Fine structure of angular selectivity of diffraction efficiency of holograms recorded on materials polymerized by IR radiation

2004 ◽  
Vol 99 (1) ◽  
pp. 101-108 ◽  
Author(s):  
R. S. Akopyan ◽  
A. V. Galstyan ◽  
T. V. Galstian
Keyword(s):  
Fine Structure ◽  
Diffraction Efficiency ◽  
Ir Radiation ◽  
Angular Selectivity

Design of high-performance holographic gratings using siloxane-containing mesogenic compounds

2006 ◽  
Vol 78 (10) ◽  
pp. 1835-1842 ◽  
Author(s):  
Yusuke Kawakami ◽  
Man He ◽  
Yeong Hee Cho
Keyword(s):  
Diffraction Efficiency ◽  
Ring Opening ◽  
High Performance ◽  
Liquid Crystalline ◽  
Diglycidyl Ether ◽  
Matrix Component ◽  
Holographic Gratings ◽  
Glycol Diacrylate ◽  
Trimethylolpropane Triacrylate ◽  
Angular Selectivity

Fine holographic gratings were fabricated using siloxane- and mesogen-containing compounds. A grating with 40 % diffraction efficiency was formed with 10 wt % non-liquid-crystalline 4-methoxyphenyl 4-[4-(pentamethyldisiloxanyl)butoxy]benzoate and trimethylolpropane triacrylate. 4-Methoxyphenyl 4-[4-(1,1,3,3,5,5,5-heptamethyltrisiloxan-1-yl)butoxy]-benzoate gave 50 % diffraction efficiency and angular selectivity of 5°. Siloxane-containing liquid-crystalline compounds were also effective in fabricating fine gratings. These compounds induced distinct phase separation over a concentration range from 6 to 20 wt % in the formation of holographic gratings. The use of ring-opening polymerizable bifunctional epoxides as one of the reactive cross-linking matrix components, together with penta- or tetra-acrylate initiated by 3,3'-carbonylbis(7-diethylaminocoumarin)diphenyliodonium hexafluorophosphate, greatly improved the diffraction efficiency. Fine gratings with 70 and 78 % diffraction efficiency and angular selectivity of 5° were formed with 10 wt % 4-cyano-4'-[(5-heptamethyltrisiloxan-1-yl)pentyloxy]-biphenyl and 4-cyanophenyl 4-[(5-heptamethyltrisiloxan-1-yl)pentyloxy]benzoate using pentaerythritol pentaacrylate-neopentylglycol diglycidyl ether-tripropylene glycol diacrylate (4:5:1) as the polymer matrix component.

Theoretical diffraction efficiency for slanted uncoupled absorption multiplex holograms

1985 ◽  
Vol 63 (10) ◽  
pp. 1372-1374
Author(s):  
Jean J. A. Couture ◽  
R. A. Lessard
Keyword(s):  
Diffraction Efficiency ◽  
Analytical Solutions ◽  
Angular Separation ◽  
Simple Generalization ◽  
Angular Selectivity

Analytical solutions describing the reconstruction obtained from a multiplex hologram that has been made with two incoherent holographic exposures are presented. Angular separation between the two object waves is greater than the angular selectivity bandwidth of each of the two elementary uncoupled gratings. The analysis gives results characterizing the diffraction efficiency of these gratings. Incoherent superposition of N uncoupled and slanted gratings is easily described by a simple generalization.

scholarly journals Study of the Effect of Methyldiethanolamine Initiator on the Recording Properties of Acrylamide Based Photopolymer

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 734
Author(s):  
Brian Rogers ◽  
Suzanne Martin ◽  
Izabela Naydenova
Keyword(s):  
Refractive Index ◽  
Diffraction Efficiency ◽  
Prolonged Exposure ◽  
Uv Light ◽  
Holographic Recording ◽  
Refractive Index Modulation ◽  
Optical Elements ◽  
The Stability ◽  
Angular Selectivity ◽  
Index Modulation

