682 results about "Polarization modulation" patented technology

A multiple path stereoscopic projection system is disclosed. The system comprises a polarizing splitting element configured to receive image light energy and split the image light energy received into a primary path and a secondary path, a reflector in the secondary path, and a polarization modulator or polarization modulator arrangement positioned in the primary path and configured to modulate the primary path of light energy. A polarization modulator may be included within the secondary path, a retarder may be used, and optional devices that may be successfully employed in the system include elements to substantially optically superimpose light energy transmission between paths and cleanup polarizers. The projection system can enhance the brightness of stereoscopic images perceived by a viewer. Static polarizer dual projection implementations free of polarization modulators are also provided.

The objective of the present invention is providing a method for fabricating high quality diffractive waveplates and their arrays that exhibit high diffraction efficiency over large area, the method being capable of inexpensive large volume production. The method uses a polarization converter for converting the polarization of generally non-monochromatic and partially coherent input light beam into a pattern of periodic spatial modulation at the output of said polarization converter. A substrate carrying a photoalignment layer is exposed to said polarization modulation pattern and is coated subsequently with a liquid crystalline material. The high quality diffractive waveplates of the present invention are obtained when the exposure time of said photoalignment layer exceeds by generally an order of magnitude the time period that would be sufficient for producing homogeneous orientation of liquid crystalline materials brought in contact with said photoalignment layer. Compared to holographic techniques, the method is robust with respect to mechanical noises, ambient conditions, and allows inexpensive production via printing while also allowing to double the spatial frequency of optical axis modulation of diffractive waveplates.

A polarization-modulating optical element (1) consisting of an optically active crystal material has a thickness profile where the thickness, as measured in the direction of the optical axis, varies over the area of the optical element. The polarization-modulating optical element (1) has the effect that the plane of oscillation of a first linearly polarized light ray and the plane of oscillation of a second linearly polarized light ray are rotated, respectively, by a first angle of rotation and a second angle of rotation, with the first angle of rotation and the second angle of rotation being different from each other.

A wavelength selective switch, in which an input optical signal is wavelength-dispersed and polarization-split in two angularly oriented planes. A polarization rotation device, such as a liquid crystal polarization modulator, pixelated along the wave-length dispersive direction such that each pixel operates on a separate wavelength channel, rotates the polarization of the light signal passing through the pixel, according to the control voltage applied to that pixel. The polarization modulated signals are then wave-length -recombined and polarization-recombined by means of similar dispersion and polarization combining components as were used to respectively disperse and split the input signals. The direction of the output signal is determined by whether the polarization of a particular wavelength channel was rotated by the polarization modulator pixel, or not. In this way, a fast, wavelength dependent, optical switch is provided, capable of use in WDM switching applications.

The invention discloses a broadband tunable single-passband microwave photon filter generating system. The system comprises a laser, an optical coupler, a polarization modulator, a dispersion displacement optical fiber, a photoelectric detector, a vector network analyzer, a strength modulator and an optical fiber; the laser is used for providing continuous light signals; the optical coupler is used for dividing the continuous light signals into the first path of light signals and the second path of light signals; the polarization modulator is used for modulating the polarization state of the first path of light signals; the dispersion displacement light fiber is used for performing stimulated Brillouin scattering on the detection light signals under the induction effect of pump light signals; the photoelectric detector is used for receiving the detection light signals which are processed in a stimulated Brillouin scattering mode and output by the dispersion displacement optical fiber and generating microwave signals; the vector network analyzer is used for receiving microwave signals output by the photoelectric detector, performing measurement frequency response on the microwave signals, and outputting the microwave signals to the a first polarization modulator at the same time; the strength modulator is used for modulating the polarization state of the first path of light signals and outputting the first path of light signals which are modulated; the optical fiber is used for filtering the first path of light signals which are modulated, and the first path of light signals serve as the pump light signals.

