BACTERIORHODOPSIN-BASED SINGLE AND DUAL-WAVELENGTH HOLOGRAPHIC-INTERFEROMETRY FOR MONITORING CRYSTAL-GROWTH

Bacteriorhodopsin-based holographic interferometry is a new technique with which high-resolution interferograms can be recorded at one or mo re 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 patte rns combining the high resolution of conventional silver halide record ing materials with the real-time properties of CCD cameras. In this co ntext, 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 prod uce a continuous stream of interferometric images. This allows real-ti me data buffering and immediate, on-line observation of results. In th is paper, we present real-time single and dual wavelength interferogra ms of growing KAI(SO4)(2) and melting sugar crystals recorded on bR th in films. The interferograms were produced with a shuttered cw argon o r 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 o f bR thin films. (C) 1998 Society of Photo-Optical Instrumentation Eng ineers. [S0091-3286(98)03206-1].