We describe a modal wavefront sensing technique of using multiplexed holographic optical elements (HOEs). The phase pattern of a set of aberrations is angle multiplexed in a HOE, and the correlated information is obtained with a position sensing detector. The recorded aberration pattern is based on an orthogonal basis set, the Zernike polynomials, and a spherical reference wave. We show that only two recorded holographic patterns for any particular aberration type are sufficient to allow interpolated readout of aberrations to lambda/50. In this paper, we demonstrate the capability of detecting errors between +/-2lambda PV for each orthogonal set at rates limited only by the speeds of the detection electronics, which could be up to 1 MHz. We show how we take advantage of the unavoidable intermodal and intramodal cross talks in determining the type, amplitude, and orientation of the wavefront aberrations.
We have applied electric-field-induced optical second-harmonic generation to measure the distribution of chromophore sites in a dye-doped polymer [disperse red 1 in poly (methyl methacrylate)] in terms of the standard α and β parameter, that is, the decay rate and the breadth parameter. These parameters have been measured from 100 to 430 K and are modeled with a smooth function over that temperature range. Over a narrow region of temperature where second-harmonic data from other groups exist, we find that our temperature dependence of β is in excellent agreement with these other experiments. In principle, our method can be applied to any glassy polymer to characterize the temperature dependence of the distribution of nonlinear-optical dye sites.
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