The NanoTest measures the movement of a stylus in contact with a surface. For indentation measurements, the stylus is impressed into the surface under the influence of an increasing load; after reaching a pre-determined maximum value, the load is reduced and the penetration depth decreases due to elastic recovery of the deformed material. The depth and load are monitored continuously, which allows both hardness and Young's modulus data to be derived. In the scanning module, a static or increasing load is applied as the specimen is moved perpendicularly to the stylus axis, and variations in topography, scratch resistance or frictional force are indicated.

As shown, the NanoTest utilises a pendulum pivoted on frictionless bearings. A coil is mounted at the top of the pendulum; with a coil current present, the coil is attracted towards a permanent magnet, producing motion of the diamond towards the specimen and into the specimen surface. The displacement of the diamond is measured by means of a parallel plate capacitor, one plate of which is attached to the diamond holder; when the diamond moves, the capacitance changes, and this is measured by means of a capacitance bridge. The capacitance bridge unit is located close to the measuring capacitor in order to minimise stray capacitance effects.

Specimen manipulation is by means of three DC motors driving micrometer stages in an XYZ configuration.

The limit stop shown defines the maximum outward movement of the diamond, and also the operating orientation of the pendulum, when a load is applied. Its position is manually adjusted with a micrometer.

A main electronic control unit receives an AC signal from the capacitance bridge. This is then amplified, rectified, digitised and transferred via the IEEE bus to the computer. In addition, the control unit contains a ramp generator which supplies the coil current.

Schematics of data obtainable in the indentation and scanning modules are shown on the right.