Ideal for determining "flat field" resolution across field of view. Diameter is 38.1mm with a USAF 1951 Resolving Power Target reproduced 9 (nine) times. Each image includes Group 2, Element 1 (4lp/mm) through Group 7, Element 6 (228lp/mm). Clear pattern on an opaque field.(Negative) Patterned on stable glass etched in reflective chrome, on top surface. (Right reading looking at.)
