Electro-optic Transducer Research Articles

非接触型変位計測装置とその応用について 歯科領域に導入した電子光学式変位・振動測定器および高出力赤外発光ダイオードと４分割・ｐ‐ｉ‐ｎ・フォトダイオードとの組み合わせによる変位計測装置

非接触型変位計測装置とその応用について 歯科領域に導入した電子光学式変位・振動測定器および高出力赤外発光ダイオードと４分割・ｐ‐ｉ‐ｎ・フォトダイオードとの組み合わせによる変位計測装置

Influence of electrical field inhomogeneities on the characteristics of a voltage transducer with a cylindrical Kerr cell

A block diagram of the electrooptical Kerr transducer is presented in Fig. i. When there is no voltage at the terminals of the Kerr cell 3 the light from the source 1 passes through the polarizer 2 and is captured by the analyzer 4 that is orthogonal to the polarizer; consequently, the signal at the photomultiplier FEU output 5 is zero. Upon delivery of a voltage to the optically active fluid filling the cell, an induced birefringence occurs resulting in a change in the nature of light beam polarization, and therefore, in the appearance of a signal at the FEU output. The Kerr cell is ordinarily a flat capacitor, where the electrode dimensions are such that the edge effects (field inhomogeneity at the electrode edges) do not substantially affect the apparatus function of the transducer, and can, as a rule, be neglected. In this case the transducer apparatus function has the form [2]

(Invited) Silicon TFTs for Flat Panel Displays

A general investigation of flat panel displays, leads to the conclusion that an electrooptic transducer (liquid crystal for instance) operates in optimized conditions when directly driven by an active matrix system. Such a matrix can be fabricated by different procedures, but one of the most promising is the a-Si TFT technology. a-Si TFT seems quite suitable for LC driving, nevertheless polysilicon TFT should be preferred for fast peripheral addressing circuits. Two basic TFT processes are proposed, using a-Si and SiO2 films deposited on glass by the glow discharge technique. In the first process, silicon was deposited at 300°C instead of 500°C in the second. Only in this last case silicon could be easily recrystallized to get polysilicon TFT on glass. In this paper, the major attention was focused on amorphous Si TFT. Static and dynamic characteristics are presented putting forward the predominant role of traps, and a LC switching simulation is shown. Finally a large area circuit is proposed and the relevant problems discussed.

Electro Optical Transducer for Monitoring Biaxial Displacement

Electro Optical Transducer for Monitoring Biaxial Displacement

Multichannel polarization interferometers

The solution of a number of practical problems, in particular, the contactless investigation of shock processes, requires the multichannel extraction of information from different points of the object being measured. The operating principle of multichannel interferometers, like that of single-channel interferometers, is based on the use of the Doppler effect, i.e., on measuring the Doppler frequency, which is detected by superimposing two waves shifted in frequency with respect to one another. We can divide multichannel interferometers into two groups depending on their construction: those with normally incident optical signals in the reference and measuring arms of the interferometer, and those in which the optical signals are incident at different angles [I]. The incidence of optical signals at different angles is due to the change in the frequency modulation index, and enables the measurement limits to be changed. A multichannel vibratlon-resistant measuring system belonging to the first group is shown in Fig. la. Radiation from the source 1 is converted into n parallel beams by means of the splitter I. The first reference beam is directed via the splitter II onto the reflecting surface of the vibrator support i0, and the remaining measuring beams are directed via electrooptical transducers consisting of quarter-wave plates 2 and 5, lithium niobate crystals 3, fed from a shaper 4 and the beam splitting device II onto the reflecting surface II of the object being measured. The optical signals reflected from i0 and ii are combined in space using the beam splittee II and are applied to the photoreceiver 13 via the polarizer 12.

Application of thin film electroluminescent devices

The main application for electroluminescent devices is considered to be in alphanumeric readout devices with several hundred to several tens of thousand picture elements. The use of high-field electroluminescence in less complex application fields like domestic appliances or vehicle dashboards may also attain considerable commercial importance in the future. In this paper, however, specifications for matrix addressed alphanumeric readouts are given and compared to the features of efficient electroluminescent layer structures. It is concluded that the present a.c. addressed thin films with high contrast and good lifetime data are well suited for application as electro-optic transducers for flat, solid state, medium-sized displays.

