Large Measurement Range Research Articles

Development of an Angular Displacement Measurement by Birefringence Heterodyne Interferometry

The birefringence heterodyne interferometry for the angular measurement is presented. The advantage of the instrument is the large measurement range and high resolution. When p- and s-polarized beams pass through a birefringence crystal, the phase difference between these two polarized beams is sensitive to the incident angle. We can determine the angular variation with the heterodyne interferometer which can precisely detect the phase difference between these two polarized beams. Moreover, a new optical path is designed to enhance the sensitivity by means of a prism which combines the light to the birefringence crystal. There are two measurement modes in our system, a linear and a circular polarized mode. The experimental results show that the resolution of the linear polarized mode is 1.2°×10−4 and the resolution of the circular polarized mode is 3°×10−5.

Magnetostrictive composite material-based polarimetric heterodyning fiber-grating laser miniature magnetic field sensor

A novel fiber-optic magnetic field sensor is demonstrated based on a dual-polarization fiber-grating laser, which is embedded in an epoxy resin-bonded magnetostrictive composite material with doped Terfenol-D particles. A simple structure is designed to convert the magnetic field-induced strain to transversal stress, which is applied to the fiber laser to produce beat note frequency changes for measurement purposes. The response of the proposed sensor is measured, and shows quite a good directivity and linearity with a sensitivity of 10.5 Hz/?T to the magnetic field. It also shows a large measurable range up to about 0.3 T.

S1320201 低測定力変位プローブによる工具刃先形状測定に関する研究

This paper presents the development of the contact-type displacement probe with low measuring force for the profile measurement of the cutting edge on-machine and non-damaging. This probe is consisted of a triangulation-based laser displacement sensor and both-ends supported leaf spring, on which a stylus tip will be mounted. The displacement of the stylus tip can be measured by detecting the deflection of the leaf spring with the laser displacement sensor. The probe is mounted on the linear stage to scan the cutting edge. To realize the large measurement range and low measurement force, the probe tip is contacted intermittently in the vertical direction. The low measurement force of less than 0.1 mN can be achieved. The measurement accuracy is evaluated, and then, the profile of the sharpened edge is measured by utilizing the developed probe system.

A compact super sensitive nonplanar ring laser magnetometer

A novel compact super sensitive nonplanar ring laser magnetometer with the wavelength at 632.8nm is proposed. A well-designed structure enables the super sensitivity of the magnetometer to the magnetic field. The device obtains a scale factor of 150Hz/nT and achieves a magnetic field noise limited sensitivity of 13fT/Hz1/2. The device inherits with all the advantages of the ring laser gyros such as large bandwidth (fast response), large measurement range, short starting time and higher impact resistance, good temperature performance.

Vanadium dioxide nanowire-based microthermometer for quantitative evaluation of electron beam heating.

Temperature measurement is critical for many technological applications and scientific experiments, and different types of thermometers have been developed to detect temperature at macroscopic length scales. However, quantitative measurement of the temperature of nanostructures remains a challenge. Here, we show a new type of microthermometer based on a vanadium dioxide nanowire. Its mechanism is derived from the metal-insulator transition of vanadium dioxide at 68 °C. As our results demonstrate, this microthermometer can serve as a thermal flow meter to investigate sample heating from the incident electron beam using a transmission electron microscope. Owing to its small size the vanadium dioxide nanowire-based microthermometer has a large measurement range and high sensitivity, making it a good candidate to explore the temperature environment of small spaces or to monitor the temperature of tiny, nanoscale objects.

Sensitivity-Improved Strain Sensor over a Large Range of Temperatures Using an Etched and Regenerated Fiber Bragg Grating

A sensitivity-improved fiber-optic strain sensor using an etched and regenerated fiber Bragg grating (ER-FBG) suitable for a large range of temperature measurements has been proposed and experimentally demonstrated. The process of chemical etching (from 125 μm to 60 μm) provides regenerated gratings (at a temperature of 680 °C) with a stronger reflective intensity (from 43.7% to 69.8%), together with an improved and linear strain sensitivity (from 0.9 pm/με to 4.5 pm/με) over a large temperature range (from room temperature to 800 °C), making it a useful strain sensor for high temperature environments.

Design of Ring Core Fluxgate Magnetometer as Attitude Control Sensor for Low and High Orbit Satellites

We have designed a fluxgate magnetometer which utilizes the detection of ultra-low DC fields down to (even less) 3 nT. In addition to high sensitivity, it also has quite a large dynamical measurement range. The second harmonic voltage used as the sensor signal shows linear dependence on the applied field up to 1 Oe. We report some critical factors affecting the noise level and sensitivity of magnetometer. The core diameter and magnetic properties are some of them. We will report optimal core dimensions resulting in minimal electrical noise. During experiments, we have recognized that ring-shaped six-layered ribbon core must be well attached to the template, since otherwise, it may vibrate on its original position as a function of the excitation frequency. Thus, additional electrical noises become unavoidable.

