Showing papers on "Spectrum analyzer published in 2015"

Multi-wavelength optical measurement to enhance thermal/optical analysis for carbonaceous aerosol

Abstract: . A thermal/optical carbon analyzer equipped with seven-wavelength light source/detector (405–980 nm) for monitoring spectral reflectance (R) and transmittance (T) of filter samples allowed "thermal spectral analysis (TSA)" and wavelength (λ)-dependent organic-carbon (OC)–elemental-carbon (EC) measurements. Optical sensing was calibrated with transfer standards traceable to absolute R and T measurements, adjusted for loading effects to report spectral light absorption (as absorption optical depth (τa, λ)), and verified using diesel exhaust samples. Tests on ambient and source samples show OC and EC concentrations equivalent to those from conventional carbon analysis when based on the same wavelength (~ 635 nm) for pyrolysis adjustment. TSA provides additional information that evaluates black-carbon (BC) and brown-carbon (BrC) contributions and their optical properties in the near infrared to the near ultraviolet parts of the solar spectrum. The enhanced carbon analyzer can add value to current aerosol monitoring programs and provide insight into more accurate OC and EC measurements for climate, visibility, or health studies.

Wide bandwidth instantaneous radio frequency spectrum analyzer based on nitrogen vacancy centers in diamond

Abstract: We propose an original analog method to perform instantaneous and quantitative spectral analysis of microwave signals. An ensemble of nitrogen-vacancy (NV) centers held in a diamond plate is pumped by a 532 nm laser. Its photoluminescence is imaged through an optical microscope and monitored by a digital camera. An incoming microwave signal is converted into a microwave field in the area of the NV centers by a loop shaped antenna. The resonances induced by the magnetic component of that field are detected through a decrease of the NV centers photoluminescence. A magnetic field gradient induces a Zeeman shift of the resonances and transforms the frequency information into spatial information, which allows for the simultaneous analysis of the microwave signal in the entire frequency bandwidth of the device. The time dependent spectral analysis of an amplitude modulated microwave signal is demonstrated over a bandwidth of 600 MHz, associated to a frequency resolution of 7 MHz , and a refresh rate of 4 ms. Wi...

Theory and Design of a Quadrature Analog-to-Information Converter for Energy-Efficient Wideband Spectrum Sensing

Abstract: A flexible bandwidth, blind sub-Nyquist sampling approach referred to as the quadrature analog-to-information converter (QAIC) is proposed. The QAIC relaxes the analog frontend bandwidth requirements at the cost of some added complexity compared to the modulated wideband converter (MWC) for an overall improvement in sensitivity and energy consumption. An approach for detailed frequency domain analysis of the proposed system with linear impairments is developed. A process for selecting QAIC parameter values is illustrated through examples. The benefits of the QAIC are highlighted with cognitive radio use cases where a wide range of spectrum is observed at various resolution bandwidth settings. We demonstrate that the energy consumption of the QAIC is potentially two orders of magnitude lower than the swept-tuned spectrum analyzer (STSA) and an order of magnitude lower than the MWC. We also demonstrate that the QAIC significantly improves upon the sensitivity performance delivered by the MWC.

Repeatability, reproducibility, and age dependency of dynamic Scheimpflug-based pneumotonometer and its correlation with a dynamic bidirectional pneumotonometry device.

Abstract: Purpose:To assess the repeatability, reproducibility, and age dependency of dynamic Scheimpflug-based pneumotonometry (Corvis)–generated parameters and their correlation with dynamic bidirectional pneumotonometry device [Ocular Response Analyzer (ORA)] measurements [corneal hysteresis (CH) and corne

The PennBMBI: Design of a General Purpose Wireless Brain-Machine-Brain Interface System

