Laser emission unit, optical head and optical memory device

An optical head, comprising:

• a housing;
• a lens holder disposed in said housing;
• a laser emission unit disposed in said holder and including
• a laser diode for forwardly emitting a laser beam onto an optical medium from which the laser beam is reflected and returns as a returning beam, and
• signal detection means for detecting the returning beam for determining signals;
• converging means, disposed in said lens holder, for focusing the forwardly emitted laser beam onto the medium and for passing through the returning beam reflected from the optical medium;
• position control means, disposed in said housing, for finely controlling the position of said holder so as to finely control the position of the forwardly emitted laser beam on the optical medium;
• laser noise reduction means, disposed in said housing, for superposing a high frequency wave component onto an externally supplied driving current for driving said laser diode and for reducing coherence of the forwardly emitted laser beam;
• and
• connection means, disposed in said housing, for connecting said laser noise reduction means to external circuits;
• wherein said housing is made of conductive material and has a shape for shielding noise from said laser noise reduction means and said connection means.