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SummaryWe propose an extension to Nomarski differential interference contrast microscopy that enables isotropic linear phase imaging. The method combines phase shifting, two directions of shear and Fourier-space integration using a modified spiral phase transform. We simulated the method using a phantom object with spatially varying amplitude and phase. Simulated results show good agreement between the final phase image and the object phase, and demonstrate resistance to imaging noise.

The effect of detector array size on resolution and signal collection efficiency of image scanning microscopy based on pixel reassignment is studied. It is shown how the method can also be employed if there is a Stokes shift in fluorescence emission wavelength. With no Stokes shift, the width of the point spread function can be sharpened by a factor of 1.53, and its peak intensity increased by a factor of 1.84.

We describe a full-field phase-gradient imaging method: asymmetric illumination-based differential phase contrast (AIDPC). Imaging properties of AIDPC are evaluated using the phase-gradient transfer-function approach and elucidated with experimental images of an optical fiber and a histochemical preparation of a skeletal muscle section. In comparison with full-field differential interference contrast, AIDPC does not require phase shifting for quantitative imaging of phase gradient, provides artifact-free images of birefringent specimens, requires shorter camera exposure, and has larger depth of focus. It is amenable to transfer-function engineering, simultaneous fluorescence imaging, and automated live cell imaging.

An annular pupil, which can be used to produce a Bessel beam, when combined with radially polarized illumination promises improvements in microscope resolution, increased packing density for optical storage, and finer optical lithography. When combined with a circular detection pupil in confocal microscopy a point-spread function 112 nm wide results (lambda = 488 nm). Radially polarized annular illumination of a solid-immersion lens can yield a focal spot smaller than 100 nm for lambda = 488 nm. Use of radially polarized illumination with pupil masks is discussed.

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