Optical Pickup Beam Shaping for Rim Intensity

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Solution Overview

Problem

Conventional optical pickups do not effectively adjust or increase Rim intensity, which is crucial for improving recording and reproducing quality on high-density optical disks, due to the lack of consideration for beam shaping methods and element positioning.

Innovation Solution

An optical pickup design that incorporates a beam shaping element with at least one cylindrical plane, which shapes the divergent beam to shorten the major axis length and adjusts the optical axis to be perpendicular to the recording surface, enhancing Rim intensity by rotating the beam shaping direction to conform to the radial direction of the optical disk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If an anomorphic prism is used for beam shaping, then beam shaping performance is improved, but the optical pickup size increases and downsizing is inhibited

Engineering Contradiction:

Improvebeam shapeVSAvoidoptical pickup size

Core Design Contradiction:

ShapeVSVolume of moving object

Solution Approach 1:

The patent replaces the mechanical beam shaping system (anomorphic prism requiring collimation) with an optical beam shaping system (anomorphic lens working with divergent light). This substitution eliminates the need for collimation optics and enables compact integration while achieving the same beam shaping function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameter of the beam shaping element from requiring collimated light (prism) to accepting divergent light (lens). This parameter change fundamentally alters the optical configuration, allowing direct coupling with the laser diode and eliminating intermediate collimation components, thus reducing overall system size.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional optical elements are used, then device simplicity is maintained, but Rim intensity is insufficient for high-density optical disks

Engineering Contradiction:

Improveoptical pickup structureVSAvoidRim intensity

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The patent introduces a beam shaping element with specific local optical properties (cylindrical surface geometry) that selectively modifies the beam profile in the radial direction while maintaining simplicity in other areas. This localized functional enhancement achieves high Rim intensity without requiring complete system redesign.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If beam shaping is not optimized, then alignment is simpler, but recording and reproducing quality on high-density disks is insufficient

Engineering Contradiction:

Improvealignment simplicityVSAvoidrecording quality

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The beam shaping element is designed to automatically align with the laser diode's divergent beam without requiring complex adjustment mechanisms. The cylindrical geometry inherently guides the beam shaping process, making the system self-aligning while producing the precise beam profile needed for high-density recording quality.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design increases Rim intensity, leading to improved recording and reproducing quality on high-density optical disks, while also enabling a downsized optical pickup by optimizing beam shaping and reducing astigmatism.

Implementation Method 1

a beam shaping element (2) having at least one cylindrical plane and which shapes a far-field pattern of light emitted from the light source (1)

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS8000209B2Optical pickup, optical element, optical information device, computer, optical information medium player, car navigation system, optical information medium recorder and optical disk server for use with a light source which emits a divergent beam

Publication Date: 2011.08.16 PANASONIC HOLDINGS CORP

AI summary

An optical pickup includes: a laser light source which outputs an divergent beam having an elliptical far-field pattern; a beam shaping element having at least one cylindrical plane and which shapes the divergent beam outputted from the laser light source into an divergent beam having a prescribed shape in which at least the length in the major axis direction of the elliptical shape is shortened; a light collecting portion having a beam splitter which perpendicularly collects the divergent beam that is outputted from the beam shaping element and which has a prescribed shape on the recording surface of an optical disk , and a mirror or the like; and a light detecting portion The optical axis of the divergent beam is rotated so that the direction in which the major axis of the divergent beam having a prescribed shape is shortened conforms to the radial direction of an optical information recording medium.