A new optical system for moiré methods

A new optical system for moiré methods is proposed in which the light path from the model grating and that from the master grating are diffent. They are combined by mirrors to form moiré patterns. Its application to Ligtenberg's reflective moiré method extends the method to dynamic problems and also facilitates the use of linearmismatch fringes. It can also be applied to in-plane moiré method in cases where deformation is large and diect contact with model grating is to be avoided.