1298 results about "Heterodyne" patented technology

A method for the detection of analytes using resonant mass sensors or sensor arrays comprises frequency encoding each sensor element, acquiring a time-domain resonance signal from the sensor or sensor array as it is exposed to analyte, detecting change in the frequency or resonant properties of each sensor element using a Fourier transform or other spectral analysis method, and classifying, identifying, and/or quantifying analyte using an appropriate data analysis procedure. Frequency encoded sensors or sensor arrays comprise sensor elements with frequency domain resonance signals that can be uniquely identified under a defined range of operating conditions. Frequency encoding can be realized either by fabricating individual sensor elements with unique resonant frequencies or by tuning or modifying identical resonant devices to unique frequencies by adding or removing mass from individual sensor elements. The array of sensor elements comprises multiple resonant structures that may have identical or unique sensing layers. The sensing layers influence the sensor elements' response to analyte. Time-domain signal is acquired, typically in a single data acquisition channel, and typically using either (1) a pulsed excitation followed by acquisition of the free oscillatory decay of the entire array or (2) a rapid scan acquisition of signal from the entire array in a direct or heterodyne configuration. Spectrum analysis of the time domain data is typically accomplished with Fourier transform analysis. The methods and sensor arrays of the invention enable rapid and sensitive analyte detection, classification and/or identification of complex mixtures and unknown compounds, and quantification of known analytes, using sensor element design and signal detection hardware that are robust, simple and low cost.

A nanoparticle sensor is capable of detecting and recognizing single nanoparticles in an aqueous environment. Such sensor may find applications in broad areas of science and technology, from the analysis of diesel engine emissions to the detection of biological warfare agents. Particle detection is based on interferometric detection of multi-color light, scattered by the particle. On the fundamental level, the detected signal has a weaker dependence on particle size (ÿ R³), compared to standard detection methods (ÿ R⁶). This leads to a significantly larger signal-to-noise ratio for smaller particles. By using a multi-color or white excitation light, particle dielectric properties are probed at different frequencies. This scheme samples the frequency dependence of the particle's polarizability thereby making it possible to predict the composition of the particle material. The detection scheme also employs a heterodyne or pseudoheterodyne detection configuration, which allows it to reduce or eliminate noise contribution from phase variations, which appear in any interferometric measurements.

An improved safety related compact hand-portable apparatus for home or office use, EQ-Alert TM is ceiling or shelf mountable, activating upon sensing a minimum-threshold earthquake preferably of about 3.25/Rictor-scale intensity, instantly emitting a series of approximate 110-decibel level siren-alarms; preferably along with activation of a safety-lamp to illuminate an immediate floor-area in event of community power-outage. A preferably dry-cell powered dc/electronic IC-chip timer-circuit, limits duration of the audible-alarm, triggered by sufficient movement of an internal omni-directional mercury n.o./jiggle-switch. Upon completion of the timed audible-alarm and optional voice-chip announcement, the timer-circuit sequences a conventional integral superheterodyne-AM/radio user has preset to a local Conelrad/news-station, for ongoing notification of any earthquake rescue procedures. Optional provision for plug-in circuit-modules, facilitates adding of allied safety-units, such as substantially conventional smoke-alarm, and carbonmonoxide-alarm detectors, sharing the audio-transducer and IC-microprocessor; to issue forth separate short programed voice-announcements as to the detected hazards.

A method for inspecting a package to identify an object concealed in the package includes passing two beams of THz-radiation through the package. The frequency of THz radiation in one beam is different from that in the other, and the beams are at an angle to each other. Each of the transmitted beams is used to form an image of the package and the object. The absorption coefficient of the object is determined from the two images. The material of the object is determined from the absorption coefficients at the two frequencies. The method is useful for detecting explosive material concealed in baggage.

The present invention is directed to a heterodyne reflectometer system and method for obtaining highly accurate phase shift information from heterodyned optical signals, from which extremely accurate film depths can be calculated. A linearly polarized light comprised of two linearly polarized components that are orthogonal to each other, with split optical frequencies, is directed toward a film causing one of the optical polarization components to lag behind the other due to an increase in the optical path in the film for that component. A pair of detectors receives the beam reflected from the film layer and produces a measurement signal, and the beam prior to incidence on the film layer and generates a reference signal, respectively. The measurement signal and reference signal are analyzed by a phase detector for phase shift. The detected phase shift is then fed into a thickness calculator for film thickness results. A grating interferometer may be included with the heterodyne reflectometer system with a grating, which diffracts the reflected beam into zeroth- and first-order bands, which are then detected by separate detectors. A detector receives the zeroth-order beam and generates another measurement signal. Another detector receives the first-order beam and generates a grating signal. The measurement signal from the grating and reference signal may be analyzed by a phase detector for phase shift, which is related to the thickness of the film. Conversely, either measurement signal may be analyzed with the grating signal by a phase detector for detecting a grating phase shift. The refractive index for the film may be calculated from grating phase shift and the heterodyne phase shift. The updated refractive index is then used for calculating thickness.

