Optical Module Spectral Filter Nanohole Array Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Filter array-based spectrometers face limitations in miniaturization, process reproducibility, and resolution due to the linear structure of linear variable filters, and the number of filters required for high resolution, which affects signal restoration capability and operation stability.
Innovation Solution
An optical module with a spectral filter array and a band-limited filter that selectively transmits a narrower wavelength range than the operating band, combined with an optical detection unit, to enhance resolution and signal restoration, allowing for improved miniaturization and integration with two-dimensional imaging sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a linear variable filter (LVF) with linear structure is used, then the spectrometer can be miniaturized and integrated with optical detector array, but the process reproducibility and productivity are limited
Solution Approach 1:
The patent uses a transmission filter with extraordinary optical transmission (EOT) phenomenon occurring in a nanohole array structure periodically arranged on a metal thin film. This filter copies the spectral filtering function of complex LVF structures but implements it through a simpler periodic nanohole array that can be manufactured with standard photolithography processes, thereby improving process reproducibility and productivity while maintaining miniaturization benefits
Solution Approach 2:
The patent changes the structural parameters of the filter from a linearly varying thickness profile (LVF) to a periodic nanohole array configuration. By controlling the period, size, and arrangement of nanoholes in the metal film, the transmission spectrum can be tuned to achieve the desired spectral filtering characteristics without requiring complex linear gradient structures, thus improving manufacturability while maintaining compact size
2Measurement precision
If the number of filters is increased to improve resolution, then the spectrometer resolution increases, but the signal restoration capability and operation stability are degraded
Solution Approach 1:
The patent changes the approach from increasing the number of filters to improving the quality of each filter. By using transmission filters with EOT phenomenon in periodic nanohole arrays, each filter achieves sharper spectral selectivity and better transmission characteristics. This allows achieving high resolution with fewer filters, thereby maintaining operation stability and signal restoration capability while improving measurement precision
3Ease of manufacture
If linear variable filter structure is used, then band filtering function is achieved, but the resolution is limited by height-to-length ratio
Solution Approach 1:
The patent transitions from a one-dimensional linear gradient structure (LVF with varying thickness in length direction) to a two-dimensional periodic nanohole array structure. This dimensional change allows achieving spectral filtering and high resolution through in-plane periodic variations rather than out-of-plane thickness gradients, overcoming the height-to-length ratio limitation while maintaining ease of manufacture through standard planar fabrication processes
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 solution effectively overcomes the limitations of filter array-based spectrometers by increasing resolution and signal restoration capability, enabling more precise wavelength range analysis and improved operation stability, suitable for miniaturized and portable spectroscopic instruments.
Implementation Method 1
a band-limited filter configured to selectively transmit light of a wavelength region narrower than a wavelength region designed to be measured through the spectral filter array
Implementation Method 2
an optical detection unit configured to detect an optical signal passing through the spectral filter array and the band-limited filter
Data Source
AI summary
The present invention provides an optical device including a spectral filter and an optical detection unit for detecting light passing through the spectral filter. A band-limited filter is provided on the path of light.