NONDESTRUCTIVE READOUT OF A 3-DIMENSIONAL PHOTOCHROMIC OPTICAL MEMORYWITH A NEAR-INFRARED DIFFERENTIAL PHASE-CONTRAST MICROSCOPE

A three-dimensional (3D) rewritable optical memory using photochromic material is described for high-density memory. The bits are recorded i n a 3D volume of photochromic material. A transformation of the photoc hromic molecule between two isomers with different absorption spectra can be stimulated by irradiation with appropriate wavelengths. We show that a nondestructive readout of photochromic memory is possible by u se of a small difference in the refractive index of the photochromic i somers in the near-IR range. For this purpose a near-IR laser-scan dif ferential phase-contrast microscope is used. Experimental results of 3 D recording and nondestructive reading are presented. (C) 1997 Optical Society of America.