Ultrashort, high-brightness bunch length diagnostic with sub-femtosecond resolution

The determination of the longitudinal bunch parameter of light sources requires ever-increasing precision. As novel schemes to create bunches at the level of tens of femtoseconds become more widespread, the diagnosis of these bunches with increased resolution is necessary. Currently available techniques have resolutions on the order of tens of femtoseconds, but there is no technique that surpasses the femtosecond barrier. The diagnostic proposed by RadiaBeam Technologies exploits the angular modulation imposed on the beam during its interaction with a high power laser in the presence of a magnetic field. The trajectory projection on a distant screen produces a horizontal sweep of electrons. The resolution (on the plane of laser polarization), using standard imaging techniques, is on the order of 1/200 of the laser wavelength (for CO2 laser light, this corresponds to a resolution of 150 attoseconds). An additional angular kick in the perpendicular dimension, using a novel x-band travelling wave deflecting cavity, produces an observable sweep in the vertical dimension creating an oscillating trace proportional to the bunch length. Commercial Applications and Other Benefits: The proposed structure will allow the study of beam events on the sub-femtosecond time scale. This addresses needs of modern-day and future accelerators and light sources that necessitate precise resolution of longitudinal beam parameters. The resolution of the scheme is on the order of 1/200 of the laser wavelength, which can be used in other applications, such as precision timing systems, or as an optical streak camera, or fast oscilloscope with greater than 10THz bandwidth.