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 servo and tracking servo mechanism for causing the focal point of a laser beam irradiating said optical disk to follow the guide groove of said optical disk, for generating an output signal proportional to the intensity of the reflected beam coming from said optical disk;
• a feed mechanism for moving said measuring head in the radial direction of said optical disk;
• a control circuit for controlling the operations of said spindle motor, the focus servo and the tracking servo mechanism of said measuring head, and said feed mechanism;
• a measurer for performing desired measurements in response to the output signal of said measuring head;
• and
• a computer for commanding said control circuit and said measurer and for processing the measured data of said measurer,
• wherein said measurer comprises a reference plate and calibrates reflectivity and transparency by using said reference plate, said reference plate comprising a plurality of standard specimen, each formed with a reflective or transparent film of a dielectric multi-layered film on one side of a glass substrate having a thickness equal to an ordinary optical disk and evaluated at a predetermined value;
• a clamp to be commonly clamped by a clamp mechanism of said optical disk, and a substrate for arranging said standard specimen in a common circumference and for holding said standard such that the positions of said reflective or transparent films and the heights of the standard specimen from the clamp face are identical to those of the face of the recording film of the ordinary optical disk to be clamped by said clamp mechanism.

A test system for optical disks, comprising

• a measuring head for applying a laser beam having predetermined optical power to an optical disk;
• a measuring photodiode for measuring the optical power of the laser beam having passed through the optical disk;
• a calibrating photodiode for measuring the optical power of the laser beam emitted from the measuring head;
• and
• a sliding holder for integrally holding the measuring and calibrating photodiodes, and capable of selectively moving the measuring photodiode or the calibrating photodiode to a light receiving position.