361 results about "Fiber transmission" patented technology

Methods and systems are disclosed for detecting overheating in an optical device before harmful consequences, such as severe local heating, can result. In one embodiment of the invention, a blackbody emitter is disposed in close proximity to a therapeutic optical fiber to absorb therapeutic radiation at a fault and re-emit blackbody (infrared) radiation. The emitter can be coupled to the fiber but, during normal operation, lies outside the optical path between the output of the laser radiation and the site of treatment. Systems and catheters incorporating such emitters are also described for effective monitoring of the laser power transmitted along the optical fiber within the phototherapy device.

Devices, arrangements and apparatus adapted to propagate at least one electro-magnetic radiation are provided. In particular, a probe housing, a sample arm section and a reference arm section can be included. For example, the sample arm section can be at least partially situated within the probe housing, and configured to propagate a first portion of the electro-magnetic radiation that is intended to be forwarded to a sample. The reference arm section can be at least partially situated within the probe housing, and configured to propagate a second portion of the electro-magnetic radiation that is intended to be forwarded to a reference. In addition or as an alternative, an interferometer may be situated within the probe housing. The first and second portions may travel along substantially the same paths, and the electro-magnetic radiation can be generated by a narrowband light source that has a tunable center wavelength. Further, the first and second portions may be at least partially transmitted via at least one optical fiber. A splitting arrangement may be provided which splits the electro-magnetic radiation into the first and second portions, and positioned closer to the sample than to the source of the electro-magnetic radiation, and the first and second portions may be adapted to propagate in different directions. An apparatus may be provided that is configured to control an optical path length of the second portion.

A bend-loss tolerant multimode fiber transmission system is provided. The system includes: a transmission fiber having a core and a cladding, and a mode-launching system for selectively exciting only a useful portion of the transmission modes, that portion corresponding to high effective refractive indices relative to a refractive index of the cladding the useful portion corresponding to a substantial number of modes. The mode-launching system may include a lead-in fiber, coupled to the transmission fiber, supporting a number of lead-in modes substantially corresponding to the number of transmission modes in the useful portion. The transmission fiber may have a refractive index profile, within a region of its core that is aligned with the lead-in fiber core, which has a shape that matches a refractive index profile shape in the lead-in fiber core. The transmission fiber core may have a graded refractive index profile that is parabolic or nearly parabolic or truncated.

A method of converting legacy HFC CATV cable systems, which transmit data over the optical fiber portion of the system using the optical counterpart of analog RF waveforms, such as RF QAM waveforms transduced to corresponding optical QAM waveforms, to improved HFC CATV systems that transmit data over the optical fiber using optical fiber optimized protocols, such as Ethernet frames and other optical fiber optimized digital transport protocols. According to the method, most aspects of the legacy HFC CATV system may be retained, however at the CATV head end, the optical fiber transmitter system is replaced by an improved system that extracts the underlying symbols from legacy waveforms, packages these symbols into optical fiber optimized packets, and transmits downstream. The legacy optical fiber nodes are replaced with improved nodes capable of receiving the packets and remodulating the symbols into RF waveforms suitable for injection into the system's CATV cable.

The present invention is to provide an optical fiber preform suitable for the production of an energy-transmitting or ultraviolet light-transmitting optical fiber, which has an excellent transmittance of a high-energy light of 50 KW / cm2 or more in terms of laser peak power or an ultraviolet light, to be transmitted through the optical fiber and which exhibits excellent durability that causes almost no deterioration by the irradiation with those two lights; and a production process thereof. The present invention relates to an energy-transmitting or ultraviolet light-transmitting optical fiber preform, having a core and a cladding each comprising a silica glass, wherein the core has an average OH concentration of 0 to 10 ppm, an average O2 concentration of ≦1015 molecules / cm3, an average ODC (I) concentration of ≦1013 defects / cm3, an average ODC (II) concentration of ≦1012 defects / cm3 and an average F concentration of ≦1,000 ppm, and the cladding has an average OH concentration of 0 to 10 ppm, an average F concentration of ≧7,000 ppm, an average O2 concentration of ≦1016 molecules / cm3, an average ODC (I) concentration of ≦1013 defects / cm3 and an average ODC (II) concentration of ≦1012 defects / cm3.

