For thin film ablation one can often not take full advantage of the relatively high output power and high pulse energy of lasers. A solution might be the use of parallel processing technique with multiple beams which help to increase process speed and to save process costs. Within this contribution we demonstrate thin film scribing of GZO and ITO which shows the potential of parallel processing combined with Top-hat beam shaping. The beam shaping optic provides process optimized beam profiles leading to a more efficient process and an improved ablation quality.
The Gaussian laser beam profile is for many applications in laser micromachining not optimally adapted. Therefore process optimized beam profiles with e.g. Top-Hat or torus shape are required to improve process quality. Other applications require multiple beam-lets for parallel processing to increase process efficiency. TOPAG’s new diffractive FBS (Fundamental Beam-Mode-Shaper) concept allows the generation of square, round or line Top-Hat profiles with near diffraction limited size for smallest possible patterning and spot sizes with just a few micrometers. FBS elements can be placed at nearly any position within the beam path and do not substitute the focusing system (objective) but can be integrated in existing optics. Furthermore the FBS beam shapers feature very homogeneous beam profiles (+/- 2.5%), a high efficiency (> 95%) and simplified handling. In combination with diffractive beam splitters the quality and throughput of the laser process can be improved as a result of several optimized beams from just one beam source. TOPAG presents also application results using FBS shapers and diffractive beam splitters for OLED scribing.
An optical beam shaping system based on a single Computer Generated Hologram has been realized. It focuses a laser beam with Gaussian profile to a square area with uniform intensity. In order to achieve a rectangular focal spot which is as close as possible to the size of the diffraction spot, we investigated two different hologram calculation methods. The first is based on a ray tracing approach, while the second one uses an iterative Fourier transform algorithm. Computer simulations and experimental results are shown.
We propose a real-time phase visualization technique using a phase conjugating mirror. An image of the phase derivative is formed in a coherent optical differentiation system and reflected by the phase conjugating mirror. After passage of the reflected light through the original phase object, its phase variation is compensated and its amplitude vanation only remains. This amplitude value is the derivative of the phase function and is fed to a second coherent optical integration system. An image inradiance of the output of this system is proportional to the square of the phase variation. This allows a neal-time quantitative visualization of actual object phase. There are no limitations to the phase objects in relation to the fine structures and large variations. Design of the setup for implementation of phase visualization is discussed. Computer simulations and experimental results are demonstrated.
A new kind of amplitude-encoded phase-only filter (AE POF) is presented. The interference of the Fourier phase value with a tilted plane reference wave encodes the pure Fourier phase information of the object wave and results in an off-axis phase-only filter (OA POF). After the binarization step the filter function is recorded directly into the recording medium in final size using a laser scanner. Comparing them with the conventional matched filter, the conventional phase-only filter, and the AE
POF, as well as their binary versions, we discuss the performances of OA POFs (OA BPOFs), present computer simulations, and demonstrate experimental results.
A real-time phase visualization technique is proposed which utilizes a phase conjugating mirror that reflects an image of the phase derivative formed within an optical differentiation system. The technique compensates for the phase variation, and the amplitude variation is handled by a coherent optical integration system, allowing real-time quantitative visualization of the actual object phase. Computer simulation and experimental results demonstrate the implementation of the phase contour visualization.