Light field cameras have been extensively used in a variety of applications, thanks to their snapshot three-dimensional imaging capability. However, little is known regarding their pros and cons for a given application. Herein we report a fundamental comparison between two types of light field cameras-focused and unfocused. Our results indicate that the unfocused light field camera outperforms its focused counterpart in depth range and number of resolvable depth steps, while the focused light field camera has an edge in lateral resolution and reconstruction accuracy.

In this Letter, we present, to our knowledge, the first endoscopic diffraction phase microscopy (eDPM) system. This instrument consists of a gradient-index-lens-based endoscope probe followed by a DPM module, which enables single-shot phase imaging at a single-cell-level resolution. Using the phase information provided by eDPM, we show that the geometric aberrations associated with the endoscope can be reduced by digitally applying a spectral phase filter to the raw data. The filter function is a linear combination of polynomials with weighting optimized to improve resolution. We validate the principle of the proposed method using reflective semiconductor samples and blood cells. This research extends the current scope of quantitative phase imaging applications, and proves its potential for future in vivo studies.

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