  The first measurement of diffractive scattering of quasi-real photons with
large momentum transfer is made using the H1 detector at HERA. Single
differential cross sections are measured as a function of W, the incident
photon-proton centre of mass energy, and t, the square of the four-momentum
transferred at the proton vertex. The W dependence is well described by a
perturbative QCD model using a leading logarithmic approximation of the BFKL
evolution, whereas the measured |t| dependence is harder than predicted.
