Fixed-Source Array Test Station for SAL Seeker Calibration
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Solution Overview
Problem
Current calibration methods for semi-active laser (SAL) seekers are expensive and time-consuming, requiring a 3-axis stage and Q-switched lasers, resulting in high costs and lengthy calibration times, especially for high-fidelity calibrations.
Innovation Solution
A cost-effective test station using a fixed-source array with LEDs or VCSELs, where an array of collimated optical sources is positioned at fixed angular positions to overlap the entrance pupil of the SAL seeker, allowing for rapid calibration by activating sources in a phase-delayed manner to create a calibration table mapping spatial displacement to azimuth and elevation angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a 3-axis stage and Q-switched lasers are used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent divides the calibration system into multiple fixed optical sources arranged in an array, each representing a specific angular position. Instead of using a single movable laser and 3-axis stage, the system segments the calibration function across multiple fixed sources, eliminating the need for complex positioning mechanisms while maintaining calibration precision.
Solution Approach 2:
The patent uses multiple fixed optical sources (LEDs or VCSELs) that copy the functional role of the movable laser at different angular positions. Each source in the array replicates the light emission function at a predetermined position, eliminating the need for mechanical movement while achieving the same calibration effect.
2Measurement precision
If a 3-axis stage is used for calibration, then measurement precision is improved, but calibration time increases
Solution Approach 1:
The patent pre-positions multiple optical sources at fixed angular positions around the seeker entrance pupil before calibration begins. This preliminary arrangement eliminates the need for time-consuming mechanical movement during calibration, as all required angular positions are already prepared and accessible.
Solution Approach 2:
The patent enables continuous calibration by having multiple sources available simultaneously, allowing the system to rapidly switch between sources without mechanical interruption. This eliminates the downtime associated with moving and repositioning equipment between measurement points, maintaining continuous useful action throughout the calibration process.
3Manufacturing precision
If Q-switched lasers and 3-axis stages are used, then calibration accuracy is improved, but productivity decreases
Solution Approach 1:
The calibration function is segmented across multiple fixed sources, allowing parallel or rapid sequential measurement at different angular positions. This eliminates the sequential bottleneck of moving a single laser to each position, dramatically increasing calibration throughput while maintaining accuracy through the fixed geometric arrangement of sources.
Solution Approach 2:
The patent replaces the mechanical 3-axis positioning system with a fixed optical array. This substitution eliminates mechanical movement entirely, replacing it with electronic control of source activation. The result is both higher accuracy (through fixed, stable geometry) and higher productivity (through rapid electronic switching between sources).
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 fixed-source array test station significantly reduces costs and calibration time, achieving a throughput that is at least three orders of magnitude faster than traditional methods while maintaining performance, making it practical for manufacturing environments.
Implementation Method 1
Each SAL source may comprise an inexpensive light emitting diode (LED) or vertical cavity surface emitting laser (VCSEL) and collimator
Implementation Method 2
An array of fixed collimated optical sources generates respective temporally pulsed optical beams
Implementation Method 3
The SAL seeker includes a non-imaging optical system that captures and focuses the scattered laser EMR into a spot onto a segmented non-imaging detector
Implementation Method 4
The detector compares the integrated EMR incident on each cell (segment) to calculate a spatial displacement of the centroid of the spot
Data Source
AI summary
A fixed-source array test station provides a cost-effective high-throughput test bed for testing optical sensors that require stimulus at fixed angular positions. A SAL seeker requires stimulus at fixed angular position across its FOV to calibrate its spatial transfer function (STF). An array of fixed collimated sources at different angular positions is aligned so that their beams overlap the entrance pupil of the sensor under test. Each source may comprise an inexpensive light emitting diode (LED) or vertical cavity surface emitting laser (VCSEL) and collimator. To simplify alignment the sources may be positioned on and perpendicular to the surface of a sphere with the seeker's entrance pupil located at the center of the sphere. The sources are activated in accordance with an activation profile in order to calibrate or otherwise test the sensor.