Light modulator and optical head adjustment method

A method for adjusting elements of an optical-head during manufacture without using a reference medium, comprising the steps of:

• modulating a laser beam by:
• transmitting the laser beam through a Faraday rotator having a solenoid coal set around a piece of glass having a large Faraday constant, the solenoid coil for rotating a plane of polarization of the laser beam by applying current to the solenoid coil, the rotation occurring in a manner proportional to the applied current;
• transmitting the laser beam through an objective lens connected to a first mechanism which moves along an optical axis direction of the laser beam in accordance with current applied or voltage charged therein;
• and
• transmitting the laser beam onto a target to be at least partially reflected thereby, the target having at least one groove at a surface and connected to a second mechanism moving along the direction perpendicular to a track of a storage medium in accordance with current applied or voltage charged therein, the groove having a light reflecting member on the optical axis;
• detecting the laser beam after it has been reflected off of the target;
• generating a servo signal from the detected laser beam;
• and
• determining a position of each element in a detecting system of the optical head based upon the generated servo signal.

A method for adjusting elements of an optical-head during manufactors without using a reference medium, comprising the steps of:

• modulating a laser beam by:
• transmitting the laser beam through a Faraday rotator having a solenoid coil set around a piece of glass having a large Faraday constant, the solenoid coil for rotating a plane of polarization of the laser beam by applying current to the solenoid coil, the rotation occurring in a manner proportional to the applied current;
• transmitting the laser beam through an objective lens connected to a first mechanism which moves along an optical axis direction of the laser beam in accordance with current applied or voltage charged therein;
• and
• transmitting the laser beam onto a target to be at least partially reflected thereby, the target having at least one groove at a surface and connected to a second mechanism moving along the direction perpendicular to a track of a storage medium in accordance with current applied or voltage charged therein, the groove having a light reflecting member on said optical axis;
• translating a light path of a definite system into an infinite system by setting a convex lens on the optical axis of the definite-system laser beam;
• detecting the laser beam after it has been reflected off of the target;
• generating a servo signal from the detected laser beam;
• and
• determining a position of each element in a detecting system of the optical head based upon the generated servo signal.