Non-Contact Laser Beam Profiling via Rayleigh Scattering
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Solution Overview
Problem
Conventional methods for measuring laser beam profiles and power are impractical for high-power lasers due to potential damage to optical components and lack of non-contact measurement capabilities, and existing systems require insertion of elements into the beam path, making them cumbersome and complex.
Innovation Solution
The use of Rayleigh scattering measurements from ambient air to characterize laser beams without inserting elements into the beam path, utilizing non-contact methods that image or collect Rayleigh scattered light for beam profiling and power measurement, and employing data processing algorithms and filtered laminar air flow to reduce interference from dust and debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods (beam splitters, attenuators, diffusion screens) are used to measure laser beam profiles, then beam profile measurements can be obtained, but high-power laser beams will damage these optical components
Solution Approach 1:
The patent introduces Rayleigh scattering from air molecules as an intermediary mechanism to transfer beam information to the camera. Instead of directly imaging the beam through optical elements, the system images the scattered light field, which carries beam profile information without requiring physical interaction between the beam and measurement components.
Solution Approach 2:
The patent replaces the mechanical/optical system of beam splitters, attenuators, and diffusion screens with a non-contact optical field measurement system. The measurement is performed by capturing the electromagnetic radiation pattern of the scattered light, eliminating the need for physical optical elements in the beam path.
2Measurement precision
If optical elements are inserted into the beam path for measurement, then beam characteristics can be measured, but the apparatus becomes cumbersome and complex
Solution Approach 1:
The patent extracts the measurement function from physical optical elements and transfers it to the optical field itself. By measuring the spatial distribution of Rayleigh scattered light, the system obtains beam profile information without requiring any optical elements to be present in the measurement apparatus.
Solution Approach 2:
The system uses the air molecules themselves as the scattering medium, which are already present in the environment. The air naturally provides the Rayleigh scattering effect needed for measurement, eliminating the need for additional scattering screens or specialized optical components.
3Ease of operation
If Rayleigh scattering measurements are performed in ambient air, then non-contact measurement is achieved, but interference from dust and debris scattering reduces measurement accuracy
Solution Approach 1:
The patent exploits the different temporal characteristics of Rayleigh scattering from air molecules versus Mie scattering from dust particles. By using pulsed laser illumination and measuring the temporal profile of scattered light, the system can distinguish between the two scattering mechanisms and filter out dust interference.
Solution Approach 2:
The system uses background subtraction by measuring and subtracting the ambient scattered light level from the total scattered light signal. This feedback mechanism removes the contribution from dust and debris scattering, isolating the Rayleigh scattering signal from air molecules.
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
Enables practical, portable, and non-contact measurement of laser beam characteristics, including profile and power, without damaging high-power lasers, using Rayleigh scattered light from ambient air, effectively reducing interference and maintaining system simplicity and accuracy.
Implementation Method 1
measuring various characteristics of a laser beam which overcomes at least some of the disadvantages of prior art systems... using measurements performed on light which has been Rayleigh scattered from the beam
Data Source
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Figure 5A~5C
AI summary
New systems for characterizing laser beams, using measurements performed on light which has been Rayleigh scattered from the beam. Different implementations are used for beam profiling, using images of the Rayleigh scattered light, and for laser beam power measurement, using the integrated Rayleigh scattered light. Both of these implementations can be applied to laser beams having high powers, since the measurements do not require insertion of any element into the beam itself, but rather depend on light scattered laterally from the passing beam. The measurements can thus be termed "non contact" measurements, in contrast to prior art methods which require an element inserted into the beam. The systems use Rayleigh scattering from the laser beam passing through ambient air, such that no special scattering chambers or liquids are required for the measurements. Special cancelation algorithms or filters are used to discriminate from light arising from scattering from dust particles.