Optical metrology is one of the key technologies in today’s manufacturing industry. In this article, we provide an insight into optical measurement technologies for precision positioning and quality assessment in today’s manufacturing industry. First, some optical measurement technologies for precision positioning are explained, mainly focusing on those with a multi-axis positioning system composed of linear slides, often employed in machine tools or measuring instruments. Some optical measurement technologies for the quality assessment of products are then reviewed, focusing on technologies for form measurement of products with a large metric structure, from a telescope mirror to a nanometric structure such as a semiconductor electrode. Furthermore, we also review the state-of-the-art optical technique that has attracted attention in recent years, optical coherence tomography for the non-destructive inspection of the internal structures of a fabricated component, as well as super-resolution techniques for improving the lateral resolution of optical imaging beyond the diffraction limit of light. This review article provides insights into current and future technologies for optical measurement in the manufacturing industry, which are expected to become even more important to meet the industry’s continuing requirements for high-precision and high-efficiency machining.

Laser interference lithography is an attractive method for the fabrication of a large-area two-dimensional planar scale grating, which can be employed as a scale for multi-axis optical encoders or a diffractive optical element in many types of optical sensors. Especially, optical configurations such as Lloyd’s mirror interferometer based on the division of wavefront method can generate interference fringe fields for the patterning of grating pattern structures at a single exposure in a stable manner. For the fabrication of a two-dimensional scale grating to be used in a planar/surface encoder, an orthogonal two-axis Lloyd’s mirror interferometer, which has been realized through innovation to Lloyd’s mirror interferometer, has been developed. In addition, the concept of the patterning of the two-dimensional orthogonal pattern structure at a single exposure has been extended to the non-orthogonal two-axis Lloyd’s mirror interferometer. Furthermore, the optical setup for the non-orthogonal two-axis Lloyd’s mirror interferometer has been optimized for the fabrication of a large-area scale grating. In this review article, principles of generating interference fringe fields for the fabrication of a scale grating based on the interference lithography are reviewed, while focusing on the fabrication of a two-dimensional scale grating for planar/surface encoders. Verification of the pitch of the fabricated pattern structures, whose accuracy strongly affects the performance of planar/surface encoders, is also an important task to be addressed. In this paper, major methods for the evaluation of a grating pitch are also reviewed.