Olympus Optical Company, Ltd.

Eishi Ikuta

Shinichi Imade

Masayoshi Omura

Akira Hasegawa

Tatsuo Nagasaki

Koji Taguchi

Kazunori Shionoya

Hitoshi Watanabe

Hiroyuki Yoshimori

Seiichi Wakamatsu

Toyoo Nishiyama

Chiaki Sato

Kazuhisa Yanagisawa

Outaro Andou

An acoustic lens system is constructed so that at least one surface of acoustic lenses constituting the acoustic lens system is an aspherical surface, which has such a shape that curvature moderates progressively in separating from the axis of the acoustic lens system, and an acoustic beam stop is provided therein. As a result, aberrations can be favorably corrected even when the angle of view and the numerical aperture are increased and this brings about the acoustic lens system suitable for an objective lens of an acoustic system for securing an image of an object having a two-dimensional size in particular.

Acoustic lens system

The acoustic lens system is used for ultrasonic imaging in an ultrasonic system which displays an image of an object while transmitting ultrasonic waves and receiving the ultrasonic waves reflected from the object, and has a half field angle .omega. expressed as follows: ##EQU1## wherein the reference symbol v.sub.0 represents the velocity of sound in the medium located on the incidence side of the first lens surface and the reference symbol v.sub.1 designates the velocity of sound in the medium located on the emergence side of the first lens surface. Accordingly, the acoustic lens system according to the present invention is remarkably excellent in the performance thereof in respect of field angles, aberrations, aperture angles, attenuation, etc., and has an advantage to permits further reducing acoustic attenuation and preventing spurious images from being formed due to multiple reflections by arranging antireflection films on the lens surfaces.

An acoustic lens system is constructed so that at least one surface of acoustic lenses constituting the acoustic lens system is an aspherical surface, which has such a shape that curvature moderates progressively in separating from the axis of the acoustic lens system, and an acoustic beam stop is provided therein. As a result, aberrations can be favorable corrected even when the angle of view and the numerical aperture are increased and this brings about the acoustic lens system suitable for an objective lens of an acoustic system for securing an image of an object having a two-dimensional size in particular.

A laser beam emitted from a laser diode 12 is converted to parallel beams through a collimator lens 14. The beams pass through a stop 15, a polarizing beam splitter 16 and a .lambda./4 plate 18. The beams are then converged on an optical disc 22 through an objective lens 20 and diffracted by mark set provided on the disc 22. The diffracted beams reflected by the disc 22 enter the objective lens 20, pass through the .lambda./4 plate 18, are reflected by the polarizing beam splitter 16, and are divided into two parts by a half mirror 24. The reflected part of the beams enters a data reproducing detector 26, and the transmitted part of the beams enters a tracking servo detector 27.

Optical high density data reproducing apparatus using interference

A ferroelectric memory includes a ferroelectric thin film having first and second surfaces opposite to each other, a first electrode assembly having a plurality of stripe electrodes arranged in parallel on the first surface side of the ferroelectric thin film, a second electrode assembly having a plurality of stripe electrodes arranged in parallel on the second surface side of the ferroelectric thin film to intersect the stripe electrodes of said first electrode assembly, first and second common electrodes arranged separately from the end portions of the respective first and second electrode assemblies to extend in respective directions in which the stripe electrodes of the first and second electrode assemblies are arranged, and selecting sections for respectively connecting the first and second electrode assemblies to the first and second common electrodes and selectively activating at least one of the stripe electrodes of each of the first and second electrode assemblies.

Ferroelectric memory

An ultrasonic endoscope apparatus in which an ultrasonic vibrating element radiating an ultrasonic wave to obtain an image of an object to be inspected is rotatably housed in a distal end of an insertion section of the endoscope, and a rotation angle sensing mechanism is also housed in the distal end. The rotation angle sensing mechanism has a magnetic recording section having a magnetization pattern for forming a magnetic field, and a magnetic sensor having at least one magneto-resistive element for sensing the magnetic field. One of the magnetic recording section and the magnetic sensor is rotated integrally with the ultrasonic vibrating element so that a rotation angle of the ultrasonic vibrating element is sensed in a precise manner.

Ultrasonic endoscope apparatus

A pulse compression apparatus comprises a quadrature detector for converting an echo signal obtained by an ultrasonic transducer into a complex signal, a reference wave oscillator for producing a reference wave signal, and a correlation circuit for deriving a correlation between the complex signal and the reference wave signal to compress the echo signal.

Pulse compression apparatus for ultrasonic image processing

Ultrasonic endoscope equipment transmits signals by providing a signal coupler such as rotary transformer or optical coupling device without using the signal line between the rotating part which introduces a signal line from an ultrasonic transducer housed in a rotatable way in the end of the inserting part of the endoscope and outputs the ultrasonic high frequency signal via a preamplifier and an ultrasonic image display unit which receives the ultrasonic high-frequency signal output from the rotating part and displays an ultrasonic image, the primary input side being provided on the output side of the said rotating part and the secondary output side on the input side of the said ultrasonic image display unit.

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Sagamihara, Japan

Eishi Ikuta