System, apparatus and method of optical communication are provided for performing digital compensation of the self-phase modulation (SPM) effect experienced by a polarization-division multiplexed (PDM) orthogonal frequency-division multiplexed (OFDM) signal in fiber transmission by compensating a complex digital waveform representing one orthogonal polarization component of the optical PDM-OFDM signal based on both digital waveforms representing two orthogonal polarization components of the PDM-OFDM signal. The compensation of the digital waveform may be further based on an anticipated mean total nonlinear phase shift experienced by the signal during fiber transmission due to SPM. The compensation may be divided into pre-compensation at the PDM-OFDM transmitter and post-compensation at the PDM-OFDM receiver. The fiber transmission link preferably includes a pre-dispersion compensation module, distributed inline dispersion compensation modules, and a post-dispersion compensation module arranged in a judiciously chosen manner.

Apparatus and method for measuring the fluorescence of nanodrop liquid samples is described in which the sample is held by surface tension between two anvil surfaces. Each anvil surface has an embedded optical fiber with its end finished flush with the surface in the containment area wetted by the sample with the fiber in line. Sample excitation is provided from the side of the sample remote from the containment area. By selection of the fiber transmission numeric aperture the impact of exciting and ambient light on the measurement is minimized. A method of virtual filtering is taught in which any ambient or exciting light that does impinge on the measuring sensor is corrected by subtracting a scaled representation of the source from the measurement. The method and apparatus is capable of detecting 1 femptomole of sodium fluorescein in 1 microliter of TE buffer.

The invention discloses a roadway surrounding rock stress monitoring device based on fiber bragg grating sensing. Grooves are symmetrically carved in a metal rod along the axial center, an FBG set is fixedly installed inside each groove, FBGs serve as sensitive elements, when roadway surrounding rock is deformed, the stress of the surrounding rock will be changed, therefore, force is generated through the metal rod, surface micro-deformation is generated, the grating distances of the FBGs attached to the metal rod are changed along with the metal rod, the center reflection wavelength of the FBGs can be caused to generate drifting, wavelength signals are demodulated into electrical signals through an FBG interrogator, and the stress situations of different sites can be obtained. The roadway surrounding rock stress monitoring device has the advantages that installation is easily achieved, and the roadway surrounding rock stress monitoring device is suitable for wide popularization; power is not required to be supplied to the working face end, and site safety is guaranteed; all-optical measurement and fiber transmission are adopted, and influences of electromagnetic interference are effectively avoided; the temperature error is compensated, and the accuracy is improved; the surrounding rock stress monitoring results can be timely and accurately provided, and guidance on site production and scientific research is facilitated.

Digital compensation of chromatic dispersion (CD) effect experienced by optical orthogonal frequency-division multiplexed (OFDM) signal in fiber transmission is provided in the frequency domain using a Fast Fourier Transform / Inverse Fast Fourier Transform (FFT / IFFT) pair with equal length of digital samples prior to OFDM receiver signal processing, wherein the equal length is larger than the length of a FFT used for OFDM subcarrier demultiplexing of the received signal. The OFDM signal processing is independent of fiber CD, so small guard-interval (GI) can still be used to achieve high spectral efficiency even under the experience of large CD. The GI need only to be large enough to accommodate other effects such as polarization-mode dispersion. The length of an IFFT used for OFDM subcarrier multiplexing, as well as the FFT for OFDM demultiplexing can be sufficiently small so subcarrier spacing is sufficiently large to tolerate typical frequency offsets between the transmitter laser and the optical local oscillator.

