Visual Testing by PCN.  This Classroom Training Handbook is published by PCN and covers the PCN examination syllabus for the Visual Testing NDT method. It is essential reading for candidates in the PCN level 2 and level 3 certification examinations described in PCN/GEN appendix E5, and is intended for use by instructors and students on PCN-approved training courses covering this method, although it may be found equally useful by those preparing themselves for other examinations covering Visual Testing. Contents: Overview. Physics of light, The eye and vision, Environmental conditions, Light sources, Optical aids, Measuring equipment, Temperature measurement, Surface conditions, Inspection procedures, Recording & reporting, Definitions.