Paper
20 September 2023 Interferometric surface inspection with movable measurement spot: high-speed OCT imaging for thickness and topography in industry
M. Kogel-Hollacher, T. Nicolay, S. Mieth, Jens Reiser
Author Affiliations +
Abstract
The increasing demands in industry, for example for products in the consumer electronics sector or for assistance systems in cars, and the continuous development in semiconductor are leading to significant miniaturization in electronic components. These requirements are inevitably also transferred to ultra-precise manufacturing and thus ask for monitored production steps. In the context of Industry 4.0 and other developments in the context of modern production sensors to supervise production steps are crucial. An essential component here is non-destructive testing (NDT) and specifically optical metrology. Complete 3D measurement of objects using white light interference in mass production is time consuming and therefore not well-suited for use as a means of inline inspection. In addition, the long measurement cycles with complex sequences generate large amounts of data and the effort for processing the data must also be included in overall considerations. The Flying Spot Scanner (FSS) intelligently avoids these disadvantages and is therefore ideal for inline inspections. To meet the need of additional, even complex and time sensitive measurement tasks, Precitec Optronik has developed the Flying Spot Sensor. The active measuring head was specially developed for in-line use and ideally complements the spectral interferometric sensor to form a smart inspection system. The light from the sensor is coupled into the measuring head via a light guide and deflected by a mirror system, a so-called galvanometer scanner. Finally, the light passes through a telecentric lens, which serves as a focusing module on the outward path and as a measuring aperture for the reflected light. Due to the movable mirror system, the measuring light beam can be deflected at different angles and thus the measuring spot can be freely positioned within the field of view of the lens. Long paths of linear axes are replaced by short rotary movements, resulting in an extreme reduction of the measuring, or scanning time. By using specialize focusing modules, the Flying Spot Scanner can be adapted to different application scenarios. These optics are characterized by a low curvature of the focal plane, very small telecentric errors and a very large depth of field. The measurement system can also be used in two operating modes, a thickness mode, or a distance mode. The two operating modes can be selected at will via the digital interface, which means that the switching process can be easily integrated into an automatic measuring sequence.
© (2023) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. Kogel-Hollacher, T. Nicolay, S. Mieth, and Jens Reiser "Interferometric surface inspection with movable measurement spot: high-speed OCT imaging for thickness and topography in industry", Proc. SPIE 12607, Optical Technology and Measurement for Industrial Applications Conference, 1260702 (20 September 2023); https://doi.org/10.1117/12.3005058
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KEYWORDS
Sensors

Inspection

Scanners

Interferometry

Head

Industry

Information technology

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