An instrument for optical waveguide lightmode spectroscopy (OWLS) was designed and
developed for measurements at different and controlled temperatures in a range of
15 degreesC around room temperature. The instrument allows to scan the waveguide modes
at different wavelengths on the same optical chip using different lasers. This instrument
was used to monitor DMPC lipid bilayer main phase transition around the critical temperature.
The main problem in these experiments is that the OWLS measurements do not give enough
information about an optically anisotropic system like a lipid bilayer. Experimental
OWLS data at two different wavelengths can however approximately solve the problem.
The temperature dependence of the thickness and the refractive indices (ordinary and
extraordinary) for the lipid bilayer around the phase transition is presented. (A
theoretical derivation of the extraordinary refractive index is given in Appendix
A.) (C) 2002 Elsevier Science B.V. All rights reserved.
