Spectral Image Sensor CRA Correction Lens
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Spectral image sensors face issues with varying transmission characteristics due to chief ray angle (CRA) variations across different locations on the image sensor, leading to blue-shifting of wavelengths and degradation of spectral characteristics, especially for oblique incident light.
Innovation Solution
Incorporating a second lens system that adjusts the CRA of oblique incident light, which can be a meta-lens or Fresnel lens, to reduce the incident angle and minimize blue-shifting, thereby improving spectral characteristics by ensuring consistent transmission across the image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spectral filter based on Fabry-Perot cavity is used, then spectral filtering function is achieved, but transmission characteristics vary depending on chief ray angle causing blue-shifting
Solution Approach 1:
A CRA correction lens is introduced as an intermediary optical element between the spectral filter and the image sensor. This lens specifically corrects the chief ray angle for off-axis light rays, ensuring that light reaching the spectral filter maintains a consistent angle regardless of its origin position in the field of view, thereby eliminating blue-shifting and ensuring uniform transmission characteristics across the entire image sensor
Solution Approach 2:
The patent applies different optical correction strategies for different regions of the image sensor. The CRA correction lens is designed to provide position-dependent angle correction, where light rays from different locations in the field of view receive appropriate angular adjustment to compensate for the spectral filter's angle-sensitive transmission characteristics
2Adaptability or versatility
If the field of view is increased to +/−40°, then wider coverage is achieved, but chief ray angle increases to approximately 30° causing blue-shifting
Solution Approach 1:
The CRA correction lens serves as a mediator that enables the system to maintain high measurement precision even when operating with a wide field of view. By correcting the chief ray angle for oblique light rays that enter at up to 30° angles, the lens allows the spectral imaging system to utilize the full wide field of view without sacrificing spectral accuracy
Solution Approach 2:
The patent changes the optical parameters (chief ray angle) of light rays passing through the system by using the CRA correction lens to adjust the angle of incidence at the spectral filter, thereby maintaining consistent transmission characteristics across different field of view positions
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 solution effectively corrects the CRA of oblique incident light, reducing blue-shifting and enhancing spectral image quality and analysis accuracy compared to traditional spectral image sensors.
Implementation Method 1
a second lens system configured to adjust a chief ray angle (CRA) of oblique incident light to reduce an incident angle of the oblique incident light with respect to a spectral filter
Implementation Method 2
A spectral filter of a multispectral image sensor (MIS) is based on the resonance principle of a Fabry-Perot (FP) cavity
Implementation Method 3
a wavelength region, in which constructive interference of transmitted light occurs
Implementation Method 4
The image sensor may be configured to detect light passing through the first lens system, the infrared blocking filter, the second lens system, and the spectral filter
Implementation Method 5
an infrared blocking filter
Data Source
AI summary
A spectral image sensor includes: a first lens system; an infrared blocking filter; a second lens system configured to adjust a chief ray angle (CRA) of oblique incident light to reduce an incident angle of the oblique incident light with respect to a spectral filter; the spectral filter; and an image sensor. The image sensor may be configured to detect light passing through the first lens system, the infrared blocking filter, the second lens system, and the spectral filter.