Laser Head Optical Element Positioning via Low-Coherence Interferometry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser processing machines face challenges in precisely controlling the position of optical elements along the laser beam path due to variations from installation errors, construction tolerances, and operating conditions, leading to inconsistent processing quality.
Innovation Solution
Employing low coherence interferometry techniques with detection in the space domain to accurately determine the local position of optical elements within the laser processing machine, using a system that integrates a measurement optical path with a reference path to measure deviations in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional laser processing machines are used without position monitoring, then the device complexity is lower, but the manufacturing precision deteriorates due to installation errors and construction tolerances
Solution Approach 1:
The patent replaces mechanical position measurement methods with optical interferometry. A measurement beam travels along a measurement optical path that includes the optical element, and interference between the measurement beam and reference beam enables precise position detection without mechanical contact or complex mechanical sensors
Solution Approach 2:
The patent introduces an optical interferometry system as an intermediary measurement mechanism. The system uses a measurement beam, reference beam, and sensor arrangement to indirectly detect optical element positions through optical interference patterns, avoiding direct mechanical measurement
2Manufacturing precision
If real-time position monitoring is implemented, then the manufacturing precision is maintained, but the device complexity increases due to additional measurement systems
Solution Approach 1:
The measurement optical path is designed to be integrated with the existing laser beam path, allowing the same optical infrastructure to serve both laser processing and position measurement functions. The system can monitor multiple optical elements simultaneously using the same interferometry setup
Solution Approach 2:
The sensor arrangement detects interference patterns and generates position information that can be fed back to the control system. This enables real-time monitoring and potential automatic compensation for position deviations, maintaining processing quality through continuous feedback
3Measurement precision
If low coherence interferometry is used for position determination, then the measurement precision is improved, but the difficulty of detecting and measuring increases due to specialized optical requirements
Solution Approach 1:
The patent extracts only the essential measurement function from complex interferometry systems. By using low coherence light sources and simplified detection in the space domain, it isolates the core position measurement capability from unnecessary complexity, achieving high precision with a streamlined setup
Solution Approach 2:
The system uses low coherence light sources (such as LEDs or superluminescent diodes) that are simpler and less expensive than traditional coherent laser sources for interferometry. These sources have shorter coherence lengths, which simplifies the interferometry implementation by reducing interference from multiple reflections
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, real-time monitoring of optical element positions, ensuring consistent laser processing quality by compensating for deviations caused by installation errors and operating conditions.
Implementation Method 1
generating a measurement optical beam M from a low coherence optical radiation source (100), said measurement optical beam being led towards an optical element (34), reflected by a back-reflective surface (S1, S2) of said optical element and led through the working head (14) towards a sensor arrangement (S)... generating a beam of reference low coherence optical radiation R... superimposing said measurement optical beam M and said reference optical radiation R... detecting the position of a pattern of interference fringes F between said measurement optical beam M and said reference optical radiation R
Data Source
Figure 1
Figure 2
Figure 3~4a
AI summary
A method and a system are described for determining the local position of at least one optical element associated with an optical path for transporting a laser beam in a working head of a machine for laser processing of a material, comprising: - generating a respective measurement low coherence optical radiation beam, leading the measurement beam towards the optical element and leading the reflected or diffused measurement beam from the optical element towards an optical interferometric sensor arrangement; - generating a respective beam of the reference low coherence optical radiation and the leading of the reference beam towards the interferometric optical sensor arrangement; - superimposing the measurement beam and the reference beam on a common region of incidence of the sensor means; - detecting the position of a pattern of interference fringes between the measurement beam and the reference beam on the region of incidence; and - determining a difference in optical length between the measurement optical path and the reference optical path as a function of the position of the interference pattern along an illumination axis of the region of incidence, or of the frequency of the interference pattern in the frequency domain, which is indicative of a difference between (a) the current local position of the optical element and (b) the predetermined nominal local position of the optical element.