The Wide Field Camera 3 (WFC3) is an instrument which is being developed for the Hubble Space Telescope. It will have a UV/VIS channel which will include two 2051 x 4096 pixel, thin, backside illuminated CCDs. These CCDs produce interference fringes in narrow band or monochromatic light images taken in the 700 nm to 1000 nm wavelength range. We have obtained 146 monochromatic images for each of the four flight candidate CCDs. These images can be used to model the physical structure of the CCD, which are described by a set of parameters deduced by solving the Fresnel equations for the absorption within the CCD as a function of wavelength. We have used the formalism developed to model the Space Telescope Imaging Spectrograph's CCD by Malumuth et. al.(1) to determine the free parameters for a large portion of one of the WFC3 flight candidate CCDs. From these fits we are able to evaluate the ability to fit the fringing of real data by comparing a model fringe flat to an observed fringe flat. We find that we should be able to reduce the observed fringe amplitude by a factor of five or better. Finally we show that for a certain class-of object (extended emission line object with a variety of radial velocities) this model is an excellent method for removing the effect of fringing.
