Malaria is one of the most widespread diseases, particularly in Asia and Africa. Correct diagnosis of malaria is necessary for its proper treatment. A compact automated tool for malaria identification will greatly benefit healthcare professionals in these regions. We propose a method that has the potential to automatically detect malaria-infected red blood cells (RBCs). This method combines the simplicity and robustness of lateral shearing interferometry with the flexibility of statistical methods to achieve the classification of diseased RBCs. Shearing interferograms generated using a glass plate in a common path setup were Fourier analyzed to retrieve the gradient phase and amplitude information of the cell. Then, multiple features based on the complex amplitude information of the cells are measured automatically and used to differentiate healthy and malaria-infected cells. Multivariate statistical inference algorithm of the experimental data shows that there is a difference between the populations of healthy and malaria-infected RBCs by using the measured RBC features.

We describe and experimentally demonstrate a phase shifting method based on the lateral displacement of a grating implemented with a twisted-nematic liquid-crystal spatial light modulator. This method allows an accurate implementation of the phase shift without requiring moving parts. The technique is implemented in a Mach–Zehnder digital holography setup in which the field transmitted by the sample object freely propagates to the hologram plane.

In computer generated holograms, a random phase is added to spread out the object wave, but this introduces a strong speckle noise in the reconstructed image. Spreading out the object wave helps to record a large object in a smaller hologram. We propose a random repeated and displaced phase, which reduces the speckle noise in the reconstructed image and spreads out the object information in a limited area. The phase is independent of the object, and it could be calculated by sections reducing the hologram computing time. We present simulated and experimental results that prove the improvement in quality of the reconstructed image and the whole object reconstruction, using only a small part of the hologram.

We propose a low-cost optical system that is able to simply generate computer-generated holograms and rainbow type and true-color Lippmann type holograms. In this system, a microimaging system is applied to reduce the digitized optical data/patterns to achieve about 0.45 μm of optical resolution for rainbow hologram recording and an about 60-deg viewing angle for the Lippmann hologram. The system is designed as a turn-key machine switching between different operating modes. Custom-generated software is applied to calculate and write digital fringe patterns at real-time speed. Applications for the digital rainbow hologram include computer-generated holograms, anticounterfeiting security labels, 3-D display, and 2-D/3-D truecolor holographic stereogram images for the Lippmann hologram. This single-process synthesizing system can be considered as a fully functioning hologram printer.

Fourier interferometry (FI) is a robust and simple method for reconstruction of phase modulated objects. Its main advantage is that it only requires the recording of one interference pattern, avoiding the problems caused by mechanical vibrations in the optical setup. Unfortunately, the conventional FI method can be employed in digital holography (DH) only for samples with reduced frequency bandwidth, because of the low spatial resolution of available electronic image recording devices (CCDs). We report two methods that partially overcome this bandwidth limitation of the FI technique implemented in DH. The first of these methods consists in a modified version of the conventional FI approach where, instead of processing the Fourier transform of the hologram, we calculate its Fresnel back propagation to the object plane. Although this modified FI approach provides appropriate reconstruction of objects with increased bandwidth, the local SNR tends to be low at thin phase modulated features of the object. In order to increase this SNR we employ the sample reconstructed with the modified FI method as the input in a Gerchberg-Saxton (GS) iterative method. In this GS procedure, the constraints are the modules of the fields at the object and at the hologram planes. This iterative method, implemented by numerical simulations, provides highly accurate phase corrections with fast convergence.