Doubling the field of view in off-axis low-coherence interferometric imaging

Pinhas Girshovitz and Natan T. Shaked

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Abstract: We present a new interferometric and holographic approach, named interferometry with doubled imaging area (IDIA), with which it is possible to double the camera field of view while performing off-axis interferometric imaging, without changing the imaging parameters, such as the magnification and the resolution. This technique enables quantitative amplitude and phase imaging of wider samples without reducing the acquisition frame rate due to scanning. The method is implemented using a compact interferometric module that connects to a regular digital camera, and is useful in a wide range of applications in which neither the field of view nor the camera frame rate can be compromised. Specifically, the IDIA principle allows doubling the off-axis interferometric field of view, which might be narrower than the camera field of view due to low-coherence illumination. We demonstrate the proposed technique for scan-free quantitative optical thickness imaging of microscopic biological samples, including live neurons, and rapid human sperm cell in motion under large magnification. In addition, we used the IDIA principle to perform non-destructive profilometry during a rapid lithography process of transparent structures.

Quantitative optical thickness maps of a human spermatozoon swimming,  as recorded by IDIA under low coherence illumination, enabling the acquisition of the fast dynamics of the spermatozoon with fine details on a doubled field of view. The white dashed line indicates the location of the stitching between the two fields of view. The color bar represents the quantitative optical thickness.