Optical apparatus for optically reading and recording information

Claim 2

An optical head having a forward optical path and a rearward optical path through which a light beam travels for use in an optical recording apparatus, comprising: a light beam emitting assembly that emits a light beam in said forward optical path; a light beam separating assembly, wherein the light beam travels through said light beam separating assembly in said forward optical path as a non-diffracted light beam; a light beam focusing element that focuses the non-diffracted light beam in said forward optical path onto an optical recording medium; a light detection device, wherein a rearward light beam reflected from said optical recording medium follows said rearward optical path through said light beam focusing element and said light beam separating assembly such that the rearward light beam is deflected in said rearward optical path to said light detection device; and a lens element positioned in at least one of said forward optical path and said rearward optical path such that at least one of a magnification and a numerical aperture of the optical head associated with said forward optical path and at least one of a magnification and a numerical aperture of the optical head associated with said rearward optical path are independently set wherein the magnification of said forward optical path is greater than the magnification of said rearward optical path.

Claim 3

The optical head according to claim 1, wherein said light beam emitting assembly is a semiconductor laser.

Claim 4

The optical head according to claim 1, wherein said light beam separating assembly is a hologram element.

Claim 5

The optical head according to claim 1, wherein said light beam separating assembly is a beam splitter.

Claim 6

The optical head according to claim 1, wherein the magnification of said optical head associated with said forward optical path is greater than or equal to 1/4 and the magnification of said optical head associated with said rearward optical path is less than or equal to 1/4.

Claim 7

The optical head according to claim 1, wherein an effective numerical aperture of said optical head associated with said forward optical path is greater than or equal to 0.12.

Claim 8

The optical head according to claim 1, wherein said lens element has a lens surface, said lens surface is one of a spherical surface, an aspheric surface, a cylindrical surface and an anamorphic surface.

Claim 9

The optical head according to claim 1, wherein said lens element is grating lens.

Claim 10

The optical head according to claim 1, wherein said lens element is a Fresnel lens.

Claim 11

The optical head according to claim 1, wherein at least one of said magnification and said numerical aperture of said optical head associated with said forward optical path and at least one of said magnification and said numerical aperture of said optical head in said rearward optical path are set to increase the coupling efficiency of said optical head and thereby increase the detection sensitivity regarding focusing error.

Claim 12

The optical head according to claim 1, further comprising: a housing containing said light beam emitting assembly and said light detecting device; and a transparent cover for sealing an opening in said housing, wherein said lens element being formed as part of said transparent cover.

Claim 13

The optical head according to claim 11, wherein said light beam separating assembly is positioned on said transparent cover.

Claim 14

The optical head according to claim 11, wherein transparent cover includes a non-lens region, said lens element produces positive refractory power and is positioned in said forward optical path such that the light beam passes through said lens element and is focused onto said optical recording medium by said focusing element, the rearward light beam reflected from said optical recording medium travels to said light detecting device through said non-lens region of said cover.

Claim 15

The optical head according to claim 11, wherein said transparent cover includes a non-lens region, said lens element produces negative refractive power and is positioned in said rearward optical path such that the light beam emitted by said light beam emitting assembly passes through said non-lens region of said cover and is focused onto said optical recording medium by said focusing element, the rearward light beam reflected from said optical recording medium travels to said light detecting device via said focusing element and further via said lens element of said cover.

Claim 16

The optical head according to claim 11, further comprising: a polarizing element, wherein said optical recording medium is a magneto-optical recording medium and the rearward light beam reflected from said magneto-optical recording medium travels through said polarizing element.

Claim 17

The optical head according to claim 15, wherein said polarizing element is integral with said cover.

Claim 18

An optical head having a forward optical path and a rearward optical path through which a light beam travels for use in an optical recording apparatus, comprising: light beam emitting means for emitting a light beam through said forward optical path; light beam separating means for deflecting the light beam in said rearward optical path, the light beam travels through said light beam separating means as non-diffracted light in said forward optical path; focusing means for focusing the light beam in said forward optical path onto an optical recording medium; detection means for detecting reflected light beams, wherein a rearward light beam reflected from said optical recording medium follows said rearward optical path passing through said focusing means and said light beam separating means such that said light beam separating means deflects the rearward light beam to said light beam detection means; a lens means positioned in at least one of said forward optical path and said rearward optical path such that at least one of a magnification and a numerical aperture of the optical head associated with said forward optical path and at least one of a magnification and a numerical aperture of the optical head associated with said rearward optical path are independently set; and light beams refraction means for refracting the light beam such that at least one of a magnification and a numerical aperture of said optical head associated with said forward optical path and at least one of a magnification and a numerical aperture of said optical head associated with said rearward optical path are independently set wherein the magnification of said forward optical path is greater than the magnification of said rearward path.

