player; however, the present invention is applicable to any optical disk device. The system invention includes a gray-scale grating, which provides more efficient diffraction of tracking and processing portions of the laser(s) used in optical disk devices.

An illuminating tweezers for grasping and manipulating small articles includes a single light emitting diode (LED) and powering battery located in an upper centrally-located barrel end of a monolithic body made of a light transmissive polymer. A beam-splitter lens molded into the body splits a single beam of light emitted by the LED into a pair of beams which are directed into upper ends of a pair of elastically bendable arms that depend downwardly from opposed longitudinal sides of the barrel. The pair of light beams are conducted downwardly through the arms by total internal reflection, and reflected downwardly and inwardly towards an illumination region located between lower ends of the arms by downwardly and inwardly oriented oblique end faces at lower ends of the arms.

A waveguide device includes a first diffractive element, a second diffractive element, a third diffractive element, and a waveguide element. The first diffractive element has a first grating configured to diffract light of a wavelength to propagate with a first diffraction angle. The second diffractive element has a second grating configured to diffract the light of the wavelength to propagate with a second diffraction angle. The third diffractive element has a third grating and a fourth grating. The third grating is configured to diffract the light of the wavelength to propagate with the first diffraction angle. The fourth grating is configured to diffract the light of the wavelength to propagate with the second diffraction angle. The waveguide element configured to guide light propagated from the first diffractive element and the second diffractive element to the third diffractive element.

A lens surface (22) of an objective lens (20) includes an optical surface (221) formed of a plurality of annular optical surfaces (22a, 22b, 22c, and 22d) which include an approximately stair-shaped cross section and which are annularly partitioned centered around an optical axis (OA) of the objective lens (20), and a plurality of connecting surfaces (251) that connect the plurality of mutually adjacent annular optical surfaces to each other. The plurality of connecting surfaces (251) include cylindrical connecting surfaces (25b and 25c) formed of a cylindrical surface centered around the optical axis (OA) and a conical connecting surface (26a) formed of a conical surface centered around the optical axis (OA), and the conical connecting surface (26a) connects the annular optical surface (22c) and the annular optical surface (22d).