Optical Head Light Separator Adhesive Deterioration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical heads using blue light sources suffer from adhesive layer deterioration in polarization beam splitters, leading to degraded recording and reproducing characteristics due to high luminous energy, which affects the reliability and longevity of the optical head.
Innovation Solution
Incorporating a light separator with a multilayer film on a glass substrate, bonded to a second glass without an adhesive layer on the light path approaching the optical recording medium, and using a quarter wave plate with crossed birefringent members to prevent blue light transmission through the adhesive layer, thereby reducing deterioration and maintaining high reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polarization beam splitter with adhesive layer is used to separate light paths, then the optical head can function properly for recording and reproducing, but the adhesive layer deteriorates due to high luminous energy from blue light source
Solution Approach 1:
The patent removes the adhesive layer from the light path by bonding the polarization beam splitter prism directly to the glass plate through optical contact. This extraction of the adhesive layer from the harmful blue light path eliminates the deterioration problem while maintaining the light separation function.
Solution Approach 2:
The patent introduces a reflective film as an intermediary element to redirect the light path. By using the reflective film to bounce light at 45-degree angles, the design achieves light path separation without requiring the adhesive layer to be in the direct light path, thus protecting the adhesive from blue light deterioration.
2Productivity
If blue light source with high luminous energy is used to achieve high-density recording, then recording density increases, but adhesive layer deterioration accelerates
Solution Approach 1:
The adhesive layer is extracted from the direct blue light path by using optical contact bonding between the prism and glass plate. This allows high-density recording with blue light while eliminating the harmful exposure of adhesive to intense blue light.
Solution Approach 2:
The patent employs a reflective film as a disposable or replaceable component that absorbs the harmful effects of blue light on the adhesive structure. This simple reflective element protects the overall system by sacrificing itself or being easily replaced, allowing continuous high-density recording operations.
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
The optical head achieves reliable high-density information recording and reproduction by preventing adhesive layer degradation, ensuring consistent performance even with increased luminous energy, and allowing for downsizing of the optical head.
Implementation Method 1
a multilayer film which is formed on the first glass
Implementation Method 2
polarization beam splitter which shows different transmittance and reflectance according to a polarization direction of incident light
Implementation Method 3
The quarter wave plate 92 is an optical device made of a birefringent material. The quarter wave plate 92 is used to convert linearly-polarized light to circularly-polarized light.
Implementation Method 4
The objective lens 94 condenses light onto a recording layer of the optical recording medium
Implementation Method 5
The objective lens 94 condenses light onto a recording layer of the optical recording medium
Implementation Method 6
The photodetector 98 receives the light which is reflected by the recording layer of the optical recording medium 95 and converts the light to electrical signals.
Data Source
AI summary
An optical head for recording or reproducing a signal on or from an optical recording medium including a light source, an objective lens for condensing light emitted from the light source to the optical recording medium, and a light-separating device arranged between the light source and the objective lens in order to separate the light reflected from the optical recording medium from the light emitted from the light source. The light-separating device includes a first glass, a multilayer film formed on the first glass, and an adhesive layer arranged on the multilayer film in order to bond a second glass onto the multilayer film. The majority of the light emitted from the light source enters into the light-separating device through the first glass and is reflected by the multilayer film.