Three-Mirror Imaging System Stray Light Reduction via Segmented Baffles
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Solution Overview
Problem
Imaging optical systems with three mirrors face challenges in reducing stray light while maintaining a small size, especially in applications requiring rapid rotation, such as optronic pods for surveillance, where existing baffles increase system size and rotational inertia.
Innovation Solution
The imaging optical system configures its secondary and tertiary mirrors to offset the image sensor's upstream boundary relative to the primary mirror, and incorporates reduced-length entrance baffles to block stray light, allowing for a compact design with a large entrance field and low cost manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If efficient baffles are used to reduce stray light, then stray light levels are reduced, but system size increases
Solution Approach 1:
The baffle is divided into multiple segments (first baffle segment, second baffle segment, third baffle segment) positioned at different locations along the optical path. Each segment blocks stray light from specific angles, collectively achieving effective stray light reduction without requiring a single large baffle, thus reducing overall system size.
Solution Approach 2:
The patent positions baffles in three-dimensional space at specific distances from mirrors (e.g., first distance from primary mirror, second distance from secondary mirror). By utilizing spatial dimensionality and angular positioning rather than simply increasing baffle size, the system achieves effective stray light blocking in a compact configuration.
2Object-affected harmful factors
If efficient baffles are used to reduce stray light, then stray light levels are reduced, but rotational inertia increases
Solution Approach 1:
The baffle is divided into multiple smaller segments positioned at different locations along the optical path. Each segment is compact and positioned to block stray light from specific angles, collectively achieving effective stray light reduction without requiring a single large, heavy baffle, thus reducing rotational inertia.
Solution Approach 2:
The patent positions baffles in three-dimensional space at specific distances from mirrors and at specific angles. By utilizing spatial dimensionality and angular positioning rather than simply increasing baffle size and mass, the system achieves effective stray light blocking with minimal impact on rotational inertia.
3Volume of moving object
If baffle length is reduced to minimize system size, then system size is reduced, but stray light blocking effectiveness decreases
Solution Approach 1:
The baffle is divided into multiple segments (first, second, and third baffle segments) positioned at different locations along the optical path. Each segment blocks stray light from specific angles, collectively achieving effective stray light reduction without requiring a single long baffle, thus reducing overall system size.
Solution Approach 2:
The patent positions baffles in three-dimensional space at specific distances from mirrors (e.g., first distance from primary mirror, second distance from secondary mirror). By utilizing spatial dimensionality and angular positioning rather than simply increasing baffle length, the system achieves effective stray light blocking in a compact configuration.
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 configuration effectively reduces stray light, minimizes system size, and allows for efficient imaging with reduced baffle length, enabling applications in surveillance and detection systems with rapid rotation capabilities.
Implementation Method 1
light rays originating from a scene located in an entrance field of the system are reflected first by mirror M1
Implementation Method 2
then by mirror M2
Implementation Method 3
then by mirror M3, to form an image of the scene in a focal plane of the system
Data Source
AI summary
An imaging optical system including three mirrors has a configuration adapted to block stray rays which could otherwise reach an image sensor of the system, while permitting large fields, high apertures, and good system compactness. The system may also incorporate two entrance baffles which are arranged one on either side of an optical entrance of the system. Functions of the two entrance baffles may be limited to intercepting rays originating from fields which are angularly distant from the entrance field useful to each captured image. The two entrance baffles can thus have reduced lengths upstream, so that the system has a small size.