Spatially multiplexed interferometric microscopyfrom basic principles to advanced arrangements

Resumen

The possibility of visualizing and analysing transparent microscopic objects in a non-invasively manner was one of the addressed challenges in the microscopy field during 20th century. Several microscopy techniques were created for that purpose, including quantitative phase imaging. Quantitative phase imaging provides numerical information about the morphology and the refractive index of such objects, so that it can be very appealing in diverse fields of knowledge such as medicine, biophotonics or life science, just to cite a few. One of the easiest ways of achieving quantitative phase imaging is employing digital holographic microscopy techniques. Digital holographic microscopy arises from the combination of digital holography and optical microscopy. In recent years, many novel digital holographic microscopy approaches have been successfully developed in order to improve their capabilities in terms of robustness, simplicity, usability, accuracy, and price. In line with that, this thesis is focused on the development and improvement of the technique named "Spatially Multiplexed Interferometric Microscopy". This technique introduces minimal modifications in the embodiment of a conventional bright field microscope in order to convert it into a holographic one in an extremely simple, low-cost and highly-stable way. The modifications are aimed to implement a common-path interferometer by a spatially multiplexed approach in the embodiment of the microscope and are mainly three: 1) the replacement of the broadband illumination source of the microscope by a coherent one; 2) the spatial multiplexed of the input plane by dividing it into two or three regions; 3) and the insertion of an interferometric component such as a diffraction grating or a beam splitter cube. All performed arrangements and phase retrieval procedures are focused on the enhancement of such a technique regarding: 1) coherent noise; 2) spatial multiplexed input plane; 3) spatial resolution; 4) ability for reflective samples analysis; 5) refractive index characterization; and 6) real-time analysis. Experimental validations carried out during the thesis demonstrate that spatially multiplexed interferometric microscopy is a powerful, versatile, and low-cost technique for achieving quantitative phase images from a commercially available standard microscope.