Image Sensor Uniformity Testing via Light Source Inversion
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Solution Overview
Problem
Existing methods for testing charge couple devices (CCDs) face challenges in accurately measuring intrinsic uniformity due to non-uniform light intensity caused by optical components like lenses in the light path, making it difficult to quantify CCD uniformity effectively.
Innovation Solution
A method involving a light source with inherent non-uniformity, a light sensing device to measure intensity, interpolation to estimate non-measured points, and applying an inverted image to compensate for light source non-uniformity, allowing for accurate quantification of image sensor uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If optical components like lenses are used in the light path of LEDs, then the light intensity becomes non-uniform, but this is necessary to focus or direct light onto the image sensor
Solution Approach 1:
The patent measures the non-uniformity of the light source at predetermined points before conducting the actual image sensor test. By characterizing the light source non-uniformity in advance, the system can compensate for it during testing, thereby resolving the contradiction between using optical components for light direction and maintaining uniform light distribution.
Solution Approach 2:
The system uses measured data from predetermined points to interpolate non-measured points and generate a correction map. This feedback mechanism allows the system to quantify and compensate for light source non-uniformity, enabling accurate measurement of image sensor uniformity despite the presence of optical components.
2Illumination intensity
If individual control of each color LED is implemented, then spectral illuminance can be achieved, but device complexity increases
Solution Approach 1:
The patent employs a single light sensing device that can measure intensity across different spectral conditions. This universal measurement approach allows the system to handle multiple LED colors and spectral configurations without requiring separate measurement systems for each color, thereby reducing overall device complexity while maintaining spectral illuminance capability.
3Measurement precision
If predetermined points are measured to characterize light source non-uniformity, then non-measured points can be interpolated, but measurement time increases
Solution Approach 1:
The patent measures only predetermined points rather than the entire image plane, which is sufficient to characterize light source non-uniformity. By sampling at strategic locations and using interpolation to estimate non-measured points, the system achieves adequate measurement precision without the time cost of exhaustive full-plane measurement.
Solution Approach 2:
The light source non-uniformity is characterized in advance at predetermined points before the actual image sensor testing begins. This preliminary characterization allows the interpolation and correction processes to occur efficiently during the main testing phase, reducing the overall testing time while maintaining measurement accuracy.
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 method enables accurate compensation for light source and optical component non-uniformity, allowing for precise quantification of image sensor uniformity and removal of optical artifacts.
Implementation Method 1
a light sensing device for measuring an intensity response of the light source on a predetermined image plane
Data Source
AI summary
A method for testing an image sensor for photoresponse uniformity, the method includes the steps of providing a light source having inherent non-uniform light intensity characteristics; providing a light sensing device for measuring an intensity response of the light source on a predetermined image plane; determining an area on the image plane corresponding to an area for the image sensor; measuring pre-selected points of the determined area by the light sensing device for measuring incident light intensity from the light source on the image plane; interpolating non-measured points on the image plane representing an estimate of the non-uniformity of the light source at the non-measured points; inverting the interpolated image to represent the inverse of the light source non-uniformity; and applying the inverted image to the response of the image sensor which compensates for light source non-uniformity and enables the ability to quantify accurately the non-uniformity of the image sensor.