Precise measurement of spatial coherence and axial brightness based on the Wigner function reconstruction in transmission electron microscopes with field emission guns and a thermionic emission gun.

The spatial coherence and the axial brightness of a cold field emission gun, a Schottky field emission gun and a lanthanum hexaboride thermionic gun are precisely measured. By analyzing the Airy pattern from a selected area aperture, various parameters including the spatial coherence length are determined. Using the determined coherence length, the axial brightness of the field emission guns is estimated using the equation which we previously derived based on the discussion of the Wigner function of an electron beam.

Phase locking of a mode-locked titanium-sapphire laser-based optical frequency comb to a reference laser using a fast piezoelectric actuator.

We phase lock an octave-spanning optical frequency comb, generated using a mode-locked titanium-sapphire laser and a photonic-crystal fiber, to a continuous-wave laser line-narrowed to a reference cavity. To phase lock the pulse-repetition frequency, the cavity length of the mode-locked laser is controlled by using a fast piezoelectric-actuated mirror of a servo bandwidth up to 80 kHz. The residual phase noise is 0.