Fiber-based white-light interferometer with improved sensor tip and stepped mirror

White-light interferometry has been a well-known and established measurement technique for years. However, in certain fields of production technology, such as microassembly or small-cavity inspection, there is a need for miniaturized metrology systems. This request can be answered, among other variants, with the use of fiber-based interferometry. The application of fibers enables, e.g., separation of a sensor (probe) from an optical receiver. The result is that the sensor probe can theoretically be miniaturized down to the curve diameter of the used fiber. On the one hand, this paper demonstrates how the use of a continuously improved miniaturized sensor probe can enable the application of such a measurement system in the mentioned technological fields. On the other hand, it describes the present state of a special mirror to increase the measuring range, frequency, and stability of the sensor system. This mirror replaces the moving reference mirror, which is commonly needed in an interferometer. It is designed with a certain number of steps to compensate the path difference between the object and reference beams. The fundamental aspects of white-light interferometry are presented and lead to the concept of a miniaturized fiber-based distance-measurement system.