Abstract: In this paper, a general purpose wireless Brain- Machine -Brain Interface (BMBI) system is presented. The system integrates four battery-powered wireless devices for the implementation of a closed-loop sensorimotor neural interface, including a neural signal analyzer, a neural stimulator, a body-area sensor node and a graphic user interface implemented on the PC end. The neural signal analyzer features a four channel analog front-end with configurable bandpass filter, gain stage, digitization resolution, and sampling rate. The target frequency band is configurable from EEG to single unit activity. A noise floor of 4.69 $\mu{\rm Vrms}$ is achieved over a bandwidth from 0.05 Hz to 6 kHz . Digital filtering, neural feature extraction, spike detection, sensing-stimulating modulation, and compressed sensing measurement are realized in a central processing unit integrated in the analyzer. A flash memory card is also integrated in the analyzer. A 2-channel neural stimulator with a compliance voltage up to $\pm$ 12 V is included. The stimulator is capable of delivering unipolar or bipolar, charge-balanced current pulses with programmable pulse shape, amplitude, width, pulse train frequency and latency. A multi-functional sensor node, including an accelerometer, a temperature sensor, a flexiforce sensor and a general sensor extension port has been designed. A computer interface is designed to monitor, control and configure all aforementioned devices via a wireless link, according to a custom designed communication protocol. Wireless closed-loop operation between the sensory devices, neural stimulator, and neural signal analyzer can be configured. The proposed system was designed to link two sites in the brain, bridging the brain and external hardware, as well as creating new sensory and motor pathways for clinical practice. Bench test and in vivo experiments are performed to verify the functions and performances of the system.

High power frequency comb based on mid-infrared quantum cascade laser at λ ∼ 9 μm

Abstract: We investigate a frequency comb source based on a mid-infrared quantum cascade laser at λ ∼ 9 μm with high power output. A broad flat-top gain with near-zero group velocity dispersion has been engineered using a dual-core active region structure. This favors the locking of the dispersed Fabry-Perot modes into equally spaced frequency lines via four wave mixing. A current range with a narrow intermode beating linewidth of 3 kHz is identified with a fast detector and spectrum analyzer. This range corresponds to a broad spectral coverage of 65 cm−1 and a high power output of 180 mW for ∼176 comb modes.

Scanning-free BOTDA based on ultra-fine digital optical frequency comb.

Abstract: We realize a scanning-free Brillouin optical time domain analyzer (BOTDA) based on an ultra-fine digital optical frequency comb (DOFC) with 1.95MHz frequency spacing and 2GHz bandwidth. The DOFC can be used to reconstruct the Brillouin gain spectrum (BGS) and locate the Brillouin frequency shift (BFS) without frequency scanning and thus can improve the measurement speed about 100 times compared with the conventional BOTDA. This scanning-free BOTDA scheme has also been demonstrated experimentally with 51.2m spatial resolution over 10km standard single mode fiber (SSMF) and with resolution of 1.5°C for temperature and 43.3μe for strain measurement respectively.

Control of ion energy distributions using phase shifting in multi-frequency capacitively coupled plasmas

Abstract: Control of ion energy distributions (IEDs) onto the surface of wafers is an ongoing challenge in microelectronics fabrication The use of capacitively coupled plasmas (CCPs) using multiple radio frequency (rf) power sources provides many opportunities to customize IEDs In dual-frequency CCPs using a fundamental frequency and its second harmonic, varying the relative voltages, powers, and phases between the fundamental and second harmonic biases have demonstrated potential as control mechanisms for the shape of the IEDs In this paper, we report on computational and experimental investigations of IED control in dual-frequency and triple-frequency CCPs where the phase between the fundamental and second harmonic frequency voltage waveform is used as a control variable The operating conditions were 5–40 mTorr (067–533 Pa) in Ar and Ar/CF4/O2 gas mixtures By changing the phase between the applied rf frequency and its second harmonic, the Electrical Asymmetric Effects was significant and not only shifted the dc self-bias but also affected plasma uniformity When changing phases of higher harmonics, the energies and widths of the IEDs could be controlled With the addition of a 3rd high-frequency source, the plasma density increased and uniformity improved Computed results for IEDs were compared with experimental results using an ion energy analyzer in systems using rf phase locked power supplies

