Polygon Laser Scanning Optics for Thermal Drift-Free Processing
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Solution Overview
Problem
Existing laser processing apparatuses face challenges in maintaining the precise position of the laser beam's condensing point due to thermal expansion caused by friction heat, leading to potential displacement during processing.
Innovation Solution
The apparatus incorporates a scanning unit with a polygon scanner, a first lens with curvature in the X-direction to make the laser beam perpendicular to the workpiece, and a second lens with curvature in the Y-direction to condense the laser beam, ensuring the laser beam is scanned over the workpiece without moving the holding unit in the X-direction, thus minimizing thermal expansion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shaft unit using a ball screw or linear motor is used to move the holding unit, then the workpiece can be positioned and processed, but thermal expansion due to friction heat causes displacement of the laser beam condensing point
Solution Approach 1:
The patent replaces the mechanical shaft unit (ball screw or linear motor) with an optical scanning system consisting of a polygon scanner and lens assembly. The laser beam is scanned in the X-direction through the polygon scanner while the holding unit only moves in the Y-direction, eliminating the mechanical components that generate friction heat and thermal expansion, thereby preventing condensing point displacement.
2Productivity
If the holding unit is moved in the X-direction to scan the laser beam over the workpiece, then the entire workpiece can be processed, but thermal expansion from the moving mechanism causes processing position displacement
Solution Approach 1:
The patent divides the scanning function into two independent directions: the polygon scanner handles X-direction scanning by rotating to deflect the laser beam across the workpiece width, while the holding unit only moves in the Y-direction to position different sections of the workpiece under the laser. This segmentation eliminates the need for X-direction mechanical movement, preventing thermal expansion-induced positioning errors.
Solution Approach 2:
The patent transforms the traditional approach where the holding unit moves in both X and Y directions into a system where scanning is achieved through angular deflection in the X-direction (via polygon scanner rotation) while linear movement is restricted to the Y-direction only. This dimensional transformation separates the scanning function from the positioning function, eliminating friction heat generation in the scanning path.
3Ease of operation
If a conventional scanning system is used, then the laser beam can be scanned, but thermal expansion of the shaft unit and condensing lens holder causes the condensing point to deviate from the desired position
Solution Approach 1:
The patent replaces the mechanical scanning system (shaft unit moving the condensing lens) with an optical scanning system using a polygon scanner. The laser beam is reflected by the rotating polygon scanner mirrors to achieve scanning without mechanical movement of the condensing lens holder, thereby eliminating friction heat and preventing condensing point displacement while maintaining full scanning capability.
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 effectively suppresses displacement of the processing position by maintaining the laser beam's alignment and reducing thermal expansion impacts, while also reducing aberration and preventing debris from refilling processed grooves.
Implementation Method 1
a first lens that the laser beam from the scanner enters and is configured to have, in the X-direction, a curvature that makes the laser beam perpendicular to the workpiece held by the holding unit
Implementation Method 2
a second lens configured to have, in the Y-direction, a curvature that causes the laser beam emitted from the first lens to be condensed in the Y-direction
Implementation Method 3
the scanner is formed by a polygon scanner having a plurality of mirrors configured to reflect the laser beam emitted from the laser oscillator
Data Source
AI summary
A laser processing apparatus includes a laser oscillator that generates a laser beam to be condensed and applied to a workpiece held by a holding unit, and a scanning unit that scans the laser beam over the workpiece in an X-direction orthogonal to a Y-direction. The scanning unit includes a scanner that scans the laser beam emitted from the laser oscillator, in the X-direction, a first lens that the laser beam from the scanner enters and that makes the laser beam perpendicular to the workpiece, and a second lens that condenses the laser beam emitted from the first lens, in the Y-direction. A length in the X-direction of each of the first lens and the second lens is set equal to or more than a length in the X-direction of the workpiece held by the holding unit.