Laser Interference Optics With Adjustable Period and Low Power Loss
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Solution Overview
Problem
Current direct laser interference structuring methods are costly, inflexible, and suffer from significant power losses, especially when using diffractive optical elements, and are limited to specific wavelengths and interference patterns.
Innovation Solution
An optical arrangement where a laser beam is split at 45° and directed through a series of beam splitters and penta mirrors, allowing for adjustable interference periods by displacing a reflecting element, enabling flexible structuring with different wavelengths and pulse lengths without significant power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If diffractive optical elements (DOEs) are used to split the laser beam, then the beam splitting function is achieved, but significant power losses occur and the damage threshold is low
Solution Approach 1:
The patent replaces diffractive optical elements (DOEs) with a combination of reflective beam splitters and penta mirrors. This substitution eliminates the power losses and low damage threshold associated with DOEs while maintaining the beam splitting function. The reflective elements achieve beam division without the energy dissipation inherent in diffractive methods.
2Device complexity
If DOEs are used for beam splitting, then the configuration is compact, but the production costs are high and the element is designed for only one wavelength
Solution Approach 1:
The patent employs reflective beam splitters and penta mirrors that can handle multiple wavelengths, unlike DOEs which are wavelength-specific. This universal approach allows the same optical configuration to work with different laser wavelengths without requiring wavelength-specific component design, thereby achieving versatility while maintaining a compact arrangement.
3Device complexity
If reflective elements are used to split the laser beam, then the configuration is simple, but no influence on the interference period is possible and the arrangement is prone to adjustment
Solution Approach 1:
The patent introduces a movable reflecting element that can be displaced parallel to the optical axis to dynamically adjust the interference period. This dynamic capability transforms a static reflective configuration into an adjustable system, allowing the interference pattern to be tuned without changing the fundamental simplicity of the reflective element approach.
4Adaptability or versatility
If two bi-prisms are used to generate interference patterns, then the configuration is known, but the energy distribution is highly dependent on alignment and no more than two partial beams can be used
Solution Approach 1:
The patent uses a first beam splitter to divide the laser beam into two partial beams, then uses a second beam splitter to further divide one of these into two additional partial beams. This segmented approach creates multiple interfering beams (up to three or more) from a single laser source, overcoming the limitation of bi-prism systems that can only produce two beams.
5Loss of energy
If the paths covered by individual partial beams differ significantly, then power losses occur, but maintaining equal paths limits the flexibility of the optical arrangement
Solution Approach 1:
The patent introduces compensating optical elements (such as additional mirrors or path-length adjustment mechanisms) that act as intermediaries to equalize the optical paths of different partial beams. These intermediaries allow the system to maintain equal path lengths for minimal power loss while preserving the flexibility to configure different beam arrangements and interference patterns.
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 solution provides a cost-effective, flexible, and efficient method for direct laser interference structuring, capable of varying interference patterns and accommodating different wavelengths and pulse lengths, with minimal power loss, enhancing the adaptability and precision of the structuring process.
Implementation Method 1
a laser beam emitted by a laser radiation source is directed onto a reflecting element and reflected by this reflecting element which is aligned at an angle of 45° with respect to the optical axis of the laser beam
Implementation Method 2
The laser beam reflected by the reflecting element impinges on a first beam splitter, with which the reflected laser beam is divided into two partial beams
Implementation Method 3
A transmitted second partial beam obtained with the first beam splitter impinges on a first penta mirror, in particular a roof penta mirror (roof penta mirror) or a pentaprism and is thus, after multiple reflection and/or refraction, parallel to the optical axis of the first partial beam directed to the focusing optical element
Implementation Method 4
the partial beams, which are aligned with their optical axes parallel to one another, are directed onto this surface in an interfering manner with the focusing optical element, which is preferably a lens, in order to form a structure on or in the region of a surface
Implementation Method 5
direct laser interference structuring (DLIP)... the partial beams, which are aligned with their optical axes parallel to one another, are directed onto this surface in an interfering manner
Data Source
Figure 1a~1b
Figure 2
Figure 3~4
AI summary
The invention relates to an optical arrangement for direct laser interference structuring, wherein a laser beam is directed to a reflecting element having an inclined reflecting surface. According to the invention, the reflected laser beam strikes a first beam splitter, by means of which it is divided into two partial beams and one partial beam is deflected in the direction of a focusing optical element. A second partial beam is directed to a first pentamirror and thus, after multiple reflection and/or refraction, the focusing optical element, or it is directed to a second beam splitter, by means of which it is divided into a first partial beam of the second partial beam and a third partial beam. Said partial beams are directed to the focusing element by means of a first pentamirror. According to the invention, the partial beams are directed by means of the focusing optical element to the surface to be structured in a manner interfering with each other. The reflecting element can be moved in a translational manner, maintaining the angle of 45°, parallel to the optical axis of the laser beam emitted by the laser beam source, in order to influence the interference period Λ.