Beam shaping of ultrashort laser pulses by means of acousto-optic deflection and refraction

重复率为几MHz，平均功率超过50W的超短脉冲激光已在商业上获得。从理论上讲，这种激光确实允许以更高的消融率进行微结构。然而，在目前的实践中，波束引导和整形技术存在严重的局限性。该项目的主要目标是利用声光偏转和折射技术、实验分析和理论进展，为新一代超短激光脉冲的导光和整形方法奠定基础。我们的初步研究表明，通过使声光偏转器的控制信号与超短激光脉冲的发射同步，可以实现快速柱面透镜自由光束引导和基本光束整形。我们的发现有力地表明，该项目的主要目标可以通过开发控制信号来实现，控制信号允许使用衍射操作模式进行光束引导、光束整形和光束分裂。利用这种方法，光束的各部分可以独立于同一光束的其他部分来引导和整形，而光束的形状和光束分裂可以从一个激光脉冲改变到下一个激光脉冲。此外，我们打算开发可用于使声光偏转器通过折射而不是衍射来工作的控制信号。为了达到本研究方案的目的，需要建立分析模型，并规划、实现和表征实验装置。为了证明新方法的有效性，我们还打算在微结构方面进行实验。预计原型实现和应用将确定和解决将新技术转化为应用的实际挑战。通过实际论证，使创新的高度具体化、明了、醒目。在微结构中，可以使用更少的脉冲和更高的重复率来产生几何结构，从而实现远高于今天可能的消融率。

Ultrashort pulsed lasers with repetition rates of several MHz and an average power of more than 50 W are commercially available. In theory such lasers do allow for microstructuring at increased ablation rates. However in current practice, the beam guiding and shaping technology provoke severe limitations. Concurrent machinery, for example, does not allow the user to efficiently use the available pulse energy or repetition rate in the micro production technology.Primary objective of the project is to found the basis of a new generation of novel beam guiding and shaping methods of ultrashort laser pulses by the use of acoustooptical deflection and refraction technologies, experimental analysis and theoretical advances. Particularily, we seek to significantly reduce limitations in microstructuring caused by concurrent beam guiding and beam shaping systems.Our preliminary research shows, that fast and cylinder lens free beam guiding and basic beam shaping is possible by synchronizing the control signal of the acoustooptical deflector with the emission of the ultrashort laser pulse. Our findings strongly indicate, that the primary objective of the project can be achieved by developing control signals, which allow for beam guiding, beam shaping and beam splitting using diffractive mode of operation. With such methods fractions of a beam can be guided and shaped independently from other fractions of the same beam while beam shape and beam splitting are alterable from one laser pulse to the next one. Furthermore we intend to develop control signals that can be used to allow acoustooptic deflectors to operate by refraction instead of diffraction. Then, diffractive power losses due to diffraction can be prevented.To achieve the aim of this research proposal analytical models need to be developed and an experimental setup has to be planned, realized and characterized. To demonstrate the effectiveness of the new methods we also intend to carry out experiments in microstructuring. Prototypical implementation and application is forseen to identify and solve practical challenges of transferring the novel technology to the application. By practical demonstration we intend to make the high degree of innovation concrete, obvious and striking. In microstructuring, geometric structures may be produced using less pulses and higher repetition rates enforcing desirable ablation rates that are far higher than those possible today.