Optical measurements are generally defined as all measurements that work with natural or artificial light. This includes both an observation of objects with simple metrological tools and state-of-the-art ultra-precise microscopy methods in specialized measurement laboratories. The variety of optical measurement techniques is enormous, and their number is constantly growing as new technologies and opportunity continue to advance optical metrology methods and equipment. In general, the procedures are divided into four approximate sub-areas. Visual methods are used for superficial inspection of details on workpieces and assemblies. Microscopic methods are used for more precise inspection of the material structure. Photometric 2D and 3D methods serve as a rapid metrological means of measuring components and creating 3D models. These in turn are suitable for checking dimensional accuracy and tolerances. Laser-based metrology systems are characterized by potentially particularly high precision. Surface structures can be reproduced almost as precisely as by tactile methods. Compared to tactile measurement methods, optical measurements offer a fast and non-contact measurement method with low wear.
With their current progress, optical measuring methods can replace tactile measuring technology in many areas. Among other things, this can have advantages in terms of the speed at which measurements are taken. Optical measurement methods have their beginnings in photography. The very first photographic methods were used to take measurements of buildings and other objects, using photographed measuring rods and triangulation. Visual stencil inspection by workers can also be counted among the early optical measurement methods. Today, validation of more complex geometries is still standardly performed with tactile measuring devices, although optical 3D measuring devices are slowly making their way into the market. Modern optical measurement techniques include laser scanning and white light interferometry, fringe and pattern projection, confocal measurement methods, and many other techniques that continue to evolve as technology changes. The advantages of 3D metrology include high speed, the ability to make comprehensive 3D measurements, and simple, non-contact metrology with automation options.