Semi-Active Laser Seeker with Spatial and Temporal Sensors
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Solution Overview
Problem
Current image seekers for spinning projectiles, such as mortars and artillery shells, face challenges in accurately determining the target's location due to the lack of temporal data and high angle errors, which are exacerbated by the weapon's motion, leading to increased target location angle errors and limited effective range, especially in adverse weather conditions.
Innovation Solution
A semi-active laser seeker is developed, combining a spatial sensor with a temporal sensor to collect image data and detect laser time of arrival in the nanosecond range, allowing for precise navigation of spinning projectiles by integrating inertial measurement unit data with pixel coordinate information, thereby reducing angle errors and enabling effective pulse interval module decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional image seeker is used for spinning projectiles, then the seeker can collect image data, but the angle error increases significantly due to weapon motion during frame time
Solution Approach 1:
The patent divides the measurement process into two independent segments: a spatial sensor (imager) that captures image data and a temporal sensor that measures laser pulse arrival time. This segmentation allows each sensor to specialize in one type of measurement, with the temporal sensor providing precise timing information that compensates for weapon motion during the spatial sensor's frame time, thereby resolving the angle accuracy problem without requiring faster frame rates.
Solution Approach 2:
The patent introduces an intermediary processing system that combines data from both the spatial sensor and temporal sensor. This intermediary processor uses the precise time-of-arrival measurements from the temporal sensor to correct the spatial position measurements from the imager, effectively mediating between the two sensors to achieve high angle accuracy despite weapon motion during frame time.
2Measurement precision
If the frame time is reduced to minimize weapon motion, then angle accuracy improves, but the cost and complexity of the seeker increases
Solution Approach 1:
The patent replaces the mechanical approach of reducing frame time (which would require faster, more complex, and more expensive imaging systems) with a temporal measurement system that uses nanosecond-precision time-of-arrival measurements. This substitution allows the use of a standard-speed imager while achieving high angle accuracy through temporal correction, significantly reducing device complexity and cost.
Solution Approach 2:
The patent changes the measurement parameter from purely spatial (image position) to a combination of spatial and temporal parameters. By measuring the time of arrival of laser pulses with nanosecond precision and combining this with spatial image data, the system achieves high angle accuracy without requiring the imager to operate at extremely high frame rates, thereby reducing overall system complexity.
3Measurement precision
If a temporal sensor is added to provide precise time measurements, then angle accuracy improves, but the device complexity increases
Solution Approach 1:
The patent merges the spatial sensor and temporal sensor into a single integrated seeker system with a unified field of view. Both sensors observe the same target area simultaneously, and their data are processed together to produce the final angle measurement. This merging approach allows the system to achieve high accuracy while keeping the overall device complexity manageable through coordinated operation of the two sensor types.
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 solution provides accurate target positioning and enhanced countermeasure capabilities with improved angle accuracy and reduced cost, achieving an angle error of less than 0.1 degrees at 300 Hz spin rates and 40-degree field of view, while maintaining a compact and cost-effective design.
Implementation Method 1
a temporal sensor configured to detect laser time of arrival in the nanosecond range
Implementation Method 2
a spatial sensor for collecting image data
Data Source
AI summary
A system and method for a semi-active laser seeker combining a temporal and a spatial sensor to form a seeker with a wide angle FOV and low angle error for use with spinning projectiles with spin rates of up to 300 Hz. The FOV is about 40 degrees and the angle error is less than 0.1 degrees. The seeker utilizes a CCA and fits into a small, low cost package, of about 1.5 in3 or less.