A Wireless Spectrum Analyzer in Your Pocket

Abstract: We propose Snoopy, a system that can translate one's mobile phone or tablet into a low-cost, yet effective RF spectrum analyzer. Since typical spectrum analyzers are specialized hardware that is both expensive to acquire and cumbersome to carry around, they are rarely available for quick-and-easy spectrum sensing while on the go. To address this challenge, Snoopy augments popular mobile devices with a small attachable hardware unit (RF frequency translator) that can provide a reasonable view of the wireless spectrum across different frequency bands. It achieves this by leveraging the spectral scan functionality available in certain 802.11 NICs (e.g., the Atheros 9280 family of chipsets), which provides an unique lens towards the WiFi spectrum (2.4 GHz). Through the use of suitable frequency translators, such a view can be flexibly shifted to other spectrum bands. Although such a construction might not match the precision of the most sophisticated but expensive spectrum analyzers, we show that by leveraging some carefully designed spectral features, Snoopy can achieve decent accuracy in determining TV whitespaces (512 -- 698 MHz) -- it can detect primary signals at up to - 90dBm with an error rate of

W-state Analyzer and Multi-party Measurement-device-independent Quantum Key Distribution.

Abstract: W-state is an important resource for many quantum information processing tasks. In this paper, we for the first time propose a multi-party measurement-device-independent quantum key distribution (MDI-QKD) protocol based on W-state. With linear optics, we design a W-state analyzer in order to distinguish the four-qubit W-state. This analyzer constructs the measurement device for four-party MDI-QKD. Moreover, we derived a complete security proof of the four-party MDI-QKD, and performed a numerical simulation to study its performance. The results show that four-party MDI-QKD is feasible over 150 km standard telecom fiber with off-the-shelf single photon detectors. This work takes an important step towards multi-party quantum communication and a quantum network.

High-Speed Frequency Modulation of a 460-GHz Gyrotron for Enhancement of 700-MHz DNP-NMR Spectroscopy

Abstract: The high-speed frequency modulation of a 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) was achieved by modulation of acceleration voltage of beam electrons. The modulation speed f m can be increased up to 10 kHz without decreasing the modulation amplitude δf of frequency. The amplitude δf was increased almost linearly with the modulation amplitude of acceleration voltage ΔV a. At the ΔV a = 1 kV, frequency spectrum width df was 50 MHz in the case of f m < 10 kHz. The frequency modulation was observed as both the variation of the IF frequency in the heterodyne detection system measured by a high-speed oscilloscope and the widths of frequency spectra df measured on a frequency spectrum analyzer. Both results well agree reasonably. When f m exceeds 10 kHz, the amplitude δf is decreased gradually with increasing f m because of the degradation of the used amplifier in response for high-speed modulation. The experiment was performed successfully for both a sinusoidal wave and triangle wave modulations. We can use the high-speed frequency modulation for increasing the enhancement factor of the dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy, which is one of effective and attractive methods for the high-frequency DNP-NMR spectroscopy, for example, at 700 MHz. Because the sensitivity of NMR is inversely proportional to the frequency, high-speed frequency modulation can compensate the decreasing the enhancement factor in the high-frequency DNP-NMR spectroscopy and keep the factor at high value. In addition, the high-speed frequency modulation is useful for frequency stabilization by a PID control of an acceleration voltage by feeding back of the fluctuation of frequency. The frequency stabilization in long time is also useful for application of a DNP-NMR spectroscopy to the analysis of complicated protein molecules.

Pulse-doppler signal processing with quadrature compressive sampling

Abstract: Quadrature compressive sampling (QuadCS) is a recently introduced sub-Nyquist sampling scheme for effective acquisition of inphase and quadrature (I/Q) components of sparse radio frequency signals. In applications to pulse-Doppler radars, the QuadCS outputs can be arranged into a two-dimensional data format, in terms of slow time and virtual fast time, similar to that by Nyquist sampling. This paper develops a compressive sampling pulse-Doppler (CoSaPD) processing scheme which performs Doppler estimation/detection and range estimation from the sub-Nyquist data without recovering the Nyquist samples. The Doppler estimation is realized through a spectrum analyzer as in classical processing, whereas the detection is performed using the Doppler bin data. The range estimation is performed using sparse recovery algorithms only for the detected targets to reduce the computational load. A low detection threshold is used to improve the detection probability and the introduced false targets are then removed in the range estimation stage by exploiting the inherent target detection capability of the recovery algorithms. Simulation results verify the effectiveness of the proposed CoSaPD scheme, which requires only one-eighth of the Nyquist rate to achieve similar performance to the classical processing with Nyquist samples, provided that the input signal-to-noise ratio (SNR) is above −25 dB.

