The images above show the star SAO 68075 before and after closing the AO loop on the sodium laser guide star during June 1999. 

The K-band image improved from 0.65'' (left) to 0.19'' during a 200 sec integration on the Omega-Cass Camera. For this long exposure time a Strehl of 12% was achieved. 

The image at right shows the best 10 sec during which a Strehl of 23% was reached, and a diffraction limited core (0.14'') as well as diffraction rings are clearly visible. The high-order AO loop was closed on the LGS, correcting 18 modes at 75 Hz; tip-tilt was corrected on the star itself, offset by 10'' from the LGS. 

This excellent performance - the best we are aware of - shows the exciting future potential of adaptive optics with laser guide stars. 
 
More details can be found here.