Monocentric Lens Star Camera Stray Light Shielding
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Solution Overview
Problem
Conventional image-based trackers for navigation in vehicles, such as spacecraft and aircraft, face issues with stray light noise due to the use of optical fiber bundles, which are heavy and require precise alignment, and omitting these bundles introduces stray light into the system.
Innovation Solution
A digital camera design that optically couples a monocentric lens to pixelated optical sensor arrays without optical fibers, using baffles and masks to shield the sensors from stray light, with baffles disposed between the lens and sensor arrays and masks defining apertures to limit light entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fiber bundles are used to couple the lens to sensor arrays, then the system can transmit light effectively, but the device becomes heavy and requires very precise alignment
Solution Approach 1:
The patent removes the optical fiber bundles from the system entirely. Instead of using fibers to transmit light from the lens to the sensor arrays, the design uses a direct optical coupling where the lens focuses light onto the sensor arrays without intermediate transmission media, thereby eliminating the alignment complexity associated with fiber coupling
Solution Approach 2:
The patent introduces a beam splitter and mirror system as an intermediary optical path. The beam splitter directs light from the lens to multiple sensor arrays arranged in a circular pattern, eliminating the need for direct fiber coupling while maintaining effective light transmission to all sensors
2Reliability
If optical fiber bundles are used to couple the lens to sensor arrays, then light transmission is maintained, but the device becomes heavy
Solution Approach 1:
The patent removes the heavy optical fiber bundles from the system. By eliminating the fiber coupling mechanism and using direct optical coupling with a beam splitter and mirror system, the overall weight of the camera assembly is significantly reduced while maintaining effective light transmission to the sensor arrays
3Device complexity
If no optical fiber bundles are used, then the device is lighter and alignment is easier, but stray light enters the system and increases noise
Solution Approach 1:
The patent segments the optical path into distinct, controlled routes using beam splitters and mirrors. Each optical path from the lens to the sensor arrays is separately defined and controlled, allowing precise management of light transmission while blocking stray light through the segmented optical structure
Solution Approach 2:
The patent converts the potential harm of stray light into a benefit by using the beam splitter and mirror system to create well-defined optical paths. The same optical elements that enable light transmission to multiple sensors also serve to block stray light, turning a potential problem into a solution for stray light rejection
4Area of stationary object
If a monocentric lens is used with direct optical coupling, then the field of view is widened, but stray light management becomes more difficult
Solution Approach 1:
The patent segments the optical paths using beam splitters and mirrors to manage the wide field of view from the monocentric lens. This segmentation allows the system to capture a broader angular range while controlling stray light through the structured optical elements that define precise light transmission paths
Solution Approach 2:
The patent introduces beam splitters and mirrors as intermediary elements between the monocentric lens and the sensor arrays. These intermediaries manage the complex optical paths generated by the wide-field lens, directing light to appropriate sensors while blocking stray light that would otherwise contaminate the images
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 design reduces noise and eliminates the need for external baffles, providing high signal-to-noise performance while maintaining a wide field of view and high-resolution imaging without the bulk and alignment challenges of optical fiber bundles.
Implementation Method 1
A monocentric lens focuses light from celestial objects onto a set of pixelated optical sensor arrays
Implementation Method 2
baffles disposed between the lens and sensor arrays to shield the sensors from stray light
Data Source
AI summary
A digital camera optically couples a monocentric lens to image sensor arrays, without optical fibers, yet shields the image sensor arrays from stray light. In some digital cameras, baffles are disposed between an outer surface of a monocentric lens and each image sensor array to shield the image sensor arrays from stray light. In other such digital cameras, an opaque mask defines a set of apertures, one aperture per image sensor array, to limit the amount of stray light. Some digital cameras include both masks and baffles.