Claim 19

An optical head having a forward optical path and a rearward optical path through which a light beam travels for use in an optical recording apparatus, comprising: light beam emitting means for emitting a light beam through said forward optical path; light beam separating means for deflecting the light beam in said rearward optical path, the light beam travels through said light beam separating means as non-diffracted light in said forward optical path; focusing means for focusing the light beam in said forward optical path onto an optical recording medium; detection means for detecting reflected light beams, wherein a rearward light beam reflected from said optical recording medium follows said rearward optical path passing through said focusing means and said light beam separating means such that said light beam separating means deflects the rearward light beam to said light beam detection means; a lens means positioned in at least one of said forward optical path and said rearward optical path such that at least one of a magnification and a numerical aperture of the optical head associated with said forward optical path and at least one of a magnification and a numerical aperture of the optical head associated with said rearward optical path are independently set; and light beams refraction means for refracting the light beam such that at least one of a magnification and a numerical aperture of said optical head associated with said forward optical path and at least one of a magnification and a numerical aperture of said optical head associated with said rearward optical path are independently set wherein the magnification of said forward optical path is greater than the magnification of said rearward path.

Claim 20

The optical head according to claim 17, further comprising: housing means for containing said light beam emitting means and said detection means; and cover means for covering an opening in said housing means, wherein said cover means includes said lens means.

Claim 21

The optical head according to claim 18, wherein said light beam separating means is positioned on cover means.

Claim 22

The optical head according to claim 17, further comprising means for polarizing the light beam.

Claim 23

The optical head according to claim 17, wherein the magnification of said optical head associated with said forward optical path is greater than or equal to 1/4 and the magnification of said optical head associated with said rearward optical path is less than or equal to 1/4.

Claim 24

The optical head according to claim 17, wherein an effective numerical aperture of said optical head associated with said forward optical path is greater than or equal to 0.12.

Claim 25

The optical head according to claim 17, wherein at least one of said magnification and said numerical aperture of said optical head associated with said forward optical path and at least one of said magnification and said numerical aperture of said optical head in said rearward optical path are set to increase the coupling efficiency of said optical head and thereby increase the detection sensitivity regarding focusing error.

Claim 28

The method according to claim 24, further comprising the step of determining focusing error by detecting a light beam in said rearward optical path.

Claim 29

The method according to claim 25, wherein said step of determining the focusing error includes deflecting the light beam with said light separator assembly towards said light detection assembly.

Claim 30

The method according to claim 24, wherein the step of providing a lens element includes independently setting the magnification of said optical head associated with said forward optical path to greater than or equal to 1/4 and the magnification of said optical head associated with said rearward optical path to less than or equal to 1/4.

Claim 31

The method according to claim 24, wherein the step of providing a lens element includes independently setting an effective numerical aperture of said optical head associated with said forward optical system to greater than or equal to 0.12.

Claim 32

The method according to claim 24, wherein said optical head includes a housing containing said light beam emitting assembly and said light detecting device and a transparent cover for sealing an opening in said housing, wherein said step of providing a lens element includes forming said lens element as part of said transparent cover.

Claim 33

The method according to claim 24, wherein the step of providing a lens element includes positioning said lens element in said forward optical path to produce a positive refractory power whereby the light beam passes through said lens element and is focused onto said optical recording medium by said focusing element.

Claim 34

The method according to claim 24, wherein the step of providing a lens element includes positioning said lens element in said rearward optical path to produce a negative refractive power whereby the light beam reflected from said optical recording medium travels to said light detecting device through said lens element.

Claim 35

The method according to claim 24, further comprising the steps of setting said at least one of a magnification and the numerical aperture of said optical head associated with said forward optical path and at least one of said magnification and said numerical aperture of said optical head in said rearward optical path to increase the coupling efficiency of said optical head and thereby increase the detection sensitivity regarding focusing error.

