Laser-induced optical recording in thin films

Broer, Dirk J.; Vriens, L.

doi:10.1007/bf00616606

Cited by 39 publications

(4 citation statements)

References 27 publications

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“…Table 1 summarizes the threshold energy at different laser powers and shows that it varies slightly with the marking power, but apparently levels off a t high powers. This calculated phenomenon seems to be consistent with previous experimental results where El values are close to that of published data (Novotny and Alexandru, 1979;Broer and Vriens, 1983). At present, there are various proposals to calculate E,, and there are many factors affecting E, value.…”

Section: Resultssupporting

confidence: 92%

“…Wrobel et al (1982) found that the surface tension forces were unimportant in rapid pit formation in thin polymer films. Broer and Vriens (1983) presented models to describe the hole-opening process, and concluded that surface tension is one dominant force during the process. Suh and coworkers investigated the writing mechanism in thin-textured inorganic films, and believed the surface tension gradient force to be one of the most effective driving forces to overcome the energy barriers for forming a pit (Suh and Craighead, 1985;.…”

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confidence: 99%

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Laser‐induced fluid motion on a dye/polymer layer for optical data storage

Chung

1987

AIChE Journal

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The interaction of highly focused light with active dye/polymer layers has received considerable attention in these days because it creates micron-size pits useful as optical data storage sites. Pit formation during laser marking takes place in a very short period of time, usually between 50 and 500 nanoseconds (ns). It consists of the following steps: the material heats, then melts, and finally flows in the lateral direction. In other words, the highly focused laser pulse results in an uneven temperature profile on the surface of an active dye/polymer layer; the variation in surface tension from one point to another creates tangential stresses on the free surface and a capillary fluid motion is therefore induced. As a result, the free surface of the pit center depresses and a bulge is formed around the pit. To be a good recording medium, an active dye/polymer layer should have high light absorption and reflectivity a t the wavelength of the emitting laser beam. The greater the absorption, the faster the marking. The encoded data can be read back based on the difference in the surface reflectivity between the surroundings and the pit.The detailed mechanism of pit formation is not fully understood yet, but it is a typical transport phenomenon problem for a chemical engineer. Surprisingly, however, almost no attention has been given to this issue by chemical engineers; most of the work has been done by optical physicists and published in physical journals. For example, Novotny and Alexandru (1 979) calculated the temperature profile during the light-induced marking process and described the mechanism of structure change in dye/polymer systems. Wrobel et al. (1982) found that the surface tension forces were unimportant in rapid pit formation in thin polymer films. Broer and Vriens (1983) presented models to describe the hole-opening process, and concluded that surface tension is one dominant force during the process. Suh and coworkers investigated the writing mechanism in thin-textured inorganic films, and believed the surface tension gradient force to be one of the most effective driving forces to overcome the energy barriers for forming a pit (Suh and Craighead, 1985;. Chung (1986) derived the governing equations for the transitional laser-induced fluid motion in extremely thin dye/polymer layers. The temperature rise in an optical layer is calculated based on the complicated Poynting vector theorem and Maxwell equations. Chung found that there are two factors controlling the pit formation, namely, the surface tension force and the gravitational force, the former being much more important than the latter.In this paper we attempt to extend our previous work to simulate the transitional pit formation in a relatively thick optical recording layer, while the temperature profile of the recording layer is determined using a conventional chemical engineering method. Calculations will be compared to the previous experimental results to determine if the model is meaningful. TheoryIn addition to the assumptions used in the...

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Section: Resultssupporting

confidence: 92%

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Laser‐induced fluid motion on a dye/polymer layer for optical data storage

Chung

1987

AIChE Journal

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“…Therefore, the propelled material is propagated in the forward direction with significant transverse velocity component. On the other hand, in case of GP produced plume, a non-uniform heating/melting of the film favors bubble formation in between the substrate-film interface (Broer & Vriens, 1983). With increase in vapor pressure, ultimately an opening may be formed to release the material rather than the occurrence of explosive rupture.…”

Section: Resultsmentioning

confidence: 98%

Influence of laser beam intensity profile on propagation dynamics of laser-blow-off plasma plume

et al. 2010

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Effect of intensity profile of the ablating laser on the dynamics of laser-blow-off (LBO) plume has been studied by fast imaging technique. This work emphasizes the geometrical aspect of the LBO plume, which is an important parameter for various applications. Visualization of the expanding plume reveals that geometrical shape and directionality (divergence) of the plume are highly dependent on the laser intensity profile. Present results demonstrate that the Gaussian profile laser produces a well-collimated, low divergence plasma plume as compared to the plume formed by a top-hat profile laser. The sequence of film removal processes is invoked to explain the role of energy density profile of the ablating laser in LBO mechanism.

