An apparatus has been designed for real-time and double-exposure holographic interferometry to determine radiation absorbed dose distributions in transparent liquids. The change in refractive index of the liquid due to a temperature rise after irradiation is measured interferometrically. In a cylindrically symmetrical radiation field, the dose distribution can be computed from data supplied by the reconstruction of the holographic interferogram taken as side-view profile of the change in optical pathlength. Relatively inexpensive components such as a low-powered He-Ne laser together with a conventional photographic shutter and low-cost mirrors and lenses were used. The mathematical procedure for unfolding the three-dimensional dose distribtion is described, and an example is given for use with a high-intensity, pulsed, 2-MV electron source.
E. K. Hussmann, "A Holographic Interferometer for Measuring Radiation Energy Deposition Profiles in Transparent Liquids," Appl. Opt. 10, 182-186 (1971)