Real-Time Triple Field of View Interferometry for Scan-Free Monitoring of Multiple Objects

Abstract

Synchronous scanning of multiple objects is essential to health monitoring of cells with high reliability. In general, monitoring multiple objects with fixed optical resolution in a total area larger than the sensor size of the camera requires asynchronous scanning; therefore, the recorded images of different scanned areas are asynchronous. We have developed a novel single-shot triple field of view (FOV) interferometric technique that rectifies this asynchronous problem and the effect of high-frequency noise due to the motorized scanning components utilized to extend imaging area. The proposed technique is a novel setup, calibration, and correction algorithm that facilitates a wider 3-D imaging area and higher mechanical stability with fixed imaging parameters. In addition, objects are exposed to a low-power light source and images can be formed with lower intensity light, which is important for sensitive objects in practical applications. The technique separates the light exiting a microscope using four mirrors, which results in all beams having the same intensity and the recorded image possessing a higher fringe contrast than with techniques that use beam splitters. Furthermore, the arrangement it adopts, in which a pinhole is employed to produce a clear reference beam, makes it appropriate for complex industrial fabrication monitoring. A sub-Nyquist sampling scheme is also employed to facilitate recording of the maximum possible FOV for single-shot three holograms recording, and the phase retrieval process is modified to refocus the beam on different image planes. The feasibility of the proposed technique for monitoring multiple biological cells with different morphologies is demonstrated by using it to image human embryonic kidney 293 cells.