Laser Marking Optics for Extended Focus Depth and Scan Field
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Solution Overview
Problem
Conventional laser marking systems have limited focal depth and scan field, making them inconvenient for marking targets with varying shapes and sizes at different positions, as they require precise alignment within a narrow working range to maintain high power density and accuracy.
Innovation Solution
A laser system with a configuration that includes a first optical element introducing spherical aberrations, followed by a second optical element that generates an essentially non-diffractive beam with a central focus volume extending over a longer working range, allowing for accurate marking across a broader area without the need for complex additional optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional laser focusing system with a single positive lens is used, then the laser beam can be focused to a small spot with high power density, but the focal depth is limited to approximately +/â1 mm, making it inconvenient for marking targets at varying positions
Solution Approach 1:
The optical system is divided into multiple optical elements (first positive lens, second positive lens, and optionally a negative lens) arranged in sequence, where each element contributes to extending the focal depth while maintaining the focusing capability. This segmentation allows the system to achieve both high power density and extended working range.
Solution Approach 2:
The patent changes the optical parameters by introducing multiple lenses with different focal lengths and positions. By adjusting the distances between lenses and their focal lengths, the system extends the focal depth from +/â1 mm to a much larger range while maintaining the ability to focus the laser beam to a small spot for high power density marking.
2Adaptability or versatility
If the focus depth is extended to accommodate targets at varying positions, then the scan field can be increased, but additional complex optical elements are required
Solution Approach 1:
The combination of optical elements serves multiple functions simultaneously: the first positive lens focuses the beam, the second positive lens extends the focal depth, and the negative lens (when present) further adjusts the beam parameters. This multi-functional arrangement achieves both extended scan field and focal depth without requiring separate systems for each function.
Solution Approach 2:
Multiple optical elements are merged into a single integrated optical system that works together to extend both the scan field and focal depth. The lenses are positioned at specific distances from each other to achieve the desired beam characteristics, combining their effects to produce an extended working range without needing additional complex components.
3Manufacturing precision
If the target surface is positioned outside the narrow working range, then the illuminated area increases and power density decreases rapidly, but precise alignment is difficult to maintain
Solution Approach 1:
The optical system is segmented into multiple elements that work together to maintain beam focus over an extended distance range. This allows the laser to maintain high power density on the target surface even when the target is positioned at varying distances, significantly increasing alignment tolerance while preserving marking accuracy.
Solution Approach 2:
By changing the optical configuration to include multiple lenses with specific focal lengths and spacing, the system extends the depth of field. This parameter change allows the target surface to be positioned outside the narrow working range of conventional systems while maintaining sufficient power density for accurate marking.
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 provides a significantly increased working range and focus depth, enabling efficient and reliable laser marking of targets with varying shapes and sizes, while maintaining high power density and accuracy, even when the target is positioned farther from the optical system than traditional systems allow.
Implementation Method 1
a first optical element configured to receive the laser beam, wherein the laser source and the optical system are configured to have the laser beam illuminate a predetermined illumination area of the first optical element, wherein the first optical element is shaped to introduce spherical aberrations in the received laser beam
Implementation Method 2
a second optical element arranged at a predetermined distance from the first optical element and configured to receive the intermediate beam, wherein the second optical element is shaped to introduce further spherical aberrations in the received intermediate beam, resulting in the generation of an essentially non-diffractive beam
Implementation Method 3
resulting in the generation of an essentially non-diffractive beam, wherein the essentially non-diffractive beam converges along an optical axis of the diffractive beam to produce a central focus volume extending over a working range along the optical axis
Data Source
AI summary
Disclosed is a laser marking system for marking an object, comprising a laser source, an optical system, and a targeting system. The laser source configured to generate a laser beam. The optical system comprises a first optical element and a second optical element. The first optical element is configured to receive the laser beam. The laser source and the optical system are configured to have the laser beam illuminate a predetermined illumination area of the first optical element. The first optical element is shaped to introduce spherical aberrations in the received laser beam, resulting in an intermediate beam produced by the first optical element. The second optical element is arranged at a predetermined distance from the first optical element and configured to receive the intermediate beam. The second optical element is shaped to introduce further spherical aberrations in the received intermediate beam, resulting in the generation of an essentially non-diffractive beam. The essentially non-diffractive beam converges along an optical axis of the