Search results for "holography"
showing 10 items of 210 documents
<title>Application of amorphous chalcogenide thin films in optical recording technologies</title>
2005
A review of the recent advances and developments in the practical application of amorphous chalcogenide materials is presented, focusing special attention to holography and lithography. The main functional principles and practical application of amorphous chalcogenide photoresists for production of the embossed rainbow holograms and holographic optical elements are discussed. The laser interference lithography can be used as a low-cost method for the exposure of large surfaces with regular patterns like subwavelength-gratings and microsieves. The surface-relief and reftactive-index modulated gratings with a period of about 50 nm and less can be fabricated by immersion holographic method. Th…
Surface relief formation in amorphous chalcogenide thin films during holographic recording
2010
Abstract This report present the studies of direct holographic recording of the surface relief gratings on amorphous As2S3 films by 532 nm laser light. By giving extra time for recording exposure (more than necessary for volume amplitude-phase optical recording, e.g. Kikineshi, 2000 [2] ), changes of surface relief in the resist material can be observed. This direct surface relief formation phenomenon during holographic recording is discussed here from the side of recording light polarization. Efficiency of the relief formation may also depend on softening temperature of the film material and this influence was studied as well by using additional incoherent light for extra exposure during r…
Diffraction-efficiency oscillations in amorphous As_2S_3 films
1999
An experimental study of the holographic gratings recorded in nonannealed, thermally with time relaxed amorphous As2S3 films by 514.5-nm light in the presence of 632.8-nm readout light is carried out. The dependences of the maximal first-order diffraction efficiency on the holographic grating period was studied in a wide range of periods, from 0.40 to 70.0 µm. A peculiar oscillatory diffraction-efficiency temporal behavior occurring under certain conditions is reported. The obtained results are discussed in terms of photoinduced structural changes, relaxational structural changes, photoinduced anisotropy, and photoinduced recharging of the localized states in the bandgap. The diffraction-ef…
Model of holographic recording in amorphous chalcogenide films using subband-gap lightat room temperature
1997
The subband-gap light holographic recording in amorphous as-evaporated ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$ films at room temperature is experimentally studied. Properties are considerably different from those of usual holographic recording based on the band-gap light induced structural changes. The most important characteristic features of this nonpermanent recording include photoinduced refractive index increase, weak photobleaching, the absence of the photoinduced thickness changes, light polarization dependence, large exposures, holographic grating shifts during the exposure and a peculiar two maxima spatial frequency response. The first order diffraction efficiency up to 4.1% is achie…
<title>Structure-relaxation-induced peculiarities of the holographic recording in amorphous As<formula><inf><roman>2</roma…
1997
The results of the experimental study of holographic recording in a-As2S3 films are reported such as exposure and intensity dependencies, spatial frequency dependence. Several peculiarities are found including recording intensity threshold, nonmonotonical intensity dependencies, nonlinear exposure curves, the change of the spatial frequency response due to films aging. These peculiarities are explained in terms of phenomenological model which is based on the simultaneous action of the photostructural changes and the relaxational structural changes.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Influence of the age of amorphous nonannealed As2S3 thin films on holographic properties
1998
The dependences of the maximal first order diffraction efficiency and the corresponding specific recording energy on the holographic grating period were studied. Grating period was varied from 0.40 to 70.0 μm. Both fresh and aged films were used. A large holographic recording efficiency decrease in the course of aging is found to take place. These changes are due to the effective film grain size increase caused by the relaxational structural changes and atmospheric oxygen exposure. Results are explained with the aid of stress fields induced by the evaporation and holographic recording. The obtained results can be used to optimize the hologram recording in amorphous chalcogenide films.
Two-color holographic-grating formation in amorphous As_2S_3 films
1998
A detailed experimental study of the holographic gratings recorded in nonannealed amorphous As2S3 films by 514.5-nm light in the presence of 632.8-nm readout light is carried out. A strong influence of a continuous 632.8-nm readout is found. The dependences of the maximal first-order diffraction efficiency and the corresponding specific recording energy on the holographic grating period were studied in a wide range of periods from 0.40 to 70.0 μm for 2-yr-old films. The obtained results are discussed in terms of photoinduced structural changes, relaxational structural changes, photoinduced anisotropy, and photoinduced recharging of the localized states in the bandgap. The photoinduced sulph…
Single-Element Reflective Digital Holographic Microscopy
2021
Digital holographic microscopy (DHM) is a well-known microscopy technique using an interferometric architecture for quantitative phase imaging (QPI) and it has been already implemented utilizing a large number of interferometers. Among them, single-element interferometers are of particular interest due to its simplicity, stability, and low cost. Here, we present an extremely simple common-path interferometric layout based on the use of a single one-dimensional diffraction grating for both illuminating the sample in reflection and generating the digital holograms. The technique, named single-element reflective digital holographic microscopy (SER-DHM), enables QPI and topography analysis of r…
Partially Coherent Optical Diffraction Tomography Toward Practical Cell Study
2021
Optical diffraction tomography (ODT) is a computational imaging technique based on refractive index (RI) contrast. Its application for microscopic imaging of weakly absorbing and scattering samples has been demonstrated by using a specially designed holographic microscope with angular scanning of the coherent sample illumination direction. Recently, an alternative low cost technique based on partially coherent sample illumination (PC-ODT), which is compatible with the conventional wide-field transmission microscope, has been established. In this case, the 3D refractive index distribution of the sample is obtained by deconvolution from a single stack of through-focus intensity images. The pe…
Phase-shifting digital lensless Fourier holography for high numerical aperture in-line interferometric microscopy
2012
A new common-path and phase-shifting digital lensless Fourier architecture for high numerical aperture (NA) imaging in lensless in-line holographic microscopy based on the use of a spatial light modulator (SLM) is presented and experimentally validated.