The invention relates to the technical field of optical instruments, in particular to an underwater video camera system based on polarization identification and a method thereof. The technical scheme is that the underwater video camera system comprises an underwater light source, a polarization modulation part and an image acquisition and processing part, wherein the underwater light source comprises a semiconductor laser, an optical filter, a polarizer, a polarization rotator and a beam expander; the polarization modulation part comprises an analyzer, a stepper motor, a stepper motor controller and an infrared detector; and the image acquisition and processing part comprises a high-frequency CCD (Charge Coupled Device) video camera, an image acquisition system and a computer. The underwater video camera system has the benefits that with the adoption of the underwater camera system and the method, the contrast degree and the definition of target imaging as well as the target detectionand the identification efficiency can be effectively improved; the polarization imaging can utilize the differences of different target back polarizations to eliminate the interference of background light; and as a means for identifying the target from messy background is provided, the method has remarkable advantage as compared with the commoner method for imaging and identifying the target by using light intensity.

The invention discloses a spectrum polarization detection device and a method for synchronous polarization modulation interference imaging. The spectrum polarization detection device comprises a preposed polarization imaging system, an image plane interference imaging spectrometer and a signal processing system which are arranged on the same optical axis in sequence. Incident light forms four groups of light beams with different polarization state information through a polarization element and the light beams are separated on a space of a back focal plane of a microlens array. The separated light beams shoot into a lateral cutting beam splitter after passing through a collimator objective lens and are divided into two crosswise, and optical path difference information is brought in. Two branches of emergent light passes through a postpositional imaging objective lens, a target image with interference information and polarization state information is obtained on a target face of a detector, and the target image is transformed into an electrical signal and enters a signal processing system. Fourier transform is carried out, and light intensity information, spectral information and complete Stokes polarization information of a two-dimensional space of each target point are obtained. The spectrum polarization detection device for synchronous polarization modulation interference imaging has the advantages of being high spectral resolution, high in signal to noise ratio and simultaneous in complete Stokes polarization information and can be used for spectrum detection of a narrow band or a wide band.

The invention discloses a quantum key distribution system and method based on time-slot mixed active polarization compensation. The quantum key distribution system comprises a transmitting terminal, an optical signal generation module, a polarization modulator, a synchronous signal generator, a wavelength division multiplexing module, a wavelength division multiplexing solution module, a synchronous signal receiver, a polarization demodulator, a signal detection module and a receiving terminal. According to the quantum key distribution system and method, adopted reference light pulse signals and quantum pulse signals have the same wavelength, the magnitude of single pulse energy of the reference light pulse signals is far larger than the magnitude of single pulse energy of the quantum pulse signals, and the magnitude can be detected through a photoelectric detector. The reference light pulses do not need to be accumulated repeatedly to calculate sums when the detection is carried out, and the polarization compensation rate can be greatly promoted. After the active polarization compensation, and different polarization codes are detected based on a unified polarization detection device, so the quantity of SPAD can be reduced. An optical switch is utilized to carry out switchover on a detection light path, the phenomenon that the strong reference light pulse signals directly impact the SPAD, and therefore communication quality of quantum signals can be guaranteed.

An optical device includes an encoding surface having a micro-relief pattern (22) over at least part thereof designed to produce a predetermined diffracted first image when illuminated in use, and an optically anisotropic layer (26) such as a polymerized liquid crystal provided whereby at least part of the micro-relief pattern (22) induces local orientation of the optically anisotropic layer (26) thereby to impose a predetermined polarization modulation, thereby to produce a predetermined polarization dependent second image when illuminated in use.

A quantum cryptographic device provides authentication services over the optical (quantum) channel and the public channel. In one implementation, polarizers generate optical pulses that have a polarization state based on a bit from a first bit sequence. A polarization rotator further rotates the polarization basis of the optical pulse by a rotation angle specified by one or more bits of a second bit sequence. A receiving device receives the modulated optical pulses, demodulates the pulses, and may determine whether the optical channel can be authenticated. In an alternate implementation, phase modulation, instead of polarization modulation, is used to similarly modulate the optical pulses.

