  Strong field QED is an active research frontier. The investigation of
fundamental phenomena such as pair creation, photon-photon and photon-electron
interactions in the nonlinear QED regime are a formidable challenge -- both
experimentally and theoretically. Several experiments around the world are
being planned or in preparation to probe this strong field regime. LUXE (Laser
Und XFEL Experiment) is an experimental platform which envisages the collision
of the high quality 16.5 GeV electron beam from the European XFEL accelerator
with a 100 TW class high power laser. One of the unique features of LUXE is to
measure the key observables such as pair rates ($e^+e^-$) with unprecedented
accuracy in the characterization of both beams together with ample statistics.
The state-of-art detector technologies for high energy particle and photon
detection enable percent level precision. The state-of-art high power lasers
offer high quality laser beams, however, the residual shot-to-shot fluctuations
coupled with the large nonlinearity of the processes under investigation form a
particular challenge. An uncertainty of 5 percent on the absolute laser
intensity already leads to a very large ( about 40 percent) uncertainty in the
pair rate. Hence it becomes essential to control the laser parameters
precisely. To mitigate this issue a full suite of laser diagnostics is being
currently developed at the JETI40 laser in Jena with the aim of tagging the
shot intensity to less than 1 percent. In this presentation, details of the
laser and the diagnostics suit for the single shot tagging of all the laser
parameters will be presented. Moreover, results from an ongoing campaign to
properly relay image the beam without significant distortion of the laser beam
parameters for post-diagnosis will be discussed.
