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A single-pixel digital holography system with phase-encoded illumination using a digital micromirror device (DMD) as a spatial light modulator (SLM) is presented. The enhanced switching rate of DMDs, far exceeding the stringent frame-rate of liquid crystal SLMs, allows recording and reconstruction of complex amplitude distributions in just a few seconds. A single amplitude binary modulation device is used for concurrently displaying the phase-encoded sampling patterns, compensating the distortion of the wavefront, and applying phase-shifting, by means of computer generated holograms. Our detection system consists of a simple photodiode that sequentially records the irradiance fluctuations corresponding to the interference between object and reference beams. The system recovers phase and amplitude information even when a diffuser is placed in front of the photodiode., Comment: 9 pages, 5 figures

In wide-field nonlinear microscopy, wavefront modulation by means of phase-only spatial light modulators (SLMs) allows achieving simultaneous two-photon excitation and fluorescence emission from specific region-of-interests (ROIs) of biological specimens. This is basically accomplished at the illumination path of the microscope by the reconstruction of computer generated holograms (CGHs) onto the sample plane. However, as two-photon absorption (TPA) is inherently an intensity-square dependent process and iterative Fourier transform algorithms (IFTAs) can only approximate the illumination of selected ROIs with the reconstructed CGHs, both signal acquisition and/or image formation can be largely affected by the spatial irregularities of the illumination patterns. In addition, the speckle associated with the superposition of coherent light at the selected ROIs prevents illumination strategies based on CGHs to be successfully used for large-area (more than 50x50 $\mu$m2) excitation tasks. To overcome these limitations, we propose an alternative complex illumination method (CIM) able to generate simultaneous nonlinear excitation of large-area ROIs with full control over the amplitude and phase of the optical wavefront. We experimentally demonstrate spatially uniform illumination, as well as structured illumination with user-defined intensity levels onto micrometric but large-area ROIs. Furthermore, a proof-of-concept experiment on wide-field second harmonic generation (SHG) is provided. We believe that the proposed CIM could find applications in wide-field nonlinear microscopy, particularly for speed up signal acquisition time or improve two-photon image formation., Comment: 8 pages, 4 figures

We present a novel approach for imaging through scattering media that combines the principles of Fourier spatial filtering and single-pixel imaging. We compare the performance of our single-pixel imaging setup with that of a conventional system. Firstly, we show that a single-pixel camera does not reduce the frequency content of the object, even when a small pinhole is used as a low-pass filter. Second, we show that the introduction of Fourier gating improves the contrast of imaging through scattering media in both optical systems. We conclude that single-pixel imaging fits better than conventional imaging on imaging through scattering media by Fourier gating., Comment: 7 pages, 4 figures

Since its discovery, the "ghost" diffraction phenomenon has emerged as a non-conventional technique for optical imaging with very promising advantages. However, extracting intensity and phase information of a structured and realistic object remains a challenge. Here, we show that a "ghost" hologram can be recorded with a single-pixel configuration by adapting concepts from standard digital holography. The presented homodyne scheme enables phase imaging with nanometric depth resolution, three-dimensional focusing ability, and shows high signal-to-noise ratio.

The construction of fractal generalized zone plates (FraGZPs) from a set of periodic diffractive optical elements with circular symmetry is proposed. This allows us to increase the number of foci of a conventional fractal zone plate (FraZP), keeping the self-similarity property within the axial irradiance. The focusing properties of these fractal diffractive optical elements for points not only along but also in the close vicinity of the optical axis are investigated. In both cases analytical expressions for the irradiance are derived. Numerical simulations of the energetic efficiency of FraGZPs under plane wave illumination are carried out. In addition, some effects on the axial irradiance caused by the variation in area of their transparent rings are shown., Comment: Submitted to Optics Express, 2008

The analysis of optical pulse generation by phase modulation of narrowband continuous-wave light, and subsequent propagation through a group-delay-dispersion circuit, is usually performed in terms of the so-called bunching parameter. This heuristic approach does not provide theoretical support for the electrooptic flat-top-pulse generation reported recently. Here, we perform a waveform synthesis in terms of the Fresnel images of the periodically phase-modulated input light. In particular, we demonstrate flat-top-pulse generation with a duty ratio of 50% at a quarter of the Talbot condition for the sinusoidal phase modulation. Finally, we propose a binary modulation format to generate a well-defined square-wave-type optical bit pattern., Comment: 10 pages, 5 figures. Submitted to Optics Express