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0Features of thermal elastic deformation of polymer film caused by laser radiation of different powers
I. Zisser1*, N. Rekunova1, S. Piachin1, Y. Zisser1
1- Far Eastern State Transport University, 680021, Russia, Khabarovsk, Serysheva st., 47
* irinazisser@gmail.com
When laser radiation acts on a polymer film, it heats up and the surface of this film warps due to elastic thermal deformation [1,2]. As a result of the change in the surface shape, the film becomes analogous to a spherical mirror with a variable focal length. The effects induced by laser radiation are one of the mechanisms of creating the relief of holograms [3]. A detailed study of this phenomenon is required for a controlled change in the relief of a polymer film exposed to laser radiation.
The kinetics of the change in the diameter of the light spot on the screen formed by the reflection of the laser beam from the deformed film were investigated. The higher the intensity of the laser radiation incident on the film, the greater the diameter of the reflected laser beam on the screen. The values of the laser spot diameter obtained from experiment were used to calculate the radius of curvature of the polymer film and the relative change in the film volume AV/V0 during its deformation:
AV _ 2R2
V0 = ~hr[ 1
M
h2
1-й*-
In the equation above, R is the radius of curvature of the deformed plate, h is the radius of the laser irradiation zone on the film. The ratio AV/V0 during film deformation in the laser beam spot grows within the first 10 seconds, and then remains practically unchanged.
The temperature of the film in the laser impact zone was measured. The coefficient of volumetric thermal expansion of the film material was calculated.
Table 1. Temperature, relative change in volume, coefficient of thermal expansion at different laser radiation intensities.
1
/0, kW/m2 1.6 3.2 4.9 6.5
AT, °C 21 32 44 58
AVV0-105 0.27 1.46 3.86 5.1
av107, 1/°C 1.24 4.54 8.68 8.72
Analysis of the obtained results is presented. At low intensities of incident laser radiation, the calculations yield a smaller value of the coefficient of volumetric expansion than at high radiation intensities.
[1] N.I. Koroteev, Физика мощного ядерного излучения (Physics of high-power laser radiation) (Moscow: Nauka), Chapter 2, (1991).
[2] V.I. Ivanov, K.N. Okishev, N.N. Rekunova, Деформация полимерной плёнки под действием лазерного излучения (Deformation of a polymer film under laser radiation), Bulletin of scientific reports, № 19, pp. 52-55, (2014).
[3] V.I. Ivanov, T.N. Livashvily, T.N. Bruhanova, N.N. Rekunova, Пространственно-временные характеристики механизма записи
рельефных динамических голограмм (Spatio-temporal characteristics of the recording mechanism for relief dynamic holograms), Vestnik
TOGU, № 1, pp. 065-068, (2011).
