Holography
Holography(from the Greek, ὅλος hólos whole + γραφή grafē writing, drawing) is a technique that allows the light scattered from an object to be recorded and later reconstructed so that it appears as if the object is in the same position relative to the recording medium as it was when recorded. The image changes as the position and orientation of the viewing system changes in exactly the same way as if the object were still present, thus making the recorded image (hologram) appear three dimensional.
“In holography, some of the light scattered from an object or a set of objects falls on the recording medium. A second light beam, known as the reference beam, also illuminates the recording medium, so that interference occurs between the two beams. The resulting light field generates a seemingly random pattern of varying intensity that is recorded in the hologram. It can be shown that if the hologram is illuminated by the original reference beam, the reference beam is diffracted by the hologram to produce a diffracted light field that is identical to the light field that was scattered by the object or objects. Thus, someone looking into the hologram ‘sees’the objects even though they are no longer present. A variety of recording materials can be used, including photographic film.”
(Wikipedia, Holography, 11/6/2010)
Recent US Patents
9/20/2011
8,021,800
Hologram recording material, process for producing the same and hologram recording medium
Kosuda, Hayashida and Yoshinari, Japan, developeda hologram recording material for volume hologram record with high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage and high multiplicity in holographic memory record using not only a green laser but also a blue laser: This material consists of a metal oxide containing at least Si and Zr with an aromatic carboxylic acid compound is coordinated to Zr; and a photopolymerizable compound. The aromatic carboxylic acid compound is, for example, toluic acid. A hologram recording medium (11) comprising the hologram recording material layer (21).
10/26/2010
7,820,263
Volume hologram laminate
Ohtaki and Ueda of Dai Nippon Printing, Japan has deloped a volume hologram laminate consisting of a first adhesive layer, a volume hologram layer, a second adhesive layer and a surface protective film. The volume hologram layer is a hologram recording in a recording material consisting of a matrix polymer and a photopolymerizable compound. (RDC 2/15/2011)
Recent Journal Articles
11/26/2010
High Intensity Response of Photopolymer Materials for Holographic Grating Formation
(9462–9472) Macromolecules 43 #22 (2010)
Liu et al of the University College Dublin developed a detailed photoinitiation model into the nonlocal photopolymerization driven diffusion model. This model describes the following: (1) Photon absorption behavior and primary radical generation during initiation; (2) nonlocal macro-radical chain growth through propagation; (3) oxygen diffusion and replenishment for inhibition; (4) multiple termination mechanisms. This extended model is experimentally validated for high intensity holographic exposures to a polyvinylalcohol/acrylamide based photopolymer material. (RDC 11/23.2010)
Photopolymer for Optical Holography and Holographic Interferometry
(pages 107–113)Macromolecular Symposia 296 #1 (2010)
Květoň et al modified acrylamide-based photopolymer recording material. Which was successfully applied to holographic interferometry. (RDC 11/24/2010
11/19/2010
Holographic recording in a photo-cross-linkable liquid crystalline copolymer using a 325-nm laser with various polarizations
(980-985) Reactive and Functional Polymers 70 #12 (2010)
Kawatsuki et al of University of Hyogo, Japan, fabricated surface relief gratings with a molecularly oriented structure and pure polarization hologram on a photo-cross-linkable liquid crystalline copolymer using a 325-nm laser with various two-beam polarization modes. (RDC 11/18/2010)
11/6/2010
Enhancement of electro-optical properties in holographic polymer-dispersed liquid crystal films by incorporation of multiwalled carbon nanotubes into a polyurethane acrylate matrix
(1289–1295)Polymer International 59 #9 (2010)
Kim et al fabricatedholographic polymer-dispersed liquid crystal films with varying amounts (up to 5 wt%) ofmultiwalled carbon nanotubes to optimize the electro-optical performance of the films. The oligomer chains wrap the nanotubes along their length, producing high diffraction efficiency and good phase separation. (RDC 11/6/2010)