Abstract: An apparatus and method for surface profile measurements of large samples. The sample is held by a stationary chuck, while a four-axis (X, Y, Z and theta axis) positioning assembly manipulates and positions an overhead scan assembly and measurement stylus to perform the profilometry. To observe the sample surface in the vicinity of the measurement stylus, an illumination and imaging capability is also provided. Backlash and error are reduced in the Z axis assembly through use of cams and cam followers, and in the scan assembly through use of multiple tensioned wires, with low-friction sliding elements. The apparatus reduces vibration and supports heavy (up to 400 kg) samples while allowing accurate profile measurements.