Wyniki wyszukiwania - BazTech

1

Magnified holographic projection based on spatial light modulators

Su Y., Cai Z., Shi L., Zhou F., Chen H., Wu J.

Optica Applicata

|

2018

|

Vol. 48, nr 4

589--600

EN

In this paper, a magnified holographic projection based on spatial light modulators is proposed and implemented by combining four magnification methods, including similarity principle of Fourier transform, spatial division, digital lens, and image splicing methods. The Fourier holographic display system is constructed for the experimental verification of the proposed methods. With such four methods of holographic magnification, the reconstruction image can be magnified to 10 × 5 times in two-dimensional directions, which is verified by the experiments. Furthermore, the undesirable light of holographic projection is eliminated by encoding the linear phase onto the computer-generated holograms. The experimental results prove that the proposed system can realize magnified holographic projection with good reconstructed quality, which provides a promising potential for the dynamic holographic projector.

2

Aspects of nanometer scale imaging with extreme ultraviolet (EUV) laboratory sources

Wachulak P. W., Marconi M. C., Isoyan A., Urbanski L., Bartnik A., Fiedorowicz H., Bartels R. A.

Opto-Electronics Review

|

2012

|

Vol. 20, No. 1

1-14

EN

Imaging systems with nanometer resolution are instrumental to the development of the fast evolving field of nanoscience and nanotechnology. Decreasing the wavelength of illumination is a direct way to improve the spatial resolution in photon-based imaging systems and motivated a strong interest in short wavelength imaging techniques in the extreme ultraviolet (EUV) region. In this review paper, various EUV imaging techniques, such as 2D and 3D holography, EUV microscopy using Fresnel zone plates, EUV reconstruction of computer generated hologram (CGH) and generalized Talbot self-imaging will be presented utilizing both coherent and incoherent compact laboratory EUV sources. Some of the results lead to the imaging with spatial resolution reaching 50 nm in a very short exposure time. These techniques can be used in a variety of applications from actinic mask inspection in the EUV lithography, biological imaging to mask-less lithographic processes in nanofabrication.

3

Neural network based automatic diffraction pattern recognition

Cyran K. A., Jaroszewicz L. R., Niedziela T.

Opto-Electronics Review

|

2001

|

Vol. 9, No. 3

301-307

EN

The paper presents automatic recognition of images using the diffraction pattern sampling. This method, based on proporties of Fourier transform, utilisies special shapes of sampling element and gives the possibility to deal with data invariant with respect to typical transformation (shift, rotation and scaling) of the input images. Furthermore, if computer-generated hologram is used as feature extractor, instead of commercialy available ring-wedge detector, then the process of feature extraction can be optimised with a method proposed by the authors. The method uses rough set theory for objective function definition and stochastic evolutionary algorithms for space search. The features obtained by optimised sampling of the diffraction pattern are the input data for the semantic classifier. Since noise present in images has got typically Gaussian distribution, therefore classification should be made in the model with statistical neural network is used. The presented method is illustrated with experiments of specle pattern recognition performed with optimised and standard computer-generated holograms. The experiments confirmed good overall accuracy of the optimised system outperforming the results obtained for standard one by a factor of two to five.

4

Computer generated holograms versus synthetic diffraction gratings in optically variable devices.

Stępień P.

Optica Applicata

|

2000

|

Vol. 30, nr 2-3

257-269

EN

Diffractive optically variable devices (DOVDs) are optical imaging elements such as holograms and diffraction gratings of all types. Visual applications of holograms consist in recording and reconstruction of 3D or 2D objects. Diffraction grating structures are used for visualisation of 2D images with cinematic effects. Computer generated holograms (CGHs) form 3D images of the quality which is hardly acceptable for commercial applications. The method of formation of high quality 3D images using multistereograms based on CGHs is presented. CGHs are also used to make Fourier type hidden elements. CGH based hidden elements may be combined with 2D visual features. Grating based DOVDs are used to record bright 2D images with cinematic effects. We show that diffraction gratings recorded using high-resolution equipment can be applied to true colour 3D image recording taking advantage of the stereogram concept. Similarly as in CGHs the recording of simple hidden information is possible in synthetic diffraction gratings.