Camera System Dome Ghost Reduction via Circular Polarizer
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Solution Overview
Problem
Surveillance cameras with transparent dome covers experience 'dome ghosts' due to light reflection, causing image distortion and inaccurate image information, especially when light is incident at angles between 10° and 30°, leading to unintended spots on captured images.
Innovation Solution
A camera system with a circular polarizer placed between the camera and the dome cover, controlled by a system that moves the camera to face or avoid the polarizer based on the presence of beam spots in the image, utilizing a polarizer and wavelength phase retarder to block reflected light and reduce dome ghost occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent dome cover is used to protect the camera, then protection from rainwater, moisture, dust, and foreign matters is improved, but light reflection causes dome ghosts that distort image information
Solution Approach 1:
A circular polarizer is introduced as an intermediary component between the transparent dome cover and the camera lens. The polarizer selectively blocks reflected light (dome ghosts) while allowing useful light to pass through, thereby eliminating the harmful effect of reflection without removing the protective dome cover.
2Adaptability or versatility
If the camera is exposed to strong light at angles between 10° and 30°, then the camera can capture images in various lighting conditions, but light reflects from lenses and the dome inner surface creating unintended spots on captured images
Solution Approach 1:
The circular polarizer acts as a mediator that selectively filters reflected light based on its polarization properties. When light reflects off the dome cover at angles between 10° and 30°, it becomes polarized, and the circular polarizer blocks this polarized reflected light while allowing non-polarized or differently polarized useful light to pass through, thereby maintaining adaptability while improving image quality.
Solution Approach 2:
The system changes the polarization state parameter of light passing through the system. The circular polarizer transforms the polarization characteristics of incident light, converting linearly polarized reflected light into circularly polarized light that can be selectively blocked, thereby controlling the behavior of light at different angles of incidence.
3Object-affected harmful factors
If a circular polarizer is added to block reflected light, then dome ghost reduction is improved, but device complexity increases
Solution Approach 1:
A single circular polarizer component serves as an efficient intermediary that addresses the dome ghost problem without requiring complex multi-component systems. The circular polarizer combines the functions of a linear polarizer and a quarter-wave plate into one integrated element, simplifying the overall device structure while effectively blocking reflected light.
4Manufacturing precision
If the camera position is dynamically adjusted relative to the polarizer, then image quality is maintained in different environments, but the system requires active control mechanisms
Solution Approach 1:
The system employs dynamic adjustment of the camera's angular position relative to the dome cover and polarizer based on detected light conditions. When dome ghosts are detected, the controller automatically adjusts the camera angle to optimize the relative positioning, thereby maintaining image quality while adapting to changing environmental lighting conditions.
Solution Approach 2:
The system uses feedback from image analysis to detect the presence of dome ghosts and automatically triggers camera position adjustment. The controller monitors captured images for reflected light patterns and dynamically repositions the camera to eliminate the interference, creating a closed-loop control system that maintains optimal image quality.
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
Effectively reduces dome ghost occurrences by blocking reflected light, ensuring accurate image capture and maintaining image quality without the need for costly modifications, by dynamically adjusting the camera's position relative to the polarizer based on environmental light conditions.
Implementation Method 1
a circular polarizer disposed between the camera and the transparent cover
Implementation Method 2
the light may be reflected from at least one of a plurality of lenses included in the camera after passing through the transparent dome, and then reflected again from the dome upon reaching the inner surface of the dome
Implementation Method 3
The circular polarizer may include a polarizer and a wavelength phase retarder sequentially arranged in a direction from the cover to the camera
Data Source
AI summary
A camera system includes a camera, a base configured to support the camera, a transparent cover that covers at least a portion of the camera and the base; a circular polarizer disposed between the camera and the transparent cover; and a controller configured to move at least one of the camera and the circular polarizer to arrange the camera to face the circular polarizer in a first surrounding environment, and move at least one of the camera and the circular polarizer to arrange the camera not to face the circular polarizer in a second surrounding environment.