  Transverse deflecting structures (TDS) are widely used in accelerator physics
to measure the longitudinal density of particle bunches. When used in
combination with a dispersive section, the whole longitudinal phase space
density can be imaged. At the Linac Coherent Light Source (LCLS), the
installation of such a device downstream of the undulators enables the
reconstruction of the X-ray temporal intensity profile by comparing
longitudinal phase space distributions with lasing on and lasing off. However,
the resolution of this TDS is limited to around 1 fs rms (root mean square),
and therefore, it is not possible to resolve single self-amplified spontaneous
emission (SASE) spikes within one X-ray photon pulse. By combining the power
spectrum from a high resolution photon spectrometer and the temporal structure
from the TDS, the overall resolution is enhanced, thus allowing the observation
of temporal, single SASE spikes. The combined data from the spectrometer and
the TDS is analyzed using an iterative algorithm to obtain the actual intensity
profile. In this paper, we present some improvements to the reconstruction
algorithm as well as real data taken at LCLS.
