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We explore the principles, implementation details, and performance characteristics of a lensless multi-spectral digital holographic sensor and demonstrate its potential for quality assurance in semiconductor manufacturing. The method is based on capturing multi-spectral digital holograms, which are subsequently utilized to evaluate the shape of a reflective test object. It allows for a compact setup satisfying high demands regarding robustness against mechanical vibrations and thus overcomes limitations associated with conventional optical inspection setups associated with lens-based white light interferometry. Additionally, the tunable laser source enhances the versatility of the system and enables adaptation to various sample characteristics. Experimental results based on a wafer test specimen demonstrate the effectiveness of the method. The axial resolution of the sensor is ± 2.5 nm, corresponding to 1σ. [ABSTRACT FROM AUTHOR]

The editorial discusses the recent advancements in Digital Holographic Microscopy (DHM) and its applications in various fields such as industrial inspection, biomedical imaging, and semiconductor manufacturing. DHM combines digital holography and optical microscopy to provide label-free and quantitative phase imaging, allowing for detailed analysis of samples. The research topic emphasizes cutting-edge techniques like lensless multispectral digital holography and lensless digital holography for in-situ non-destructive testing, showcasing their high-resolution capabilities and real-time metrology. The editorial aims to serve as a valuable resource for students, researchers, engineers, and industry professionals interested in quantitative imaging and non-destructive testing in industrial applications. [Extracted from the article]