Diffractive Structure for Laser Power Density Measurement
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Solution Overview
Problem
Existing devices for measuring power density distribution of radiation sources, particularly at high intensities, face issues such as material degradation, thermal conductivity limitations, and distortion due to absorption-based methods, which are unsuitable for industrial laser applications with short and high radiation intensities.
Innovation Solution
A device utilizing a diffractive structure on a substrate to separate the radiation into zeroth and first orders of diffraction, allowing for measurement of the transmitted radiation without absorption, thereby extending the device's lifetime and enabling operation at higher intensities, and optionally using higher orders of diffraction for further attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absorbent diaphragms are used to measure power density distribution at high intensities, then measurement capability is achieved, but the diaphragm material is eroded and the device degrades rapidly
Solution Approach 1:
The patent replaces the mechanical/absorptive measurement system (diaphragms that physically block and absorb light) with an optical/diffractive system. The diffractive structure on the substrate redirects light through diffraction into higher orders, allowing measurement without direct absorption by the measuring element, thus eliminating erosion and degradation.
Solution Approach 2:
The patent introduces a diffractive structure as an intermediary between the radiation source and detector. This intermediary redirects the light path through diffraction, enabling the detector to measure power density without the detector or substrate being directly exposed to high-intensity radiation that would cause degradation.
2Ease of operation
If transmissive materials such as ZnSe, GaAs, Ge, ZnS or Si are used as substrates for coupling out laser beam, then beam coupling is achieved, but cooling must be effected along the circumference and thermal conductivity is poor
Solution Approach 1:
The patent replaces the transmissive substrate approach with a reflective/diffractive approach. Instead of light passing through the substrate requiring thermal management, the diffractive structure on a reflective substrate redirects light through diffraction, eliminating the need for light transmission through the substrate and thus removing the thermal conductivity constraint.
3Reliability
If neutral density filters are used to attenuate laser beam to protect CCD camera, then camera protection is achieved, but distortions occur due to surface irregularities or thermal lens formation
Solution Approach 1:
The patent introduces a diffractive structure as an intermediary that attenuates light intensity through diffraction into higher orders rather than absorption. This provides intensity reduction without the thermal effects and surface irregularity distortions that plague neutral density filters, preserving measurement accuracy while protecting the detector.
Solution Approach 2:
The patent changes the mechanism of attenuation from absorption-based (neutral density filters) to diffraction-based. By utilizing the diffraction efficiency and redirecting light into higher orders, the system achieves intensity reduction without the harmful thermal and optical distortions associated with absorptive filters.
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
The diffractive structure-based device provides a longer operational lifetime, reduces material degradation, and allows for precise measurement of power density distribution, even at high intensities, enhancing measurement accuracy and cost-effectiveness.
Implementation Method 1
the first region comprises a diffractive structure designed to separate the light beam impinging on the substrate into a zeroth order of diffraction and at least one first order of diffraction
Data Source
AI summary
A device and method for measuring a power density distribution of a radiation source is provided. The device includes a radiation source designed to emit a light beam in a radiation direction; a substrate disposed downstream of the radiation source in the radiation direction and having an extent in an x-direction and a y-direction, the substrate having a first region and at least one further second region, and the first region comprises a diffractive structure designed to separate the light beam impinging on the substrate into a zeroth order of diffraction and at least one first order of diffraction; and a detector unit disposed downstream of the substrate in the radiation direction and designed to measure the intensity of the first order of diffraction transmitted through the substrate and to derive a power density distribution therefrom.