Integrated Spectral and Polarization Optical Filter for Image Sensors
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Solution Overview
Problem
Image sensors face challenges in clearly imaging objects due to scattered light from moisture or glass surfaces and complex background light sources, leading to limitations in image clarity and color accuracy, particularly in high-resolution RGB imaging.
Innovation Solution
An optical filter is designed with a spectral filter and a polarizing filter on the same plane, featuring multiple spectral and polarization unit filters with different central wavelengths, which include metal reflectors, cavities, dielectric layers, and polarizers to enhance light transmission and polarization, improving image clarity and color accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical filters are used in image sensors, then basic spectral filtering is achieved, but image clarity deteriorates due to scattered light from moisture or glass surfaces and complex background light sources
Solution Approach 1:
The optical filter is divided into multiple independent unit filters (first unit filter, second unit filter, third unit filter, fourth unit filter) arranged in different regions. Each unit filter has specific spectral transmission characteristics tailored to its location, allowing independent optimization for different lighting conditions and reducing scattered light interference in each region.
Solution Approach 2:
Different regions of the optical filter are assigned different spectral transmission characteristics. The first and second unit filters transmit specific wavelength ranges optimized for certain viewing angles, while the third and fourth unit filters handle different wavelength ranges for other viewing angles, creating locally optimized performance throughout the filter.
2Measurement precision
If multiple optical elements are used to achieve comprehensive spectral and polarization filtering, then imaging accuracy improves, but device complexity and volume increase
Solution Approach 1:
The patent combines spectral filtering and polarization filtering functions into a single integrated optical filter structure. The unit filters are designed to simultaneously achieve both spectral selectivity and polarization control, eliminating the need for separate optical elements and reducing overall device complexity while maintaining high imaging accuracy.
Solution Approach 2:
Each unit filter is designed as a multi-functional element that performs both spectral filtering and polarization filtering simultaneously. This universal design allows a single optical filter to replace what would traditionally require multiple separate filters, reducing device complexity while achieving comprehensive imaging functionality.
3Measurement precision
If conventional single-plane filters are used, then manufacturing is simple, but spectral and polarization separation is insufficient for high-resolution RGB imaging
Solution Approach 1:
The optical filter is segmented into multiple unit filters with distinct spectral transmission characteristics. Each unit filter can be independently designed and manufactured with specific wavelength ranges and polarization properties, allowing modular fabrication that maintains high spectral resolution while simplifying the manufacturing process through standardized unit structures.
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 filter effectively addresses the issue of scattered light and complex background light by enabling clear imaging of objects even in the presence of moisture or glass surfaces, while also capturing spectral and polarized images, thereby enhancing image quality and accuracy.
Implementation Method 1
each unit filter includes a metal reflector, a cavity provided on the metal reflector
Implementation Method 2
The spectral unit filters may each include a lower metal reflector, a first cavity provided on the lower metal reflector, and an upper metal reflector provided on the first cavity
Implementation Method 3
An effective refractive index or a thickness of the first cavity may be adjusted based on the central wavelength of each of the spectral unit filters. The spectral unit filters may each further include a lower dielectric layer provided on the lower metal reflector and an upper dielectric layer provided on the upper metal reflector
Implementation Method 4
The polarization unit filters may each include the lower metal reflector, a second cavity provided on the lower metal reflector, and a polarizer provided on the second cavity. The polarizer may include a metal grid
Implementation Method 5
The spectral unit filters may each include a lower Bragg reflective layer, a first cavity provided on the lower Bragg reflective layer, and an upper Bragg reflective layer provided on the first cavity
Data Source
AI summary
Provided is an optical filter including a spectral filter, and a polarizing filter provided on the same plane as the spectral filter, wherein the spectral filter includes a plurality of spectral unit filters having different central wavelengths, and wherein the polarizing filter includes a plurality of polarization unit filters having different central wavelengths.