A versatile retarding potential analyzer for nano-satellite platforms.

Abstract: The design of the first retarding potential analyzer (RPA) built specifically for use on resource-limited cubesat platforms is described. The size, mass, and power consumption are consistent with the limitations of a nano-satellite, but the performance specifications are commensurate with those of RPAs flown on much larger platforms. The instrument is capable of measuring the ion density, temperature, and the ram component of the ion velocity in the spacecraft reference frame, while also providing estimates of the ion composition. The mechanical and electrical designs are described, as are the operating modes, command and data structure, and timing scheme. Test data obtained using an ion source inside a laboratory vacuum chamber are presented to validate the performance of the new design.

Universal Grid Analyzer design and development

Abstract: This paper promotes a better understanding of the power grid quality and dynamics through the introduction of a newly developed Universal Grid Analyzer (UGA). The UGA is a real-time, highly accurate, and GPS synchronized power grid monitoring device used at distribution level. They can function as a power quality analyzer by performing harmonics measurement along with voltage sag and swell detection. They can also be used as a phasor measurement unit (PMU) at distribution level. Accurate synchronous sampling is challenging and it is the hardware core of PMUs, thus a new synchronous sampling method is proposed to achieve accurate synchronous sampling. More importantly, the UGA can analyze power grid signal in a wide-frequency range through the “noise analysis” function, and analyze true synchrophasor measurement errors when the UGA is connected to the power grid. A prototype UGA is built to evaluate functions and measurement accuracy of the UGA.

Implementation of a Real-Time Spectrum Analyzer on FPGA Platforms

Abstract: Spectral analysis plays an essential role in different applications. General-purpose spectrum analyzers are too expensive and are not appropriate for real-time applications. Therefore, a low-cost instrument for spectral analysis is needed. This paper describes a real-time field-programmable gate arrays implementation of a spectrum analyzer based on a modified periodogram of the input signal. It is able to detect and estimate the power and frequency of up to $N_{S}$ narrow-band signals given an analysis bandwidth, instantaneous dynamic range and frequency resolution.

Modified quadrupole mass analyzer RGA-100 for beam plasma research in forevacuum pressure range

Abstract: The industrial quadrupole RGA-100 residual gas analyzer was modified for the research of electron beam-generated plasma at forevacuum pressure range. The standard ionizer of the RGA-100 was replaced by three electrode extracting unit. We made the optimization of operation parameters in order to provide the maximum values of measured currents of any ion species. The modified analyzer was successfully tested with beam plasma of argon, nitrogen, oxygen, and hydrocarbons.

Real-time absolute frequency measurement of continuous-wave terahertz radiation based on dual terahertz combs of photocarriers with different frequency spacings

Abstract: Real-time measurement of the absolute frequency of continuous-wave terahertz (CW-THz) radiation is required for characterization and frequency calibration of practical CW-THz sources. We proposed a method for real-time monitoring of the absolute frequency of CW-THz radiation involving temporally parallel, i.e., simultaneous, measurement of two pairs of beat frequencies and laser repetition frequencies based on dual THz combs of photocarriers (PC-THz combs) with different frequency spacings. To demonstrate the method, THz-comb-referenced spectrum analyzers were constructed with a dual configuration based on dual femtosecond lasers. Regardless of the presence or absence of frequency control in the PC-THz combs, a frequency precision of 10−11 was achieved at a measurement rate of 100 Hz. Furthermore, large fluctuation of the CW-THz frequencies, crossing several modes of the PC-THz combs, was correctly monitored in real time. The proposed method will be a powerful tool for the research and development of practical CW-THz sources, and other applications.

