Claims
- 1. A lens for multiple wavelengths condensing plural kinds of monochromatic lights respectively, the lens comprising:
a lens surface sectioned into plural aspherical zones having different refractive power in a common use area for all the monochromatic lights, wherein the plural sectioned aspherical zones respectively have one common single focal point corresponding to an inherent wavelength of each of the monochromatic lights, one focal point corresponding to the inherent wavelength of one of the monochromatic lights is arranged in different position with other focal points corresponding to the inherent wavelengths of other monochromatic lights, each of the aspherical zones, with regard to each of the monochromatic lights, differs in optical path length from each other by approximately integral multiple of wavelength λi (i is an integral number of 1, 2 . . . , meaning each of the monochromatic lights) of each of the monochromatic lights, when a difference between a maximum value and a minimum value of a wavefront aberration of each of the monochromatic lights in each of the aspherical zones is (ΔVd(λi)) where d is an integral number of 1, 2 . . . , meaning each of the aspherical zones, the difference of a wavefront aberration in each of the aspherical zones is no more than 0.14 λi, a ratio between differences of each of the monochromatic lights is between 0.4 and 2.5 in each of the aspherical zones, and the wavelength λi comprises at least two kinds of wavelength selected from a group of around 790 nm, 655 nm, and 405 nm.
- 2. A lens for multiple wavelengths condensing two kinds of monochromatic lights respectively, the lens comprising:
a lens surface sectioned into plural aspherical zones having different refractive power in a common use area for all the monochromatic lights, wherein the plural sectioned aspherical zones respectively have one common single focal point corresponding to an inherent wavelength of each of the monochromatic lights, one focal point corresponding to a first inherent wavelength of one of the monochromatic lights is arranged in different position with another focal point corresponding to a second inherent wavelength of another monochromatic light, each of the aspherical zones, with regard to each of the monochromatic lights, differs in optical path length from each other by approximately integral multiple of wavelength λp (p is an integral number of 1 or 2, meaning each of the monochromatic lights) of each of the monochromatic lights, and when a difference between a maximum value and a minimum value of a wavefront aberration of each of the monochromatic lights in each of the aspherical zones is (ΔVd(λp)) where d is an integral number of 1, 2 . . . , meaning each of the aspherical zones, the difference of a wavefront aberration in each of the aspherical zones is no more than 0.14 λp, a ratio between differences of each of the monochromatic lights is between 0.4 and 2.5 in each of the aspherical zones, and the wavelength λi comprises at least two kinds of wavelength selected from a group of around 790 nm, 655 nm, and 405 nm.
- 3. A lens according to claim 1, wherein the lens condenses each wavelengths of light onto an information surface with a Root Mean Square (RMS) wavefront aberration of no more than 0.035λ.
- 4. A lens according to claim 2, wherein the lens condenses each wavelengths of light onto an information surface with a Root Mean Square (RMS) wavefront aberration of no more than 0.035λ.
- 5. An optical head using a lens according to claim 1.
- 6. An optical head using a lens according to claim 2.
- 7. An optical disc apparatus using a lens according to claim 1.
- 8. An optical disc apparatus using a lens according to claim 2.
- 9. A lens for multiple wavelengths condensing plural kinds of monochromatic lights respectively, the lens comprising:
a lens surface sectioned into plural aspherical zones having different refractive power in a common use area for all the monochromatic lights, wherein the plural sectioned aspherical zones respectively have one common single focal point corresponding to an inherent wavelength of each of the monochromatic lights, one focal point corresponding to the inherent wavelength of one of the monochromatic lights is arranged in different position with other focal points corresponding to the inherent wavelengths of other monochromatic lights, each of the aspherical zones, with regard to each of the monochromatic lights, differs in optical path length from each other by approximately integral multiple of wavelength λi (i is an integral number of 1, 2 . . . , meaning each of the monochromatic lights) of each of the monochromatic lights, and one wavefront aberration for a wavelength with a smaller numerical aperture of the lens is smaller than other wavefront aberration for a wavelength with a larger numerical aperture of the lens in each of the aspherical zones in the common use area, a ratio between differences of each of the monochromatic lights is between 0.4 and 2.5 in each of the aspherical zones, and the wavelength λi comprises at least two kinds of wavelength selected from a group of around 790 nm, 655 nm, and 405 nm.
