This paper describes the evaluation of a fiber-optic reflective displacement sensor that is compensated for variations in light source intensity, pressure, temperature and opacity of ambient medium. Additionally, the distance information is averaged over several points on the target surface, which reduces signal fluctuations due to inhomogeneities. Furthermore, a practical optical fiber reflective sensor model of measuring oil film thickness for thrust bearing is set up in this paper. Actual measurements were made with HEC 3000 tons' thrust bearing and the results were in good agreement with theoretical calculations.

This paper describes the design and results of low cost integrated CMOS local and remote temperature sensors with digital outputs. No trimming is needed to obtain good temperature linearity, so that only one-temperature calibration is needed which greatly reduces testing cost. The base-emitter voltage of the parasitic substrate bipolar transistor is used to measure the local temperature. A diode-connected external bipolar transistor is used to measure the remote temperature. Chopper techniques were used to cancel the offset voltage of the op-amp, so that a precise bandgap voltage can be obtained without resistance trimming. A first order ΣΔ ADC was used to produce the digital output. The local and remote temperature sensors were realized in a 0.6 µm single-poly triple-metal CMOS technology with active area of 0.6 mm2 and 0.65 mm2, respectively. After calibration, the error is 1 for the local temperature sensor over the temperature range of -20 to 130, and 2 for the remote temperature sensor over the range of 0 to 120. The supply currents of the local and remote temperature sensors are 3.5 µA and 38 µA at 8 samples/s, respectively.

This paper describes a novel IDDQ sensor circuit that is driven by only an abnormal IDDQ. The sensor circuit has relatively high sensitivity and can operate at a low supply voltage. Based on a very simple idea, it requires two additional power supplies. It can operate at either 5-V or 3.3-V VDD with the same design. Simulation results show that it can detect a 16-µA abnormal IDDQ at 3.3-V VDD. This sensor circuit causes a smaller voltage drop and smaller performance penalty in the circuit under test than other ones.

A tunable optical Fabry-Perrot filter was designed by setting a single-mode optical fiber normal to the diaphragm of a capacitive pressure sensor. The silicon diaphragm is deflected by the electrostatic force generated by applying a voltage to the capacitive electrodes. According to the movement of the diaphragm, the peak wavelength changed from 1546 to 1551 nm when applied voltage was increased from 20 to 50 V. The relationship of the wavelength change to the applied voltage was derived from the silicon diaphragm deflection theory. That measured change of the wavelength agrees well with the wavelength change calculated from this relationship. The commercial pressure sensors are expected to be able to be used as a tunable optical filter.

The contribution of the paper is two-fold: Firstly, a review of the point set registration literature is given, and secondly, a novel covariance weighted least squares formulation of the multiple view point set registration problem is presented. Point data for surface registration is commonly obtained by non-contact, 3D surface sensors such as scanning laser range finders or structured light systems. Our formulation allows the specification of anisotropic and heteroscedastic (point dependent) 3D noise distributions for each measured point. In contrast, previous algorithms have generally assumed an isotropic sensor noise model, which cannot accurately describe the sensor noise characteristics. For cases where the point measurements are heteroscedastically and anisotropically distributed, registration results obtained with the proposed method show improved accuracy over those produced by an unweighted least squares formulation. Results are presented for both synthetic and real data sets to demonstrate the accuracy and effectiveness of the proposed technique.

A novel chemical sensor for sulfate detection was proposed in this study, utilizing sulfate binding protein (SBP) derived from Escherichia coli as sulfate recognition element. Purified SBP was immobilized on a gold electrode modified with cysteamine and glutaraldehyde. In this study the surface potential change of the SBP modified electrode to sulfate and various ions were investigated. In order to evaluate nonspecific interaction with ionic species, proteins with various isoelectric point were immobilized on the surface of gold electrode and response to ions were measured and compared to sulfate binding protein modified electrode. We made clear that the protein modified electrode shows the potential change to ions and these potential change was effected by the isoelectric point of the protein molecule, and BSA, whose isoelectric point is closest to that of SBP, showed the similar response to ions except sulfate. With use BSA modified electrode as a reference electrode, this sensing system showed selective response to sulfate, probably because of the selective binding sulfate by SBP. This potential change difference between the SBP modified electrode and the BSA modified electrode depended on the concentration of sulfate with in the range of 5 - 150 mM.

Two types of biomimetic chemical sensing systems are reviewed. One is an electronic nose and tongue which can recognize odor or taste from the output pattern of arrayed chemical sensors with different but overlapped specificities. The other is a chemical plume tracing system which has been developed to mimic the moth behavior in tracing the sexual pheromone from a female. We have created an odor/gas tracing robot and a compass, both of which can detect the direction from which an odor/gas is issuing.

