Angular Filter for Image Sharpness in Large Sensor Systems
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Solution Overview
Problem
Image acquisition systems face challenges in achieving sharp image formation when the image sensor occupies a significant surface area and the distance between the object and the sensor is limited, leading to insufficient image sharpness for applications like fingerprint capture.
Innovation Solution
An image acquisition system comprising a source of radiation, an image sensor with an array of photodetectors, and an angular filter that blocks radiation with incidence greater than a threshold, allowing only radiation with incidence within a specific angle to reach the photodetectors, enhancing image sharpness without an optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the image sensor occupies a significant surface area and the distance between the object and sensor is limited, then the sensor can capture a larger field of view, but the image sharpness becomes insufficient
Solution Approach 1:
The patent introduces an angular filter comprising an array of holes that segments the incoming radiation paths. Each hole acts as an independent optical channel, allowing only radiation from specific angular directions to reach corresponding photodetectors. This segmentation enables sharp image formation across the entire sensor surface without requiring a large optical system, resolving the contradiction between large sensor area and image sharpness.
Solution Approach 2:
The angular filter serves as an intermediary element positioned between the object and the image sensor. It mediates the radiation paths by selectively blocking or transmitting radiation based on its angle of incidence, thereby enabling sharp image formation on a large sensor surface without requiring the object to be extremely close to the sensor.
2Manufacturing precision
If the distance between the object and image sensor is reduced to improve sharpness, then image quality increases, but the system loses adaptability to different object distances
Solution Approach 1:
The angular filter changes the effective optical parameters of the system by filtering radiation based on angle of incidence. This parameter change allows the system to maintain sharp images at various object distances, as the angular selectivity compensates for variations in object-to-sensor distance, thereby improving both sharpness and distance adaptability.
3Manufacturing precision
If an optical system is introduced to improve image sharpness, then image quality increases, but the device complexity increases
Solution Approach 1:
The patent extracts the essential function of image sharpness enhancement from complex optical systems (lenses, mirrors, etc.) and implements it through a simpler angular filter structure. The filter directly selects radiation based on angle of incidence without requiring complex optical components, thereby achieving sharp images with reduced device complexity.
Solution Approach 2:
The patent replaces complex mechanical optical systems with a simpler angular filtering mechanism. Instead of using lenses and mirrors to focus light, the system uses an angular filter that selectively transmits or blocks radiation based on its angle of incidence, substituting a complex mechanical optical system with a simpler filtering approach.
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 system effectively increases image sharpness and allows for larger sensor surfaces and shorter object-to-sensor distances, improving applications such as fingerprint detection by filtering radiation to enhance image quality.
Implementation Method 1
an angular filter, covering the image sensor, and capable of blocking the rays of said radiation having an incidence relative to a direction orthogonal to the surface greater than a threshold and of giving way to rays of said radiation having an incidence relative to a direction orthogonal to the surface smaller than the threshold
Implementation Method 2
an image sensor comprising an array of photodetectors capable of detecting said radiation
Data Source
AI summary
An image acquisition system includes a source of a radiation, an image sensor including an array of photodetectors capable of detecting the radiation and including a surface, and an angular filter, covering the sensor, and capable of blocking the rays of the radiation having an incidence relative to a direction orthogonal to the surface greater than a threshold and of giving way to at least certain rays of the radiation having an incidence relative to a direction orthogonal to the surface smaller than the threshold.