Reflection confocal microscope reads out three-dimensional optical data

Reading out data stored in a three-dimensional photochromic medium has always proved harder than writing them into the medium. Researchers at Osaka University (Osaka, Japan) and Victoria University of Technology (Victoria, Australia) have applied a reflection confocal microscope (RCM) to the task with promising results. An RCM eliminates the problem encountered by a transmission confocal microscope, in which the focus deviates from the pinhole because of refractive index inhomogeneity in the mem

Reflection confocal microscope reads out three-dimensional optical data

Reading out data stored in a three-dimensional photochromic medium has always proved harder than writing them into the medium. Researchers at Osaka University (Osaka, Japan) and Victoria University of Technology (Victoria, Australia) have applied a reflection confocal microscope (RCM) to the task with promising results. An RCM eliminates the problem encountered by a transmission confocal microscope, in which the focus deviates from the pinhole because of refractive index inhomogeneity in the memory medium and substrate. With the detector and pinhole located in the reflected path between the laser source and the memory medium and with proper optical parameters, the researchers found that an RCM is able to accurately read out data in the same spatial band in which they were written. Poly(methylmethacrylate) films doped with a photochromic molecule provided the optical memory medium. The three-dimensional data were written with a Ti:sapphire laser at 760 nm, which induced photoconversion of the chromophores at the focus position via two-photon absorption. Readout was performed by a helium-neon laser emitting at 633 nm. Contact S. Kawata at kawata@ap.gifng.osaka-u.ac.jp.

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