There are methods used to test the optical purity of enantiomers; however, most of the simple methods are not precise and more complicated methods are better. As a result, these methods cannot be widely used for industrial purposes. The aim of this research is to design a sensor which can discriminate D-amino acids from L-amino acids. The designed sensor has chiral membranes and uses the technique of impedance change of these chiral membranes to discriminate the amino acids. We used a noise-FFT (Fast Fourier Transform) technique to determine the membrane impedance. When an enantiomer membrane resides in a chiral environment, (E*), diastereomeric interactions (E*-D) and (E*-L) are created, which may differ sufficiently in the arrangement of molecules of the membranes so as to permit the discrimination of optical substances due to the change in membrane characteristics. With increasing concentrations of the amino acids, the membrane resistance changes depended on the optical activity of the amino acids. The results suggest that the impedance changes of the chiral membrane with diastereomeric reaction can be used for the high-performance chemical sensor to measure the optical purity of different substances.

Saltiness elicited by salt is one of the basic tastes. However, components of salt on the market differ depending on manufacturing processes and its taste as well. Salt manufactured by ion-exchange membrane process is composed of more than 99% pure sodium chloride, while bay salt contains trace coexisting components. Despite reports on sensory evaluation, the differences in taste are still uncertain because of a small amount of coexisting components. We studied the taste of salt with trace coexisting components; the bittern ("nigari" in Japanese) was evaluated objectively and quantitatively using a multichannel taste sensor with lipid/polymer membranes. A taste sensor is comprised of several types of lipid/polymer membranes for transforming information of taste substances into electric signals. The model samples were composed of sodium chloride and trace coexisting components such as magnesium sulfate, magnesium chloride, calcium chloride and sodium chloride. The taste sensor clearly discriminated each sample according to the response patterns. Based on the sensor outputs, we evaluated the taste by means of the combination of principal component analysis and ionic strength. The results show the taste of salt with nigari has a correlation with ionic strength.

In the food, beverage and cosmetic industry and so on, odor sensing systems instead of human sensory test are demanded. We have developed odor sensing systems using QCM (quartz crystal microbalance) sensor array and pattern recognition method. Since the properties of the sensors depend on the gas sorption characteristics of the sensing films coated on them, the optimum films according to target odors should be selected. In this study, we tried to select sensing films appropriate for discrimination of slightly different apple flavors. The examples of typical apple flavors were prepared blending 9 compounds. The sensing films were extracted from various kinds of materials such as lipid, stationary phase material of GC (gas chromatography) and cellulose. The selection method under the condition of the small number of measurements was studied. We analyzed the data of steady-state sensor responses in terms of the Euclidean distance, and the films appropriate for apple flavor discrimination were successfully selected.

We propose a new sampling control system on image sensor array. Contrary to the random access pixels, the proposed sensor is able to read out spatially variant sampled pixels at high speed, without inputting pixel address for each access. The sampling positions can be changed dynamically by rewriting the sampling position memory. The proposed sensor has a memory array that stores the sampling positions. It can achieve any spatially varying sampling patterns. A prototype of 64 64 pixels are fabricated under 0.7 µm CMOS precess.

We describe FMCW reflectometry for characterization of long optical fibers by using an external-cavity laser diode as a light source. Since the optical path difference between the reference beam and the reflected beam from the optical fiber under test is much longer than the coherence length of the light source, the reference and the reflected beams are phase-decorrelated. As a result, the beat spectrum between the reference and the reflected beams is measured. In the phase-decorrelated FMCW reflectomety, the spatial resolution is enhanced by narrowing the spectral linewidth of the light source and increasing the repetition frequency of the optical frequency sweep as well as increasing the chirping range of the optical frequency sweep. In the experiments, an external-cavity DFB laser is used as a narrow linewidth light source, and the optical frequency is swept by minute modulation of the external cavity length. Long single mode optical fibers are characterized, and the maximum measurement range of 80 km is achieved, and the spatial resolutions of 46 m, 100 m and 2 km are achieved at 5 km, 11 km and 80 km distant, respectively. The Rayleigh backscattering is clearly measured and the propagation loss of optical fiber is also measured. The optical gain of an erbium-doped optical fiber amplifier (EDFA) is also estimated from the change in the Rayleigh backscattering level in the optical fiber followed after the EDFA.

This paper reports the performance of an AC-voltage sensor with a LiNbO3 integrated retroreflective structure based on the Y-junction Mach-Zehnder interferometer. This structure is capable of realizing a low-cost sensor chip because of the small chip size and single optical-fiber connection. In the sensitivity and frequency response evaluation, detection sensitivities of 6.3 µ V / Hz have been measured with a frequency response from 6 Hz to 2 GHz. These measurement limitations were also analyzed theoretically and compared with the experimental results. This unique sensor enables precise voltage measurement in an EMI environment, even inside a computer.

