17369 results about "Ultrasound attenuation" patented technology

The Laser Induced Fluorescence Attenuation Spectroscopy (LIFAS) method and apparatus preferably include a source adapted to emit radiation that is directed at a sample volume in a sample to produce return light from the sample, such return light including modulated return light resulting from modulation by the sample, a first sensor, displaced by a first distance from the sample volume for monitoring the return light and generating a first signal indicative of the intensity of return light, a second sensor, displaced by a second distance from the sample volume, for monitoring the return light and generating a second signal indicative of the intensity of return light, and a processor associated with the first sensor and the second sensor and adapted to process the first and second signals so as to determine the modulation of the sample. The methods and devices of the inventions are particularly well-suited for determining the wavelength-dependent attenuation of a sample and using the attenuation to restore the intrinsic laser induced fluorescence of the sample. In turn, the attenuation and intrinsic laser induced fluorescence can be used to determined a characteristic of interest, such as the ischemic or hypoxic condition of biological tissue.

A low attenuation surface wave transmission line system for launching surface waves on a bare and unconditioned conductor, such as are found in abundance in the power transmission lines of the existing power grids. The conductors within the power grid typically lack dielectric and special conditioning. Accordingly, the present invention includes a first launcher, preferably including a mode converter and an adapter, for receiving an incident wave of electromagnetic energy and propagating a surface wave longitudinally on the power lines. The system includes at least one other launcher, and more likely a number of other launchers, spaced apart from one another along the constellation of transmission lines. The system and associated electric fields along any given conductor are radially and longitudinally symmetrical.

A signal processor which acquires a first signal, including a first primary signal portion and a first secondary signal portion, and a second signal, including a second primary signal portion and a second secondary signal portion, wherein the first and second primary signal portions are correlated. The signals may be acquired by propagating energy through a medium and measuring an attenuated signal after transmission or reflection. Alternatively, the signals may be acquired by measuring energy generated by the medium. A processor of the present invention generates a primary or secondary reference signal which is a combination, respectively, of only the primary or secondary signal portions. The secondary reference signal is then used to remove the secondary portion of each of the first and second measured signals via a correlation canceler, such as an adaptive noise canceler, preferably of the joint process estimator type. The primary reference signal is used to remove the primary portion of each of the first and second measured signals via a correlation canceler. The processor of the present invention may be employed in conjunction with a correlation canceler in physiological monitors wherein the known properties of energy attenuation through a medium are used to determine physiological characteristics of the medium. Many physiological conditions, such as the pulse, or blood pressure of a patient or the concentration of a constituent in a medium, can be determined from the primary or secondary portions of the signal after other signal portion is removed.

Methods are disclosed for measuring target structures formed by a lithographic process on a substrate. A grating structure within the target is smaller than an illumination spot and field of view of a measurement optical system. The optical system has a first branch leading to a pupil plane imaging sensor and a second branch leading to a substrate plane imaging sensor. A spatial light modulator is arranged in an intermediate pupil plane of the second branch of the optical system. The SLM imparts a programmable pattern of attenuation that may be used to correct for asymmetries between the first and second modes of illumination or imaging. By use of specific target designs and machine-learning processes, the attenuation patterns may also be programmed to act as filter functions, enhancing sensitivity to specific parameters of interest, such as focus.

A system for determining a biologic constituent including hematocrit transcutaneously, noninvasively and continuously. A finger clip assembly includes including at least a pair of emitters and a photodiode in appropriate alignment to enable operation in either a transmissive mode or a reflectance mode. At least one predetermined wavelength of light is passed onto or through body tissues such as a finger, earlobe, or scalp, etc. and attenuation of light at that wavelength is detected. Likewise, the change in blood flow is determined by various techniques including optical, pressure, piezo and strain gage methods. Mathematical manipulation of the detected values compensates for the effects of body tissue and fluid and determines the hematocrit value. If an additional wavelength of light is used which attenuates light substantially differently by oxyhemoglobin and reduced hemoglobin, then the blood oxygen saturation value, independent of hematocrit may be determined. Further, if an additional wavelength of light is used which greatly attenuates light due to bilirubin (440 nm) or glucose (1060 nm), then the bilirubin or glucose value may also be determined. Also how to determine the hematocrit with a two step DC analysis technique is provided. Then a pulse wave is not required, so this method may be utilized in states of low blood pressure or low blood flow.