An optical access network (OAN) system is provided. In the system, a remote radio unit (RRU) receives and sends a wireless signal and implement conversion between the wireless signal and a first frequency signal; an optical network device receives and sends the wireless signal, and implement conversion between the wireless signal and the first frequency signal and conversion between the first frequency signal and a fiber transmission signal; an optical distribution network (ODN) connected to the optical network device transmits the fiber transmission signal; an optical line terminal (OLT) device receives and sends the fiber transmission signal, and implements conversion between the fiber transmission signal and a second frequency signal, conversion between the second frequency signal and a base band signal, and conversion between the base band signal and a signal of another standard protocol.

The invention belongs to the technical field of fiber communication and optical network transmission signal equalization treatment, and particularly discloses a single-sideband modulated single carrier frequency-domain equalization technology-based fiber communication system. In a transmission system of fiber communication, by using a DSP equal high-speed digital signal processing mode, single-sideband modulated electrical signals received by direct detection are transformed to a frequency domain from a time domain by adopting FFT transformation, an equalization module designed aiming at a transmission link is adopted for performing equalization compensation in the frequency domain, and finally the signals processed by the equalization module are transformed to the time domain from the frequency domain through IFFT to acquire the final equalization signal. The fiber communication system can improve the transmission quality of the signals, and has the signal equalization compensation capacity of the self-adaptive fiber transmission link.

A fiber laser beam processing apparatus is configured by a fiber laser oscillator, a laser power source unit, a laser beam injecting unit, a fiber transmission system, a laser beam irradiating unit, a processing table, etc. A portion of a fiber laser beam oscillated and outputted by the fiber laser oscillator is received by a photo diode for monitoring the power through a beam splitter. An output signal of the photo diode is sent to a laser power source unit. The power source unit receives the output signal of the photo diode as a feedback signal and controls a driving current or an excitation current to be supplied to a laser diode of a pumping unit such that the laser output of the fiber laser beam equals a set value.

The invention relates to the apparatus for and a method of sensing impact between a vehicle and an object and particularly between a pedestrian and the front bumper (12) of a vehicle. An optical fiber array (14) extends along the bumper (12) and the array (14) has sensors spaced along the bumper (12). A sensor comprises light loss areas spaced peripherally and axially on a fiber. An impact distorts the sensors, modulating light transmitted along the fiber or fibers. A signal is produced which is processed by a signal processor and an output signal generated. The output signal is used to actuate a safety device, such as elevating the vehicle hood to increase clearance between hood and engine, to reduce the severity of any injuries.

The invention discloses a manufacturing method of copper-based brazing filler metal laser brazing cubic boron nitride grinding materials. The method particularly comprises the following steps that 1, a 45 steel substrate and CBN grinding particles are put in organic solvent, and deoiling and decontamination treatment are conducted through an ultrasonic cleaning method; 2, copper-based brazing filler metal is laid on the 45 steel substrate, and the CBN grinding particles are orderly distributed on the brazing filler metal; 3, a sample to be added is put on brazing equipment composed of a CO2 laser device, a numerical control machining tool and a gas shielding device, the copper-based brazing filler metal is heated and melted through laser which has certain frequency and is emitted by the CO2 laser device, and the brazing filler metal has good infiltration property on the steel substrate and the CBN grinding particles. According to the manufacturing method of the copper-based brazing filler metal laser brazing cubic boron nitride grinding materials, the manufacturing cost is low, brazing CBN particle grinding is conducted through laser, the energy density is high, the speed of increasing and decreasing the temperature is high, local heating can be achieved, a heat-affected zone is small, and heat damage is not prone to occurrence; laser beams can be transmitted through optical fibers, machining can almost be conducted on any brazing parts, and the flexibility is better.

