Strap-down seeker optics with scattering surface for wide field of regard
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Solution Overview
Problem
Existing semi-active laser seekers face challenges in transitioning from gimbal-based to strap-down designs, as they struggle to balance wide field of regard with high angular discrimination while maintaining reliability, cost-effectiveness, and reducing weight, due to limitations in signal-to-noise ratio and mechanical motion.
Innovation Solution
The implementation of a strap-down seeker optics system with a scattering surface behind the objective and before the detector, which redirects light at large off-boresight angles to the detector, enabling detection and tracking in a wide field of regard without mechanical motion, combined with a narrow bandpass filter for solar radiation suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow IFOV is used for high-resolution target tracking, then measurement precision is improved, but the field of regard is limited
Solution Approach 1:
The detector is divided into multiple zones: a central region for high-resolution tracking (narrow IFOV) and peripheral regions for wide-angle detection (wide FOR). This segmentation allows the same detector to simultaneously provide both narrow angular discrimination for locked-on targets and wide field of regard for target acquisition, resolving the contradiction between measurement precision and field coverage.
Solution Approach 2:
The patent transitions from a single-field-of-view optical system to a multi-field-of-view system by introducing additional optical paths or detector regions that capture light from different angular ranges. This dimensional expansion in angular space allows the system to maintain narrow IFOV for precision tracking while simultaneously achieving wide FOR for target search, effectively adding another dimension to the field of view coverage.
2Area of stationary object
If the field of view is increased using a lens with reduced focal length, then the field of regard is improved, but aperture size and light throughput are reduced
Solution Approach 1:
Different regions of the optical system are assigned different functions: the central optical path maintains high light throughput for precision tracking, while peripheral optical paths or detector regions are optimized for wide-angle detection. This local differentiation allows the system to achieve wide field of regard without sacrificing light throughput in the critical central region, as each zone is optimized for its specific function.
3Area of stationary object
If a larger detector is used to widen the field, then the field of regard is improved, but noise increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The detector is segmented into central and peripheral regions with different functional roles. The central region maintains high signal-to-noise ratio for precision tracking, while peripheral regions provide wide-angle coverage. By processing signals differently from these segments, the system achieves wide field of regard without compromising the signal-to-noise ratio in the critical central tracking region.
Solution Approach 2:
The patent applies partial action by using only the necessary portion of the detector area for each function. The central region is optimized for high-SNR tracking with minimal detector area, while peripheral regions are activated only when wide-angle detection is needed. This partial activation strategy maintains high signal-to-noise ratio for precision functions while enabling wide field coverage when required.
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 solution provides high-resolution target tracking in a narrow field of view and a wide field of regard, offering extreme simplicity, low cost, and reduced weight, while maintaining compatibility with existing laser pulse coding schemes and signal processing, and allowing for potential retrofitting of existing missiles.
Implementation Method 1
a scattering surface behind the objective and before the detector, which redirects light at large off-boresight angles to the detector
Implementation Method 2
combined with a narrow bandpass filter for solar radiation suppression
Implementation Method 3
an objective for collecting and transmitting light from a target
Data Source
AI summary
Seeker optics and a related method comprising: an objective for collecting and transmitting light from a target; at least one scattering surface; and a photo detector; wherein: the light transmitted from the objective at small off-boresight target angles propagates to and impinges upon the photo detector without impinging upon the scattering surface; the light transmitted from the objective at large off-boresight target angles propagates to, impinges upon and scatters upon the scattering surface; and the light scattered by the scattering surface propagates to and impinges upon the photo detector; whereby: the target may be detected and tracked at both small and large off-boresight angles, in a wide field of regard.