A waveform adaptive transmitter that conditions and/or modulates the phase, frequency, bandwidth, amplitude and/or attenuation of ultra-wideband (UWB) pulses. The transmitter confines or band-limits UWB signals within spectral limits for use in communication, positioning, and/or radar applications. One embodiment comprises a low-level UWB source (e.g., an impulse generator or time-gated oscillator (fixed or voltage-controlled)), a waveform adapter (e.g., digital or analog filter, pulse shaper, and/or voltage variable attenuator), a power amplifier, and an antenna to radiate a band-limited and/or modulated UWB or wideband signals. In a special case where the oscillator has zero frequency and outputs a DC bias, a low-level impulse generator impulse-excites a bandpass filter to produce an UWB signal having an adjustable center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, a low-level impulse signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic center frequency and bandwidth characteristics. The UWB signal may be modulated to carry multi-megabit per second digital data, or may be used in object detection or for ranging applications. Activation of the power amplifier may be time-gated in cadence with the UWB source thereby to reduce inter-pulse power consumption. The UWB transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more, frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and extensibility from below HF to millimeter wave frequencies.

A camera acquires a 4D light field of a scene. The camera includes a lens and sensor. A mask is arranged in a straight optical path between the lens and the sensor. The mask including an attenuation pattern to spatially modulate the 4D light field acquired of the scene by the sensor. The pattern has a low spatial frequency when the mask is arranged near the lens, and a high spatial frequency when the mask is arranged near the sensor.

An active-pulse blood analysis system has an optical sensor that illuminates a tissue site with multiple wavelengths of optical radiation and outputs sensor signals responsive to the optical radiation after attenuation by pulsatile blood flow within the tissue site. A monitor communicates with the sensor signals and is responsive to arterial pulses within a first bandwidth and active pulses within a second bandwidth so as to generate arterial pulse ratios and active pulse ratios according to the wavelengths. An arterial calibration curve relates the arterial pulse ratios to a first arterial oxygen saturation value and an active pulse calibration curve relates the active pulse ratios to a second arterial oxygen saturation value. Decision logic outputs one of the first and second arterial oxygen saturation values based upon perfusion and signal quality.

The present invention intends to provide particles for displaying images used in an image display device capable of displaying and eliminating repeatedly accompanied by flight and movement of particles utilizing Coulomb force, being superior in stability, particularly in repetition durability, memory characteristic stability, adaptability for temperature change, having capability of regulating charge amount, and accordingly, favorable images with sufficient contrast should be stably obtained. The present invention provides particles coated with a resin; specifying Span of particle diameter distribution, charge attenuation property, thermal change of the surface hardness, tensile break strength, Izod impact strength (with a notch), abrasion loss (Taber), tensile elastic modulus, flexural elastic modulus, or tear strength. The present invention also proposes about the structure of the particles.

The invention provides an optical switch and modulator which uses a closed loop optical resonator. The optical resonator is a dielectric cavity whose primary function is to store optical power. Various structures are possible, and a particularly advantageous one is a ring shaped cavity. The wavelength response at the output port of a ring resonator side coupled to two waveguides is determined by the details of the resonator, and the coupling between the resonator and the waveguides. By coupling to adjacent resonators, the modulator response can be improved over that of a single resonator. One such improvement is in modulator efficiency, which is defined as the ratio of the change in optical intensity at the output, to a change in absorption in the ring waveguides. Absorption is used for switching and modulation without incurring significant optical attenuation. Another improvement involves making the resonance insensitive to small deviations in wavelength or index change. The latter improves fabrication tolerances and compensates for possible drift of the signal wavelength. Collectively, the behavior of multiple coupled resonators yields higher order responses.

The present invention relates to a lighting device using an LED. One embodiment of the invention provides a lamp-shaped LED lighting device that can replace a known lighting device. The lamp-shaped LED lighting device promptly emits the heat generated by an LED element, which influences the optical output and the lifespan of the LED lighting device, through a lamp-shaped frame with a heat-ventilation structure that facilitates air circulation. In addition, the lamp-shaped LED lighting device prevents glare from an LED light source by using a lateral reflecting member, a diffusion lens and a diffusion cover and diffuses the light from the light source widely without optical attenuation. Another embodiment of the invention provides a tube and panel-shaped LED lighting devices that can be replaced with a previous tube-shaped fluorescent light and a panel-shaped lighting device. The tube and panel-shaped LED lighting devices rapidly emit the heat generated by an LED element, which influences the optical output and the life span of the LED lighting device, through a tube and panel-shaped frame with a heat-sink structure. In addition, the tube and panel-shaped LED lighting devices prevent glare from the LED light source by optically arranging a curved reflecting plate, a diffusion plate and a diffusion window which include a diffusion lens at the upper portion of the LED element. Furthermore the tube and panel-shaped LED lighting devices diffuse the light from the LED light source widely without optical attenuation.

Optical waveguide fiber that has large effective area and low loss characteristics, such as low attenuation and low bend loss. The optical waveguide fiber includes a dual trench design wherein an annular region closer to the core is preferably doped with at least one downdopant such as fluorine, which annular region is surrounded by another annular region that preferably includes closed, randomly dispersed voids.