Oblique illumination lateral shearing digital holographic microscopy

• Published in: Journal of optics (2010) 2020-09, Vol.22 (9), p.95601
• Main Authors: Ganjkhani, Yasaman, Calabuig, Alejandro, Pedrini, Giancarlo, Moradi, Ali-Reza
• Format: Article
• Language: English
• Subjects: digital holographic microscopy; Fourier filtering; lateral shearing; resolution enhancement
• ISSN: 2040-8978; 2040-8986
• DOI: 10.1088/2040-8986/aba4c0

In this paper we present oblique illumination lateral shearing digital holographic microscopy (OILS-DHM) to remove the overlapping information of one of the two wave-fronts forming the holograms and enhance the lateral resolution. Lateral shearing DHM as a self-referencing scheme makes use of the interference of the object beam with itself to form the hologram, and thus is a compact and simple technique and is immune to environmental vibrations. Nonetheless, like all self-referencing techniques it suffers from restrictions on the sample and the field of view. We show that by applying oblique illumination in lateral shearing DHM, it is possible to remove the overlapping information of one of the interfering wave-fronts and thus lift the restriction on the sample. Furthermore, due to the intrinsic characteristic of oblique illumination the lateral resolution of the holographic imaging system is enhanced. The technique is validated through conducting experiments on 1D and 2D static objects. The presented methodology can be extended to other off-axis DHM schemes, and may be considered as a highly stable benchtop 3D imaging microscope for variety of samples.