sentences:  It was built between 1983 and 1986, with first light in 1988.It has a 70-centimetre (28-inch) diameter primary mirror and a focal length of .Thanks to an adaptive optics system "KAOS" ("K"iepenheuer-institute "A"daptive "O"ptic "S"ystem), in operation since spring 2000, it is able to resolve details down to 0.2 arc seconds (150 km) on the Sun's surface.