Hitachi, Ltd.

Toshio Akatsu

Sadao Mori

Kenji Mori

Kazuto Kinoshita

Tsugio Udagawa

Akira Hirai

Nobuo Shibata

Jun Nakajima

Tokio Yamagiwa

Yasunori Hamada

Masao Fukunaga

Jun Naruse

Chuuichi Miyazaki

Toshimitsu Fujiyoshi

Chyuuichi Miyazaki

Light from a light source is fed to a sensing probe through a polarization plane-reserving fiber, and is split into two light beams, that is, a reference beam and a measurement beam. The reference beam is passed through a reference medium, and the measurement beam is passed through a pressure-sensitive medium, which may be in the form of gas. Then, the reference beam and the measurement beam are fed to a light-receiving portion via the polarization plane-reserving fiber, and are converted into electrical signals. The electrical signals are inputted into a signal processing portion, and the optical path length difference between the reference and measurement beams, passed through their respective mediums, is determined, and the pressure of the pressure-sensitive medium is detected from this optical path length difference.

Optical pressure detection method and apparatus

A physical quantity measuring apparatus in which the measurement range of the physical quantity such as displacement, pressure or the like can be widened. Laser beams different in wavelength are radiated through an optical fiber onto a diaphragm and the light reflected on the diaphragm and the light reflected on a reference face opposite to the diaphragm are returned to the optical fiber so that the distance between the reference face and the diaphragm which is transformed, and hence a pressure difference, is measured by a light interference method. The quantity of displacement of the diaphragm is measured optically by using laser beams different in wavelength from each other so that it is possible to make the measurement accuracy high and to effect measurement in a wide range with respect to a physical quantity such as displacement, pressure, or the like, without being influenced by a change in characteristic of the optical fiber.

Physical quantity measurement apparatus and instrument therefor

The spacing between a magnetic disk surface and a magnetic head tends to greatly decrease with an increasing request for higher density records. Measuring and controlling the small spacing is important for stabilized recording or reading. A substrate is attached to a side of a support which supports the magnetic head. Light is irradiated onto a surface of the substrate and totally reflected thereby. The small spacing is measured by measuring the quantity of the totally reflected light. An actuator is controlled such that the measured small spacing is maintained at a target value to thereby realize constant small-spacing control.

Method and apparatus for controlling a small spacing between a magnetic

A positional measuring laser interferometer splits a laser beam into a measuring beam and a correcting beam. Each of these beams is further split into a measurement beam and a reference beam. The reference beams travel along a fixed length path of fixed optical properties. Each of the measurement beams travels along respective optical paths in air adjacent each other so that they travel in air having substantially the same changing optical properties, such as the fraction index, preferably with the paths differing in length by a fixed amount regardless of the movement of the object to be measured. The reference beam and measurement beam, for each of the measuring and correcting beams, form an interference pattern that is detected to produce respective outputs correlated to positional information of the object and subjected to positional error due to changing refraction index of air. These two information signals are combined, preferably with a reference refraction index and a reference object position, to obtain a positional information signal of the object that is independent of varying optical characteristics of air. The solid/air interface surface for the interferometer, with respect to the measurement beams, is fixed in position independently of thermal or like expansion of the interferometer by an adjacent abutment surface spring biased into a fixed base abutment surface, which abutment surfaces are generally coplanar with the solid/air interface surface and perpendicular to the path of the measurement beams in air.

Laser gauge interferometer and locating method using the same

A light beam is projected on a reference plane and an object to-be-measured, a phase difference between reflected lights from them is changed by a phase shifter, a drive voltage for causing the change of the phase difference is applied to the phase shifter, a magnitude of phase shift of the phase of the reflected lights is detected by a phase shift detector on the basis of the drive voltage at a point of time at which the change of the phase difference of the reflected lights has been compensated, and an up pulse or down pulse is generated by an up-down pulse generator upon detecting a discontinuous change in the magnitude of phase shift attributed to the displacement of the object to-be-measured, while a pulse is generated by another pulse generator upon sensing a change in brightness of an interference signal of the reflected lights attributed to the displacement of the object to-be-measured. Besides, a mode selecting circuit supplies the output of the up-down pulse generator to a counter when a displacement speed of the object to-be-measured is lower than a reference speed, whereas it supplies the output of the other pulse generator to the counter when the displacement speed is higher than the reference speed. The displacement of the object to-be-measured is measured by utilizing an output of the counter.

Method of and apparatus for optically measuring displacement

The welding position detecting apparatus incorporates a detecting portion including light emitter for emitting a light stripe onto a beveling surface of a work to be welded and a camera for receiving a reflected light from the beveling surface, a support member to which the detecting portion is mounted, which is disposed for rotation about an axis of the welding torch, and a motor for rotating the support member, whereby the detecting portion is rotated to a desired angular position about the axis of the welding torch.

Apparatus utilizing light stripe image for detecting portion to be

The magnitude of displacement of an object to-be-measured is measured by projecting light beams on the object to-be-measured and a reference plane and utilizing the interference of lights reflected therefrom. The reflected lights from the object to-be-measured and the reference plane have their phase difference changed cyclically and forcibly. The discontinuous change of the magnitude of phase shift at the moment at which the phase difference of the two reflected lights caused by the displacement of the object to-be-measured has been compensated, and the magnitude of displacement of the object to-be-measured is found from the counted result of the discontinuous changes and the magnitude of phase shift at the moment at which the phase difference has been compensated.

In a grip device wherein bimorph type piezoelectric elements are employed for fingers or claws for grasping a workpiece, a grip device comprising bimorph type piezoelectric elements which are mounted on a grip body and which form finger or claws, a voltage feed circuit which is connected to the piezoelectric elements in order to bend and deform the piezoelectric elements, and a control circuit is connected to an end of the piezoelectric elements providing an output signal for controlling a grasping force for a workpiece.

Grip device

A welding position detecting apparatus provided on a welding torch which forms an arc between a welding wire and a groove face on a work piece. The apparatus has an optical system for irradiating the groove face with a converging ray at a point in advance of the point of the arc so as to form a groove face crossing image, and an observing optical system which introduces this groove face crossing image and an arc image into its field of view and by which the groove face crossing image and the arc image are detected at the same time.

Welding position detecting apparatus

A clearance formed between two members is measured by optical means projecting a light beam on the respective members and utilizing lights reflected therefrom. The reflected lights from the two members are passed through means capable of regulating an optical length and polarization means, whereupon they are caused to interfere. The irradiance of the interference light is converted into an electric signal. The electric signal is applied to a control circuit, and is fed back to the means capable of regulating an optical length so that the optical-path difference of the reflected lights may be held constant. The change of the clearance between the two members is found by measuring the factor of the feedback.

Method and apparatus for optically measuring clearance change

A method and system are disclosed for measuring physical quantities of a rotating body at many points thereof in a contact-free manner. The present measurement comprises electromagnetically applying control signals to the rotating body outside the body and taking out such physical quantities as mechanical strains, temperatures, etc. at many points of a rotating body with high accuracy, in a desired manner irrespective of the revolution of the body. Detecting circuits for detecting physical quantities such as mechanical strains or temperatures of a rotating body are additively and detachably provided at many measuring points of the body. The rotating body is also provided with electronic switches which can be arbitrarily changed over by control signals transmitted electromagnetically from the stationary side. The output signals from the detecting circuits are switched over by the electronic switches and transmitted electromagnetically to the stationary side.

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Ushiku, Japan

Toshio Akatsu