A polarization modulator for time-multiplexed stereoscopic 3D applications rapidly switches between two polarization states in alternate subframes. The polarization modulator uses two liquid crystal devices arranged in optical series and driven such that the second device compensates a change the first device makes to an input polarization state of incident light during alternate subframes. The compensating liquid crystal devices are characterized in that, if the same voltage is applied to both of them, the second device compensates the change that the first device makes to the input polarization state, regardless of the applied voltage level. If the applied voltage is changed from one level to another and the liquid crystal material in the liquid crystal devices relaxes to the new voltage level, polarization state compensation will take place throughout the duration of the relaxation so that the slow, unpowered transition does not manifest itself as a change in polarization state.

A system for detecting piston diversity between mirror segments. The system includes a pupil plane mask, a transform optical element, and an image detector. The pupil plane mask includes two or more open mask areas and two or more polarizers. Each polarizer is disposed within a respective one of the open mask areas. A first one of the two or more polarizers has a first polarization orientation, and a second of the two or more polarizers has a second polarization orientation.

The invention discloses a snapshot integral view field imaging full-polarization hyperspectral detection device. The snapshot integral view field imaging full-polarization hyperspectral detection device is composed of a front optical lens set, an integral view field unit, a collimating lens set, a full-polarization modulation module, a spectrum light splitting module, an imaging lens set, an area array detector and a data collecting and processing system all of which are sequentially arranged in the direction of incident light. Light emitted by a two-dimensional spatial target sequentially enters the front optical lens set, the integral view field unit, the collimating lens set, the full-polarization modulation module, the spectrum light splitting module and the imaging lens set, and finally reaches the area array detector. The data collecting and processing system controls the area array detector to shoot a frame of image to obtain distribution information of hyperspectral images corresponding to polarized components; then the data collecting and processing system extracts and processes data of the frame of image to obtain information of the spatial morphology, the one-dimensional high spectrum and the full Strokes polarization parameter of the detected two-dimensional spatial target. By means of the snapshot integral view field imaging full-polarization hyperspectral detection device, three-dimensional information of the space, the spectrum and polarization can be obtained in real time.

The invention discloses an ultra-long distance optical communication system and an ultra-long distance optical communication method based on single-photon detection, which is particularly applicable to the occasions with ultra-long distance communication. In the invention, aiming at the contradictions between the international requirements on deep-space exploration and deep-space communication and the limits of traditional microwave communication system on power consumption, bandwidth and the like, the spatial optical communication mode with the following advantages is adopted: large channel capacity, low power consumption, small volume, light weight, high confidentiality, strong anti-interference and the like; based on the rising single-photon detection technology, the invention provides the ultra-long distance optical communication system and the ultra-long distance optical communication method based on single-photon detection; the coding modulation mode in which the differential pulse position modulation and the polarization modulation are combined with each other is adopted; furthermore, the spatial high-precision tracking, capturing and aiming technology is adopted; by the optical machine structure with reasonable design and the communication method of the system, the chain and system consumption of the spatial optical communication can be reduced; the communication bandwidth can be improved; and the power consumption of communication system can be greatly reduced, thus meeting the requirement on the ultra-long distance optical communication, therefore, the system and the method are especially applicable to the occasions with ultra-long distance optical communication.

For coherent fiber optic communications, the nonlinear XPolM impairment is the most important issue to realize over-100 Gbps high-speed transmissions. A method provides a way to cancel time-varying XPolM crosstalk by introducing multi-stage adaptive mechanism. In the method, a low-complexity adaptive filtering based on recursive least-squares (RLS) first tracks the time-varying crosstalk along with the per-survivor trellis-state decoding. The estimated channel and the decoded data are then used to calculate the empirical covariance, which is in turn exploited to obtain more accurate channel estimates by means of optimal-weighted least-squares. This is performed with a low-complexity processing over frequency domain with fast Fourier transform. The performance is significantly improved with turbo principle decoding, more specifically, iterative decoding and iterative estimation over a block.