- 10. A lens for multiple wavelengths condensing two kinds of monochromatic lights respectively, the lens comprising:
a lens surface sectioned into plural aspherical zones having different refractive power in a common use area for all the monochromatic lights, wherein the plural sectioned aspherical zones respectively have one common single focal point corresponding to an inherent wavelength of each of the monochromatic lights, one focal point corresponding to a first inherent wavelength of one of the monochromatic lights is arranged in different position with another focal point corresponding to a second inherent wavelength of another monochromatic light, each of the aspherical zones, with regard to each of the monochromatic lights, differs in optical path length from each other by approximately integral multiple of wavelength λp (p is an integral number of 1 or 2, meaning each of the monochromatic lights) of each of the monochromatic lights, and first wavefront aberration for a wavelength with a smaller numerical aperture of the lens is smaller than second wavefront aberration for a wavelength with a larger numerical aperture of the lens in each of the aspherical zones in the common use area, a ratio between differences of each of the monochromatic lights is between 0.4 and 2.5 in each of the aspherical zones, and the wavelength A d comprises at least two kinds of wavelength selected from a group of around 790 nm, 655 nm, and 405 nm.
- 11. A design method of a lens for multiple wavelengths condensing plural kinds of monochromatic lights respectively,
wherein the method designs the lens in such a way that the lens comprises a lens surface sectioned into plural aspherical zones having different refractive power in a common use area for all the monochromatic lights, the plural sectioned aspherical zones respectively have one common single focal point corresponding to an inherent wavelength of each of the monochromatic lights, one focal point corresponding to the inherent wavelength of one of the monochromatic lights is arranged in different position with other focal points corresponding to the inherent wavelengths of other monochromatic lights, each of the aspherical zones, with regard to each of the monochromatic lights, differs in optical path length from each other by approximately integral multiple of wavelength λi (i is an integral number of 1, 2 . . . , meaning each of the monochromatic lights) of each of the monochromatic lights, and one wavefront aberration for a wavelength with a smaller numerical aperture of the lens is smaller than other wavefront aberration for a wavelength with a larger numerical aperture of the lens in each of the aspherical zones in the common use area, a ratio between differences of each of the monochromatic lights is between 0.4 and 2.5 in each of the aspherical zones, and the wavelength λi comprises at least two kinds of wavelength selected from a group of around 790 nm, 655 nm, and 405 nm.
- 12. A design method of a lens for multiple wavelengths condensing two kinds of monochromatic lights respectively,
wherein the method designs the lens in such a way that the lens comprises a lens surface sectioned into plural aspherical zones having different refractive power in a common use area for all the monochromatic lights, the plural sectioned aspherical zones respectively have one common single focal point corresponding to an inherent wavelength of each of the monochromatic lights, one focal point corresponding to a first inherent wavelength of one of the monochromatic lights is arranged in different position with another focal point corresponding to a second inherent wavelength of another monochromatic light, each of the aspherical zones, with regard to each of the monochromatic lights, differs in optical path length from each other by approximately integral multiple of wavelength λp (p is an integral number of 1 or 2, meaning each of the monochromatic lights) of each of the monochromatic lights, and first wavefront aberration for a wavelength with a smaller numerical aperture of the lens is smaller than second wavefront aberration for a wavelength with a larger numerical aperture of the lens in each of the aspherical zones in the common use area, a ratio between differences of each of the monochromatic lights is between 0.4 and 2.5 in each of the aspherical zones, and the wavelength λi comprises at least two kinds of wavelength selected from a group of around 790 nm, 655 nm, and 405 nm.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2002-004993 |
Jan 2002 |
JP |
|
2002-267451 |
Sep 2002 |
JP |
|
Parent Case Info
[0001] CROSS-REFERENCE TO RELATED APPLICATION
[0002] This is a Continuation of application Ser. No. 10/670,209 filed Sep. 26, 2003, which is a Continuation of application Ser. No. 10/330,289 filed Dec. 30, 2002. The entire disclosure of the prior application is hereby incorporated by reference herein in its entirety.
Continuations (2)
|
Number |
Date |
Country |
Parent |
10670209 |
Sep 2003 |
US |
Child |
10895352 |
Jul 2004 |
US |
Parent |
10330289 |
Dec 2002 |
US |
Child |
10670209 |
Sep 2003 |
US |