Sky Camera Spatial Light Modulator Sun Saturation
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Solution Overview
Problem
Conventional total sky imaging systems face challenges with pixel saturation and blooming due to high-intensity direct sunlight, requiring mechanical sun blockers that increase costs and reduce reliability, while also losing critical data near the sun and adjacent areas essential for solar power forecasting.
Innovation Solution
A multifunctional sky camera system with a wide-angle objective lens, spatial light modulator for dynamic light attenuation, and semiconductor image sensors, allowing for high dynamic range imaging without mechanical blockers, enabling complete sky imaging including the sun and adjacent areas, and facilitating spectrally-resolved irradiance/radiance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical sun blockers are used to prevent direct sunlight from entering the camera, then pixel saturation and blooming are avoided, but the cost increases and reliability decreases
Solution Approach 1:
The patent replaces mechanical sun blockers with an electronic control system that dynamically adjusts the aperture opening based on detected sun position and intensity. This substitution eliminates moving mechanical parts while achieving the same light attenuation function through electronic control of aperture blades, thereby improving reliability and reducing mechanical complexity.
Solution Approach 2:
The system incorporates automatic sun tracking and detection capabilities that enable the camera to self-adjust its aperture settings without external intervention. The sun sensor automatically detects sun position, and the control system automatically adjusts the aperture to prevent saturation, making the system self-regulating and eliminating the need for manual mechanical blocker adjustment.
2Loss of information
If mechanical sun blockers are used to prevent direct sunlight, then sensor saturation is avoided, but information on the sun and adjacent sky is lost
Solution Approach 1:
The patent implements a dynamic aperture control system that continuously adjusts the aperture opening size based on real-time sun detection. Unlike static mechanical blockers that permanently block certain areas, the dynamic aperture can be precisely controlled to attenuate only the direct sun light while allowing light from adjacent sky regions to reach the sensor, thereby preserving information while preventing saturation.
Solution Approach 2:
The system applies different light attenuation levels to different regions of the field of view. The aperture control selectively attenuates light from the sun's position while allowing unattenuated or less attenuated light from adjacent sky regions to reach the sensor. This spatially selective attenuation preserves information in critical adjacent areas while protecting against sun-induced saturation.
3Device complexity
If mechanical sun blockers are deployed, then direct sunlight is blocked, but additional radiometric instruments are required to measure solar radiation
Solution Approach 1:
The patent transforms the sky camera system into a multi-functional instrument that simultaneously performs both imaging and radiometric measurement functions. By incorporating precise aperture control with known transmission characteristics and sun position detection, the system can capture images while also measuring solar irradiance and radiance data, eliminating the need for separate pyranometers, spectroradiometers, and pyrheliometers.
Solution Approach 2:
The system merges previously separate functions (imaging and radiometric measurement) into a single integrated camera system. The aperture mechanism serves dual purposes: protecting the sensor from saturation while enabling radiometric measurements through controlled light attenuation. This consolidation reduces overall system complexity while maintaining all necessary measurement capabilities.
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 provides cost-effective, reliable, and comprehensive sky imaging and radiation measurement capabilities, enhancing cloud tracking and solar power forecasting by avoiding pixel saturation and blooming, and integrating sun data for accurate orientation and triangulation-based cloud height calculations.
Implementation Method 1
a spatial light modulator at an image plane of the objective lens, wherein the spatial light modulator is configured to attenuate light from objects in images captured by the objective lens
Implementation Method 2
a semiconductor image sensor, and one or more relay lens configured to project the images from the spatial light modulator to the semiconductor image sensor
Data Source
AI summary
A multifunctional sky camera system and techniques for the use thereof for total sky imaging and spectral irradiance/radiance measurement are provided. In one aspect, a sky camera system is provided. The sky camera system includes an objective lens having a field of view of greater than about 170 degrees; a spatial light modulator at an image plane of the objective lens, wherein the spatial light modulator is configured to attenuate light from objects in images captured by the objective lens; a semiconductor image sensor; and one or more relay lens configured to project the images from the spatial light modulator to the semiconductor image sensor. Techniques for use of the one or more of the sky camera systems for optical flow based cloud tracking and three-dimensional cloud analysis are also provided.