The invention relates to a BOTDR (Brillouin Optical Time Domain Reflectometer) for calibrating optical power of reference light and a calibrating method thereof. The calibrating method comprises the following steps of: acquiring an electric signal of local reference light from a heterodyne photoreceiver on a basis of a traditional BOTDR for heterodyne coherent detection; transmitting the electric signal subjected to analog-to-digital conversion in a computer to be used as the optical power calibrating feedback quantity of the reference light; sending out an instruction by the computer to adjust the output power of a microwave source and change the optical power of the local reference light so that the difference between the optical power of the local reference light and the preset reference light power is smaller than a set value; calibrating the power; and detecting a BOTD signal. In the invention, the BOTDR in a working process can not be influenced by the working environment temperature, a microwave transmission line connecting the microwave source with an electro-optic modulator and different power responses of the electro-optic modulator on microwave signals of different frequencies, the error between the reference light power at different frequency points and the preset power is smaller than a set value, and the accurate measurement of the stress and the temperature is ensured.

Systems and methods are disclosed for distributed temperature and strain sensing along a length of an infrastructure. Two optical sources, such as, external cavity lasers with a narrow linewidth, are used for launching a probe signal into a sensing fiber coupled to the infrastructure, and for producing a local oscillation signal, respectively. The optical sources are coherently locked with a predefined frequency offset with respect to each other, the predefined frequency offset being in the order of the Brillouin frequency shift. The optical sources are included in an optical phase lock loop (OPLL) system. A balanced heterodyne receiver for narrow band detection at radio frequency (RF) bandwidth receives an optical signal generated by coherent mixing of a backscattered probe signal with the Brillouin frequency shift and the local oscillation signal, and produces an output indicative of one or both of a measured temperature and a measured strain.

A multi-beam laser Doppler vibrometer simultaneously measures velocity, displacement, and vibration history of multiple locations on an object. A beam of coherent light is split into an object beam and a reference beam. The object beam is divided into a plurality of object beams to simultaneously illuminate multiple locations on the object under inspection. The reference beam is frequency shifted and split into a corresponding plurality of frequency-shifted reference beams. A portion of each object beam is reflected by the object as a modulated object beam. The plurality of modulated object beams are collected and respectively mixed with the plurality of frequency-shifted reference beams to provide a plurality of beam pairs. Each beam pair may be focused onto a photodetector or an optical fiber connected to a photodetector.

An electronic receiver array for decoding data encoded into electromagnetic radiation (e.g., light) is described. The light is received at an ultra-small resonant structure. The resonant structure generates an electric field in response to the incident light and light received from a local oscillator. An electron beam passing near the resonant structure is altered on at least one characteristic as a result of the electric field. Data is encoded into the light by a characteristic that is seen in the electric field during resonance and therefore in the electron beam as it passes the electric field. Alterations in the electron beam are thus correlated to data values encoded into the light.

A three-dimensional imaging radar operating at high frequency e.g., 670 GHz, is disclosed. The active target illumination inherent in radar solves the problem of low signal power and narrow-band detection by using submillimeter heterodyne mixer receivers. A submillimeter imaging radar may use low phase-noise synthesizers and a fast chirper to generate a frequency-modulated continuous-wave (FMCW) waveform. Three-dimensional images are generated through range information derived for each pixel scanned over a target. A peak finding algorithm may be used in processing for each pixel to differentiate material layers of the target. Improved focusing is achieved through a compensation signal sampled from a point source calibration target and applied to received signals from active targets prior to FFT-based range compression to extract and display high-resolution target images. Such an imaging radar has particular application in detecting concealed weapons or contraband.

A spread spectrum waveform generator has a photonic oscillator and an optical heterodyne synthesizer. The photonic oscillator is a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier. The optical heterodyne synthesizer includes first and second phase-locked lasers, where the first laser feeds the multi-tone optical comb generator and the second laser is a single tone laser whose output light provides a frequency translation reference. At least one photodetector is provided for heterodyning the frequency translation reference with the optical output of the photonic oscillator to generate a spread spectrum waveform. A receiver pre-processor may be provided to operate on the spread spectrum waveform.

Disclosed are hybrid heterodyne transmitters and receivers for use in communications systems, or other systems, and the corresponding methods for hybrid heterodyne transmitting and receiving. A heterodyne receiver for converting a continuous time modulated signal to a discrete time digital baseband signal includes a sigma-delta modulator. The sigma-delta modulator is a sigma-delta analog-to-digital converter constructed and arranged to receive a modulated signal at an RF carrier frequency and provide a quantized output at a first intermediate frequency. The heterodyne receiver may also include a digital mixer constructed and arranged to receive a data stream quantized by the sigma-delta analog-to-digital converter and receive a signal at a second mixing frequency. The digital mixer then provides digital signals representative of a baseband signal suitable for digital signal processing.

