685 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 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.

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 CARS system and method for probing a Raman signature of a sample are described. A short femtosecond pulse from one or more lasers is split into two pulses, a stimulus pulse and a probe pulse, whereby the probe pulse is time-delayed with respect to the stimulus pulse. Both pulses can be phase- and polarization-modulated. The stimulus pulse excites a vibronic level in the sample and the probe pulse probes molecular Raman transitions in the sample. A difference in the signals with and without excitation can be used to determine on which molecule a bond is most likely located. This will allow an accurate and sensitive determination of the presence of specific molecules in the sample. The system and method can be used to analyze biological samples and to discriminate between molecules having overlapping Raman signatures.

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.

An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

A technique for suppressing stimulated Brillouin scattering SBS along an optical fiber signal path utilizes polarization modulation at the transmitter to split the launched power into orthogonal polarization states. By reducing the power along each polarization, SBS will be reduced. Linewidth broadening of the optical source is achieved by introducing: (1) a incoherence between the polarization states (using a time delay along the signal path of one polarization state); and (2) a frequency shift between the polarization states (using an acousto-optic modulator along the signal path of the remaining polarization state).

A polarization-modulating optical element 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 has the effect that the plane of oscillation of a first linearly polarized light ray and the plane of oscillation of a second line early 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.

An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

Techniques to bolster the security of an AlphaEta cryptosystem using spectral phase encoding. In one aspect, a spatial light modulator (SLM) is used to change the spectral code (spectral phase) of each optical bit in response to the output of an extended key generator based on a cryptographic algorithm. In other aspects, additional time and polarization modulations are used to maintain high security levels as well as good performance levels. Such methods are combined with traditional key generation methods such as key-distribution centers or one-way mathematical algorithms to bolster the security of traditional key generation as well.

The present invention provides a high brightness color selective light modulator (CSLM) formed by a polarization modulator positioned between two retarder stacks. The modulator changes the apparent orientation of one retarder stack relative to the other so that, in a first switching state of the modulator the two retarder stacks cooperate in filtering the spectrum of input light, and in a second switching state the two retarder stacks complement each other, yielding a neutral transmission spectrum. Two or more CSLM stages can be used in series, each stage providing independent control of a primary color. One preferred embodiment eliminates internal polarizers between CSLM stages, thereby providing an additive common-path full-color display with only two neutral polarizers. Hybrid filters can be made using the CSLMs of this invention, in combination with other active or passive filters. The CSLMs of this invention can be used in many applications, particularly in the areas of recording and displaying color images. They can be arranged in a multi pixel array by pixelating the active elements, and can be implemented as color filter arrays, using patterned passive retarders rather than active polarization modulators.

An optical component for modulation of polarization, a Mueller polarimeter and ellipsometer containing such an optical component. The optical component modulates a linearly polarized incident beam and returns a modulated beam. It includes a coupled phase modulator which modulates the incident beam twice in succession, the two modulations having the same frequency of omega / 2pi, and a coupling system modifying the polarization state of the light between the two modulations. The ellipsometer includes the means for detection of a measurement beam returned by a sample, which receives the modulated beam, in addition to a processing unit. The means of detection include a polarimeter producing n measured quantities representing the polarization states of the beam, and the processing unit produces m values for each of these quantities by Fourier transform, with nxm>=16 and m>=4, providing simultaneous access to the sixteen components of the Mueller matrix of the sample.

The invention discloses a method for two-photon fluorescence stimulated emission differential super-resolution microscopy. The method includes the steps that (1) after being collimated, pulsed laser beams are converted into linear polarized light and polarization modulation is conducted on the linear polarized light, so that radial polarized light is obtained; (2) the radial polarized light is converted into circular polarized light and projected onto a sample to be tested, two-photon stimulated emission is conducted, fluorescence is collected, and therefore first signal light intensity I1 is obtained; (3) polarization modulation is conducted on the linear polarized light obtained in the step (1) and the linear polarized light is converted into tangential polarized light; (4) the tangential polarized light is converted into circular polarized light and projected onto the sample to be tested, two-photon stimulated emission is conducted, fluorescence is collected, and therefore second signal light intensity I2 is obtained; (5) effective signal light intensity I is calculated according to a formula I=I1-gammaI2 , so that super-resolution imaging is achieved. The invention further discloses a device for two-photon fluorescence stimulated emission differential super-resolution microscopy. The device is simple, free of light division, low in light power, capable of weakening the photobleaching effect, higher in resolution and larger in imaging depth.

