Optical information reproducing device and reference beam adjusting method

An optical information reproducing device to reproduce information recorded on an optical information recording medium using interference of a signal beam and a reference beam, comprising:

• a light source that emits light to the optical information recording medium;
• a light source control unit that controls a wavelength of the light emitted from the light source;
• a reference beam angle control unit that controls an incidence angle of the reference beam to the optical information recording medium;
• a light detector that detects a reproduction image from the optical information recording medium or a brightness distribution of the reproduction image;
• a reproduction image processing unit that detects a bright line of the reproduction image on the basis of a detection result of the light detector and outputs a detection result of the bright line;
• and
• a control unit that controls the wavelength of the light emitted from the light source through the light source control unit, on the basis of an output of the reproduction image processing unit, and controls the incidence angle of the reference beam through the reference beam angle control unit, wherein
• the reproduction image processing unit detects a bright line position error to be a difference of a bright line position of the reproduction image on the light detector when the incidence angle of the reference beam and the wavelength of the light source are optimal and a bright line position of the reproduction image detected on the light detector, and
• the control unit controls the incidence angle of the reference beam and the wavelength of the light source, on the basis of the bright line position error.

A reference beam adjusting method to reproduce information recorded on an optical information recording medium using interference of a signal beam and a reference beam, comprising:

• radiating the reference beam to the optical information recording medium;
• detecting a reproduction image from the optical information recording medium and a brightness distribution of the reproduction image;
• detecting a bright line of the reproduction image, on the basis of a detection result of the reproduction image and the brightness distribution of the reproduction image;
• controlling an incidence angle and a wavelength of the reference beam, on the basis of a detection result of the bright line of the reproduction image;
• moving a radiation position of the reference beam to the optical information recording medium to a predetermined position;
• changing an incidence angle of a first direction in the reference beam to a predetermined angle;
• and
• setting an incidence angle of a second direction in the reference beam to an angle at which brightness of the reproduction image is maximized, wherein
• in detecting the bright line of the reproduction image, an angle between bright lines formed by a bright line of the reproduction image when the incidence angle of the second direction in the reference beam and the wavelength of the reference beam are optimal and the bright line of the detected reproduction image is detected, and
• in controlling the incidence angle and the wavelength of the reference beam, the incidence angle of the second direction in the reference beam and the wavelength of the reference beam are controlled on the basis of the angle between the bright lines.

A reference beam adjusting method to reproduce information recorded on an optical information recording medium using interference of a signal beam and a reference beam, comprising:

• radiating the reference beam to the optical information recording medium;
• detecting a reproduction image from the optical information recording medium and a brightness distribution of the reproduction image;
• detecting a bright line of the reproduction image, on the basis of a detection result of the reproduction image and the brightness distribution of the reproduction image;
• controlling an incidence angle and a wavelength of the reference beam, on the basis of a detection result of the bright line of the reproduction image;
• moving a radiation position of the reference beam to the optical information recording medium to a predetermined position;
• changing an incidence angle of a first direction in the reference beam to a predetermined angle;
• and
• setting an incidence angle of a second direction in the reference beam to an angle at which the brightness of the detected reproduction image is maximized, wherein
• in detecting the bright line of the reproduction image, a bright line position error to be a difference of a bright line position of the reproduction image when the incidence angle of the second direction in the reference beam and the wavelength of the reference beam are optimal and a bright line position of the detected reproduction image is detected, and
• in controlling the incidence angle and the wavelength of the reference beam, the incidence angle of the second direction in the reference beam and the wavelength of the reference beam are controlled on the basis of the bright line position error.