Measurement System for Very Small Photoelastic Constant of Polymer Films

Abstract

Summary: We produced a new system for measuring the small photoelastic constant of a polymer thin film with a small birefringence. Using our mesurement system, we evaluated the photoelastic constant of a polymer film in real time by quantitative analysis. Photoelastic constants of 11.30 Â 10 À12 Pa À1 for a cellulose triacetate film and 78.38 Â 10 À12 Pa À1 for a polycarbonate film were obtained. Furthermore, we obtained a small photoelastic constant of 0.12 Â 10 À12 Pa À1 for a cycloolefin film for liquid crystal displays, using our new measurement system. This value is very small. We emphasize that, if a small change in retardation and stress cannot be detected simultaneously using our system, then we cannot obtain such a small photoelastic constant.

Estimation of electrostriction coefficients of a nonlinear optical polymer electret

“…Experimental values of the ESC of various polymers are usually in the range ~2•10 -11 tõ 9•10 -11 Pa -1 , 25 with the exception for polyurethanes, for which these coefficients are, on the average, tenfold larger. 25, 30 Thus, the contribution to Q estimated in this * In the system of units MKS(I) one has P (n) = ε 0 χ (n) E (n) , ε 0 = 8.8542•10 -12 C 2 N -1 m -2 . 28 Note that our definition of ESC differs from that used by experimentalists by a factor of ½. Q r cdl work coincides in order of magnitude with the experimental value.…”

“…We also made an estimation for DANS doped polycarbonate 7 characterized by N/V = 1.86•10 26 m -3 and α = 4.3•10 -28 m 3 ; 31 for the piezo optical constant, we also used the value π ijkl = 9.5•10 -12 Pa -1 . 29, 30 The ESC value estimated with inclusion of the contribution pro portional to the polarizability α is Q ≈ 1•10 -12 Pa -1 . Our calculations are approximate and only aimed at evalua ting the ESCs in the order of magnitude; the more so the complexity of polymers as subjects of experimental re search consists in that the measured value of the coeffi cient can depend on the sample preparation and treat ment procedure.…”

Evaluation of Phase Retardation of Curved Thin Polycarbonate Substrates for Wide-viewing Angle Flexible Liquid Crystal Displays

“…The change in refractive indices depend on the bending stress in curved plastic substrates and the stress optical coefficient (SOC). The amount of change in optical phase retardation δ of the plastic substrate can be calculated by following equation [15], [16],…”

Investigation of optical and thermal properties of N-(alkyl-substituted) maleimides for use in zero–zero-birefringence polymer

“…The photoelastic birefringence Δn ph of the film samples in the upstretched state was measured at various levels of uniaxial tensile stress (approximately 1% strain) at room temperature using optical heterodyne interferometry at a wavelength of 633 nm using a birefringence measurement system (ABR-10A, UNIOPT Corp., Ltd.) [22]. The stress was measured at the same time.…”