Laser Marking Transparent Optical Elements
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Solution Overview
Problem
Existing methods for marking transparent optical elements, such as spectacle lenses, face challenges in producing high-precision, permanent, near-surface markings using laser radiation, particularly due to materials' low absorption in the visible spectral range and issues with conventional laser technologies like excimer and CO2 lasers.
Innovation Solution
A method utilizing laser radiation with a working wavelength between 1.1 µm and 9.2 µm, offering partial absorption (60-98% transmittance) to achieve material changes near the surface, allowing for high-precision markings without the need for auxiliary absorption layers and simpler laser processing systems, enabling finer structures and improved productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser radiation with wavelengths in the visible spectral range is used for marking transparent optical elements, then the material absorption is low, but the marking precision and visibility are insufficient
Solution Approach 1:
The patent changes the wavelength parameter of the laser radiation from the visible spectral range to the infrared spectral range (specifically 8-10.6 µm). This parameter change exploits the strong absorption characteristics of transparent optical materials in the infrared range, enabling precise and visible markings while maintaining material integrity through controlled thermal effects.
2Use of energy by moving object
If CO2 lasers are used for marking transparent materials, then the absorption is improved, but the equipment complexity and maintenance requirements increase
Solution Approach 1:
The patent replaces complex CO2 laser systems with simpler, more economical laser sources operating in the 8-10.6 µm wavelength range. This substitution maintains the beneficial absorption characteristics while reducing equipment complexity and maintenance requirements, making the marking process more accessible and cost-effective.
3Manufacturing precision
If high power density laser radiation is used for marking, then material removal occurs, but debris is generated on the surface
Solution Approach 1:
The patent changes the laser radiation parameters by using wavelengths in the 8-10.6 µm range with controlled power density. This parameter change enables material modification through thermal effects without excessive ablation, thereby achieving clear markings while minimizing or eliminating surface debris generation.
4Manufacturing precision
If excimer lasers are used for marking, then ultraviolet radiation is generated, but atmospheric oxygen reacts to form ozone and weaken laser intensity
Solution Approach 1:
The patent avoids the use of excimer lasers that operate in the ultraviolet range and instead uses infrared laser radiation (8-10.6 µm). This choice eliminates the problem of atmospheric oxygen reacting to form ozone, as the infrared radiation does not have sufficient energy to break molecular bonds in oxygen, thereby maintaining laser intensity without requiring special atmospheric conditions.
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 approach enables cost-effective, high-precision, and high-productivity marking of transparent optical elements with reduced equipment complexity and maintenance, achieving permanent, visible markings without material removal debris, and allowing for the production of microlens arrays with raised structural elements.
Implementation Method 1
a working wavelength for which the material of the optical element shows partial absorption with a transmittance between 60% and 98%
Implementation Method 2
a marking area of the optical element is irradiated with laser radiation to produce local material changes near the surface
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In a method for producing a permanent marking in an optical element consisting essentially of a material transparent in the visible spectral range, a marking area of the optical element is irradiated with laser radiation to generate local, near-surface material changes such that a marking of a predefinable shape and size is produced. The laser radiation has a working wavelength λ in the wavelength range between 1.1 µm and 9.2 µm and is selected depending on the material of the optical element such that the material of the optical element exhibits partial absorption with a transmittance between 60% and 98%. Preferably, a thulium-doped fiber laser is used as the laser radiation source. The method can be used, in particular, to provide spectacle lenses, contact lenses, or intraocular lenses made of plastic with markings that have raised structural elements.