The invention provides a device and a method for measuring the diameter of plant stems based on machine vision. The measurement device comprises a camera (1), an annular LED light source (2), a support frame (3), a cylindrical reference object (4), an IEEE 1394 signal fiber transmission device (5), a data transmission cable (6) and a computer (7). The measurement method comprises the following steps of utilizing the camera (1) to acquire images of a to-be-measured plant stem and the cylindrical reference object (4) within a certain time interval, transmitting the images to the computer (7) through the IEEE 1394 signal fiber transmission device (5) and the data transmission cable (6) and utilizing image processing software installed in the computer to calculate the diameter of the plant stem. The invention effectively solves the constraint influence of the prior measurement tool on the diameter changes of the plant stem, avoids the trouble of replacing different range sensors for measuring different plant stems, and can be used for nondestructively monitoring the diameter of the plant stem and small variable quantity of diameter within a certain period of time on line.

An optical access network (OAN) system is provided. In the system, a remote radio unit (RRU) receives and sends a wireless signal and implement conversion between the wireless signal and a first frequency signal; an optical network device receives and sends the wireless signal, and implement conversion between the wireless signal and the first frequency signal and conversion between the first frequency signal and a fiber transmission signal; an optical distribution network (ODN) connected to the optical network device transmits the fiber transmission signal; an optical line terminal (OLT) device receives and sends the fiber transmission signal, and implements conversion between the fiber transmission signal and a second frequency signal, conversion between the second frequency signal and a base band signal, and conversion between the base band signal and a signal of another standard protocol.

The invention discloses a microwave signal photonic frequency conversion and multichannel fiber transmission device and method realized by a polarization multiplexing modulator. The device, as shown by a figure, comprises a laser diode (LD), a polarization multiplexing Mach-Zehnder modulator (PDM-MZM), an erbium doped fiber amplifier (EDFA), a 1:N light splitter (Splitter), a polarizer (Pol), a polarization controller (PC), and a standard single-mode fiber (SMF) and a photoelectric detector (PD). The PDM-MZM is used to carry out carrier suppressed double side band modulation on radio frequency (RF) and local oscillation (LO) signals and then implement frequency mixing, and the RF and LO isolation degree of frequency conversion gain and frequency conversion signals is improved. Optical signals output by the modulator can be divided into multiple paths to implement fiber transmission, each path is adjusted via an independent polarization state, and power attenuation caused by dispersion can be compensated.

The invention discloses a double-laser-beam composite welding method. Two lasers are adopted to output two laser beams; the two laser beams are transmitted by two independent optical fibers, and are focused to synchronously weld workpieces; the two laser beams are divided into a welding light beam and a scanning light beam according to the effects; the scanning light beam is transmitted to the surface of a welding line through a galvanometer for reciprocating scanning with an acting point of the welding light beam on the surface of the welding line as center; the two laser beams form common molten pool welding on the surface of the welding line; and in the welding process, the scanning light beam performs high-speed reciprocating scanning on two sides of the welding line according to a set scanning path, a molten pool is stirred in the scanning process, and meanwhile, the connection between two sides of the welding line can be improved. Through reciprocating scanning and stirring of the laser beams, the flowing of the molten pool can be reinforced to easily exhaust gas, and gas holes are eliminated, so that such problems as non-melting and gas holes generated in single-laser-beam welding can be eliminated, and the welding quality is greatly improved.

A gob-side entry retaining pasty filler on-line detection method comprises the steps that before each monitored space is ready to be filled, supporting rods are fixed to a base plate of a space to be filled through ground anchors, the upper ends of the supporting rods support a top plate of the space to be filled, measuring optical fibers are arranged between the supporting rods, an optical fiber connector is introduced out of the tail portion of the last supporting rod in each set of supporting rods and is connected in a mining optical cable through optical fibers so that optical fiber monitoring signals can be transmitted to a distributed optical fiber demodulator, demodulated signals are transmitted to a computer system, and pasty filler is monitored in real time on line and is analyzed and processed after the space is filled. The gob-side entry retaining pasty filler on-line detection method has the advantages that equipment installation is easy, the method is suitable for being universally popularized, no power supply is needed under a well, a site is safe, all-optical measurement and optical fiber transmission are adopted, influences caused by electromagnetic interference are effectively avoided, a monitoring result can be provided in time, and the method is favorable for directing on-site filling mining production work.

