Methods and apparatus for controlling electron density distributions

A method of compressing a density distribution comprising bunches of electrons for coherent hard X-ray, soft X-ray and/or extreme ultraviolet emitted radiation generation, the method comprising:

• receiving a plurality of electron bunches having a density distribution;
• compressing the plurality of electron bunches such that distance between the bunches along a propagation direction of the electron bunches corresponds with a wavelength of hard X-ray, soft X-ray and/or extreme ultraviolet radiation to be generated;
• modulating momentum of the plurality of electron bunches;
• accelerating the modulated plurality of electron bunches;
• and
• colliding a laser beam with the accelerated and modulated plurality of electron bunches to produce the emitted radiation generation.

A method for generating an emitted radiation comprising hard X-ray, soft X-ray and/or extreme ultraviolet, the method comprising:

• generating pulses of electrons;
• modulating momentum of the pulses of electrons with an optical modulator;
• accelerating the pulses of electrons;
• and
• colliding a laser beam with the accelerated pulses of electrons for the emitted radiation generation.

A radiation source for generating an emitted radiation comprising hard X-ray, soft X-ray and/or extreme ultraviolet, comprising:

• a pulsed electron source configured to generate pulses of electrons;
• an optical modulator comprising an arrangement of a seed laser and a counter-propagating laser with different angles of incidence of the lasers and configured to modulate momentum of the pulses of electrons;
• an electron accelerator configured to accelerate the modulated pulses of electrons;
• and
• a pulsed laser configured to generate a laser beam colliding with the accelerated and modulated pulses of electrons to generate the emitted radiation.

A metrology apparatus comprising:

• a radiation source configured to produce emitted radiation comprising:
• a pulsed electron source configured to generate pulses of electrons;
• an optical modulator comprising an arrangement of a seed laser and a counter-propagating laser with different angles of incidence of the lasers and configured to modulate momentum of the pulses of electrons;
• an electron accelerator configured to accelerate the pulses of electrons;
• and
• a pulsed laser configured to generate a laser beam colliding with the accelerated and modulated pulses of electrons to generate the emitted radiation.