The working distance of 65mm ensures that objects with highly sloped topography can be measured, and the measuring range of 180mm in Z and 110mm in X and Y ensures that a wide size-range of objects can be accommodated. Thus the microscope is capable of characterising both a vole tooth and a primate skull with the same degree of accuracy. The observer, by rotation of the specimen and the judicious use of reference points, can map relationships between any other points on the total surface.

The best resolution is dependent upon the diameter of the chosen light spot, and the magnification. 
This provides flexibility in the measurement options available to the observer, allowing matching of the instrument performance to the accuracy requirements.

Good repeatability is rapidly acquired as observation skills are developed. When the microscope is used in the manual mode, the repeatability of measurement relies upon the skill of the operator in aligning the light spot with the observation point in all three axes. This skill is developed rapidly with familiarity with the joystick control in relation to the X & Y axes, and repeatable positioning to within 2µm should be expected. Skill in measurement in the Z axis is a little more difficult to acquire, but repeatability of better than about 6µm can be obtained within one or two extended practice sessions. This further improves with practice, typically to 3 to 4µm. The microscope can also be used in a pre-programmed or automatic mode in X and Y, motoring to a predetermined point with a precision of approximately 1µm.

Absolute accuracy is improved by calibration

Under laboratory conditions, the limits of accuracy are substantially those imposed by the specifications of the optical encoder scales and the orthogonality of the three measurement axes. Linear axis calibrations are carried out at RML before despatch, and the correction factors are loaded into a specified software file. Similarly, orthogonality corrections are loaded at RML. A calibration artefact is provided to allow checking (and, if necessary, recalibration) of Z-X and Z-Y orthogonality. RML laboratory calibrations are undertaken at 20°C, and if absolute measurements are required at other ambient temperatures, correction factors of 0.1µm/°C/10mm should be applied on each axis. Values of absolute accuracy quoted in the Technical Specification are conservatively estimated, based upon calibration tolerances and scale linearity errors.