Beam Angle : The beam angle or angle of incidence is the angle between the normal to a plan surface of the specimen and the axis of the beam in the specimen. It is a function of the specimen material. (RP 2X)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}