With increasing digitalisation of engineering and the development of smart manufacturing, precision metrology is gradually moving away from the laboratory into real-world environments and production platforms. Interferometry and focus detection are the most popular optical techniques for these types of application due to their non-destructive measurement, high resolution, and fast response. In this article, we discuss their basic principles, limitations and challenges, and new opportunities. Motivated by the rapid development of artificial materials, the application of metasurfaces to drive a new era for future miniaturisation of optical systems becomes suddenly viable. The article discusses advances in modern miniaturisation of optical techniques; and introduces an approach for evolving to a future using metasurface optics. Optical principles and feasibility studies are included in the discussion.

The development of ultra-compact lightweight optical instrumentation that can be used on-machine and to carry out in-process measurements is vital in realizing improved manufacturing processes, increasing the quality of parts being made while saving time and energy by reducing scrappage rates. Only incremental progress is being made in developing suitable instrumentation based on conventional components such as traditional refractive elements as fundamental limits in terms of size and weight are already reached. Here we demonstrate a chromatic confocal sensor that utilizes the natural chromatic aberration found with a basic hyperbolic metalens to realize an ultra-compact and simple probe. Further, we demonstrate how this can be combined with a compact specklemeter as the detection element, thus realizing the whole sensing system in a compact manner. Even with the proof-of-principle instrument in its preliminary and unoptimised state we achieve the successful recovery of the location of a scatterer as it is scanned over a 227 μm range, with a standard deviation of error in the position of 1.37 μm. Sensors of this form can be deployed in areas where traditional instrumentation would typically impede the manufacturing processes, increasing the number of processes that can have metrology applied directly and providing real-time feedback to improve manufacturing outcomes.