Even if a fiber fuse phenomenon occurs to start fire spreading, the fire spreading is shut off. A graded index fiber (GIF) 3 is inserted between transmission-use single mode fibers (SMF) 2a, 2b on a fiber optics transmission line 1. The GIF 3 is so designed that its mode field diameter (MFD) gradually increases from a light entry side. The MFD exhibits a maximum value at a location ¼ of a pitch from the end of the GIF 3. A GIF 3a is disposed on the light entry side. A GIF 3b having an MFD gradually decreasing is disposed on the opposite side of the GIF 3a. The GIF 3b is disposed on the light exit side. The lengths of the GIF 3a and GIF 3b are ¼ of a pitch. The length of the GIF 3 formed by connecting the both is ½ of a pitch. According to the present invention, an expanded MFD is inserted in the middle of the fiber optics transmission line, it is possible to shut off fire spreading caused due to fiber fuse phenomenon.

The invention provides a chaotic secret optical communication system based on a dual-drive Mach-Zehnder modulator. The system comprises a sending end, a fiber transmission link and a receiving end, wherein the sending end sends signals to the receiving end through the fiber transmission link; and the sending end is used for sending information signals and chaotic signals, and the receiving end is used for decrypting received signals. According to the invention, based on the dual-drive Mach-Zehnder modulator, the information signals are hidden in electric chaotic signals, and since the synchronization feature of the electric chaotic signals is superior to that of optical chaotic signals, synchronization of the secret communication system can be easily realized; and through integrated utilization of an electric time-delay line, electric attenuators and the like, the secret key space of the secret optical communication system is increased, the invisibility of the information signals is improved, and the anti-decryption performance of the system is enhanced. Besides, the system has high universality and is applied to information signals in various modulation formats.

A filling grease for composite fibre-optical overhead earth wire is prepared by mixing 36®|hydrogenated white oil and PAO-8 synthesized oil with PriCO-3002 polybasic alcohol ester and viscosity exponential improver Lc-212, adding into additive OB fluorescent brightening agent, grease-separating inhibitor BP2400 and G1702, raising temperature, stirring, adding into organic thickening agent gas-phase carbon white H20, raising temperature, thickening, adding into antioxidant AT-215 and inorganic thickening agent SEP1650, raising temperature, thickening, shearing, circulation feeding back, cooling to normal temperature, homogenizing, degassing, filtering and obtaining the grease. It achieves good hydrogen absorption and stable fibre-optical transmitting performance.

The invention relates to a welder system and discloses a fiber transmission automatic laser welding system dedicated for a plate type solar thermal collector. The fiber transmission automatic laser welding system comprises a laser and a laser head connected with the laser by optical fibers, wherein the laser head is connected with a rotating device; the rotating device is hung on a slide rail of a gantry frame; a CCD (Charge Coupled Device) vision tracking device is tightly connected with the laser head and a small Y-axle; two end parts of the gantry frame are supported on a sliding rail of a base; a working bench for placing the plate type solar thermal collector is arranged on a conveyer belt at the center of the base; an exchangeable working bench is also arranged on the conveyer belt; and the rotating device, the gantry frame and the laser head are respectively connected with a control device. The fiber transmission automatic laser welding system is reliable and convenient to operate, has compact structure and high welding precision and improves the efficiency. The laser head not only can move along the sliding rail of the gantry frame, but also can move along the sliding rail on the base, thus the fiber transmission automatic laser welding system has the functions of longitudinal welding and transverse welding simultaneously, and also has the function of station alternation.

The present invention provides a radiation detector capable of detecting the radioactive substance accumulated in the tissue inside a body by inserting a detection unit into blood vessels. In the radiation detector of the present invention, comprising a detection unit (2) having a bar-type scintillator (4) which emits light by an incidence of radiation so as to transmit the light from the scintillator through an optical fiber, the detection unit is formed in a size capable of being inserted into the tubules while fine convexoconcaves are provided on the peripheral surface of the scintillator.

