Long working distance high resolution reflective sample imaging via structured embedded speckle illumination

• Main Authors: Haridas, Aswin, Perinchery, Sandeep Menon, Shinde, Anant, Buchnev, Oleksandr, Murukeshan, Vadakke Matham
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2020
• Subjects: Engineering::Mechanical engineering; High Resolution Imaging; Long Working Distance Imaging
• Online Access: https://hdl.handle.net/10356/144023
• Institution: Nanyang Technological University

Imaging beyond the diffraction limit at longer working distances using enhanced microscopic configurations has always been a challenge for biological and engineering samples. Even though multiple techniques have been widely used for sub-diffraction limit resolution imaging, the achievable resolution was relying on the use of objective lenses with a high numerical aperture (NA). In the case of engineering samples, in addition to sustaining higher resolutions at large working distances, improving the signal-to-noise ratio (SNR) is also critical. In this context, we propose and demonstrate a concept for high-resolution imaging at large working distances, termed as structured illumination embedded speckle microscopy. An imaging resolution of ~ 310 ± 5 nm was achieved with a microscope objective (0.55 NA; 50X) having 11 mm long working distance using a Siemen's star as the test sample. The demonstrated microscopy is therefore envisaged for engineering applications that demands high-resolution, high SNR imaging at long working distances.