如题，该灯是如何判定的，根据定义？分布光度计能实现吗？
"directional lamp" means a lamp having at least 80 % light output within a solid angle of π sr (corresponding to a cone with angle of 120°); Cited from (EC) No 244/2009 of 18 March 2009 implementing Directive 2005/32/EC of the European Parliament and of the Council with regard to ecodesign requirements for non-directional household lamps