Patent ID: 6510119
Filing Date: 2003-01-21
Classification: G11B

Abstract:
An optical head device comprising:a light source comprising a first light emitting point for emitting a first light at a first wavelength and a second light emitting point for emitting a second light at a second wavelength in approximately the same direction as said first light, said first wavelength and said second wavelength differing from each other; a collimator lens disposed to face to said first light emitting point and said second light emitting point, for converting said first light and said second light into approximately parallel lights; and a beam shaping prism having a plane of incidence, said first light and said second light as said approximately parallel lights obliquely entering said plane of incidence, said beam shaping prism changing sectional intensity distributions of said first light and said second light to approximately circular shape; wherein said collimator lens and said beam shaping prism have refractive indexes dependent on a wavelength of incident light, and said first light emitting point and said second light emitting point are placed in different positions from each other in a direction parallel to and a direction vertical to an optical axis of said collimator lens.