Optical pickup lens
AssigneeHitachi Maxell, Ltd.
InventorMitsuru Ito
Life of this patent
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Abstract
An optical pickup lens for focusing a light beam from a laser light source on an optical information recording medium is a single lens. The optical pickup lens has two surfaces, and a surface R2 opposite to a surface R1 closer to the laser light source has a continuous shape. When the surface R2 has radii h1, h2 and h3 (h1<h2<h3) from an optical axis to a lens periphery, and where sags in the radii h1, h2 and h3 are sag1, sag2 and sag3, and differentials in the sags are Δsag1, Δsag2 and Δsag3, respectively, 0>Δsag1>Δsag2 and Δsag2<Δsag3 are satisfied.
Claims8
An optical disc apparatus that reads out information from an optical disc by focusing a light beam having a wavelength of 410 nm or shorter from a laser light source onto the optical disc, which includes an optical disc substrate and a light transmitting layer, through a collimator lens and an optical pickup lens, wherein
- the optical disc apparatus comprises, as the optical pickup lens, a single lens
- for focusing a light beam from the laser light source onto the optical disc without passing through any diffraction ring zone, in which:
- a numerical aperture NA is equal to or larger than 0.84;
- an effective diameter D satisfies 1.8 mm≦D≦2.45 mm;
- and a refractive index n for 405 nm wavelength light beam is 1.51≦n≦1.5899,
- the single lens comprising:
- a first surface on which the light beam from the laser light source is made incident;
- and
- a second surface opposed to the optical disc positioned at an opposite side against the first surface, and
- the second surface has a convex aspherical shape on an optical disc side, having radii h1, h2, and h3 from an optical axis to a lens periphery side, where h1<h2<h3, and sags at the radii h1, h2, and h3, wherein the sags at the radii h1, h2, and h3 are sag1, sag2, and sag3, respectively, and differentials in the sag1, sag2, and sag3 are Δsag1, Δsag2, and Δsag3, respectively, where 0>Δsag1>Δsag2 and Δsag2<Δsag3.
An optical disc apparatus that reads out information from an optical disc by focusing a light beam having a wavelength of 410 nm or shorter from a laser light source onto the optical disc, which includes an optical disc substrate and a light transmitting layer, through a collimator lens and an optical pickup lens, wherein
- the optical disc apparatus comprises, as the optical pickup lens, a single lens
- for focusing a light beam from the laser light source onto the optical disc, in which:
- a numerical aperture NA is equal to or larger than 0.84;
- an effective diameter D satisfies 1.8 mm≦D≦2.45 mm;
- and a refractive index n for 405 nm wavelength light beam is 1.51≦n≦1.5899,
- the single lens comprising:
- a first surface having a continuous shape on which the light beam from the laser light source is made incident;
- and
- a second surface opposed to the optical disc positioned at an opposite side against the first surface, and
- the second surface has a convex aspherical shape on an optical disc side, having radii h1, h2, and h3 from an optical axis to a lens periphery side, where h1<h2<h3, and sags at the radii h1, h2, and h3, wherein the sags at the radii h1, h2, and h3 are sag1, sag2, and sag3, respectively, and differentials in the sag1, sag2, and sag3 are Δsag1, Δsag2, and Δsag3, respectively, where 0>Δsag1>Δsag2 and Δsag2<Δsag3.
An optical disc apparatus that reads out information from an optical disc by focusing a light beam having a wavelength of 410 nm or shorter from a laser light source onto the optical disc, which includes an optical disc substrate and a light transmitting layer, through a collimator lens and an optical pickup lens, wherein
- the optical disc apparatus comprises, as the optical pickup lens, a single lens
- for focusing a light beam from the laser light source onto the optical disc without passing through any diffraction ring zone, in which:
- a numerical aperture NA is equal to or larger than 0.84;
- an effective diameter D satisfies 1.8 mm≦D≦2.45 mm;
- and a refractive index n for 405 nm wavelength light beam is 1.51≦n≦1.64,
- the single lens comprising:
- a first surface on which the light beam from the laser light source is made incident;
- and
- a second surface opposed to the optical disc positioned at an opposite side against the first surface,
- the second surface has a convex aspherical shape on an optical disc side, having radii h1, h2, and h3 from an optical axis to a lens periphery side, where h1<h2<h3, and sags at the radii h1, h2, and h3 wherein the sags at the radii h1, h2, and h3 are sag1, sag2, and sag3, respectively, and differentials in the sag1, sag2, and sag3 are Δsag1, Δsag2, and Δsag3, respectively, where 0>Δsag1>Δsag2 and Δsag2<Δsag3, and
- a parallel light beam from the laser light source is converged at a point having an inter-surface distance of 0.0875 mm from a surface of the light transmitting layer in the optical disc.
An optical disc apparatus that reads out information from an optical disc by focusing a light beam having a wavelength of 410 nm or shorter from a laser light source onto the optical disc, which includes an optical disc substrate and a light transmitting layer, through a collimator lens and an optical pickup lens, wherein the optical disc apparatus comprises, as the optical pickup lens, a single lens
- for focusing a light beam from the laser light source onto the optical disc, in which:
- a numerical aperture NA is equal to or larger than 0.84;
- an effective diameter D satisfies 1.8 mm≦D≦2.45 mm;
- and a refractive index n for 405 nm wavelength light beam is 1.51≦n≦1.64,
- the single lens comprising:
- a first surface having a continuous shape on which the light beam from the laser light source is made incident;
- and
- a second surface opposed to the optical disc positioned at an opposite side against the first surface,
- is used as the pickup lens,
- the second surface has a convex aspherical shape on an optical disc side, having radii h1, h2, and h3 from an optical axis to a lens periphery side, where h1<h2<h3, and sags at the radii h1, h2, and h3, wherein the sags at the radii h1, h2, and h3 are sag1, sag2, and sag3, respectively, and differentials in the sag1, sag2, and sag3 are Δsag1, Δsag2, and Δsag3, respectively, where 0>Δsag1>Δsag2 and Δsag2<Δsag3, and
- a parallel light beam from the laser light source is converged at a point having an inter-surface distance of 0.0875 mm from a surface of the light transmitting layer in the optical disc.
Dependencies are inferred from the claim text.