Optical Sensor With Dual-Axis Gimbal and Staring Detector
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Solution Overview
Problem
Existing gimbaled optical sensors face challenges in integrating active illumination and passive detection capabilities within constrained volume, weight, and power limitations, while avoiding inefficiencies in fiber or free-space coupling of laser beams.
Innovation Solution
The optical sensor employs a dual-axis gimbal to scan a narrow laser beam over a transmit field-of-regard, coupled with an off-gimbal staring detector and a fixed receive aperture, allowing for active illumination and passive detection within a self-contained modular unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fiber is used to couple the laser beam into the sensor compartment, then the laser can be positioned behind a bulkhead, but the coupling efficiency is low and signal power is lost
Solution Approach 1:
The patent removes the fiber coupling mechanism from the system entirely. Instead of using a fiber to transmit the laser beam through the bulkhead, the invention uses a free-space optical path where the laser is positioned within the sensor compartment and beams directly through the bulkhead aperture, eliminating the fiber interface and associated coupling losses.
Solution Approach 2:
The patent introduces a beam splitter as an intermediary optical element. The beam splitter directs the laser beam from the laser source through the bulkhead aperture and into the sensor compartment, providing a clean optical interface that avoids fiber coupling while maintaining precise beam transmission and positioning.
2Adaptability or versatility
If the laser is positioned within the sensor volume, then the system becomes self-contained, but the volume and weight constraints are challenged
Solution Approach 1:
The patent employs a gimbaled optical system with movable mirrors and telescopes that can dynamically adjust the optical path. This dynamic configuration allows the laser and detector to be positioned within the sensor volume while using movable optical elements to steer and focus beams, effectively utilizing the available space without requiring a large fixed volume.
Solution Approach 2:
The patent integrates multiple optical functions within a nested configuration where the laser source, beam splitter, gimbal mechanisms, and detector are arranged in a compact, nested layout. The optical path folds back on itself using mirrors and telescopes, allowing all components to occupy a small volume while maintaining full functionality.
3Area of stationary object
If a dual-axis gimbal scans both transmit and receive beams, then the field-of-regard is extended, but the laser power consumption increases
Solution Approach 1:
The patent separates the transmit and receive optical paths through independent gimbal mechanisms. The transmit gimbal scans the laser beam over the field-of-regard, while the receive gimbal independently scans the detector across the same field. This segmentation allows each gimbal to be optimized for its specific function, reducing overall power consumption compared to a single gimbal handling both functions simultaneously.
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 minimizes power consumption and avoids the deficiencies of fiber or free-space coupling, enabling compact, rugged seekers to perform missions requiring passive detection and active laser illumination across various platforms and environments.
Implementation Method 1
an off-gimbal laser configured to emit a laser beam
Implementation Method 2
an off-gimbal staring detector, a fixed off-gimbal receive aperture that receives light within a fixed receive FOR
Data Source
AI summary
The design of an existing air-to-air missile seeker is adapted to new missions that require both active laser illumination and detection (passive or active) capabilities. The gimbal is used to point the laser beam to a desired location in a transmit FOR. This approach minimizes the size, weight and power of the sensor because only a small portion of the transmit FOR is illuminated at any instant. This minimizes the laser output required, which reduces the power to operate the laser and the power to maintain the laser at operating temperature. In existing seekers, the gimbal points the detector in the desired direction to expand its FOR. To address the limitations of coupling the laser beam into the gimbaled optical system, the gimbal cannot perform the steering function for the detector. Instead, a staring detector receives light through an off-gimbal aperture within a fixed receive FOR that overlaps the transmit FOR.