Fluorescent protein-based FRET sensor for intracellular monitoring of redox status in bacteria at single cell level.

Monitoring of intracellular redox status ina bacterial cell provides vital information about the physiological status of the cell, which can be exploited in several applications such as metabolic engineering and computational modeling. Fluorescent protein-based genetically encoded sensors can be used to monitor intracellular oxidation/reduction status. This study reports the development ofa redox sensor for intracellular measurements using fluorescent protein pairs and the phenomenon of Förster resonance energy transfer (FRET). For the development ofthe sensor, fluorescent proteins Citrine and Cerulean were genetically modified to carry reactive cysteine residues on the protein surface close tothe chromophore anda constructed FRET pair was fused using a biotinylation domain as a linker. In oxidized state, the FRET pairs are in close proximity by labile disulfide bond formation resulting in higher FRET efficiency. In reducing environment, the FRET is diminished due to the increased distance between FRET pairs providing large dynamic measurement range to the sensor. Intracellular studies in Escherichia coli mutants revealed the capability of the sensor in detecting real-time redox variations at single cell level. The results were validated by intensity based and time resolved measurements. The functional immobilization of the fluorescent protein-based FRET sensor at solid surfaces for in vitro applications was also demonstrated.

A Novel Design of Fluxgate Magnetometer: An Insect like Configuration

In the present work, we propose a novel design of the fluxgate magnetometer which utilizes the detection of ultra-low DC fields down to (even less) 10 μOe. Measurement point has four eyes, like insects, with the diameter of each having 100 μm. It means that the magnetometer can be used for the magnetization analysis of local areas as low as 8,000 μ m 2. Sensing elements used in the sensor are in the form of metallic glass with high relative permeability (∼10,000) and low coercive field (<1 Oe). In addition to high sensitivity, it also has quite a large dynamical measurement range. The 2 nd harmonic voltage used as the sensor signal shows linear dependence on the applied field till almost 0.4 Oe. Such a large dynamical range facilitates its use in spacecraft applications, mine detection, earth skills, etc.

Resolution limits of extrinsic Fabry–Perot interferometric displacement sensors utilizing wavelength scanning interrogation

The factors limiting the resolution of displacement sensors based on the extrinsic Fabry-Perot interferometer were studied. An analytical model giving the dependency of extrinsic Fabry-Perot interferometric (EFPI) resolution on the parameters of an optical setup and a sensor interrogator was developed. The proposed model enables one to either estimate the limit of possible resolution achievable with a given setup, or derive the requirements for optical elements and/or a sensor interrogator necessary for attaining the desired sensor resolution. An experiment supporting the analytical derivations was performed, demonstrating a large dynamic measurement range (with cavity length from tens of microns to 5mm), a high baseline resolution (from 14pm), and good agreement with the model.

Experimental Study of Coal Moisture Content Measurement System Based on Standing-Wave Ratio

In this paper, a measurement system is designed to deal with the problem of measurement of the coal moisture content. Based on the measurement principle including standing-wave ratio and permittivity, develop the whole measurement system from the hardware and software aspects. The measurement system of coal moisture content based on standing-wave ratio has the advantages of less measuring time, higher accuracy and larger measurement range according to the results. And it can apply in the coal moisture content measurement in many industry fields.

Research on Flow Sensor and the Pressure Sensor with Digital Asthma Diagnosis Technology

The essay discusses on the flow sensor and the pressure sensor, which collect the signals of PEFR(peak expiratory flow rate) and FEV1(forced expiratory volume in 1 second) of the human body. After the two analog signals go through signal conditioning circuit, ATMEGA128 collects the correspondent digital signals so that realizing fast measuring the PEFR and FEV1, and the result of the diagnosis on the patient’s diseases will directly appear on the LCD, at the same time storing dynamic data as objective index for doctors’ prescriptions and disease analysis. The multiparameter digital asthma diagnosis instrument has a large range of measurement and highly accurate measuring ability, with a small size and high cost, suitable for rural medium- and small-sided hospitals and domestic supervisions.

Long base hydrostatic level

The measurement capabilities of the hydrostatic level with a base of 1–3 km are described. The paper presents physical assessments of the effects related to the influence of changes in the parameters of meteorological conditions (atmospheric pressure, temperature, and its gradients along a track). The dynamic characteristics of the instrument and its limiting resolution, determined by both its own thermal fluctuations and the influence of seismic noise, are considered. A new radiotechnical method for measuring variations if the fluid level in the measuring vessel is discussed, characterized by a simple and reliable design and a large dynamic measurement range while maintaining the high sensitivity necessary for constructing long base systems.

Development of precision measurement network of experimental advanced superconducting tokamak

In order to obtain accurate position of the inner key components in the experimental advanced superconducting tokamak (EAST), a combined optical measurement method which is comprised of a laser tracker (LT) and articulated coordinate measuring machine (CMM) has been brought forward. LT, which is an optical measurement instrument and has a large measurement range and high accuracy, is employed for establishing the precision measurement network of EAST, and the articulated CMM is also employed for measuring the inner key components of EAST. The measurement uncertainty analyzed by the Unified Spatial Metrology Network (USMN) is 0.20 mm at a confidence probability of 95.44%. The proposed technology is appropriate for the inspection of the reconstruction of the EAST.

