LED source interferometer for microscopic fringe projection profilometry using a Gates’ interferometer configuration

• Published in: Optics and lasers in engineering Vol. 149; p. 106822
• Main Authors: Sánchez, José Rubén, Martínez-García, Amalia, Rayas, Juan Antonio, León-Rodríguez, Miguel
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-02-2022
• Subjects: Fringe projection; Gates’ interferometer; Microscopic fringe projection profilometry; Resolution; Surface metrology; Fringe projection; Gates’ interferometer; Surface metrology; Microscopic fringe projection profilometry; Resolution
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2021.106822

•A microscopic fringe projection profilometry system based on Gates' interferometer is introduced.•The proposed method uses a LED as a light source.•A beamsplitter cube is implemented as a core interference element.
The fringe projection technique is considered one of the most reliable solutions for structured light technology, developed for non-contact three-dimensional (3D) data acquisition. When working with this technique, applying it on a microscopic scale, one often encounters some problems such as the limited depth of field of the projected fringe pattern, typical of the imaging lenses, or the formation of speckle-noise when laser interferometric fringes are projected, which are problems that can cause significant errors on test surfaces whose height exceeds the depth of field, and on which, the other hand, speckle noise affects the resolution of the technique. This paper presents a Gates’ interferometer configuration with a LED source to project a fringe pattern without speckle noise and a very long field depth. We explain how a non-located sinusoidal fringe pattern can be obtained using two-beamsplitter cubes and a LED light source. Moreover, we compare measurements made using the LED and laser concerning a commercial contact profilometer.