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.

A method for sending a data from an electromagnetic radiator by polarization modulation of an electromagnetic wave includes radiating from the radiator first and second electromagnetic waves including first and second polarizations respectively, the first polarization being different than the second polarization. The first and second electromagnetic waves form a third electromagnetic wave having a third polarization different from the first or second polarization. The method includes modulating the third polarization responsive to the data by modulating one or more parts of the third electromagnetic wave. The data is sent in the third polarization. A system for sending a data includes an oscillator adapted to generate an oscillating signal, and a phase shifter coupled to the oscillator and adapted to generate a first phase-shifted oscillating signal having a first phase. The phase shifter is adapted to vary the phase difference across a predefined range in response to the data.

A compound polarization beam splitter (33) for use with a reflective, polarization-modulating, imaging device (10), e.g., a LCoS device, is provided. The compound PBS has: (a) an input prism (20); (b) an output prism (30), and (c) a polarizer (13), which is located between the two prisms (20,30) and which may be a wire grid polarizer (13a) or a multi-layer reflective polarizer (13b). Polarized illumination light (11) enters the input prism (20) through a first surface (21) and undergoes total internal reflection at a second surface (22) before being reflected from the polarizer (13) and polarization-modulated at the imaging device (10). The polarizer's tilt angle (β) is less than 45°, which reduces astigmatism and the required back working distance of the system's projection lens (74).

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.

An optical recording / reproducing apparatus having excellent resistance against vibration and noise is provided. In recording, coherent light is polarization-modulated with a spatial light modulator to generate signal light and reference light whose polarization directions are crossed at right angles with each other. The signal light permeates a polarizing beam splitter, and is incident to a quarter wavelength plate. The reference light passes through a passing hole, is diffused by a light diffuser and is incident to the quarter wavelength plate. The reference and signal light are converted into circularly polarized light which revolve in directions opposite to each other and condensed by a condenser lens, and then a predetermined area of an optical recording medium is irradiated with the reference and signal light. Thus, the reference and signal light are generated by modulating the incident light from the same light source and are coaxially incident to the polarizing beam splitter.

The invention discloses a holographic three-dimensional display method and a holographic three-dimensional display device based on a spatial light modulator; the display device is composed of a laser light source, a polarization modulation component, a beam splitter prism, a spatial light modulator, a computer, a lens, and a pixel-type nano grating based directional diffraction screen; and the display method comprises the following steps: obtaining a multi-view two-dimensional image of a target object and undergoing preprocessing conversion process to generate a group of image arrays used for phase type hologram calculation; calculating corresponding phase type holograms with an iterative Fourier transform algorithm, loading the holograms to the spatial light modulator, and irradiating the holograms with the laser light source to obtain holographic reproductive images; and designing and manufacturing the pixel-type nano grating based directional diffraction screen, and directionally diffracting corresponding reproductive image pixels to fixed positions to form different viewpoints. The method and the device disclosed by the invention, by combing with fast refreshing and loading of the spatial light modulator for the holograms, realize multi-view full-parallax dynamic holographic three-dimensional reproduction of the target object, and provide a feasible scheme for application of a naked-eye three-dimensional display technology.

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 polarization conversion system separates light from an unpolarized image source into a first state of polarization (SOP) and an orthogonal second SOP, and directs the polarized light on first and second light paths. The SOP of light on only one of the light paths is transformed to an orthogonal state such that both light paths have the same SOP. A polarization modulator temporally modulates thelight on the first and second light paths to first and second output states of polarization. First and second projection lenses direct light on the first and second light paths toward a projection screen to form substantially overlapping polarization encoded images. The polarization modulator may be located before or after the projection lenses. The polarization-encoded images may be viewed usingeyewear with appropriate polarization filters.

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.