Algebraic solution for phase unwrapping problems in multiwavelength interferometry

Recent advances in multiwavelength interferometry techniques [Appl. Opt.52, 5758 (2013)] give new insights to phase unwrapping problems and allow the fringe order information contained in the measured phase to be extracted with low computational effort. This work introduces an algebraic solution to the phase unwrapping problem that allows the direct calculation of the unknown integer fringe order. The procedure resembles beat-wavelength approaches, but provides greater flexibility in choosing the measurement wavelengths, a larger measurement range, and a higher robustness against noise, due to the ability to correct for errors during the calculation.

Feasibility of using pyranometers for continuous estimation of ground cover fraction in table grape vineyards

This paper evaluates the feasibility of using pyranometers for continuous estimation of ground cover fraction (GCF) at remote, unattended sites. Photographical techniques were used for measuring GCF (GCFref) at a table grape vineyard grown under a net. Daily pyranometer-driven GCF estimates (GCFpyr) were obtained from solar radiation measurements above and below the canopy. For GCFpyr computation, solar radiation was averaged for two hours around solar noon (midday periods) and for daylight periods (8:00 to 18:00 Universal Time Coordinated). GCFpyr and GCFref (daylight periods) showed a good agreement: mean estimation error, 0.000; root mean square error, 0.113; index of agreement, 0.967. The high GCF attained, the large measurement range for GCF and the presence of the net above the table grape were the likely reasons for the good performance of GCFpyr in this crop despite the short number of pyranometers used. Further research is required to develop more appropriate calibration equations of GCFpyr and for a more detailed evaluation of using a short number of pyranometers to estimate GCF.

Optical fiber anemometer using silver-coated fiber Bragg grating and bitaper

An optical fiber hot-wire anemometer based on an optical fiber bitaper and a silver-coated fiber Bragg grating (FBG) is demonstrated for airflow velocity measurement. The specially-fabricated fiber bitaper with an enlarged waist diameter couples light from a high-power pump laser into cladding area of the fiber and the silver coating absorbs the light to generate heat that increases temperature of the FBG to a certain level. In measurement, air flow takes away some heat and reduces temperature, thus Bragg wavelength of the FBG changes with velocity of air flow according to a certain relationship. Experimental results show that a large measurement range up to 13.7m/s is realized.

Fabrication and evaluation of a notched polymer optical fiber fabric strain sensor and its application in human respiration monitoring

This paper describes an intensity-based notched polymer optical fiber (POF) fabric strain sensor and its application in human respiration monitoring. A mechanical analysis illustrates geometrical profiles of constrained fiber loops on the fabric substrate. V-shaped notches are made by laser ablation on the sides of the POFs. The effects of loop parameters and processing conditions on the sensing performance are investigated. The experimental results show that the fabric sensor is more sensitive to strain with notches on the outer side of the loops, a small radius of the loops and a low scanning speed of laser. This fabric sensor exhibits a large measurable strain range of up to 21%. The achieved strain sensitivity is 3.77. The temperature and relative humidity have little effect on strain sensitivity between 0℃ and 60℃. A belt has been fabricated by integrating the fabric sensor for monitoring human respiration. The evaluation trials show a strong correlation between the belt system and a clinic monitor.

Selectively Liquid-Infiltrated Microstructured Optical Fiber for Simultaneous Temperature and Force Measurement

A dual-parameter sensor based on a liquid-infiltrated microstructured optical fiber (MOF) is constructed by selective liquid infiltration of one particular cladding air hole in the MOF. The fundamental core mode could be simultaneously coupled to several higher order modes of the adjacent liquid rod waveguide when the phase-matching condition is satisfied, resulting in the emergence of multiple resonance peaks with different sensing characteristics. Our proposed liquid-infiltrated MOF sensor has several advantages, such as high sensitivity and a large measurement range. Moreover, it is able to resolve the temperature-force cross-sensitivity issue that is commonly encountered in most practically deployed sensing components.

The Triaxial Angular Rate Measurement System Based on Two MEMS Accelerometers Used for Rotating Carrier

Considering that the MEMS Gyroscope used in rotating carrier has the problems of small range and low measurement accuracy, the tri-axial angular rate measurement system based on two MEMS accelerometers used for rotating carrier was presented in this paper. The system has the advantages of large measurement range, anti-high overload, simple structure, small volume and low price. From the principle of the tri-axial angular rate measurement system, the mathematical model of the system was established and the mechanics model of the system was discussed. The different processing method of the output signal in each condition was summarized based on the mechanics model. Finally, the semi-physical simulation experiment was done to verify these theories. The experimental results show that the system scheme is feasible and has obvious advantages in the range and measurement accuracy.