This folder contains data sets of x-y image simulations performed
for the LCLS using the three-screen method. The measurement
section is located after the first bunch compressor (BC1) at
a constant energy of 250 MeV (for all cases).

For each measurement we use 1 image per screen with no
background-images. Each OTR screen has 320 pixel in the x-direction,
240 pixel in the y-direction). The calibration of the screens is always
10 microns/pixel. It is the same for all files in both planes.

The data sets are:

1). OTR11_0.tif, OTR12_0.tif, and OTR13_0.tif
2). OTR11_n.tif, OTR12_n.tif, and OTR13_n.tif
3). OTR11_m.tif, OTR12_m.tif, and OTR13_m.tif

The first file set is a matched beam, the 2nd is the same, but with increased
pixel noise, while the last represents a poor beta match (and nominal noise).

The design twiss parameters on the first screen (60 deg phase
advance from screen to screen) are:
beta_x  = 3.133 m
alpha_x = 1.733
beta_y  = 3.133 m
alpha_y = 1.733

The transfer matrices are the same for all cases and are trivial to compute, since
the 3-screen system is simply a long drift with distance between screens:
L  = 1.356196 m (screen-1 to 2 and also screen-2 to 3).