The invention discloses an electromagnetic environment monitoring system with noise integrated and a method. The system comprises an electromagnetic field monitoring device, a noise and temperature and humidity detecting device, a Zigbee wireless communication module, a fiber transmission module and an information display unit, wherein the noise and temperature and humidity detecting device comprises a noise sensor and a temperature and humidity sensor, and the noise and temperature and humidity detecting device is connected with the electromagnetic field monitoring device; the electromagnetic field monitoring device is respectively connected with the Zigbee wireless communication module and the fiber transmission module; and the Zigbee wireless communication module and the fiber transmission module are connected with the information display unit. AC / DC electromagnetic field data at a field monitoring point are transmitted to an information display end in real time for dynamic display, power consumption is low, the cost is low, time delay is short, the data capacity is large, reliability is strong, and great convenience is brought to an electromagnetic environment monitoring worker.

A micro-sized gas detecting device with two electrodes separated by a gap of width ranging from 1 to 500 microns, where the detection is based on emission spectroscopy of gases in an electric discharge across the gap (discharge region) as the gas flows through the region. The characteristic light emitted by molecules during the discharge can be detected directly with photodiodes or transferred through optical fiber and detected with remote optical sensing components. The device can have single or multiple discharge regions in an array so that light emitted can be monitored at different wavelengths simultaneously. The device can operate under gaseous pressure ranging from a few milli-Torr to a few atmospheres. The device consumes little power (50 mW-100 mW) and can be powered with an alternating current and has the potential to be battery powered.

A high-gain transparent screen belongs to the field of transparent screen comprises a front-end transparent layer, a fiber transmission layer, a micro-lens layer and a back-end transparent layer through compounding. Wherein, the micro-lens layer is provided with a light spreading lens characterized by a horizontal spreading angle of 70 degrees to 120 degrees and a vertical spreading angle of 40 degrees to 80 degrees. The micro-lens is directly attached to a fiber head top or etched onto transparent materials of the back-end transparent layer. The fiber transmission layer is provided with even fiber diameters. The back-end transparent layer is black glass, a black real-time adhesive film, black anti-dazzle glass or a black real-time anti-dazzle adhesive film to enhance screen contrast and prevent screen reflection. The screen has the advantages of high gain, wide visual angle, lower cost, easy production of various screens with nonstandard size and seamless assembling.

The invention provides a single-fiber ultrahigh-precision time transmission method and aims to solve the problems that slow change in fiber transmission delay is uncontrollable and the extremely slow delay drift and drift accumulation cannot be solved in the existing fiber communication network time frequency synchronization technology. A single-fiber bidirectional optical transceiving module, a delay processing module and a master time synchronization device or slave time synchronization device are respectively connected to two ends of a same fiber. A cesium atomic clock is connected to the side of the master time synchronization device. Fiber delay between the master and slave time synchronization devices and a change value of the fiber delay are precisely measured and compensated. The method has the advantages that the problems that drift and drift accumulation caused by the extremely slow change in fiber transmission delay along with time, temperature, fiber ageing and the like cannot be eliminated in the prior art are solved; time synchronization precision is controlled in the range of + / -5 nanoseconds, networking can be in any form, and the method has promising market prospect and significant economic benefit.

The invention relates to an online checking method for a high-tension current transformer, which can check the high-tension current transformer in the field operation with high accuracy. The online checking method is characterized in that in a return circuit of the high-tension current transformer to be checked, a high-accuracy pincerlike hollow coil based on a PCB (Printed Circuit board) is connected in series, so that the high-tension current transformer is used as a standard current transformer, the signal of the high-tension side is digitized and transmitted to the low-tension side through fiber transmission, the output value of the standard current transformer and the output value of the checked high-tension current transformer at the synchronized instant are compared through an external synchronous trigger signal, the digital integration algorithm and error theory algorithm are realized by using a virtual instrument in a checking platform, so that the accuracy of the checked high-tension current transformer in the field operation is checked, the cost of interruption is reduced, and the checking period of the high-tension current transformer is shortened.