Liquid crystal optical modulation element and optical head device

An optical head device, comprising:

• a light source for emitting a laser beam having a wavelength of at most 500 nm,
• an objective lens for converging the laser beam emitted from the light source on an optical recording medium,
• a photodetector for receiving the light converged and reflected on the optical recording medium, and
• a liquid crystal optical modulation element to modulate a laser beam having a wavelength of at most 500 nm, comprising a layer of a polymer liquid crystal composition on one transparent substrate, wherein the transparent substrate has an alignment film on the surface which contacts the polymer liquid crystal composition, and the polymer liquid crystal composition is a polymer liquid crystal containing a hindered amine compound and a hindered phenol compound, disposed in an optical path between the light source and the optical recording medium or in an optical path between the optical recording medium and the photodetector.