Abstract: A reflective optical system (100) comprising at least one reflective aspheric surface (1) of focal length f0 and optical axis (Z), the surface being configured so that an incident laser beam (2) propagating along an axis (Z?) is focused along the optical axis (Z) with a FWHM ((Full Width at Half Maximum) of the intensity of the reflected beam along the optical axis (Z) being larger, preferably by a factor of at least 10, than the FWHM of the intensity of a focused beam reflected by a parabola having same focal length f0 and same optical axis (Z), receiving same beam.

Abstract: A reflective optical system (100) comprising at least one reflective aspheric surface (1) of focal length f0 and optical axis (Z), the surface being configured so that an incident laser beam (2) propagating along an axis (Z?) is focused along the optical axis (Z) with a FWHM ((Full Width at Half Maximum) of the intensity of the reflected beam along the optical axis (Z) being larger, preferably by a factor of at least 10, than the FWHM of the intensity of a focused beam reflected by a parabola having same focal length f0 and same optical axis (Z), receiving same beam.

Abstract: A device for collimation or focusing of a relativistic electron packet, obtained in particular by laser-plasma acceleration, including a gas cloud and a laser capable of emitting a laser pulse focused in the gas cloud in order to create therein a wave of focusing electric and magnetic fields. The invention also relates to a device for emission of a collimated or focused relativistic electron packet. The invention further relates to a collimation or focusing method for a relativistic electron packet, and to methods for emission of a collimated or focused relativistic electron packet.

Abstract: A device for collimation or focusing of a relativistic electron packet, obtained in particular by laser-plasma acceleration, including a gas cloud and a laser capable of emitting a laser pulse focused in the gas cloud in order to create therein a wave of focusing electric and magnetic fields. The invention also relates to a device for emission of a collimated or focused relativistic electron packet. The invention further relates to a collimation or focusing method for a relativistic electron packet, and to methods for emission of a collimated or focused relativistic electron packet.

Abstract: A method for producing electromagnetic radiation comprising: firing a first laser pulse and generating a plasma region, the first laser pulse penetrating at least partially into the plasma region to create a plasma density wake in the plasma region; providing a group of charged particles in the plasma region arranged so as to be accelerated in the plasma density wake of the first laser pulse; reflecting the first laser pulse after the first laser pulse has penetrated into the plasma region, to give a reflected laser pulse; and arranging the reflected laser pulse to interact with the group of charged particles to generate an electromagnetic radiation.

Abstract: A method for producing electromagnetic radiation comprising: firing a first laser pulse and generating a plasma region, the first laser pulse penetrating at least partially into the plasma region to create a plasma density wake in the plasma region; providing a group of charged particles in the plasma region arranged so as to be accelerated in the plasma density wake of the first laser pulse; reflecting the first laser pulse after the first laser pulse has penetrated into the plasma region, to give a reflected laser pulse; and arranging the reflected laser pulse to interact with the group of charged particles to generate an electromagnetic radiation.