Rotating Agile Steering Mirror for High Bandwidth Beam Pointing

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Solution Overview

Problem

Current agile beam-steering technologies for laser radar applications face limitations in rapidly pointing to a large number of widely spaced objects, requiring improved pointing agility and correction bandwidth over an extended range of angles.

Innovation Solution

A rotating agile steering mirror (RASM) assembly comprising a base, two stacked wedges with independent motors and rotary encoders, allowing the mirror to tilt to any angle between the sum of the wedges' angles, providing high torque, low mass/inertia, and wide steering angles with high mechanical stiffness and bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional agile beam-steering technologies are used, then the system can perform basic beam steering, but the pointing agility and correction bandwidth are limited when rapidly pointing to widely spaced objects

Engineering Contradiction:

Improvepointing agilityVSAvoidsystem complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The steering mirror is divided into two independently rotatable wedges (first wedge and second wedge) mounted on a common base. Each wedge can be rotated by its own motor, allowing independent control of steering angles. This segmentation enables the system to achieve wide steering angles and high pointing agility by combining the rotational movements of both wedges without requiring a single complex mechanism.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the steering angle range is extended, then the mirror can point to widely spaced objects, but the mass and inertia of the rotating assembly increase

Engineering Contradiction:

Improvesteering angle rangeVSAvoidmass and inertia

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The second wedge is mounted on top of the first wedge, creating a nested stacked configuration. Both wedges share a common base and rotational axis. This nesting allows the mirror to achieve extended steering angles through combined rotation of both wedges while keeping the overall structure compact and minimizing the moment of inertia compared to a single large rotating assembly.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Productivity

If rapid beam steering is implemented, then the correction bandwidth increases, but the response time and mechanical stiffness requirements become more demanding

Engineering Contradiction:

Improvecorrection bandwidthVSAvoidresponse time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system employs two motors with independent control capability, each driving one wedge. This dynamic configuration allows for rapid, independent adjustment of steering angles in response to tracking requirements. The independent motor-wedge pairs enable high correction bandwidth by eliminating mechanical coupling delays and allowing parallel actuation, thereby reducing overall system response time while maintaining mechanical stiffness through the rigid stacked wedge structure.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11520139B2Rotating steering mirror and methods, assemblies, and systems thereof

Publication Date: 2022.12.06 LOCKHEED MARTIN CORP

AI summary

A rotating steering mirror assembly comprising a first wedge rotatable relative to a base and a second wedge rotatable relative to the first wedge to controllably tilt a mirror on an outward- or forward-facing surface of the second wedge. Respective motors can independently rotate the first and second wedges.