Image Sensor Interference Filters Spectral Resolution
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Solution Overview
Problem
Existing image sensors face limitations in flexibly designing light transmission characteristics, particularly for longer wavelengths, which affects spectral resolution and spatial resolution in spectral imaging applications.
Innovation Solution
The use of a plurality of interference filters associated with a single photo-sensitive area allows for flexible and accurate control of light transmission characteristics, enabling compact and cost-effective image sensor design with improved spectral resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single filter is associated with a single photo-sensitive area, then the device structure is simple, but the spectral resolution and flexibility in defining light transmission characteristics are limited
Solution Approach 1:
The patent divides the filtering function into multiple discrete interference filters (first, second, third, and fourth interference filters) associated with a single photo-sensitive area. Each filter targets a specific wavelength band, allowing precise spectral segmentation and improved spectral resolution without requiring multiple photo-sensitive areas.
Solution Approach 2:
The patent combines multiple interference filters with different wavelength selectivity characteristics onto a single photo-sensitive area. This merging of filtering functions enables the system to capture multiple spectral bands simultaneously through one photo-sensitive element, improving spectral resolution while maintaining a relatively simple device structure.
2Use of energy by moving object
If the bandwidth of the filter is increased for longer wavelengths, then more light is transmitted, but the selective detection of wavelengths deteriorates
Solution Approach 1:
The patent segments the wavelength detection into multiple narrow bands using four distinct interference filters, each with specific central wavelengths and bandwidths. This segmentation allows the system to maintain narrow bandwidths for better wavelength selectivity while still capturing sufficient light intensity across the spectral range.
Solution Approach 2:
The patent carefully selects and adjusts the parameters of each interference filter (central wavelength, bandwidth, transmission characteristics) to optimize the balance between light transmission intensity and wavelength selectivity. By changing the parameters of multiple filters rather than using a single filter with broad bandwidth, the system achieves both goals.
3Productivity
If a mosaic configuration of filters is used across multiple photo-sensitive areas, then spectral information can be acquired in a single exposure, but the spatial resolution is limited by the combined size of the photo-sensitive areas
Solution Approach 1:
The patent merges multiple interference filters onto a single photo-sensitive area, allowing the system to acquire multiple spectral bands simultaneously through one photo-sensitive element. This approach maintains spatial resolution by not dividing the photo-sensitive area into multiple smaller regions, while still enabling single-exposure spectral imaging.
Solution Approach 2:
The patent resolves the spatial-resolution limitation by moving the spectral multiplexing from the spatial dimension (mosaic across multiple pixels) to the optical dimension (multiple filters on one pixel). This dimensional shift allows spectral information acquisition without sacrificing spatial resolution.
4Adaptability or versatility
If multiple interference filters are associated with a single photo-sensitive area, then flexible control of light transmission characteristics is achieved, but the filter arrangement complexity increases
Solution Approach 1:
The patent employs an asymmetric arrangement of interference filters with different transmission characteristics (different central wavelengths and bandwidths) on each photo-sensitive area. This asymmetric configuration provides flexibility in defining light transmission characteristics for spectral imaging while maintaining a relatively simple overall filter arrangement structure.
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 approach enhances spectral resolution by allowing precise control of bandwidth and wavelength selection, improving the detection of spectral information with a high signal-to-noise ratio and enabling flexible design without the constraints of pixel layout.
Implementation Method 1
an array of interference filters arranged on the array of photo-sensitive areas so that light passes through the array of interference filters before reaching the photo-sensitive areas
Data Source
Figure 1~2
Figure 3a~4b
AI summary
An image sensor for acquiring an image of an object comprises: an array (102) of photo-sensitive areas (104) formed on a substrate, wherein each photo-sensitive area (104) is a continuous area within the substrate; an array of interference filters (106), wherein each interference filter (106) is configured to selectively transmit a wavelength band, wherein the array of interference filters (106) is monolithically integrated on the array (102) of photo-sensitive areas (104); and wherein a plurality of interference filters (106a-d) is associated with a single photo-sensitive area (104a), wherein each interference filter (106a-d) in the plurality of interference filters (106a-d) is configured to selectively transmit a unique wavelength band to the photo-sensitive area (104a) and each interference filter (106a-d) in the plurality of interference filters (106a-d) is associated with a unique portion of the photo-sensitive area (104a).