## 1 Introduction  
The demonstration of the first working laser had opened up a door for photonics, a new technology that revitalized a number of fields of the physical, chemical and biological sciences. One of the early directions of its research was to reach short light pulses to make phenomena visible which are happening too fast even for high-speed photography to resolve. The technological development was so successful that the pulse durations overtook easily the response time of available electronic detectors at the time. Mode locking, as a method for the generation of short pulses, was suggested [1] and demonstrated [2] in 1964. It is well known from the Fourier analysis that the transform limited time duration of a pulse can be decreased when the broader spectrum is applied. In the 1970s, dyes, as laser materials with broad spectra, provided the breakthrough to the picosecond regime [3], later leading to the first femtosecond-scale laser pulses [4]. Colliding pulse mode-locking was the premiere technique for ultrashort pulse generation for more than a decade, and allowed for achieving pulse durations as low as 27 fs in 1984 [5]. Three years later, the compensation of the spectral phase up to the third order by prism and grating compressor combinations resulted in a 6 fs pulse duration by [PERSON] _et al._[6]. In the meantime, a new laser material was introduced and turned out to be even more advantageous for ultrashort pulse generation. The titanium-doped sapphire crystal [7] as a gain material took over the role of dyes, since broader gain bandwidth, better thermal properties and convenient handling made femtosecond lasers simple and reliable light sources. However, the fundamentally different properties of this material required the invention of a new mode-locking technique [8], identified later as Kerr-lens mode-locking [9], which enabled the Ti:sapphire lasers to achieve the same record of pulse duration [10, 11]. Once ultrashort laser pulse generation had become a routine process, researchers turned toward reaching extreme high pulse intensities. Relatively early it became obvious that although direct amplification of laser pulses proved to be a successful method in the nanosecond pulse length regime, this technique is not applicable for ultrashort pulses, since self-phase modulation and related effects would arise during amplification. This issue was addressed by [PERSON] and [PERSON] when they suggested _chirped-pulse amplification_, _CPA_[12], which later revolutionized the processes of amplified ultrashort laser pulse generation. In conventional laser laboratories, the advantages of this technique, such as economic space requirements and cost-efficient realization, promoted the design of table-top laser systems with peak intensities in the terawatt order. In the meantime, leading laboratories paved the way to the generation of petawatt-level lasers. A _CPA_ system generally consists of four main stages. A _mode-locked oscillator_ emits laser pulses of a few nJ pulse energy and a broad bandwidth. These seed pulses travel through a _stretcher_ first, in which the various spectral components cover different distances, thus the pulses will be lengthened in time by four-six orders of magnitude. An increase in pulse length induces a decrease in field strength and therefore also the maximum intensity of the laser pulse. This sufficiently reduced intensity enables the amplification of the pulses in the following stage so intensively, that the saturation level of the amplifying medium can be reached without damaging the optical elements, and the beam can be kept free of nonlinear distortions. In the final stage of _CPA_ systems, a temporal compression of optically amplified pulses is carried out by the _compressor_. The role of this unit is principally the inverse compared to that of the stretcher, since it restores the spectral phase shift of the entire system to bezero. Beside this function, the compressor must be able to maintain the spatial and temporal shape of the pulses, which is a rather complex task.