Yokogawa Electric Corporation

Shoji Uehara

Kenta Mikuriya

Hideo Hirukawa

Akira Ohya

Masuo Hanawaka

Minoru Nakagawara

Kenichi Yamakawa

A test system for optical disks, comprising a spindle motor for clamping and rotating an optical disk at a constant speed; an encoder for generating a pulse output corresponding to the angle of rotation of the motor; a measuring head comprising focus and tracking servo mechanisms for causing the focal point of a laser beam irradiating the disk to follow the guide groove thereof, and a displacement detector for optically detecting the displacement of a focusing lens driven by the servo mechanisms; the measuring head being operative to generate an output signal proportional to the displacement of the focusing lens; a feed mechanism for moving the measuring head in the radial direction of the disk; a control circuit for controlling the operations of the motor, the servo mechanisms and the feed mechanism; an analog to digital converter for converting the output of the measuring head at a timing according to the pulse output of the encoder; and a computer for commanding the control circuit and for computing the output of the analog to digital converter to determine the shape of the disk, whereby displacement of the focusing lens is directly detected by the displacement detector.

Test system for optical disks

A test system for optical disks, comprising a spindle motor for bearing and rotating an optical disk at a constant speed; a measuring head, comprising focus servor and tracking servo mechanisms for causing the focal point of a laser beam irradiating the optical disk to follow the guide groove of the disk, for generating an output signal proportional to the intensity of the reflected beam coming from the optical disk; a feed mechanism for moving the measuring head in a radial direction of the optical disk; a control circuit for controlling the operations of the spindle motor, the focus servo and tracking servo mechanism of the measuring head, and the feed mechanism; a measurer for performing desired measurements in response to the output signal from the measuring head; and a computer for commanding the control circuit and the measurer and for processing the measured data of the measurer, whereby all the measurements are accomplished with the guide groove of the disk being under the focus and tracking servos.

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Tokyo, Japan

Shoji Uehara