The use of Holographic Optical Elements (HOEs) in applications, such as in light shaping and redirection, requires certain characteristics such as a high Diffraction Efficiency, low angular selectivity and stability against UV damage. In order to maximize the performance of the HOEs, photosensitive materials are needed that have been optimised for the characteristics that are of particular importance in that application. At the core of the performance of these devices is the refractive index modulation created during holographic recording. Typically, a higher refractive index modulation will enable greater light Diffraction Efficiency and also operation with thinner devices, which in turn decreases the angular selectivity and the stability of the refractive index modulation introduced during recording, which is key to the longevity of the device. Solar concentrators based on volume HOEs can particularly benefit from thinner devices, because, for a solar concentrator to have a high angular working range, thinner photopolymer layers with a smaller angular selectivity are required. This paper presents an optimisation of an acrylamide-based photopolymer formulation for an improved refractive index modulation and recording speed. This was achieved by studying the effect of the concentration of acrylamide and the influence of different initiators in the photopolymer composition on the diffraction efficiency of holographic gratings. Two initiators of different molecular weights were compared: triethanolamine (TEA) and methyldiethanolamine (MDEA). A fivefold increase in the rate of grating formation was achieved through the modification of the acrylamide concentration alone, and it was also found that holograms recorded with MDEA as the initiator performed the best and recorded up to 25% faster than a TEA-based photopolymer. Finally, tests were carried out on the stability of the protected and unprotected photopolymer layers when subjected to UV light. The properties exhibited by this photopolymer composition make it a promising material for the production of optical elements and suitable for use in applications requiring prolonged exposure to UV light when protected by a thin melinex cover.

Optical Diffractive Memories: Angular Selectivity and Diffraction Efficiency in Dichromated Gelatin

1995 ◽  
Vol 2 (6) ◽  
pp. 434-437 ◽  
Author(s):  
Harry Ramenah ◽  
Poul Bertrand ◽  
Patrick Meyrueis
Keyword(s):  
Diffraction Efficiency ◽  
Dichromated Gelatin ◽  
Angular Selectivity

Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation

1974 ◽  
Vol 32 ◽  
pp. 58-59
Author(s):  
W. H. Zucker ◽  
R. G. Mason
Keyword(s):  
Fine Structure ◽  
Platelet Aggregation ◽  
Hydrochloric Acid ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Hemostatic Agent ◽  
Native Collagen ◽  
Fibrillar Morphology ◽  
Clinical Interest ◽  
New Form

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.

Pituitary Follicular Cells: Their Origin, Possible Function and Fate

1974 ◽  
Vol 32 ◽  
pp. 34-35
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
G. Penz ◽  
C. Ezrin
Keyword(s):  
Fine Structure ◽  
Secretory Granules ◽  
Follicular Cells ◽  
Human Pituitary ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Junctional Complexes

Follicular structures, in the rat pituitary, composed of cells joined by junctional complexes and possessing few organelles and few, if any, secretory granules, were first described by Farquhar in 1957. Cells of the same description have since been observed in several species including man. The importance of these cells, however, remains obscure. While studying human pituitary glands, we have observed wide variations in the fine structure of follicular cells which may lead to a better understanding of their morphogenesis and significance.

Ultrastructure and Staining of Developing Elastic Tissue

1971 ◽  
Vol 29 ◽  
pp. 244-245
Author(s):  
E. N. Albert
Keyword(s):  
Fine Structure ◽  
Phosphotungstic Acid ◽  
Staining Method ◽  
Rat Aorta ◽  
Uranyl Acetate ◽  
The Other ◽  
Elastic Fibers ◽  
Elastic Tissue ◽  
Lead Citrate ◽  
New Born

Silver tetraphenylporphine sulfonate (Ag-TPPS) was synthesized in this laboratory and used as an electron dense stain for elastic tissue (Fig 1). The procedures for the synthesis of tetraphenylporphine sulfonate and the staining method for mature elastic tissue have been described previously.The fine structure of developing elastic tissue was observed in fetal and new born rat aorta using tetraphenylporphine sulfonate, phosphotungstic acid, uranyl acetate and lead citrate. The newly forming elastica consisted of two morphologically distinct components. These were a central amorphous and a peripheral fibrous. The ratio of the central amorphous and the peripheral fibrillar portion changed in favor of the former with increasing age.It was also observed that the staining properties of the two components were entirely different. The peripheral fibrous component stained with uranyl acetate and/or lead citrate while the central amorphous portion demonstrated no affinity for these stains. On the other hand, the central amorphous portion of developing elastic fibers stained vigorously with silver tetraphenylporphine sulfonate, while the fibrillar part did not (compare figs 2, 3, 4). Based upon the above observations it is proposed that developing elastica consists of two components that are morphologically and chemically different.

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