Optical recording/reproducing apparatus capable of recording/reproducing information onto/from various types of optical recording media of different recording densities and different thicknesses

An optical recording/reproducing apparatus, comprising:

• a plurality of light sources emitting lights with different wavelengths for use in recording/reproducing information onto/from various types of optical recording media of different recording densities;
• an objective lens focusing the light from each of the plurality of light sources to a corresponding optical recording medium;
• a collimating lens disposed between the plurality of light sources and the objective lens, collimating the lights from the plurality of light sources;
• a hologram element installed between the collimating lens and the objective lens, refracting the light emitted from one of the plurality of light sources, in which the light to be refracted is selected by wavelength and polarization components;
• a photodetector receiving the light that is reflected from the corresponding optical recording media after being focused by the objective;
• and
• a λ/4 wavelength plate between the objective lens and the hologram element,
• wherein optical distances between the plurality of light sources to the collimating lens are the same, and
• wherein the plurality of light sources comprise:
• a first light source emitting a p-polarized light with a first wavelength;
• a second light source emitting an s-polarized light with a second wavelength shorter than the first wavelength;
• and
• a third light source emitting an s-polarized light with a third wavelength shorter than the second wavelength, and
• wherein the hologram element diffracts the p-polarized light with the first wavelength, and
• wherein the s-polarized lights emitted from the second and third light sources and transmitted through the hologram element are changed into right-circularly polarized lights by the λ/4 wavelength plate, reflected from the optical recording media and changed into left-circularly polarized plates.

An optical recording/reproducing apparatus, comprising:

• a plurality of light sources emitting lights with different wavelengths for use in recording/reproducing information onto/from various types of optical recording media of different recording densities;
• an objective lens focusing the light from each of the plurality of light sources to a corresponding optical recording medium;
• a collimating lens disposed between the plurality of light sources and the objective lens, collimating the lights from the plurality of light sources;
• a hologram element installed between the collimating lens and the objective lens for refracting the light emitted from one of the plurality of light;
• and
• a λ/4 wavelength plate between the objective lens and the hologram element,
• wherein the refracted light is selected according to the wavelength and polarization components, and
• wherein the plurality of light sources comprise:
• a first light source emitting a p-polarized light with a first wavelength;
• a second light source emitting an s-polarized light with a second wavelength shorter than the first wavelength;
• and
• a third light source emitting an s-polarized light with a third wavelength shorter than the second wavelength, and
• wherein the hologram element diffracts the p-polarized light with the first wavelength, and
• wherein the s-polarized lights emitted from the second and third light sources and transmitted through the hologram element are changed into right-circularly polarized lights by the λ/4 wavelength plate, reflected from the optical recording media and changed into left-circularly polarized plates.