AFM Image of Cross Line Grating Replica 2,000 lines/mm cross line grating replica is suitable for X-Y calibration. The replicas have well-defined trench type grooves, which makes it easy to determine the 500nm pitch. This Grating Replica is a carbon replica with Au/Pd shadowing supported on a 400 square mesh, 3mm copper TEM grid which is mounted on a 12mm disc.