In the never ending quest for better adapted and more efficient beamline instrumentation, optical devices for focusing X-ray beams have always had a very important place. Adapted means that the instrumentation must be tailored to given experimental requirements with the guideline "as simple as possible and as sophisticated as reasonably achievable". This is the reason why we have developed a great variety of focusing optics and why the activities in this field will always continue. Efficiency is closely related to the quality of the optical elements used, such as the figure and finish of surfaces, the accuracy of microfabrication, the quality of crystals and the mechanical precision and stability of supports, in particular for bending.

The first part of this chapter contains a series of reports on recently developed optics for focusing, starting off with two major systems, the famous Kirkpatrick-Baez (KB) double mirror device and the well-known compound refractive lenses (CRLs). In both areas impressive progress has been seen over the past year. Both devices permit to produce a spot size below the micron level and the so-called diffraction limit that is the ultimate performance is almost reached. Whereas the mirror based KB system is achromatic, the CRLs are not. The second contribution reports on the most recent results obtained with a two-dimensional waveguide, which is new, because until now this device concentrated the beam in only one direction. This device functions as predicted by theory and can be applied to many techniques, for example coherent imaging. The last but not least report describes a multilayer based Bragg-Fresnel optic that double focuses a hard X-ray beam to a not so small spot, but produces a focus size that is well adapted to the requirements from a protein crystallography beamline.

What can be done in visible light optics is often also possible in the X-ray domain. This has been proven many times and the shearing interferometer described in the following contribution is a beautiful example of this observation. The differential phase contrast seen in the pictures demonstrates the high quality of the manufacturing and allows us to use this device for wavefront evaluation, which is useful for following the quality of the X-ray beam before and after conditioning in a beamline.

The amount of flux that can be concentrated on the sample also depends on the amount of photons that can be digested by the first optical element of a beamline, very often a crystal monochromator. At the ESRF we have plans to increase the current from 200 to 300 mA. Will our cryogenic cooling technique of silicon crystals be capable of preserving the quality of beams generated by in-vacuum undulators? This question has been addressed in the last contribution where theoretical predictions from finite element analysis are compared to results from high heat load experiments. The excellent agreement even in detail - the dip in the rocking curve width where the crystal temperature corresponds to the zero thermal expansion point of silicon ­ show that we can have full confidence in the calculations. They also show that the power limit of about 450 W should not be exceeded for indirect cooling and that we therefore have to envision to use direct cooling in the future.

The detector is the last component in a beamline and it can be a limiting factor for the final data output rate of an experiment. It is therefore very important to dispose of high count-rate detectors that have to meet other needs as well, such as low noise, wide dynamic range and linearity. 2D pixel detectors are currently being developed and an example of this activity is presented is the last contribution. The results show that up to six orders of magnitude in intensity can be covered by such a detector allowing the 2D detection of diffuse scattering from quasicrystals.