Holographic point source for digital lensless holographic microscopy.

A holographic point source (HPS) developed for digital lensless holographic microscopy (HPS-DLHM) is presented. The HPS is an off-axis phase transmission hologram of an experimental micrometer pinhole recorded on a photopolymer holographic film. An amplitude division interferometer, adjusted to operate at maximum diffraction efficiency, has been employed to record the hologram. The results of HPS-DLHM have been contrasted with the results obtained via conventional DLHM, and the two techniques were found to give similar measurements. Compared with conventional pinhole-based DLHM illumination, our cost-effective proposal provides increased mechanical stability, the possibility of wider spherical illumination cones, and shorter reconstruction distances. These superior features pave the way to applying this quantitative phase imaging (QPI) technique in biomedical and telemedicine applications. The imaging capabilities of our HPS-DLHM proposal have been tested by using an intricate sample of a honeybee leg, a low-absorption sample of epithelial cheek cells, a 1951 USAF test target, and smeared human erythrocytes.