Variable-Focus Laser Processing With Synchronized Surface Focusing
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Solution Overview
Problem
In laser processing machines, the use of a variable focal length optical system leads to difficulties in accurately concentrating a laser beam on a desired point of a workpiece, resulting in reduced accuracy due to changes in focus position.
Innovation Solution
A laser processing machine is designed with a variable focal length optical system that periodically changes focus position in response to a drive signal, incorporating a light source, detector, signal processor, and laser oscillator synchronized to ensure accurate focusing, along with a laser-processing mask and image sensor for enhanced precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a variable focal length optical system is used to reduce re-focusing operations, then productivity is improved, but manufacturing precision deteriorates due to focus position changes
Solution Approach 1:
The patent applies periodic action by cyclically changing the focal length of the objective lens to perform focus detection. The lens focal length is periodically varied between a first value (for detection) and a second value (for processing), enabling the system to detect surface position information at regular intervals without compromising processing accuracy. This periodic focal length variation allows the system to maintain high productivity while ensuring manufacturing precision through synchronized laser beam delivery.
Solution Approach 2:
The patent implements feedback by using the detected surface position information to control the laser beam delivery timing. The focus detection unit provides real-time feedback on the workpiece surface position, and this feedback is used to synchronize the laser beam output with the focal position, ensuring that the laser beam is delivered only when the optical system is properly focused on the workpiece surface.
2Productivity
If focus position is periodically changed for image detection, then productivity is improved, but laser beam focusing accuracy worsens
Solution Approach 1:
The patent applies periodic action by cyclically changing the focal length of the objective lens to perform focus detection. The lens focal length is periodically varied between a first value (for detection) and a second value (for processing), enabling the system to detect surface position information at regular intervals without compromising processing accuracy. This periodic focal length variation allows the system to maintain high productivity while ensuring manufacturing precision through synchronized laser beam delivery.
Solution Approach 2:
The patent introduces an intermediary element - a light detector - that mediates between the variable focal length optical system and the control system. The light detector receives light that has passed through the optical system and converted it into electrical signals, providing indirect measurement of focus position. This intermediary enables accurate focus detection without directly interfering with the laser beam processing path.
3Device complexity
If a shared optical system is used for observation and laser processing, then device complexity is reduced, but measurement precision deteriorates due to focus position instability
Solution Approach 1:
The patent applies universality by designing the objective lens to serve multiple functions: it acts as both the observation optical system lens and the laser processing optical system lens. This single lens performs dual roles of imaging for detection and focusing for laser processing, eliminating the need for separate optical systems. The focal length of this universal lens is periodically varied to enable focus detection while maintaining processing capability.
Solution Approach 2:
The patent implements feedback by using the detected surface position information to control the laser beam delivery timing. The focus detection unit provides real-time feedback on the workpiece surface position, and this feedback is used to synchronize the laser beam output with the focal position, ensuring that the laser beam is delivered only when the optical system is properly focused on the workpiece surface.
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
This configuration allows for highly accurate laser processing by ensuring the pulsed laser beam is focused on the workpiece surface, reducing the frequency of re-focusing operations and maintaining consistent image magnification, even with surface steps or inclinations.
Implementation Method 1
a liquid resonant lens whose refractive index is periodically changed in response to the drive signal
Implementation Method 2
a light detector configured to receive the detection light reflected on the workpiece
Implementation Method 3
when the detection light is focused on a surface of the workpiece
Implementation Method 4
a laser oscillator configured to oscillate a pulsed laser beam in accordance with the inputted synchronization pulse signal and radiate the pulsed laser beam on the workpiece through the variable focal length optical system
Data Source
AI summary
A laser processing machine includes: a variable focal length optical system in which a focus position is periodically changed in response to a drive signal to be inputted; a position-detection light source configured to emit a detection light onto a workpiece through the variable focal length optical system; a light detector configured to receive the detection light reflected on the workpiece and output a light detection signal; a signal processor configured to output a synchronization pulse signal in synchronization with the focus timing when the detection light is focused on the surface of the workpiece in accordance with the inputted light detection signal; and a laser oscillator configured to oscillate a pulse laser beam in accordance with the inputted synchronization pulse signal to radiate the pulse laser beam on the workpiece through the variable focal length optical system.