Claim 36

An optical head having a forward optical path and a rearward optical path through which a light beam travels for use in an optical recording apparatus, comprising: a semiconductor laser that emits a light beam in said forward optical path; a hologram element that separates the light beam, wherein the light beam travels through said hologram element in said forward optical path as a non-diffracted light beam; a focusing element that focuses the non-diffracted light beam in said forward optical path onto an optical recording medium; a light detection device, wherein a rearward light beam reflected from said optical recording medium follows said rearward optical path through said focusing element and said light beam separating assembly such that the rearward light beam is deflected in said rearward optical path to said light detection device; and a lens element positioned in at least one of said forward optical path and said rearward optical path such that at least one of a magnification and a numerical aperture of said optical head associated with said forward optical path and at least one of a magnification and a numerical aperture of said optical head associated with said rearward optical path are independently set, wherein the magnification of said forward optical path is greater than the magnification of said rearward optical path.

Claim 37

An optical head having a forward optical path and a rearward optical path through which a light beam travels for use in an optical recording apparatus, comprising: a semiconductor laser that emits a light beam in said forward optical path; a hologram element that separates the light beam, wherein the light beam travels through said hologram element in said forward optical path as a non-diffracted light beam; a focusing element that focuses the non-diffracted light beam in said forward optical path onto an optical recording medium; a light detection device, wherein a rearward light beam reflected from said optical recording medium follows said rearward optical path through said focusing element and said light beam separating assembly such that the rearward light beam is deflected in said rearward optical path to said light detection device; and a lens element positioned in at least one of said forward optical path and said rearward optical path such that at least one of a magnification and a numerical aperture of said optical head associated with said forward optical path and at least one of a magnification and a numerical aperture of said optical head associated with said rearward optical path are independently set, wherein the magnification of said forward optical path is greater than the magnification of said rearward optical path.

Claim 38

The optical head according to claim 33, wherein the magnification of said optical head associated with said forward optical path is greater than or equal to 1/4 and the magnification of said optical head associated said rearward optical path is less than or equal to 1/4.

Claim 39

The optical head according to claim 33, wherein an effective numerical aperture of said optical head associated with said forward optical path is greater than or equal to 0.12.

Claim 40

The optical head according to claim 33, wherein said lens element has a lens surface, said lens surface is one of a spherical surface, an aspheric surface, a cylindrical surface and an anamorphic surface.

Claim 41

The optical head according to claim 33, wherein said lens element is grating lens.

Claim 42

The optical head according to claim 33, wherein said lens element is a Fresnel lens.

Claim 43

The optical head according to claim 33, further comprising: a housing containing said semiconductor laser and said light detecting device; and a transparent cover for sealing an opening in said housing, wherein said lens element being formed as part of said transparent cover.

Claim 44

The optical head according to claim 39, wherein said hologram element is positioned on said transparent cover.

Claim 45

The optical head according to claim 39, wherein transparent cover includes a non-lens region, said lens element produces positive refractory power and is positioned in said forward optical path such that the light beam passes through said lens element and is focused onto said optical recording medium by said focusing element, the rearward light beam reflected from said optical recording medium travels to said light detecting device through said non-lens region of said cover.

Claim 46

The optical head according to claim 39, wherein said transparent cover includes a non-lens region, said lens element produces negative refractive power and is positioned in said rearward optical path such that the light beam emitted by semiconductor laser passes through said non-lens region of said cover and is focused onto said optical recording medium by said focusing element, the rearward light beam reflected from said optical recording medium travels to said light detecting device via said focusing element and further via said lens element of said cover.

Claim 47

The optical head according to claim 33, further comprising: a polarizing element, wherein said optical recording medium is a magneto-optical recording medium and the rearward light beam reflected from said magneto-optical recording medium travels through said polarizing element.

Claim 48

The optical head according to claim 33, wherein at least one of said magnification and said numerical aperture of said optical head associated with said forward optical path and at least one of said magnification and said numerical aperture of said optical head in said rearward optical path are set to increase the coupling efficiency of said optical head and thereby increase the detection sensitivity regarding focusing error.