The characteristics of a coherent IR image converter that uses electro-absorption in a GaAs photoconductor (PC) and the electro-optic (EO) Pockels effect in a Bi12SiO20 crystal has been analyzed theoretically and experimentally. An experimental PC-EO crystal structure by which IR-radiation (0.9-1.7 mum) can be converted into coherent visible radiation was obtained on the basis of theoretical calculations. The measured threshold sensitivity of the converter, 5 x 10(-4) W/cm(2), was found to be comparable to theoretical estimates. The limiting resolution of the readout image was about 10 lp/mm. The contrast ratio depends strongly on the change in the absorption coefficient and on the thickness of the GaAs PC. The change in the absorption coefficient is estimated by use of the quadratic equation of an applied electric field that is not excessively strong. Under this condition, an optimum thickness of the GaAs PC that will yield the maximum contrast ratio can be determined. (C) 2003 Elsevier Science B.V. All rights reserved.