Mechanical-physical preparations

Replica techniques

Direct replica is used to make an inverted print of a specimen surface topography whenever the sample can not be inserted in the microscope, due to size or thickness.
Indirect replica is used to create a non inverted imprint of the surface topography by double molding of a specimen that can not be introduced in the microscope, due to size or thickness.

Extractive replica is used to extract particles from a substrate. Particles are captured in a carbon film (or in a polymer film), then the substrate is chemically dissolved.