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“…The various marking mechanisms of this process as well as the optical and thermal responses of the various media employed in optical recording have been the subject of numerous studies. [2][3][4][5][6][7][8][9][10][11][12][13][14] Thin organic layers coated upon highly reflective metallic underlayers have been utilized as optical storage media for write-once read-many (WORM) applications. [6,'5-'81 A common marking process upon laser irradiation consists of heating, melting, flow, and partial ablation of the organic layer, which leads to the formation of highly contrasting depressions or pits in the organic layer.…”

Section: Novel Materials For Non-ablative Optical Recordingmentioning

confidence: 99%

Novel materials for non‐ablative optical recording

Detty

Fleming

1994

Advanced Materials

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Communications polyelectrolytes including poly-L-glutamate, can be explained on the basis of the model proposed by Addadi et al.L4I These authors demonstrated that the P-sheet structure of the polyaspartate adsorbed on solid substrate is essential in order to induce (001)-oriented calcite nucleation by matching the charged groups of the polymer and the intercationic distances in the crystal lattice of the salt. It follows that the [3-sheet structure should be assumed by the exposed stretches of poly-L-aspartate on the surface of the gelatin films, while for the other polyelectrolytes considered the electrostatic interactions do not seem to be dictated by structural factors.Gelatin containing polyelectrolytes can be considered a versatile system for the planning of new films with tailor made surfaces. In fact, this system overcomes the compatibility problem between inert matrix and water-soluble polyelectrolytes or protein generally associated with biological mineralization. Furthermore, the nature, density and structural disposition of the charged groups on the surface can be regulated in a simple way by changing the kind and the amount of the polyelectrolytes in the film. ExperimentalType A gelatin from porcine skin was used (G-2500). The sodium salts of poly-L-aspartic acid (P-5387, average M.w. = 9900), poly-L-glutamic acid (P-4636, average M.Iv. = 6100). sulfate chondroitine A (C-8529) and C (C-4384) and carrageenan K (C-1263) were supplied by Sigma Co.3.0mlofa2% aqueousgelatinsolutioncontainingfrom5x 10-'to5 x lo-' weight percent (relative to gelatin) of polyelectrolyte was used to fill a Petri dish (diameter = 5 cm) on the bottom of which the film was obtained after water evaporation at room temperature. 5.0 ml of a 5 % glutaraldehyde solution in phosphate buffer (pH = 7.5) were placed on the film for 24 h. The films kept on the bottom of the dishes were thoroughly washed three times with water, dialyzed for 24 h against 3.0 ml of a l mM CaC1, solution to obtain calcium salts, and then washed again with water and dried. The air-dried films were 22 pm thick.Calcite crystals were grown, as reported by Addadi et a1.[4], at a temperature of 18 _+2 "C by very slow diffusion of (NH,),CO, vapor in the dishes, containing 2.9 ml of a 7.5 mM CaCI, solution. The crystals obtained after different times, up to four days, were examined by optical and scanning electron microscopy and X-ray powder diffraction. Crystals were counted under a microscope ( x 40) and nucleation density (crystals per cm2) was averaged over the total surface of the film (19.6 cm'). The (001) oriented crystals were identified by the hexagonal symmetry in two dimensional projection down the c axis.

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Laser-induced optical recording in thin films

Cited by 39 publications

References 27 publications

Laser‐induced fluid motion on a dye/polymer layer for optical data storage

Laser‐induced fluid motion on a dye/polymer layer for optical data storage

Influence of laser beam intensity profile on propagation dynamics of laser-blow-off plasma plume

Novel materials for non‐ablative optical recording

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