Some experiments in digital holographic recording

A holographic recording system, based on the use of lowpower laser sources and high-resolution photographic film, is briefly outlined. It was devised principally for the archival storage of high-quality digital television signals and these requirements are reviewed. The development of suitable electro-optic transducers is difficult, largely because of the high data-transfer rates involved, but some progress has been made. Experimental versions of the transducers have been assembled to form a recording apparatus for writing and reading investigations at realtime rates. The results of some initial experiments are given which illustrate various problems that have been encountered, particularly with regard to the recording medium.

Combined optical and electronic analysis of cells with the AMAC transducers.

Two approaches to the development of a true automated multiparameter analyzer for cells, AMAC, are discussed. The AMAC IV uses a water immersion lens mounted downstream from a Coulter Orifice for optical measurements. Although this type of device has a very high numerical aperture (0.70) and optimum light scattering characteristics, it is very difficult to minimize the distance between the objective and the orifice, and increasing this distance results in trajectory irregularities of the cells, with the possibility of exchange of sequence of cells between the orifice and the optical sensing zone. The other, the AMAC III, which is the optimal solution to this problem, performs the optical and electronic measurements simultaneously. This transducer is a small square orifice fabricated out of quartz, with sensing electrodes located at both ends. This combined electro-optical transducer has been used for fluorescence, electronic cell volume and opacity (AC amplitude divided by DC amplitude) measurements. Diffraction effects due to the orifice appear minimal and should not interfere with the scattering produced by the cells. Previous studies with a round but otherwise electronically similar orifice have indicated that it was possible to determine the shift in phase produced by the presence of a particle in the orifice. The capacity to measure all of these parameters simultaneously will greatly enhance the reliability of flow cell analysis.

Measurement of dynamic and static strain in small specimens at elevated temperatures

A method of strain measurement in small specimens is described which involves measurement of strain in terms of the net displacement of reference points within the specimen ends rather than on the gauge length. The reference points are the bottoms of axial holes drilled into the specimen heads. The method has been developed for high-frequency dynamic-strain measurement using a novel electro-optical displacement transducer and for low-frequency creep-fatigue work using conventional displacement transducers.

A Discussion on the measurement and interpretation of changes of strain in the Earth - An improved servo-controlled tiltmeter system and latest measurements in Sweden

Two serious shortcomings in horizontal pendulums used for tilt measurements are nonlinearity in their response to tilt and sensitivities which vary with time. These difficulties may be eliminated if a horizontal pendulum is used as a null indicator. A description is given of a horizontal pendulum apparatus which automatically compensates for ground tilt. The pendulum apparatus is designed so that it may be tilted by varying the pressure in an expansible bearing plate made of stainless steel which is placed at its base. Pressure changes are produced in the bearing plate by varying the height of a column of mercury, a process which can be previously calibrated with great precision. The position of the pendulum beam is sensed by an electro-optical transducer which provides a suitable servo signal to adjust the height of the mercury column when the instrument undergoes tilting. The servo signal can be recorded directly on an ink chart recorder or digitally. First results have been obtained in a test station. It is planned to establish an array of geodynamic stations in Scandinavia incorporating these tiltmeters alongside recording gravity meters in order to study crustal movements by tidal forces, atmospheric pressure effects, ocean loading effects and possibly the process of land uplift in Fennoscandia.

Electrooptical remote transducer for measurements and oscillography of voltages across components at high potential

Electrooptical remote transducer for measurements and oscillography of voltages across components at high potential

Performance of Optical Detection Systems

The power transfer efficiency between a light source and the electrooptical transducer is exceedingly small in ordinary optical detection systems. Any increase in this efficiency would improve the performance considerably. The performance of optical detection systems has been investigated on the rounds of shot-noise limitation. In discussions of means of obtaining high signal-to-noise ratios at wide electronic bandwidth, the importance of a high geometric flux in detection systems becomes apparent. Various methods of determining the rms noise in the signal are compared; also, instrumental parameters of a specific design for fluorescence detection are given. The limitations of the specific design have been determined and discussed, both from the electronic standpoint and from that of the physicochemist, using such an instrument for fast measurements of chemical parameters.

Analog Division Based on the Hall Effect

An indium antimonide film Hall generator is employed in conjunction with an electro-optic transducer in the feedback loop of a differential amplifier. The Hall voltage is compared against another input signal and the amplified difference controls the current through the Hall plate. The Hall current is shown to be proportional to the ratio of the input signal to the magnetizing current which creates the magnetic field across the Hall plate. The assembled apparatus constitutes an analog divider of fair precision and wide dynamic range.