A rapid in situ processing system for holograms to be used in real-time hologram interferometry is designed. The plates are held in a liquid gate and exposed under immersion in the developer. Interferometric evaluation takes place with fixing bath surrounding the plate. The swelling properties of photographic layers are discussed, and formulae are given for a rapid developer and a fixing bath of the same index of refraction, which are matched to keep the layers of Agfa-Gevaert Scientia 8E70 and 10E70 plates at the same thickness in both solutions. An instruction is given on how to match processing solutions by checking the fulfillment of the Bragg-angle condition. The volume character of these thick holograms suppresses intermodulation noise, making practicable high modulation and a reference source close to the object. Because of hypersensitization, exposure time is reduced by a factor of 2-3. Interferometric evaluation can start 100-180 s after exposure. Fringe-free superposition of the object field and the reconstructed field is obtained, allowing time-average observation of vibrations in real time by visual inspection or photography. Interferograms are shown and compared with the conventional method of making one time-average hologram recording for each vibration mode. The experimental results agree with the theoretical analysis made for fringe formation in real-time hologram interferometry, which shows that, in comparison with time-average hologram recordings, half the number of fringes is obtained and the fringe visibility is lower.