Segmented Diffractive Beamforming for Elongated Laser Focus Zones
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radiation shape elements for laser processing of transparent materials struggle to produce elongated, slim radiation profiles with high aspect ratios that are diffraction-free in the direction of propagation.
Innovation Solution
A diffractive optical radiation forming element with a flat grid structure is used to impose a two-dimensional phase distribution on a laser beam, creating a phase distribution that generates a long, drawn-out focus zone in the material, free from diffraction effects in the propagation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional beam shaping elements are used, then the laser beam can be focused, but the focus zone is not elongated and diffraction-free in the propagation direction
Solution Approach 1:
The beam shaping element is divided into multiple angular segments with different azimuthal segment widths. Each segment is assigned a specific phase shift value to create a two-dimensional phase distribution that generates an elongated, diffraction-free focus zone in the propagation direction, resolving the contradiction between achieving proper beam shaping and maintaining focus precision.
Solution Approach 2:
Different regions of the beam shaping element (angular segments) are assigned different phase shift values and segment widths to create localized variations in the phase distribution. This local differentiation enables the formation of an elongated focus zone with precise control over the intensity distribution in the propagation direction.
2Device complexity
If the azimuthal segment widths of all angular segments are the same, then the phase profiles are uniform, but the focus zone cannot be elongated with high aspect ratio
Solution Approach 1:
The invention introduces asymmetry by assigning different azimuthal segment widths to different angular segments. This asymmetric segmentation, combined with specific phase shift values, creates a two-dimensional phase distribution that generates an elongated focus zone with high aspect ratio in the propagation direction, overcoming the limitation of uniform segment designs.
Solution Approach 2:
The invention transitions from one-dimensional radial phase profiles to two-dimensional phase distributions by incorporating azimuthal segment width variations. This dimensional expansion enables control over the focus zone shape in both radial and longitudinal directions, achieving elongated, diffraction-free focus zones with high aspect ratios.
3Adaptability or versatility
If elongated focus zones are created in transparent materials, then volume absorption can be tailored, but control over modification geometry becomes difficult
Solution Approach 1:
The invention enables independent control of multiple parameters including phase shift values, azimuthal segment widths, and segment grating phases. By adjusting these parameters, the two-dimensional phase distribution can be optimized to achieve both tailored volume absorption and precise control over modification geometry in transparent materials.
Solution Approach 2:
The invention replaces mechanical control methods with optical phase modulation. By using a diffractive optical beam shaping element to impose phase distributions, the system achieves precise control over focus zone geometry and volume absorption without mechanical adjustments, improving both adaptability and manufacturing precision.
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 solution enables the creation of elongated, diffraction-free focus zones in transparent materials, allowing for precise and efficient laser processing with tailored volume absorption, thereby improving the control over geometry and modification types in laser processing.
Implementation Method 1
diffractive optical beam shaping element for imprinting a phase distribution onto a transverse beam profile of a laser beam
Implementation Method 2
imposing a two-dimensional phase distribution on the laser beam, wherein the two-dimensional phase distribution causes the formation of the elongated focal zone
Implementation Method 3
focusing the laser beam with the focusing lens
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C
AI summary
The invention relates to a diffractive optical beamforming element (15) for applying a phase distribution to a transverse beam profile of a laser beam (5). Said beamforming element comprises mutually adjacent planar elements (15A), which compose a planar grid structure, in which each planar element (15A) is assigned a phase shift value and the phase shift values define a two-dimensional phase distribution (25). The planar elements (15A) are assigned to a plurality of angle segments (31, 31'; 33, 33'), each angle segment (31, 31'; 33, 33') having an azimuthal segment width (Δβj) with respect to the beam center position (23). The phase shift values form, in the angle segments (31, 31'; 33, 33'), respective phase progressions which are radially symmetrical with respect to the beam center position (23), which radially symmetrical phase progressions form grid functions in the radial direction, which grid functions have the same grid period (Tr). Each of the grid functions is assigned a segment grid phase (Θ). The azimuthal segment widths (Δβj) of at least two adjacent angle segments (31, 31'; 33, 33') differ. Alternatively or additionally, the segment grid phases (Θj) of at least two adjacent angle segments (31, 31'; 33, 33') have a segment grid phase difference (ΔΘj) between 0 and 2π.