Abstract:
An objective lens for recording data to and/or reproducing data from first and second optical discs. The objective lens is provided with at least one surface including a plurality of annular zones divided by steps. The steps has functions of phase shifting a wavefront of light passing through the plurality of annular zones so that a beam spot formed at a converging point of an average wavefront of the wavefront phase shifted by the steps is used for the first and second optical discs. The plurality of annular zones of the at least one surface includes at least one annular zone structure which includes first and second annular zone groups, each of which has at least three steps for phase shifting the wavefront in a first direction, and a first return step which is a step formed at a boundary between the first and second annular zone groups. The first return step phase shifts the wavefront in a second direction opposite to the first direction. An absolute value |Δψ1| of a phase shifting amount of the first light beam given by the first return step satisfies a condition: 6π
Abstract:
In the method of forming a multi-piled bump, metal balls can be stably and securely piled so as to form the multi-piled bump having a prescribed height. The method of the present invention comprises the steps of: holding a metal wire by a capillary; sparking and melting the wire so as to form metal balls; piling a plurality of the metal balls with applying a load and ultrasonic vibrations thereto, and characterized in that a tail length of the metal wire, which is held by the capillary, is controlled to make a gap between a center of the metal wire and a center of the metal ball one half of a diameter of the metal wire or less.
Abstract:
An objective lens on which a beam having parallel light fluxes is incident includes a single element lens and a reflection suppressing coating formed on at least one surface of the single element lens. The reflection suppressing coating is formed such that the reflectivity across a radius of the objective lens exhibits a local maximal value, and the reflection suppressing coating is formed to achieve the following condition: 0.6
Abstract:
There is provided an objective lens used for a plurality of types of optical discs having a front surface and a rear surface, each of which includes an inner region and an outer region. The outer region has a surface shape which suppresses a coma caused when a beam used for a first optical disc is incident thereon obliquely with respect to an optical axis of the objective lens. The inner region is configured such that, at a boundary position between the inner region and the outer region, the coma caused when a beam used for a second optical disc is incident on the inner region obliquely at a first angle with respect to the optical axis is less than the coma caused when the beam used for the second optical disc is incident on the outer region obliquely at the first angle with respect to the optical axis. Further, an inclination θ2A of the inner region and an inclination θ2B of the outer region of the rear surface satisfy a condition: −2.5
Abstract:
Disclosed is an objective lens of an optical pick-up that converges light beams of two different wavelengths onto recording layers of optical discs of two different standards, respectively. The objective lens includes a refractive lens having a positive power and a diffractive lens structure formed on one surface of the refractive lens. The diffractive lens structure has a plurality of concentric ring areas with minute steps at the boundaries therebetween. The diffractive lens structure maximizes the diffraction efficiency of the third order diffracted light at the shorter wavelength and maximizes the diffraction efficiency of the second order diffracted light at the longer wavelength. This enables the diffractive lens structure to correct the chromatic aberration at the respective wavelengths with keeping high diffraction efficiency.
Abstract:
An objective lens for an optical pick-up has a refractive lens element provided with a diffraction lens structure on at least one surface thereof. The diffraction lens structure has a plurality of annular zones. The objective lens is capable of converging at least two beams having different wavelengths on at least two types of optical discs having different data recording densities, respectively. The objective lens is partitioned into a common area through which a beam with a low NA passes, and an exclusive high NA area which is designed to converge a beam with a high NA. The boundaries of the annular zones formed on the exclusive high NA area are designed independently from boundaries obtained from an optical path difference function so that the beam with the high NA is converged substantially on a certain point and the beam with the low NA is diffused.
Abstract:
A diffraction optical element is configured such that a plurality of annular zones having minute steps extending in a direction of the optical axis therebetween are formed on a base element. The plurality of annular zones include narrow and wide zones respectively satisfying conditions (1) and (2): &Dgr;Z(i) (3/2)·&Dgr;E(i) (2), wherein, i represents the order of the steps counted from the optical axis, &Dgr;E(i) represents an absolute value of an OPD provided by the i-th step, and &Dgr;Z(i) represents an absolute value of a difference between OPDs provided, with respect to a base curve, by an inner side end portion and outer side end portion of an annular zone between an i-th step and (i+1)-th step.
Abstract:
A relative rotational angle of a rotary body is measured with respect to a reference angle. A disk rotates integrally with the rotary body. First openings are arranged about the entire circumference of the disk and spaced from one another by a predetermined pitch. A first detecting element detects the first openings and generates a first binary code. Second openings are arranged concentrically with the first openings. A second detecting element detects the second openings and generates a second binary code. A CPU computes a relative rotational angle of the rotary body in accordance with the first binary code and initializes the reference rotational angle of the rotary body in accordance with the second binary code. When the first detecting element generates the first binary code, the CPU determines the reference angle based on a combination of the first and second binary codes stored by a ROM.
Abstract:
A scanning optical system is provided with a light source, a deflector that deflects a light beam emitted from the light source to scan in a main scanning direction, a scanning lens that converges the light beam deflected by the deflector on an imaging surface to form a spot which scans on the imaging surface in the main scanning direction, and a mirror arranged between the deflector and the imaging surface, the mirror bending an optical path of the laser beam between the deflector and the imaging surface. With this structure, the reflecting surface of the mirror has a diffraction surface to compensate for lateral chromatic aberration generated by the scanning lens.
Abstract:
Disclosed is a laser scanning optical system wherein light emitted from a laser source is deflected by a polygonal mirror to a scanning target surface via an imaging optical system. The laser source, the polygonal mirror, and the imaging optical system are arranged such that a stationary ghost image formed by an m-th reflection surface is formed out of the light source side end of an effective scanning range on the target surface, and a stationary ghost image formed by an (m+1)-th reflection surface is formed out of the other end of the effective scanning range.