Wide bandwidth instantaneous RF spectrum analyzer based on nitrogen vacancy centers in diamond

Abstract: We propose an original analog method to perform instantaneous and quantitative spectral analysis of microwave signals. An ensemble of nitrogen-vacancy (NV) centers held in a diamond plate is pumped by a 532 nm laser. Its photoluminescence is imaged through an optical microscope and monitored by a digital camera. The microwave signal is converted to an oscillating magnetic field in the area of the NV centers by a loop shaped antenna. Induced magnetic resonances are detected through a decrease of the NV centers photoluminescence. A magnetic field gradient induces a Zeeman shift of the resonances and transforms the frequency information into spatial information, which allows for the simultaneous analysis of the microwave signal in the entire frequency bandwidth of the device. The time dependent spectral analysis of an amplitude modulated microwave signal is demonstrated over a bandwidth of 600 MHz, associated to a frequency resolution of 7 MHz and a refresh rate of 4 ms. With such integration time, a field of a few hundreds of {\mu}W can be detected. Since the optical properties of NV centers can be maintained even in high magnetic field, we estimate that an optimized device could allow frequency analysis in a range of 30 GHz, only limited by the amplitude of the magnetic field gradient. In addition, an increase of the NV centers quantity could lead both to an increase of the microwave sensitivity and to a decrease of the minimum refresh rate down to a few {\mu}s.

Phase noise measurement of wideband microwave sources based on a microwave photonic frequency down-converter.

Abstract: An approach for phase noise measurement of microwave signal sources based on a microwave photonic frequency down-converter is proposed. Using the same optical carrier, the microwave signal under test is applied to generate two +1st-order optical sidebands by two stages of electro-optical modulations. A time delay is introduced between the two sidebands through a span of fiber. By beating the two +1st-order sidebands at a photodetector, frequency down-conversion is implemented, and phase noise of the signal under test can be calculated thereafter. The system has a very large operation bandwidth thanks to the frequency conversion in the optical domain, and good phase noise measurement sensitivity can be achieved since the signal degradation caused by electrical amplifiers is avoided. An experiment is carried out. The phase noise measured by the proposed system agrees well with that measured by a commercial spectrum analyzer or provided by the datasheet. A large operation bandwidth of 5–40 GHz is demonstrated using the proposed system. Moreover, good phase noise floor is achieved (−123 dBc/Hz at 1 kHz and −137 dBc/Hz at 10 kHz at 10 GHz), which is nearly constant over the full measurement range.

Increased photoelectron transmission in High-pressure photoelectron spectrometers using "swift acceleration"

Abstract: A new operation mode of a HPXPS (high-pressure X-ray photoelectron spectroscopy) analyzer is evaluated on a HPXPS system fitted with an Al K alpha X-ray source. A variety of metal foil samples (gol ...

Frequency-noise measurements of optical frequency combs by multiple fringe-side discriminator.

Abstract: The frequency noise of an optical frequency comb is routinely measured through the hetherodyne beat of one comb tooth against a stable continuous-wave laser. After frequency-to-voltage conversion, the beatnote is sent to a spectrum analyzer to retrive the power spectral density of the frequency noise. Because narrow-linewidth continuous-wave lasers are available only at certain wavelengths, heterodyning the comb tooth can be challenging. We present a new technique for direct characterization of the frequency noise of an optical frequency comb, requiring no supplementary reference lasers and easily applicable in all spectral regions from the terahertz to the ultraviolet. The technique is based on the combination of a low finesse Fabry-Perot resonator and the so-called “fringe-side locking” method, usually adopted to characterize the spectral purity of single-frequency lasers, here generalized to optical frequency combs. The effectiveness of this technique is demonstrated with an Er-fiber comb source across the wavelength range from 1 to 2 μm.

