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A transmission differential phase-contrast microscope with a split detector is used as a readout system for a multilayered three-dimensional optical memory. The system is applicable to data recorded as refractive-index changes. The system is compact and easy to use. The three-dimensional optical transfer function for the system is derived. This shows that the spatial bandwidth of the system is the same as that of a conventional microscope with incoherent illumination but with much improved contrast. Six layers of information are recorded in a photopolymer and are read out with little cross talk and high contrast. Key words: Optical memory, photorefractive, differential phase-contrast microscope, three-dimensional optics, nonlinear optics, holographic memory.

A compact scanning microscope that uses a semiconductor laser both to illuminate a specimen and to detect the signal reflected from it is described. It is demonstrated that the spatial filtering performed by the laser detector ensures confocal operation. Two detection regimes, one employing a laser power monitor and the other using the diode junction voltage as a signal, are compared.

A scanning optical microscope system is proposed that uses a slightly laterally offset optical fiber. The fiber is capable of supporting two modes, and it is shown that by detecting the interference between these modes the response to surface height is linear in the focal region. This linearity permits noncontacting surface profilometry to be readily obtained for specimens of uniform reflectivity. For other specimens, a simple feedback system is introduced to obtain surface profiles as well as intensity-coded height images.

A novel technique for obtaining differential images with a scanning microscope by using a two-mode optical fiber is proposed. It is shown that both the differential amplitude and the differential phase images can be obtained by adjusting the differential phase delay between the fiber modes. The technique is demonstrated experimentally, and differential images of a specimen consisting of sharp edges in both amplitude and phase reflectivity are presented., A new method based on a double-mode optical fiber is presented for confocal scanning microscopy. The process for generating differential images improves on the split-detector technique in that it produces images with an optical branching capability and enhanced lateral resolution. It was confirmed via experiments. The study discusses how the differential amplitude and differential phase images are obtained through changing the differential phase delay between the fiber modes.

The optical sectioning capability of a fiber-optic scanning microscope with a 9-cm-long gradient-index-rod lens probe has been demonstrated. A transverse resolution of 1.3 micrometer and a longitudinal resolution of 30 micrometer were achieved. The dimensions of the probe allow the device to be used as an endoscope.