title: The Use of Standard Test Lenses for Verifyingthe Accuracy of OTF Equipment.
abstract: The design and development of a 50-mm plano-convex lens as a test standard for OTF equipment is described. The lens has been used for checking and comparing OTF measurements made by laboratories in several different countries, and the preliminary results and conclusions of this investigation are also described.
authors.forename: T L
authors.initials: TL
authors.lastname: Williams
authors.forename: A
authors.initials: A
authors.lastname: Ashton