Near-field Light Detection Element with Conductive Scatterer
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Solution Overview
Problem
Conventional near-field light detection methods face challenges in achieving a high signal-to-noise (S/N) ratio during reproduction due to weak detectable light intensity, primarily because the near-field light generated near a scatterer is inefficiently converted into propagation light for detection.
Innovation Solution
A near-field light detection element comprising a conductive scatterer and a photoelectric conversion element arranged in the near-field light generation region, where the scatterer irradiates the information recording medium, and the intensity change of near-field light is detected based on the electrical conductivity change of the photoelectric conversion element, directly exposing it to the near-field light for enhanced signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the intensity of incident light is increased to increase the intensity of scattered light, then the signal intensity is improved, but the recording marks change by the near-field light during reproduction
Solution Approach 1:
A light shielding film is introduced as an intermediary component between the scatterer and the recording medium. This film blocks the direct path of intense incident light that would otherwise cause changes in the recording marks, while still allowing the scatterer to generate near-field light for reproduction. The light shielding film acts as a mediator that protects the recording medium from harmful light effects while preserving the necessary optical interaction for signal detection.
2Measurement precision
If a light shielding film is provided around the scatterer to eliminate reflected light, then the S/N ratio is improved, but the structure becomes more complex
Solution Approach 1:
The light shielding film is integrated with the scatterer structure, combining two functional elements into a unified component. The scatterer and light shielding film work together as a single assembly that performs both signal generation and background light blocking functions, reducing the need for separate, independent components and simplifying the overall device structure.
3Measurement precision
If a luminous body emitting different wavelength light is provided in the scatterer region, then the S/N ratio is improved by eliminating reflected light influence, but the device complexity increases
Solution Approach 1:
The invention extracts and eliminates the harmful reflected light component by using the light shielding film to block it, rather than introducing a separate luminous body to compensate for it. This approach removes the problematic element (reflected light) directly from the system rather than adding complexity to counteract its effects.
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 configuration ensures a high S/N ratio by directly detecting near-field light intensity changes, reducing the reliance on propagation light and improving signal intensity, thereby enhancing reproduction accuracy and reducing costs by eliminating the need for a reproduction optical system.
Implementation Method 1
a near-field light generating element utilizing a surface plasmon resonance of metal has been proposed as technology for drastically improving this light utilization efficiency
Implementation Method 2
an intensity change of the near-field light generated by a change of the dielectric constant of the information recording medium is detected based on an electrical conductivity change of the photoelectric conversion element
Data Source
AI summary
A near-field light detection element is provided with a light source, a conductive scatterer for generating near-field light by being irradiated with light from the light source, and a photoelectric conversion element arranged in a near-field light generation region near the scatterer. The scatterer irradiates near-field light to a recording medium, and the near-field light detection element detects an intensity change of the near-field light generated by a change of the dielectric constant of the recording medium based on an electrical conductivity change of the photoelectric conversion element.