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We present a method to obtain the phase modulation characteristic curve of a spatial light modulator (SLM) under severe vibration conditions. The procedure is based on the well-known advanced iterative algorithm (AIA), which allows wavefront extraction from unknown phase-shifted interferograms. Generally, AIA is used to determine the wavefront and the determined phase shifts are of little interest. In contrast, in our method, the main goal of using AIA is to determine the unknown phase shifts induced by an SLM during the calibration procedure. Using a segmented approach to calibration, AIA enables successful calibration even in the presence of additional random phase shifts due to environmental changes. This method has the potential to calibrate SLMs integrated in complex optical instruments with little to no modifications to the optical setup, no matter the environmental conditions. We demonstrate our technique by calibrating an SLM under vacuum conditions (10^−5mbar) in a common-path configuration compatible with usage of an SLM as a wavefront modulator at the pupil plane of an instrument. Our technique compensates for the vibrations produced by the vacuum pumps and reduces an order of magnitude the root-mean-squared error of the calibration curve evaluated with vibration errors. Our technique enhances the potential use of SLMs in complex optical systems, including aerospace optical instrumentation.

This work reports about the preparation of plasma polymerized thin films of perylene with thicknesses ∼30−150 nm and their characterization by different methods and the analysis of their optical properties. Highly absorbent and fluorescent films have been obtained by this method that combines the sublimation of the perylene molecules and their controlled polymerization by the interaction with remote Ar plasma. The polymeric films are very flat with a root mean square (rms) roughness in the range 0.3−0.4 nm. In contrast with the sublimated layers of perylene that present a high scattering of light, the polymerized films depict the well-defined absorption bands in the region 400−450 nm and fluorescence spectra of the perylene molecule at ∼475 nm. The films are formed by a matrix formed by cross-linked fragments of perylene and intact molecules that confer the observed optical properties to this material. The optical and microstructural characteristics of this type of thin films and the possibility to perform their deposition by using lithographic procedures make them suitable for their integration into photonic components for various applications. A preliminary study of the use of these films as an optical sensor of NO2is also presented.

We report the correction of the shrinkage observed during UV postrecording curing in a holographic solgel material that was recently achieved by the use of various chemical formulations for the composition of the hybrid supporting matrix. We found that a chemical modification of the matrix noticeably attenuates the shrinkage (from 1.3% to 0.4% of the material’s initial thickness with the inclusion of just 20% tetramethylorthosilicate), providing a material with improved stability for permanent data storage applications. The holographic properties of samples with different binders are also reported. In addition, a theoretical study has revealed the way by which to compensate for angular deviation in the Bragg condition during UV postrecording by tailoring the binder shrinkage (s), the maximum refractive-index modulation capability of the photosensitive mixture (Δn), or both.

An optical method to determine the nanostructure and the morphology of porous thin films is presented. This procedure is based on the response of a side-polished optical fiber with the film under study, when an adsorption-desorption cycle is carried out. Spectroscopic ellipsometry provides additional information about the optical properties and adsorption behavior of the film. Pore size distribution, anisotropy, and inhomogeneity of films can be determined by use of these two complementary techniques. To check the performances and suitability of the optical method, we have characterized a typical porous material: a TiO_2 film deposited by evaporation. Water vapor has been used for the adsorption cycles. The well-known columnar structure of the evaporated TiO_2 has been evidenced, and the relation between the nanostructure and the optical properties of the film is showed.

The variation of the optical properties of porous Vycor glass (Corning, Model 7930) under different relative-humidity conditions was studied. The adsorption of water into the glass pores was investigated with spectroscopic ellipsometry. The change of the refractive index was Δn ∼ 0.04 between 5% and 90% relative humidity. A linear relation between the ellipsometer parameter tan Ψ, the amount of water adsorbed in the glass pores, and information about the pore-size distributions was established. The results are in accord with the values obtained from N_2 isotherms, transmission electron microscope micrographs, and the manufacturer’s specifications (radius of ∼20 Å). The possibility of using this material as a transducer for implementation in a fiber-optic sensor to measure humidity was evaluated.