Tonutti, M.

Paper	Title	Page
THPLT044	Measurement of the Transverse Coherence of the TTF Free Electron Laser	2577
	R. Ischebeck, M. Tonutti RWTH, Aachen J. Feldhaus, E. Saldin, E. Schneidmiller, K. Tiedtke, R. Treusch DESY, Hamburg C. Gerth CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire P. Schmüser Uni HH, Hamburg M.V. Yurkov JINR, Dubna, Moscow Region
	The transverse coherence is important for many applications of a free electron laser (FEL). It depends on the inner structure of the electron bunch in the undulator, which is difficult to measure. It is therefore essential to determine the coherence properties of the FEL radiation directly. The coherence of the vacuum ultraviolet FEL at the TESLA Test Facility has been measured by recording the diffraction pattern of a double slit and measuring the visibility of the interference fringes. The experimental near field diffraction pattern is compared with a numerical model, taking into account the formation of the FEL radiation, the Fresnel diffraction in the near field zone and effects of the experimental set-up. Diffraction patterns have been recorded at various undulator lengths to measure the evolution of the transverse coherence along the undulator. This is compared to the expected evolution of the transverse radiation modes.
THOALH01	Bunch Length Measurements at the SLS Linac using Electro-optical Techniques	253
	A. Winter, M. Tonutti RWTH, Aachen S. Casalbuoni, P. Schmüser, S. Simrock, B. Steffen DESY, Hamburg T. Korhonen, T. Schilcher, V. Schlott, H. Sigg, D. Suetterlin PSI, Villigen
	The temporal profile of the electron bunches in the SLS Linac will be determined by means of electro-optical techniques. A mode locked Ti:Sa Laser with 15 fs pulse width is used for coincidence measurements between the laser pulse and the coherent transition radiation (CTR) generated by short electron bunches. Synchronization accuracy of 100 fs rms between the 3 GHz Linac RF and the 81 MHz repetition rate of the laser was achieved, which is important for the optimum time resolution of the applied electro-optical sampling technique. Likewise, a mode locked Nd:YAG laser with 400 ps long pulses will be used for electro-optical autocorrelation measurements between the CTR and the laser pulses. This alternative technique promises single shot capability and requires much relaxed synchronization stability between laser and electron beam.
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