Shaped Pulsed Laser Beam Positioning for Guidance Systems
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Solution Overview
Problem
Existing methods for determining the position of a moving body within a guidance beam, such as those described in British Patent Specification No. 1395246, suffer from reduced radiance and require multiple periods to convey positional information, limiting the accuracy and range of the system.
Innovation Solution
A method and apparatus that generate a shaped, pulsed laser beam cyclically deflected over a two-dimensional space, modulating the beam in phase with its movement to provide sufficient information for determining both radial and angular coordinates of a point within the beam, thereby increasing radiance and range by focusing energy into a specific area rather than shuttering the entire beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beam wide enough to illuminate the whole bounded space is shuttered progressively, then positional information can be conveyed, but the radiance of the transmitted beam is reduced
Solution Approach 1:
The bounded space is divided into multiple discrete angular sectors, each illuminated by a corresponding segment of the shaped beam. This segmentation allows the beam to be distributed across different angular positions without requiring progressive shuttering of a wide beam, thereby maintaining radiance while enabling position determination through angular sector identification.
Solution Approach 2:
The invention transitions from temporal modulation (progressive shuttering over time) to spatial modulation (shaped beam geometry). By giving the beam a specific cross-sectional shape that corresponds to the angular sectors of the bounded space, positional information is encoded in the spatial distribution of radiation rather than in temporal shuttering patterns, thus maintaining constant radiance.
2Illumination intensity
If a shaped beam is used to illuminate only part of the space, then radiance is increased, but the beam must be deflected cyclically to cover the entire space
Solution Approach 1:
The shaped beam is deflected cyclically through fixed angular positions to illuminate different sectors of the bounded space in a periodic sequence. This periodic deflection allows a compact beam to cover the entire space over time while maintaining high radiance during each illumination pulse, and the regular pattern simplifies the control mechanism compared to continuous scanning.
Solution Approach 2:
The beam deflection system uses dynamic angular positioning to redirect the shaped beam across different sectors. By employing movable deflecting elements that can rapidly change the beam direction in a controlled sequence, the system achieves complete space coverage with a compact beam while keeping the deflection mechanism relatively simple through predetermined angular positions.
3Measurement precision
If progressive shuttering is used to convey positional information, then multiple periods are required to determine both coordinates, but this reduces information transmission efficiency
Solution Approach 1:
The invention encodes both radial and angular coordinate information simultaneously in a single illumination period by using a shaped beam where the radial extent and angular position are both informative. The shaped beam's geometry provides radial position information through its extent in the radial direction, while its angular sector illumination provides angular position information, allowing both coordinates to be determined from one period rather than requiring multiple sequential periods.
Solution Approach 2:
The invention combines radial and angular position encoding into a single integrated beam shaping approach. Instead of separately determining radial and angular positions through multiple shuttering periods, the shaped beam simultaneously provides both types of information through its geometric configuration and angular deflection pattern, merging the information transmission functions into one efficient operation.
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 approach significantly enhances the radiance and useful range of the beam, allowing for precise determination of a point's position within a single illumination period, improving the accuracy and efficiency of guiding moving bodies like missiles along a predetermined path.
Implementation Method 1
providing a beam of radiation comprising a first beam component and a second beam component... generating a shaped, pulsed laser beam
Implementation Method 2
scanning the first beam component across the space in a first scanning direction... scanning the second beam component across the space in a second scanning direction... means (e.g. a Pechan prism) for rotating it around an axis
Data Source
AI summary
To determine two positional co-ordinates, of a point (D) within a space, a beam (10) a radiation is caused to illuminate a part of the space and is deflected cylindrically over the space, the beam being modulated in phase with the cyclical movement such that the radiation incident upon the point (D) includes enough information to identify the point. Embodiments with rotational (r, θ) and Cartesian (x, y) co-ordinate axes are disclosed.