Real-time absolute frequency measurement of continuous-wave terahertz wave based on dual terahertz combs of photocarriers with different frequency spacings

Abstract: Real-time measurement of the absolute frequency of continuous-wave terahertz (CW-THz) waves is required for characterization and frequency calibration of practical CW-THz sources. We proposed a method for real-time monitoring of the absolute frequency of CW-THz waves involving temporally parallel, i.e., simultaneous, measurement of two pairs of beat frequencies and laser repetition frequencies based on dual THz combs of photocarriers (PC-THz combs) with different frequency spacings. To demonstrate the method, THz-comb-referenced spectrum analyzers were constructed with a dual configuration based on dual femtosecond lasers. Regardless of the presence or absence of frequency control in the PC-THz combs, a frequency precision of 10-11 was achieved at a measurement rate of 100 Hz. Furthermore, large fluctuation of the CW-THz frequencies, crossing several modes of the PC-THz combs, was correctly monitored in real time. The proposed method will be a powerful tool for the research and development of practical CW-THz sources, and other applications.

W-state Analyzer and Multi-party Measurement-device-independent Quantum Key Distribution

Abstract: W-state is an important resource for many quantum information processing tasks. In this paper, we for the first time propose a multi-party measurement-device-independent quantum key distribution (MDI-QKD) protocol based on W-state. With linear optics, we design a W-state analyzer in order to distinguish the four-qubit W-state. This analyzer constructs the measurement device for four-party MDI-QKD. Moreover, we derived a complete security proof of the four-party MDI-QKD, and performed a numerical simulation to study its performance. The results show that four-party MDI-QKD is feasible over 150 km standard telecom fiber with off-the-shelf single photon detectors. This work takes an important step towards multi-party quantum communication and a quantum network.

A Sensitive Method to Measure the Integral Nonlinearity of a Digital-to-Time Converter Based on Phase Modulation

Abstract: A digital-to-time converter (DTC) produces a time delay based on a digital code. Similar to data converters, linearity is a key metric for a DTC and it can be characterized by its integral nonlinearity (INL). However, measuring the INL of a subpicosecond-resolution DTC is problematic, even when using the best available high-speed oscilloscopes. In this brief we propose a new method to measure the INL of a DTC by applying digital phase modulation and measuring the output spectrum with a spectrum analyzer. The frequency selectivity of this method allows for an improved measurement resolution down to a few femtoseconds and allows measuring an INL below 100 fs. The proposed method is verified by behavioral simulations and is employed to measure the INL of a high-resolution DTC realized in the 65-nm CMOS, with a time resolution of 25 fs and a standard deviation of 27 fs.

Particle Classification by the Tandem Differential Mobility Analyzer–Particle Mass Analyzer System

Abstract: Particle mass analyzers, such as the aerosol particle mass analyzer (APM) and the Couette centrifugal particle mass analyzer (CPMA), are frequently combined with a differential mobility analyzer (DMA) to measure particle mass mp and effective density ρeff distributions of particles with a specific electrical mobility diameter dm. Combinations of these instruments, which are referred to as the DMA–APM or DMA–CPMA system, are also used to quantify the mass-mobility exponent Dm of non-spherical particles as well as to eliminate multiple charged particles. This study investigates the transfer functions of these setups, focusing especially on the DMA–APM system. The transfer function of the DMA–APM system was derived by multiplying the transfer functions of DMA and APM. The APM transfer function can be calculated using either the uniform or parabolic flow models. The uniform flow model provides an analytical function, while the parabolic flow model is more accurate. The resulting DMA–APM transfer functions wer...

Microwave source phase noise test method and device based on microwave photon mixing technology

Abstract: The invention discloses a microwave source phase noise test method and device based on a microwave photon mixing technology. The device comprises a microwave source, a microwave power divider, a microwave phase shifter, a laser source, a first electro-optical modulator, an optical fiber, a second electro-optical modulator, an optical band pass filter, a photoelectric detector, an electric low pass filter and an FFT analyzer, wherein the laser source, the first electro-optical modulator, the optical fiber, the second electro-optical modulator, the optical band pass filter, the photoelectric detector, the electric low pass filter and the FFT analyzer are sequentially connected in the optical path direction. According to the method, a microwave signal to be tested generated by the microwave source is divided into two paths through the microwave power divider, one path of the signal is modulated through the first electro-optical modulator to generate an initial modulated optical signal, the other path of the signal enters the second electro-optical modulator after passing through the microwave phase shifter and conducts modulation on the initial modulated optical signal generated after the optical fiber is delayed, and the finally obtained modulated optical signal passes through the optical band pass filter, the photoelectric detector and the electric low pass filter sequentially; the signals output by the electric low pass filter are collected by the FFT analyzer, and the phase noise of the microwave signal to be tested is obtained through computing. The method and device have the advantages of being wide in operation bandwidth, high in test sensitivity, free of changing along with the frequency and the like.

