Frequency-Comb Distance Sensing for High-Range Laser Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser processing machines with OCT distance sensors face limitations such as small measurement range, insufficient z-resolution, and the need for complex and expensive spectrometer constructions.
Innovation Solution
A laser processing machine equipped with a frequency-comb-based distance sensor, which generates a sensor laser beam with a frequency comb that spectrally shifts over time, allowing for high-resolution distance measurements without the need for mechanical readjustment of the reference path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OCT distance sensors with motorized reference arms are used, then distance measurement capability is provided, but measurement range is limited to approximately 12 mm and requires hardware changes for adaptation
Solution Approach 1:
The patent replaces the motorized mechanical reference arm system with a fixed reference arm and uses optical frequency modulation (frequency combs) to achieve distance measurement. This substitution eliminates the need for mechanical readjustment while providing adaptable measurement ranges through software-controlled frequency tuning rather than hardware changes.
Solution Approach 2:
The invention changes the operational parameters of the distance sensor by using tunable frequency combs with adjustable spectral ranges. By varying the frequency comb parameters (spectral width, repetition rate) rather than mechanical dimensions, the system adapts measurement range and resolution through parameter adjustment instead of hardware reconfiguration.
2Measurement precision
If OCT distance sensors are used, then distance measurement is achieved, but z-resolution is insufficient for thin metal sheet processing requiring sub-μm precision
Solution Approach 1:
The patent employs dynamic frequency-comb-based measurement where the optical frequency is continuously tuned across a spectrum. This dynamic frequency modulation enables higher measurement precision by exploiting the time-bandwidth product relationship, achieving sub-μm z-resolution through rapid frequency sweeping rather than static measurement.
Solution Approach 2:
The invention uses periodic frequency comb generation with controlled repetition rates. By implementing periodic frequency modulation and analyzing the temporal interference patterns, the system achieves enhanced measurement resolution that exceeds conventional OCT capabilities, enabling precise measurement of thin metal sheets.
3Measurement precision
If OCT distance sensors are integrated into laser processing machines, then distance measurement is provided, but complex and expensive spectrometer construction with free-beam optical units is required
Solution Approach 1:
The patent merges the frequency comb generation, modulation, and detection functions into an integrated optical module that can be coupled with fiber-optic connections to the processing laser. This consolidation eliminates the need for separate free-beam optical paths and complex spectrometer assemblies, reducing system complexity while maintaining measurement precision through fiber-optic-based interferometry.
Solution Approach 2:
The invention introduces fiber-optic components as intermediaries to replace free-beam optical paths. By using optical fibers to guide and modulate the frequency comb beams, the system eliminates the need for complex free-space optical alignment and spectrometer construction, simplifying integration into laser processing machines while preserving measurement accuracy.
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 frequency-comb-based distance sensor provides a large axial measurement range with high axial resolution, improved signal quality, and cost-effective integration into laser processing machines, enabling precise geometric feature detection during laser processing.
Implementation Method 1
a laser source which is fed back in a frequency-shifted manner for generating a sensor laser beam with a frequency comb that spectrally shifts over time
Implementation Method 2
an evaluation device for ascertaining a distance value on the basis of a frequency difference, resulting from a time-of-flight difference between measurement beams and reference beams
Implementation Method 3
The sensor laser beam is divided into a measurement beam and a reference beam along a measurement path and a reference path, respectively
Implementation Method 4
a detector, on which returning measurement beams and returning reference beams are superposed
Data Source
AI summary
A laser processing machine for laser processing a workpiece by a processing laser beam includes a laser beam generator for generating the processing laser beam, a processing optical unit for directing the processing laser beam onto the workpiece, and a frequency-comb-based distance sensor. The distance sensor includes a laser source that is fed back in a frequency-shifted manner for generating a sensor laser beam with a frequency comb that spectrally shifts over time. The sensor laser beam is divided into a measurement beam and a reference beam along a measurement path and a reference path, respectively. The distance sensor further includes a detector, and an evaluation device configured to ascertain a distance value based on a frequency difference, resulting from a time-of-flight difference of the measurement beams and the reference beams superimposed on the detector, of two frequency combs originating from the measurement path and the reference path.