The application of an optical interferometric system using a Mireau objective to measure the surface profile of micro-components is described. The proposed system produces a uniform monochromatic illumination over the test area and introduces an interference fringe pattern localized near the test surface. Both the interference fringes and the 2D image of the test surface can be focused by an infinity microscope system consisting of a Mireau objective and a tube lens. A piezoelectric transducer (PZT) attached to the Mireau objective can move precisely along the optical axis of the objective. This enables the implementation of phase-shifting interferometry without changing the focus of a CCD sensor as the combination of the Mireau objective and the tube lens provides a depth of focus which is deep in comparison to the phase-shifting step. Experimental results from surface profilometry of the protrusion/undercut of a polished fibre within an optical connector and of the curved surface of a micromirror demonstrate that features in the order of nanometres are measurable. Measurements on standard blocks also show that the accuracy of the proposed system is comparable to an existing commercial white-light interferometer and a stylus profilometer.

Metrological atomic force microscopes are widely used in national metrology institutes for measuring step height, lateral pitch and surface roughness. However, the maximum measurable depth or height variation is limited by both the vertical scanning range of the AFM and the tip height and sharpness of the tip at the end of the cantilever. A normal commercial AFM typically has a vertical scanning range less than 10 µm and a tip height of the cantilever only up to 15 µm so that it can be used to detect only relatively smooth surfaces or shallow structures up to several micrometres. To overcome these limitations, we have successfully integrated a long diamond tip of up to 120 µm developed at Namiki Precision Jewel Co., Ltd of Japan onto our large range metrological atomic force microprobe (LRM-AFM) for deep groove structure measurement. The LRM-AFM is based on a nano-measuring machine with a large scanning range of 25 mm in the X and Y axes and 5 mm in the Z axis. This paper describes the long diamond tip fabrication process and especially its application in the LRM-AFM for measuring deep groove structures of a step height of up to 100 µm. In addition, the mechanical quality factor (Q) of the diamond tip micro-cantilever was detected in the system. The results demonstrate that the system is capable of calibrating and measuring the surface structure with deep groove in tens of micrometres.