Calibration Disc for Optical Sensor Uniform Irradiance
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Solution Overview
Problem
Optical sensor systems face challenges in calibration due to the complexity and cost of integrating dedicated mechanisms for non-uniformity correction, particularly in cryogenically cooled systems where additional components interfere with thermal and structural designs, increasing the risk of system failure.
Innovation Solution
A calibration disc with partially reflective and diffuse surfaces is used to provide uniform irradiance, scattering light from an entrance aperture to achieve the same optical uniformity as a standard 3-D integrating sphere, reducing the need for complex mechanisms and allowing for remote light source placement, thus minimizing structural and thermal design complexities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated mechanism is used to move the calibration light source into and out of the field of view, then full field calibration can be performed, but system complexity increases and reliability decreases
Solution Approach 1:
The calibration light source is extracted from the optical path and placed remotely, eliminating the need for dedicated mechanisms to move it into and out of the field of view. The light source is taken out of the cryogenic environment entirely, while still providing calibration functionality through the use of light guides and optical coupling elements.
Solution Approach 2:
Light guides and optical coupling elements serve as intermediaries between the remotely positioned calibration light source and the focal plane. These intermediaries transmit calibration light without requiring mechanical movement of the source itself, thus reducing system complexity while maintaining calibration capability.
2Measurement precision
If a dedicated mechanism is used to move the calibration light source, then full field calibration can be performed, but cost increases
Solution Approach 1:
The calibration light source is extracted from the optical path and placed remotely, eliminating the need for dedicated mechanisms to move it into and out of the field of view. The light source is taken out of the cryogenic environment entirely, while still providing calibration functionality through the use of light guides and optical coupling elements.
Solution Approach 2:
The calibration disc creates a virtual image or copy of the uniform radiance field that would be produced by a large integrating sphere, but using a compact disc-shaped structure. This copying approach achieves the same calibration effect with significantly reduced complexity and cost.
3Measurement precision
If additional mechanisms are added for calibration, then full field calibration can be performed, but the probability of system failure increases
Solution Approach 1:
The calibration light source is extracted from the optical path and placed remotely, eliminating the need for dedicated mechanisms to move it into and out of the field of view. The light source is taken out of the cryogenic environment entirely, while still providing calibration functionality through the use of light guides and optical coupling elements.
Solution Approach 2:
The calibration disc is designed to be positioned in the optical path using existing system components (such as a filter wheel or filter selector platter) that are already part of the optical sensor system. This self-service approach uses existing mechanisms for calibration purposes without requiring additional dedicated mechanisms.
4Measurement precision
If a large calibration light source is placed at the entrance aperture, then uniform illumination can be achieved, but volume and mass increase
Solution Approach 1:
The calibration system transitions from a three-dimensional integrating sphere to a two-dimensional calibration disc. This dimensional reduction achieves the same uniform illumination function with significantly reduced volume and mass, while maintaining the optical uniformity required for accurate calibration.
Solution Approach 2:
The calibration disc creates a virtual image or copy of the uniform radiance field that would be produced by a large integrating sphere, but using a compact disc-shaped structure. This copying approach achieves the same calibration effect with significantly reduced complexity and cost.
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 calibration disc enables efficient and reliable non-uniformity correction with reduced system complexity and cost, maintaining accuracy and uniformity across the optical sensor system, even in cryogenically cooled environments.
Implementation Method 1
the surfaces use specular reflection and Lambertian scattering, for example, to fill the calibration disc with scattered light
Implementation Method 2
the surfaces use specular reflection and Lambertian scattering, for example, to fill the calibration disc with scattered light
Implementation Method 3
The calibration disc may be solid with a non-zero positive index of refraction greater than 1
Data Source
AI summary
A calibration disc for providing uniform irradiance to an optical sensor system includes a first major surface, a second major surface opposite the first major surface, and an edge surface extending around a circumference of the calibration disc. The first major surface is fully reflective and partially diffuse, the second major surface is partially reflective and partially diffuse, and the edge surface is fully reflective and partially diffuse and has an entrance aperture positioned at the edge surface and configured to receive light into the calibration disc. The first major surface, the second major surface and the edge surface are configured to scatter the light received by the entrance aperture within the calibration disc. The second major surface is configured to emit at least some of the light with uniform irradiance.