OSSim (Optical System Simulation) is a wave-optics, time-domain simulation toolbox with both optical and data processing components developed for adaptive optics (AO) systems. Diffractive wavefront control elements have recently been added that accurately model optically and electrically addressed spatial light modulators as real time holographic (RTH) devices in diffractive wavefront control systems. The developed RTH toolbox has found multiple applications for a variety of Boeing programs in solving problems of AO system analysis and design. Several complex diffractive wavefront control systems have been modeled for compensation of static and dynamic aberrations such as imperfect segmented primary mirrors and atmospheric and boundary layer turbulence. The results of OSSim simulations of RTH wavefront compensation show very good agreement with available experimental data.
Using analytical calculations and wave-optic code simulations,
we study the problem of shaping the spatial distribution of laser
beam intensity in the far field by varying the near-field phase. We discuss possibilities of using adaptive-optic devices to form
the near-field phase distribution to reach the desirable far-field
intensity profile. As an example, we show how a doughnut-like
far-field intensity could be achieved by introducing a specific
phase aberration into the laser beam through a deformable
mirror. Diffraction limitations on the far-field beam shaping are
Diffraction of light by 3D phase grating layers could be effectively used for color image processing in robotic vision. Gratings with hexagonal close-packed structures have the maximum amount of cells per volume unit, which leads to an advantage for color image processing. Using the 4D spectral method, we solve the wave equation for diffraction of light by a 3D hexagonal phase grating layer of spherical particles. Both ABCA and ABAB structures are considered. Distribution of diffracted light intensity is calculated in the Fraunhofer and Fresnel diffraction zones. For particular grating distances, the incident white light diffracts in three spatially separated maximums with the central wavelengths corresponding to the three primary colors. The wavelength dependence of diffracted light intensity, for incident white light, is calculated for the three maximums. In general case, by using these three primary curves one can reconstruct the color of incident light from corresponding values of light intensities measured in the three diffracted maximums. The conditions for self-imaging of 3D grating layers are formulated and investigated. Intensity distributions for diffracted light in planes of positive and negative self-imaging, and in a plane of lowest contrast are computed.
The notion that color effects in human vision can be explained as diffraction of light by the 3D grating of retina cells was first proposed by N. Lauinger. To study this new diffraction theory of human vision, we solve the wave equation for light diffraction by a 3D-grating layer with rectangular cells, using the method of 4D Fourier spectra. In the case of weak interaction, we derive analytical expressions for the amplitude and intensity of the diffracted light field for the incident plane wave light. The bandwidth of the diffracted light intensity curves is defined by the width of the grating layer, the size of the grating cells, and the grating period. We show that the geometry of the diffracted light is reciprocal with respect to the geometry of the 3D grating. We compute the wavelength dependence of the diffracted light intensity for incident collimated white light for various geometries of the grating layer and the incident light. Within the visible spectrum range 0.4 - 0.7 micrometers , we obtain three main diffracted light intensity curves for the maxima corresponding to red, green and blue colors, which resemble the fundamental sensitivity curves. The behavior of these curves for non-zero incident angle agrees with the Stiles-Crawford effects.
We solve the 3-D Bragg diffraction problem for a plane light wave, incident on a rectangular acoustic column, in the near zone of acousto-optic (AO) diffraction for the case of weak interaction. We show that the orientation of the boundaries of the acoustic column with respect to the incident light wave vector influences the direction of the diffracted light. It appears that the wave vector of the diffracted light is not necessarily coplanar with the wave vector of the incident light and the central wave vector of the sound column. The angle of deviation of the wave vector for the diffracted light is calculated. Conditions for applying the standard solution of the 2-D AO problem are studied. The problem is solved using the 4-D spectral representation of wave fields method.