An optical head is provided, which suppresses the offset in the tracking
error signal. This head comprises (a) a light source for emitting a light
beam to be irradiated to an optical recording medium as an incident light
beam; (b) a hologram element for receiving a reflected light beam
generated by reflection of the incident light beam on the medium to
generate at least two diffracted light beams for focusing error detection
and at least two diffracted light beams for tracking error detection; and
(c) an optical detector for detecting the at lease two diffracted light
beams for focusing error detection and the at least two diffracted light
beams for tracking error detection; the detector including a first
receiving surface for receiving the at least two diffracted light beams
for focusing error detection and a second detection surface for receiving
the at least two diffracted light beams for tracking error detection;
each of the first and second receiving surfaces being divided into
receiving regions; the at least two diffracted light beams for focusing
error detection being received at the receiving regions of the first
receiving surface; the at least two diffracted light beams for tracking
error detection being received at the receiving regions of the second
receiving surface.