Microbolometer Thick Optical Filter and Waveguide Integration
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Solution Overview
Problem
Conventional cameras, including digital cameras, are polarization blind without add-on components, leading to issues such as narrow acceptance angles, low light collection, low contrast, narrow bandwidth, crosstalk, high expense, and difficulty in fabrication due to the use of thick optical filters required for ideal response in infrared imaging.
Innovation Solution
The implementation of a pixel device with a thick optical filter component having a thickness between about λ and 10λ, where λ is the operation wavelength, combined with micro-optics to guide and focus incident light effectively to the optical sensor, including a microlens and waveguide, and integrated with color and polarization filters to enhance light collection and reduce crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thick optical filters (thickness between λ and 10λ) are used to achieve ideal polarization and color filtering response, then filtering performance and contrast are improved, but light collection efficiency deteriorates and device complexity increases
Solution Approach 1:
The patent introduces micro-optics components (microlenses and waveguides) that add a new dimensional aspect to light management. The microlenses focus incident light onto the waveguide inputs, and the waveguides channel light through extended path lengths to the filter outputs, effectively adding spatial dimensions to overcome the limitations of thick filters alone
Solution Approach 2:
The waveguide acts as an intermediary component between the incident light and the thick optical filter. It captures light over an extended area and guides it to the filter output, mediating the interaction between light and the thick filter to improve both light collection and filtering performance simultaneously
2Measurement precision
If thick optical filters are used for ideal infrared imaging response, then polarization sensitivity is improved, but fabrication difficulty and device complexity increase
Solution Approach 1:
The patent divides the imaging device into separate functional modules: microlens array for light focusing, waveguide array for light channeling, and thick optical filter array for polarization filtering. This segmentation allows each component to be optimized and fabricated independently using different processes, reducing overall fabrication complexity
Solution Approach 2:
The waveguide structure serves multiple functions simultaneously: it collects light over an extended area, channels light to the filter outputs, and enables the use of thick filters that would otherwise be impossible to integrate. This multi-functionality reduces the need for additional specialized components
3Device complexity
If conventional cameras without add-on components are used, then device simplicity is maintained, but polarization detection capability is lost
Solution Approach 1:
The patent merges polarization filtering capabilities directly into the imaging sensor structure by integrating microlenses, waveguides, and thick optical filters in a single integrated array. This combination eliminates the need for separate add-on polarization components while maintaining device compactness and simplicity
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 solution mitigates the disadvantages of thick optical filters by improving light collection, contrast, and bandwidth while reducing crosstalk and fabrication complexity, enabling efficient polarization and color-sensitive imaging across a wide range of wavelengths.
Implementation Method 1
an optical component having an input and an output, adapted to focus and guide an incident light at the input
Implementation Method 2
and waveguide, and integrated with color and polarization filters to enhance light collection
Implementation Method 3
a thick optical filter component having a thickness between about λ and 10λ, where λ is an operation wavelength of the pixel device
Implementation Method 4
integrated with color and polarization filters to enhance light collection
Implementation Method 5
an optical sensor component disposed at an output of the thick optical filter component
Data Source
AI summary
A polarization and color sensitive pixel device and a focal plane array made therefrom. Each incorporates a thick color/polarization filter stack and microlens array for visible (0.4-0.75 micron), near infrared (0.75-3 micron), mid infrared (3-8 micron) and long wave infrared (8-15 micron) imaging. A thick pixel filter has a thickness of between about one to 10× the operational wavelength, while a thick focal plane array filter is on the order of or larger than the size or up to 10× the pitch of the pixels in the focal plane array. The optical filters can be precisely fabricated on a wafer. A filter array can be mounted directly on top of an image sensor to create a polarization camera. Alternatively, the optical filters can be fabricated directly on the image sensor.