Laser Speckle Range Determination via Wavefront Analysis
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Solution Overview
Problem
Existing laser range detection methods, such as time-of-flight measuring, require emitting a laser pulse and receiving reflections, making them detectable by laser detection systems and limiting their effectiveness in certain applications.
Innovation Solution
A system and method that determine the range to a laser source by processing a captured image of the laser source's wave front, utilizing an image sensor and processor to identify light speckles and calculate the distance based on their characteristic diameter and the wavelength of the coherent light beam, without the need for active emission or reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-of-flight measuring method is used to determine range, then range measurement capability is achieved, but the system becomes detectable by laser detection systems
Solution Approach 1:
Instead of actively emitting laser pulses and detecting reflections (traditional active sensing), the invention inverts the approach by passively capturing and analyzing the natural speckle pattern formed by coherent light scattered from the target. This allows range measurement without active emission, making the system undetectable by laser detection systems while maintaining measurement capability
2Measurement precision
If active laser pulse emission is used for range detection, then range measurement is achieved, but the system consumes energy and generates detectable signals
Solution Approach 1:
The system utilizes the natural coherent light field and its speckle pattern properties as the measurement source, rather than requiring external energy input for active emission. The passive capture and analysis of the speckle pattern allows range determination without consuming energy for laser pulse generation, while the target area is illuminated by the ambient coherent light source
Solution Approach 2:
The invention introduces the speckle pattern as an intermediary carrier that encodes range information. Instead of directly measuring time-of-flight of emitted pulses, the system uses the speckle pattern formed by scattered coherent light as a mediator to indirectly determine range, eliminating the need for active energy emission while preserving measurement capability
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 provides a passive and undetectable method for determining the distance to a laser source, enabling accurate range measurement without the need for active transmission or reception of laser pulses, thus avoiding detection by laser detection systems.
Implementation Method 1
The image of the wave front includes at least one light speckle. The processor identifies the light speckle on the captured image and determines the characteristic diameter of the identified light speckle.
Data Source
AI summary
Apparatus for determining a range to a coherent light source emitting a coherent light beam, the apparatus including an image sensor and a processor, the processor being coupled with the image sensor, the image sensor including an imaging plane, for capturing an image of the wave front of the coherent light beam, the image including at least one light speckle, wherein the processor identifies the light speckle on the captured image, determines the characteristic diameter of the identified light speckle, and determines the range by squaring the characteristic diameter and dividing the result of the squaring by the wavelength of the coherent light beam and by a proportionality constant.