Agilent Technologies Nano Indenter G200 User Manual page 299

Theory 7
At its most basic level, IIT employs a high-resolution actuator to force
an indenter into a test surface and a high-resolution sensor to measure
continuously the resulting penetration. One of the great advantages of
this technique is that the contact area under load can often be inferred
from the continuous load-displacement data alone. In other words, the
residual hardness impression does not have to be directly imaged, thus
facilitating property measurement at the sub-micron scale.
Hardness (H) and elastic modulus (E) are the properties most frequently
measured by IIT. Thus, the purpose of this chapter is to present the
models used to derive these properties from basic IIT data.
Agilent Nano Indenter G200 User's Guide 7-2