ASTM E2491—2008《相控阵超声波检查仪和系统工作特性评定指南》标准为相控阵设备的测试提供了指导性规定。文章根据ASTM E2491—2008标准，在无楔块情况下测试相控阵系统的聚焦能力，确定激发晶片数、聚焦深度等因素对系统聚焦能力的影响。试验采用标准规定的试块，试验激发的晶片数量为8，16和32个，设置的聚焦深度为10，30，50，100，150以及200 mm。通过试验发现，在近场区内有明显的聚焦现象，而在近场区以外则无法聚焦;随着激发晶片数量的增加，相控阵系统的聚焦能力也随着增强;在近场区中，随着相控阵聚焦深度的增加，焦点尺寸逐渐增大。

ASTM E2491—2008 provides the standard guide for evaluating performance characteristics of phased array ultrasonic testing instruments and systems. In this paper，we use the phased array technology to measure the beam focusing capability of phased array ultrasonic in direct contact condition according with ASTM E2491—2008, so that we can identify the causes and effects of the focusing capability in the factors such as the number of elements and the focal depth. In the test, the block designed in ASTM E2491—2008 was used, the elements used were 8,16 and 32,and the focal depths used were 10, 30, 50, 100, 150 and 200 mm, respectively. Through the test, we could find the focusing phenomenon clearly in the near field and we could not find this phenomenon outside the near field. When the elements used in the test increased, the focusing ability of the PAUT system increased as well. In the near field, when the focal depth increased, the focal spot size increased too, as well.