2. Articole

Permanent URI for this collectionhttps://msuir.usm.md/handle/123456789/47

Browse

Author: search.filters.author.Chirita, Arcadi

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Approximate analysis of the diffraction efficiency of transmission phase holographic gratings with smooth non-sinusoidal relief [Articol]
    (2016) Andries, Ion; Galstian, Tigran; Chirita, Arcadi
    In the article is presented the electro-dynamic model and method for numerical analysis of the diffraction efficiency of thin holographic diffraction gratings. Self-developing holographic gratings are easy to fabricate and can provide relatively high diffraction efficiency. Some photosensitive materials, such as chalcogenide glassy semiconductors of doped As-S-Se-Sn system used in a photo-thermoplastic recording process demonstrate the ability of registration the relief-phase gratings with efficiency up to 40% in transmitted light. The efficiency is highly dependent on the grating profile shape (groove shape and depth). Theoretical analysis is performed using the method of spectral expansions for periodic lattices. Semi-analytical dependences of efficiency on parameters of lattices with arbitrary continuous profile, including experimentally measured one by AFM, are obtained. They allow without using cumbersome numerical calculations to obtain the optimal shape of the lattice profile with maximum efficiency in a given diffraction order. A satisfactory agreement between numerical calculations and experimental measurements is demonstrated. It is shown that the optimal shape of the lattice for maximum efficiency tends to that of a symmetrical binary grating for which the theoretical limiting value of efficiency is 40.5%.
  • Thumbnail Image
    Item
    Holographic imaging and interferometry with non-bragg diffraction orders in lithium niobate and photo-thermoplastic materials [Articol]
    (2012) Kukhtarev, Nikolai; Kukhtareva, Tatiana; Chirita, Arcadi
    We investigated recording of holographic volume and surface-relief gratings in photorefractive crystal and in a photo-thermoplastic (PTP) holographic camera. Holographic recording with an image-bearing signal beam leads to the appearance of two Bragg and two or more non-Bragg diffracted beams that shows the transformed images in each beam (rotation and angular amplification of images). Using this real-time mode of interferometry, the hologram is retrieved with a deformed object beam, resulting in the appearance of fringes with a proper phase shift in each of four diffracted beams. Retrieval with a time-modulated single-pixel object beam lead of time- modulated response in all diffraction orders. This one-shot (one-exposure) phase-shifting interferometry results in clarifying the object wave-front information (as an example, from the surface deformation) and solving the sign ambiguity problem. This procedure demonstrates that high-resolution holographic imaging of the PTP holographic camera static deformations in the order of ~0.1mm can be revealed on the diffusion reflection surface. In addition, it was demonstrated, that using the PTP materials could achieve holographic recording and imaging through phase aberration, with the image appearing in the non-Bragg diffraction order.
  • Thumbnail Image
    Item
    Holographically amplified interferometry with coherent fringe projection for the oil on the water remote sensing and characterization [Articol]
    (2013) Kukhtarev, Nikolai; Kukhtareva, Tatiana; Chirita, Arcadi
    We suggest combining several optical methods of remote sensing and characterization of crude oil films and emulsions: coherent fringe projection illumination (CFP), holographic in-line interferometry (HILI). Combined methods of CFP and HILI are described in the frame of coherent superposition of partial interference patterns. Moreover, we evaluated different alternative schemes of interferometry with holographic recording and preliminary holographic amplification in photorefractive crystals. Holographic amplification of weak images without phase distortions is possible in a special mode of holographic recording in photorefractive crystals.
  • Thumbnail Image
    Item
    Înregistrarea imaginilor în raze X ale microobiectelor pe structuri polimer/As-Se-S dopate cu Sn, Te și Bi [Articol]
    (CEP USM, 2024) Chirita, Arcadi; Nasedchina, Nadejda; Maistruc, Irina; Sandu, Mădălina
    The processes of X-ray image recording on polymer/As-Se-S structures doped with tin, tel lurium, and bismuth were investigated. The possibility of recording images of micro-wires made of tungsten and tin in X-ray radiation was demonstrated.