Surprisingly simple and compact microscope for time-lapse phase and fluorescence imaging based on chromatic aberration (Conference Presentation)

Abstract

We propose a simple and compact microscope combining phase imaging with fluorescence. This compact setup can be easily inserted in a standard biological incubator and allows observation of cellular cultures over several days. Phase image of the sample is reconstructed from a single, slightly (~50 μm) defocused image taken under semi-coherent illumination. Fluorescence in-focus image is recorded in epi-fluorescence geometry. The phase and fluorescence images are taken sequentially using a single CMOS camera. No mechanical movement of neither sample nor objective is required to change the imaging modality. The only change is the wavelength of illumination and excitation light for phase and fluorescence imaging, respectively. The slight defocus needed for phase imaging is achieved due to specifically introduced chromatic aberration in the imaging system. We present dual modality time-lapse movies of cellular cultures observed over several days in physiological conditions inside an incubator. A field-of-view of 3 mm2 allows observation up to thousands of cells with micro-meter spatial resolution in quasi-simultaneous phase and fluorescence mode. We believe that the simplicity, small dimensions, ease-of-use and low cost of the system make it a useful tool for biological research