A Gaussian transition of an optical speckle field studied by the minimal spanning tree method

We propose to study the Gaussian transition of an optical speckle field using the Minimal Spanning Tree method. We perform an analysis of the spatial intensity distribution and show that the maxima of intensity evolve from a cluster distribution in the strongly non Gaussian regime, to a gradient distribution around the transition and then approach the random distribution area when we tend to the Gaussian regime. In the generated minimal spanning trees, we observe that the standard deviation of the edges length exhibits a maximum around the Gaussian transition when about 4 correlation cells of the surface roughness are illuminated

Study of a circular Gaussian transition in an optical speckle field

We propose a numerical approach to study optical speckle fields generated by various conditions of surface roughness and illumination, without any a priori assumption concerning the properties of the scattered field. By overcoming the limitations imposed by the use of the central limit theorem, we perform the study of the whole circular Gaussian transition undergone by the speckle field when varying the surface roughness and the size of the laser illumination. We focus our attention on the speckle contrast, the degree of circularity and the degree of assymmetry, including their radial dependence

Optical reconstruction of transparent objects with phase-only SLMs

Three approaches for visualization of transparent micro-objects from holographic data using phase-only SLMs are described. The objects are silicon micro-lenses captured in the near infrared by means of digital holographic microscopy and a simulated weakly refracting 3D object with size in the micrometer range. In the first method, profilometric/tomographic data are retrieved from captured holograms and converted into a 3D point cloud which allows for computer generation of multi-view phase holograms using Rayleigh-Sommerfeld formulation. In the second method, the microlens is computationally placed in front of a textured object to simulate the image of the textured data as seen through the lens. In the third method, direct optical reconstruction of the micrometer object through a digital lens by modifying the phase with the Gerchberg-Saxton algorithm is achieved. © 2013 Optical Society of America

Optical reconstruction of transparent objects with phase-only SLMs

Three approaches for visualization of transparent micro-objects from holographic data using phase-only SLMs are described. The objects are silicon micro-lenses captured in the near infrared by means of digital holographic microscopy and a simulated weakly refracting 3D object with size in the micrometer range. In the first method, profilometric/tomographic data are retrieved from captured holograms and converted into a 3D point cloud which allows for computer generation of multi-view phase holograms using Rayleigh-Sommerfeld formulation. In the second method, the microlens is computationally placed in front of a textured object to simulate the image of the textured data as seen through the lens. In the third method, direct optical reconstruction of the micrometer object through a digital lens by modifying the phase with the Gerchberg-Saxton algorithm is achieved. © 2013 Optical Society of America