Microstructure of variable pitch cholesteric films and its relationship with the optical properties A. Boudet, C. Binet, M. Mitov, C. Bourgerette and E. Boucher Eur. Phys. J. E, 2 3 (2000) 247-253 Published online: 15 July 2000 DOI: 10.1007/PL00013671