  We have developed a white light interferometric microscope (WLIM), which can
spatially resolve the change in the complex index of refraction and apply it to
study reversible photodegradation of 1,4-Diamino-9,10-anthraquinone doped into
(poly)methyl methacrylate. The measured change in absorbance is consistent with
standard spectrometer measurements. The refractive index of a pristine sample
measured with the WLIM is also found to be consistent with the spectrum found
by independent means (F. Yakuphanoglu and B. Senkal, Electrical conductivity,
photoconductivity, and optical properties of poly(1,4 diaminoanthraquinone)
organic semiconductor for optoelectronic applications, Polym. Adv. Technol. 19,
1193 to 1198 (2008)). We report on measurements of the change in refractive
index due to photodegradation, which is found to be consistent with Embaye's
two population model (N. Embaye et al., Mechanisms of reversible
photodegradation in disperse orange 11 dye doped in PMMA polymer, J. Chem.
Phys. 129, 054504 (2008)). We show that the WLIM can be used as a powerful tool
to image the complex refractive index of a planar surface and to detect changes
in a material's optical properties.
