F/Theta Lens System for High-Power Laser Applications
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Solution Overview
Problem
Conventional f/theta lens systems are inadequate for high-power laser applications above 1 kW due to thermal degradation, focus shift, and increased size and weight, limiting their use in materials processing.
Innovation Solution
A reduced f/theta lens system with at least two lenses, including a spherical meniscus lens and an aspherical focusing lens made of synthetic quartz glass, which maintains imaging quality and stability at high power densities by minimizing lens count and using low refractive index materials to compensate for higher-order imaging errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional f/theta lens systems with multiple spherical lenses are used, then imaging quality is maintained at moderate power levels, but thermal degradation and focus shift occur at high power levels above 1 kW
Solution Approach 1:
The patent changes the material parameter from conventional optical glass to synthetic quartz glass, which has superior thermal stability and lower absorption coefficients. This material substitution enables the lens system to maintain imaging quality at laser powers up to 10 kW by reducing thermal lensing effects and focus shift
Solution Approach 2:
The patent employs composite lens designs combining spherical and aspherical surfaces made from synthetic quartz glass. This composite approach allows simultaneous correction of spherical aberrations and thermal effects, achieving both high imaging quality and thermal stability at high power levels
2Manufacturing precision
If approximately six spherical lenses are used in conventional f/theta lens systems, then imaging quality is optimized for marking applications, but the system size and weight increase
Solution Approach 1:
The patent segments the optical function into two specialized lenses: a spherical meniscus lens for field flattening and an aspherical focusing lens for aberration correction. This segmentation achieves diffraction-limited imaging quality with only two lenses instead of six, significantly reducing weight while maintaining precision
Solution Approach 2:
The patent introduces aspherical lens surfaces to replace multiple spherical lenses. The aspherical geometry provides additional degrees of freedom for correcting higher-order aberrations, enabling high imaging quality with fewer elements and reduced system weight
3Manufacturing precision
If six spherical lenses are arranged in the beam path, then imaging quality is maintained, but the number of lenses and system complexity increase
Solution Approach 1:
The patent merges multiple optical functions into two composite lenses: the first lens combines field flattening and initial aberration correction, while the second lens combines focusing and higher-order aberration correction. This merging reduces the lens count from six to two while maintaining diffraction-limited imaging quality
Solution Approach 2:
The patent uses composite lens designs with both spherical and aspherical surfaces in synthetic quartz glass. This composite structure enables a single lens to perform multiple optical functions that traditionally required separate lenses, reducing overall system complexity
4Manufacturing precision
If conventional optical glass is used in lens systems, then imaging quality is achieved at low power, but absorption and overheating occur at high power levels
Solution Approach 1:
The patent changes the optical material parameter from conventional glass to synthetic quartz glass, which has absorption coefficients 3-5 times lower than conventional optical glasses. This parameter change enables high-power laser transmission by minimizing energy absorption and preventing overheating while maintaining imaging quality
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
The system achieves reduced size and weight while maintaining high imaging quality and stability at laser powers up to 10 kW, enabling effective beam focusing and minimization of spherical aberrations, astigmatism, and higher-order errors, thus facilitating high-power applications.
Implementation Method 1
at least one lens has one or two aspherical lens surfaces. Aspherical lens surfaces have additional degrees of freedom in comparison to spherical surfaces, by means of which in particular higher order imaging errors, which become particularly important at large scanning angles, can be compensated for
Implementation Method 2
The selection of the optical materials for the lenses takes place in particular with regard to low absorption of laser beam radiation, low thermo-optical effects and high stress resistance. An optical material that has low absorption of laser beam radiation, low thermal-optical effects, and high stress resistance can be considered to be a material that is stable when exposed to the laser beam radiation
Implementation Method 3
The selection of the optical materials for the lenses takes place in particular with regard to low absorption of laser beam radiation, low thermo-optical effects and high stress resistance
Data Source
AI summary
An F/theta lens system for focusing high-power laser radiation in a flat image field including at least two lenses. The at least two lenses are arranged sequentially in a beam path, where the at least two lenses are made from a material that is stable when exposed to laser radiation having a power of more than 1 kW, and at least one of the lenses has at least one aspherical lens surface.