Optical pickup, optical recording and/or reproducing apparatus using the same, and method for detecting tracking error signal

An optical recording and/or reproducing apparatus, comprising:

• an optical pickup;
• and
• a signal processor to receive signals detected by a photodetector in the optical pickup to detect a tracking error signal (TES), wherein the TES=MPP−K×SPP, where MPP is a main push-pull signal (MPP) of a main beam of light, SPP is a sub-push-pull signal (SPP) of first and second sub-beams of the light, and K is a coefficient, and
• wherein the optical pickup comprises:
• a light source to emit the light,
• an objective lens to collect and focus an incident beam of the light on an information storage medium,
• a holographic grating to split the light emitted by the light source into the main beam and the first and second sub-beams by diffraction to provide a continuously changing wavefront in the first and second sub-beams to reduce the amplitude of an alternating current (AC) component of the sub-push-pull (SPP) signal of the first and second sub-beams, and
• a photodetector to receive the main beam and the first and second sub-beams that are focused on and reflected from the information storage medium and formed to obtain the main push-pull (MPP) signal of the main beam and the sub-push-pull (SPP) signal of the first and second sub-beams.

A method of detecting a tracking error signal, comprising:

• splitting light emitted by a light source into a main beam and first and second sub-beams by diffraction and creating a continuously changing wavefront in the first and second sub-beams to reduce the amplitude of an alternating current (AC) component of a sub-push-pull (SPP) signal of the first and second sub-beams;
• focusing the main beam and the first and second sub-beams on an information storage medium and respectively receiving and dividing the main beam and the first and second beams reflected from the information storage medium into a plurality of parts to detect a main push-pull (MPP) signal of the main beam and the sub-push-pull (SPP) signal of the first and second sub-beams;
• and
• obtaining the main push-pull (MPP) signal and the sub-push-pull (SPP) signal from signals detected by receiving and dividing the main beam and the first and second sub-beams into the plurality of parts and detecting a result obtained by subtracting the sub-push pull (SPP) signal multiplied by a predetermined coefficient from the main push-pull (MPP) signal as the tracking error signal.