Patent ID: 6865143

Claim:
An optically recorded information recording and/or reading apparatus including a light source, an optical system for relaying a light beam from said light source, an objective lens for converging the light beam through said optical system on a recording surface, a light receiver for receiving a return beam from said recording surface through its light receiving surface to generate light receiving signals, a carriage for carrying the light source, optical system and objective lens, a carriage servo system for positioning said carriage in a direction parallel with said recording surface, a focus servo system for positioning said objective lens in a direction perpendicular to said recording surface, a level adjusting unit for adjusting signal levels of said light receiving signals, a signal combining unit for combining the light receiving signals after passing through said level adjusting unit to generate a composite signal, and controller for controlling said carriage servo system, said focus servo system and said level adjusting unit, respectively, wherein said controller includes a calibrating unit for calibrating adjustment characteristics of said level adjusting unit in accordance with a magnitude of a stray light and said calibrating unit controls said carriage servo system to move at least said objective lens to an outermost position at which said objective lens does not oppose said recording surface, and determines the magnitude of said stray light as a signal level of at least one of said light receiving signals or said composite signal at that instance.