Beam Splitter Laser Measurement with Astigmatism Correction
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Solution Overview
Problem
Conventional laser beam measurement devices struggle to accurately measure the image shape and energy intensity distribution of high-energy laser beams due to damage from heat and saturation, as well as issues with beam splitters causing astigmatism and incorrect measurements.
Innovation Solution
A laser beam measurement device employing a plate-type beam splitter inclined at specific angles to attenuate the laser beam, combined with a calculation device for numerical correction of output data to adjust for transmittance and reflectance variations, ensuring accurate measurement without damaging image acquisition devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional filter is used to attenuate the laser beam, then the laser beam intensity is reduced for measurement, but the filter is deformed by heat from the laser beam causing measurement errors
Solution Approach 1:
The patent introduces a fluorescent plate as an intermediary substance that converts high-energy laser photons into lower-energy fluorescence photons. This mediator allows the laser beam energy to be transformed into a measurable form without directly exposing the measurement device to the full laser energy, thus preventing heat deformation while enabling intensity measurement.
Solution Approach 2:
The patent replaces the mechanical/optical filter system with a fluorescent conversion system. Instead of using a filter that physically blocks and absorbs laser energy (causing heat deformation), the system uses fluorescence emission to indirectly measure intensity, substituting a thermal-mechanical process with an optical-phosphorescent process.
2Measurement precision
If a pinhole, slit, or knife edge is used to measure transmitted light intensity, then the laser beam intensity distribution can be obtained, but the image shape of the laser beam is impaired
Solution Approach 1:
The fluorescent plate serves as an intermediary that captures the entire laser beam profile and converts it to fluorescence without requiring physical interruption of the beam path. This eliminates the need for pinholes, slits, or knife edges that would block and distort the beam, while still enabling intensity distribution measurement through the emitted fluorescence pattern.
3Illumination intensity
If a beam splitter is used to attenuate the laser beam, then the laser beam intensity is reduced for safe measurement, but astigmatism occurs causing incorrect measurement
Solution Approach 1:
The fluorescent plate acts as an intermediary that converts laser photons to fluorescence photons with different energy levels. This conversion process naturally attenuates the beam intensity suitable for measurement without requiring a beam splitter, thereby avoiding the astigmatism problem that occurs when beam splitters are used to reduce intensity.
4Reliability
If a fluorescent plate is used to convert laser beam to fluorescence, then the laser beam intensity can be measured safely, but the fluorescent image is blurred unless the plate is very thin
Solution Approach 1:
The patent optimizes the thickness parameter of the fluorescent plate to achieve the right balance between safety and clarity. By carefully selecting the plate thickness, the system ensures that the plate is thin enough to produce a clear fluorescent image without being so thin that it becomes vulnerable to laser damage, thus changing the physical parameter to resolve the contradiction.
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 precise measurement of laser beam image shape and energy intensity distribution at the spot, even with high-energy beams, by correcting for biases in the Y-axis direction, thereby improving processing quality in laser processing applications.
Implementation Method 1
a laser beam is attenuated through a filter... a method in which a transmitted light intensity is measured while a partial portion of the laser beam is shielded with a pinhole, a slit, or a knife edge
Implementation Method 2
the first beam splitter is disposed to be inclined at an angle α... with the X axis as a rotation axis
Implementation Method 3
a laser beam is emitted to a fluorescent plate and an intensity distribution of fluorescence emitted from the fluorescent plate is measured
Data Source
AI summary
A laser beam measurement device includes a plate-type first beam splitter, an observation device that reads an image of a spot formed by transmitted light or reflected light of a laser beam incident on the first beam splitter, and a calculation device that performs a numerical calculation on output data of the observation device to perform a correction, in which when certain coordinate axes orthogonal to each other on a plane perpendicular to an optical axis of a laser beam irradiation optical unit with origins of the orthogonal coordinate axes being located on the optical axis are defined as X and Y axes, the first beam splitter is disposed to be inclined at an angle α in a range of 30 degrees or more and 60 degrees or less with respect to the plane perpendicular to the optical axis with the X axis as a rotation axis.