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Bacteriorhodopsin-based holographic interferometry is a new technique with which high-resolution interferograms can be recorded at one or more wavelengths in real time. The erasable nature of bacteriorhodopsin (bR), its panchromatic response to light, and the fact that recording is done on the molecular level allow for the formation of fringe patterns combining the high resolution of conventional silver halide recording materials with the real-time properties of CCD cameras. In this context, we have used bR to image changes in the crystal environment at single and dual wavelengths, using a real-time sequencing architecture whereby successive exposures of a bR thin film are overlapped to produce a continuous stream of interferometric images. This allows realtime data buffering and immediate, on-line observation of results. In this paper, we present real-time single and dual wavelength interferograms of growing KAl(SO4)2 and melting sugar crystals recorded on bR thin films. The interferograms were produced with a shuttered cw argon or a pulsed Nd:YAG write laser, and a helium-neon read laser, and show contrast more than adequate for the given application. The results of this effort clearly demonstrate the real-time recording capabilities of bR thin films.
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