The application provides a low noise fiber laser frequency combs device with controllable carrier envelope phase shift frequency. The low noise fiber laser frequency combs device with controllable carrier envelope phase shift frequency comprises an optical path structure and a circuit structure, wherein the optical path structure comprises an oscillator, an acousto-optic frequency shifter, an optical fiber amplifier, a pulse compressor, an optical fiber spread spectrum device and a coherent heterodyne beat device; and the circuit structure comprises a feed-forward circuit control phase device and a phase-locked loop circuit control repetition frequency device. The fiber laser oscillator can ensure long-time operation of a system, so that the stability of the system is superior to that of a system adopting a solid laser oscillator; through the technologies of optimizing intracavity net dispersion of the fiber oscillator, introducing an inner cavity modulator in the oscillator, adopting the feed-forward acousto-optic frequency shifter, and the like, the low noise fiber laser frequency combs device can be realized; and meanwhile, due to the application of the acousto-optic frequency shifter, the carrier envelope phase shift frequency of the optical frequency combs can be accurately regulated, so that the optical frequency combs device with precise phase position regulation and secular stability is provided for realizing applications such as optical frequency standard, attosecond science and non-linear optics.

A method and apparatus for transmitting and receiving RF signals for broadband communications using power lines as communication medium. A super-heterodyne structure is used to translate the signals from one frequency to another so as to avoid interference sources, which may corrupt the communication signals. In the heterodyne structure, a plurality of local oscillators are used to mix the local oscillator signals with the communication signals for frequency translation. A plurality of frequency filters are used to filtered out unwanted signals. The communication signals are imparted onto or received from the power lines via couplers operatively connected to modems.

The invention discloses a device of measuring the line-width of a laser with narrow line-width and a method of measuring the line-width based on a optical fiber delay self-heterodyne method; in the hardware device, an optical fiber delay line is connected between a first and a second couplers; an acousto-optic modulator is connected between the first and the second couplers; the measured laser is connected to the input of the first coupler, and a photoelectric detector is connected to the output of the second coupler; the photoelectric detector is connected with a spectrum analyzer. In the line-width measurement, simulation models of the line-width triangle v of the laser and the spectrum-width triangle f of the photoelectric current heterodyne signal are built in the frequency shift delay self-heterodyne methodology, and the function relation between the line-width triangle v of the laser and the spectrum-width triangle f of the photoelectric current heterodyne signal is obtained fitting of the three-level proportion function model. The invention presents that with the short optical fiber delay self-heterodyne method, the device can eliminate the deficiency of greatly reduced measuring precision because of not enough delayed time in the delay self-heterodyne method when the length of the delay optical fiber is less than 6 times coherence length of the laser, so as to provide an effective method of precisely measuring the line-width of the laser with narrow line-width in projects.

The embodiments of the present invention provide a configurable homodyne/heterodyne RF receiver including first and second mixers. The configurable homodyne/heterodyne RF receiver functions as a homodyne receiver when the first and second mixers are configured to operate in parallel, and as a heterodyne receiver when the first and second mixers are configured to operate in series. The embodiments of the present invention further provides an RFID reader employing the configurable homodyne/heterodyne RF receiver to facilitate a listen-before-talk function.

The invention discloses a method for calibrating phase modulation degree of spatial light modulators, and the method is used for detecting the phase modulation information by utilizing a heterodyne interference technology. In the method, two beams of coherent optical waves are led to generate a frequency difference by an acousto-optic frequency phase shifter, and the two beams of coherent optical waves are respectively used as a measuring beam and a reference beam; then the effective display area of the spatial light modulator is divided into two parts, a gray value written into one part is 0, and the part is taken as a reference area; the change range of the gray value of the other part is 0-255, and the other part is taken as a test area; the measuring beam is modulated by the spatial light modulators of the reference area and the test area and then interfered with the reference beam; then two photoelectric detectors at an interference field are utilized to respectively detect a reference signal and a measured signal; and the phase difference between the two photoelectric detectors is the phase modulation degree to be measured, therefore, the corresponding relation between the gray value and the phase modulation degree can be established, so that the phase modulation degree of the spatial light modulators can be calibrated.

The invention relates to a heterodyne three-frequency unequal range phase displacement solution phase method, and the method is as follows: selecting three frequencies, firstly adopting four-step phase shift method to obtain the package phase and average light intensity of the middle frequency, adopting two-step phase shift method to obtain the package phase corresponding to the two frequencies under the condition with known light intensity, obtaining the true phase according to the heterodyne method, adopting the contour line sine and cosine filtering method in the optical grating projection three-dimensional measurement, using stripe direction information for filtering the package phase on isophasal line, the method uses less projection picture for exactly measuring and uses the stripe direction information for filtering the package phase picture for effectively removing the inconsistent points in the package phase picture, the heterodyne three-frequency unequal range phase displacement solution phase method is used in the phase method three-dimensional shape measurement for effectively raising the measuring efficiency and measuring accuracy.