Measurement of rocking curves of crystals using an acoustically tunable monochromator

Abstract: A new scheme for measuring rocking curves (RCs) based on a previously proposed method for measuring RCs using an X-ray-acoustic analyzer crystal has been developed and implemented. In this scheme, this analyzer crystal is applied as a tunable monochromator, mounted directly after the X-ray source. This new experimental scheme has a number of significant advantages in comparison with the previously proposed scheme. The new scheme is approved and its potential is estimated.

Handheld optical high-resolution high-power intelligent skin testing analyzer and system and method thereof

Abstract: The invention discloses a handheld optical high-resolution high-power intelligent skin testing analyzer and a system and method thereof. The analyzer comprises a shell, a camera shooting module, a high-power optical macro magnification module, a comprehensive light source module, a first wireless communication module, a power module and a control module. The camera shooting module comprises a high-resolution optical sensor. The comprehensive light source module comprises multiple light sources used for obtaining different levels of information of the skin. In this way, the skin testing analyzer is utilized for freely and flexibly obtaining image information of the skin portion needing to be tested, the skin information is transmitted to a mobile intelligent terminal through the special first wireless communication module for the skin testing analyzer, and the mobile intelligent terminal processes and analyzes the image or data information so as to judge the skin condition and provide solving or optimizing suggestions. A user can monitor different levels of health conditions of the skin at any time and any place and check the health conditions synchronously on the mobile intelligent terminal. According to the design, the handheld optical high-resolution high-power intelligent skin testing analyzer has the advantages of being intelligent, convenient to use and carry, high in practicability and the like.

System and method for correcting correction factors of near field probe by utilizing microstrip line method

Abstract: The invention discloses a system and method for correcting the correction factors of a near field probe by utilizing a microstrip line method. The system comprises a microstrip line placed on a microstrip line substrate, an adjustable signal source, a spectrum analyzer, a near field probe, a load terminal and a data processing unit connected with the spectrum analyzer, wherein the near field probe is placed above the microstrip line to be used for detecting signals sent by the adjustable signal source to the load terminal through the microstrip line; the spectrum analyzer is used for being connected with the microstrip line and used for measuring the voltage value of signals sent by the adjustable signal source to the spectrum analyzer through the microstrip line; the spectrum analyzer is also used for being connected with the near field probe to be used for measuring the voltage value of signals detected by the near field probe. The technical scheme adopted by the system disclosed by the invention lies in that a near field which is generated by the microstrip line and is close to an actual test is adopted to correct the correction factors of the near field probe under correction frequency points, and the preparation for utilizing the corrected correction factors to correct a microstrip-line radiation field in a correction test is well provided, so that the accuracy of measurement data is improved.

Extending the Dynamic Range of Sweep-Free Brillouin Optical Time-Domain Analyzer

Abstract: Sweep-free Brillouin optical time-domain analysis (SF-BOTDA) replaces the sequential frequency scanning of classical BOTDA by parallel interrogation of the fiber-under-test using the simultaneous interaction of multiple pump tones with counter-propagating multiple probe tones. While the basic SF-BOTDA technique boosts the measurement speed by a factor equal to the number of probe tones used, its dynamic range is limited to approximately the pump tone spacing, which is of the order of 100 MHz. This paper provides an in-depth analysis of our method to significantly extend the dynamic range to the GHz regime. Based on sequential interrogation with up to three sets of multiple tones, each having a different frequency spacing, this method provides a major speed advantage over the classical BOTDA in spite of the use of three sets of tones. With this development, which does not require any additional hardware, SF-BOTDA offers distributed sensing of optical fibers over practical dynamic ranges of strain/temperature variations, with the potential to become one of the fastest sensing techniques.