In this paper, we will report on a fiber optic oxygen sensor using fluorescence and its application to clinical examinations. It is based on fluorescence quenching. The quenching ratio of fluorescence is proportional to oxygen partial pressure by Stern-Volmer's formula in which oxygen concentration is estimated from measured emission intensity. We fabricated a microscopic luminous probe using a Solvent Green 5 doped plastic optical fiber coupler. The probes were demonstrated to have certain advantages for example they can be operated in both liquid and gas phases. And also, they are stable to pH and flow velocities. As a clinical application, the probe can reliably measure oxygen concentrations of whole blood in vivo. Moreover, we have clarified various characteristics of this probe.

A novel technique has been developed for in situ sensing of thin film growth. In this method, a fiber optic probe is placed at an appropriate position in a deposition chamber, and the thin film builds up on the end of the fiber. This film is either the same as on the wafer where deposition occurs, or it bears a fixed relationship to the film on the wafer. By an analysis of the intensity of the light reflected from the film and guided by the fiber, information on the film may be obtained. With interference causing maxima, minima and a point of inflection as the film grows, it is possible to obtain near real time information on the following quantities: the real and imaginary parts of the refractive index of the film, a Gaussian parameter characterizing surface roughness, and the film thickness itself. To demonstrate this technique, we have studied the deposition of silicon nitride films in a CVD reactor and how reactor temperature and reactant flow rates influence film growth. This technique may be applied to measure in situ reflectivity of multi layer films, so that reflectance as a function of temperature and time may be obtained. Because the measurement is simple and direct and the information is optical, we believe that this technique has the potential to supplant quartz oscillators in the measurement of thin film growth.

This paper describes a fiber-optic level sensor designed to measure the level of liquid propane-butane in a relatively short range (60 cm) in the top part of storage tanks at oil refineries with the purpose of monitoring the level of this product in the filled or slightly underfilled or overfilled tanks during various measuring operations. A discrete multi-element device employing novel refractometric transducers was selected because it yields both a large measurement range and high resolution. Several innovations offer a competitive advantage to industrial users: 1) Special micro-optical refractometric transducer; 2) Efficient and economical sensor multiplexing scheme; 3) Fast level-tracking operational algorithm. The vertical resolution of the sensor -1 cm, the maximum excess pressure in the tank -40 atm (4 MPa). The sensor has the spark-proof and explosion-proof design and optical fiber interface for the transmission of the output data. The sensor successfully measured liquid propane-butane level in storage tanks during numerous cycles of measuring operations.

In this paper, we review recent developments in interferometric fiber-optic gyroscopes for industrial applications. These gyroscopes use only elliptical-jacket or elliptical-core polarization-maintaining-fibers to make their optical systems immune to environmental effects, and they use open-loop or closed-loop signal processing circuitry. We have begun mass production of a gyroscope for automotive navigation and location systems. The more accurate gyroscopes have been applied to a number of consumer applications such as attitude control systems of unmanned agricultural helicopter, pipe-mapping and north-finding systems. For further enhancement in terms of size, cost, and accuracy, we have developed an application specific integrated circuit and an integrated optical circuit.

This paper reviews the use of fiber optic sensors for downhole monitoring in the oil and gas industry. Due to their multiplexing capabilities and versatility, the use of Bragg grating sensors appears to be particularly suited for this application. Several types of transducer have been developed, each of which can be addressed along a single (common) optical fiber in the well and read-out using a common surface instrumentation system.

An optical fiber humidity sensor was fabricated forming a nanometer-scale Fabry-Perot interferometer by using the Ionic Self-Assembly Monolayer (ISAM) method. The materials used were Poly R-478 and poly(diallyldimethyl ammonium chloride). Taking advantage of the precision that the ISAM method can achieve in controlling the length of the nano cavity, the length was fit to obtain a maximum variation of 8.7 dB of reflected optical power between 11.3% and 85% RH. The sensor exhibited a fast response time and was able to monitor the human breathing.

The design method for sensitivity and frequency response of an electric field sensor using a Mach-Zehnder interferometer (an optical E-field sensor) has been developed in order to measure electromagnetic environments and the performance of measuring facilities. The designs of the optical modulator, sensor elements, and sensitivity were analyzed theoretically by using an accurate equivalent circuit of the sensor. Then an actual sensor was fabricated, and its characteristics of the sensor were evaluated experimentally. The results show that the designed sensitivity and frequency response were optimal. The optical output deviation when the temperature increased from 0 to 40 was reduced to within 2 dB. The minimum detectable electric field strength was 17 dBµV/m (8 µV/m), and the dynamic range was more than 100 dB. The frequency response of the sensitivity was almost flat between 200 Hz and 900 MHz.