The pitch of a cholesteric liquid crystal can be inferred from (1) the distance of the Grandjean lines in a wedge tylpe sample1; (2) the angular dependence of Bragg-scattering,2and (3> the wavelength of maximum reflection.3The present paper reports a simple method for determining the pitch based on transmission measurement. It can be particularly valuable in the infrared, i.e. a pitch range of about 0.5 to 5μ, where reflectance measurements are difficult