A method of observing 3-D phase structures through a microscope incorporating computer reconstruction is discussed. This microscope is equipped with an annular pupil in illumination optics, but no phase shifter is included in the imaging optics. The sample stage is longitudinally (z-axial) scanned to collect a focus image series. The 3-D phase transfer function is derived and computer-plotted based on Streibl's 3-D image transfer theory under the first-order Born approximation and the mutual intensity propagation theorem. Experimental results of 3-D phase reconstruction are shown with cultured tobacco cells by Helstrom's inverse filtering of the transfer function to a series of focused images.

We report a technique for measuring the three-dimensional variation of refractive indices in a microscopic sample. The technique is an adaptation of optical computed tomography and is effective in measuring the three-dimensional refractive-index distribution of a nonabsorbing microscopic sample. Our report also includes a discussion of the conditions for the unambiguous application of the technique as well as results of experiments conducted with Aspergillus oryzae (commonly known as green mold) as the sample.

By analyzing aerial images, we characterize the lowest order coma aberration measurements for the projection optics of a microlithography exposure apparatus based on scalar diffraction theory. Our developed method for measuring the coma aberration exploits the intensity difference between the sidelobe peaks appearing near the boundaries of the bright field ("negative") single-line or plural-line patterns. Our method further demonstrates linearity between the intensity difference of the sidelobe peaks and the amount of residual lowest order coma aberration. We analyze the coma aberration sensitivity formula and determine the duty ratio of the line-and-space pattern that realizes the highest aberration sensitivity.

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