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2608 results about "Double frequency" patented technology

Non-contacting temperature sensing device

The device according to the invention provides a non-contacting temperature sensing device incorporating micro-bolometric detectors as the suitable infrared sensors for automotive applications. A first and second infrared sensors each include an active infrared sensing element and a temperature drift compensating element. A current bias is applied to the active infrared sensing element as well as to the temperature drift compensating element, which is identical in structure with the active infrared sensing element, and the voltage outputs of these two elements pass through a differential amplifier. The fluctuation in the substrate temperature or the ambient temperature affects the active sensing element and the compensating element in the same way, thus it is cancelled out. Instead of using one spectral band of the infrared radiation, as in the prior art, two spectral bands are used resulting in a first and second signal generated by the first and second infrared sensors. A ratio of the first and second signals is obtained. The ratio of the signals is emissivity independent, so that the device of the present invention provides a more accurate measurement of temperature. The need to compensate for window contamination is also eliminated by this two band approach. The filtering elements for the two bands can be multi-layer thin film filters either coated on flat windows or on diffractive micro-lenses. The use of diffractive micro-lenses further reduces the size of the device, and eliminates the need for a separate optical lens.
Owner:MONTEREY RES LLC +1

Tolling highway network traffic information acquisition and induction system based on path identification system

The invention discloses a tolling highway network traffic information acquisition and induction system based on a path identification system. The tolling highway network traffic information acquisition and induction system comprises a tolling highway outlet, inlet tolling lane system, a networking tolling center system, a 5.8G path identification station, a 5.8G path identification station monitoring system, a MTC vehicle double-frequency passing card, an ETC vehicle OBU and noncash payment card, an on-board multimedia terminal, and a traffic information processing system. The tolling highway network traffic information acquisition and induction system is advantageous in that by adopting the 5.8G Hz path identification station, the double-frequency passing card provided with the Bluetooth module, the OBU, and the on-board multimedia terminal, the path identification and traffic information acquisition and the traffic information push can be realized; by adopting the combination between the cloud calculation and the 5.8G path identification station distributed calculation, the processing and the prediction of the information such as the traveling time, the traffic flow, the travel speed, the traffic state, and the vehicle position of the tolling highway segment can be realized, and therefore the accurate and reliable front traffic information can be provided for the highway user.
Owner:SOUTH CHINA UNIV OF TECH

Double-frequency grating interferometer displacement measurement system

The invention discloses a double-frequency grating interferometer displacement measurement system. The system comprises a double-frequency laser device, an interferometer, a measuring grating and an electrical signal processing portion. The measurement system achieves displacement measurement based on optical grating diffraction, the optical doppler principle and an optical beat frequency principle. The double-frequency laser device transmits double-frequency laser, the laser is divided into reference light and measuring light through a polarizing beam splitter, the measuring light transmits into a position of the measuring grating, positive and negative first-order diffraction occurs, diffraction light and the reference light form a beat frequency signal which contains displacement information in two directions at the position of a light detection unit, and linear displacement output is achieved through signal processing. According to the system, the sub-nanometer-grade or even higher grade of resolution ratio and accuracy can be achieved, and horizontal large-stroke displacement and horizontal displacement can be measured at the same time. The system has the advantages of being insensitive to the environment, high in measuring accuracy, small in volume and light in weight. The system serves as a lithography machine ultraprecise workpiece platform position measurement system, the comprehensive performance of the workpiece platform can be improved.
Owner:TSINGHUA UNIV +1

Method and device for measuring frequency scanning absolute distance based on femtosecond optical frequency comb

The invention relates to a device for measuring a frequency scanning absolute distance based on a femtosecond optical frequency comb and a method for measuring the absolute distance based on the device. The device comprises: a tunable laser (1), a polarization maintaining fiber system (2), a double-frequency heterodyne interferometer (3) and a system for measuring a laser frequency and an interferometric phase (4); the tunable laser (1) is used for generating single-frequency, single-line polarization laser, and an output laser frequency can be controlled by the working voltage and current ofthe tunable laser; the polarization maintaining fiber system (2) is used for coupling space laser with a polarization maintaining fiber in an unreflected way, and dividing the space laser into three paths of optical signals with equal optical intensity, and keeping an output laser polarization direction the same as an input laser polarization direction; the double-frequency heterodyne interferometer (3) is used for converting single-frequency laser into double-frequency orthogonal polarization laser, and converting distance information to be measured into phase information of a laser beat signal; and the system for measuring the laser frequency and the interferometric phase (4) is used for precisely measuring and locking and inputting the frequency of the laser, and measuring a phase different between the two paths of alternating current signals.
Owner:TSINGHUA UNIV
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