G. G. Levin

Tomographic microscopy of three-dimensional phase objects in spatially incoherent light

The use of spatially incoherent light is proposed for raising the quality of interference projection data in tomographic microscopy of phase objects. The optical scheme of the tomographic microscope is based on the scheme of a Linnik microinterferometer with an extended source of quasi-monochromatic light. Characteristic features of the tomography of phase objects positioned near flat reflecting surfaces are considered.

Application of the aperture synthesis technique in optical interference microscopy

A method of integrated computational processing of series of microscopic images obtained at different angles of object illumination is proposed. Numerical simulation is performed based on the rigorous solution of the vector problem of electromagnetic scattering at various objects. The possibilities of increasing the effective resolving power of microscopes by using this method are studied.

Measuring technique of a phase shift based on Fourier analysis of differential interferograms

Interferometry employing the phase-stepping method requires precise knowledge of the phase shift. A new approach to measuring a phase shift between three interferograms that is based on the Fourier analysis of three new interferograms formed using the differences between different pairs of the initial interferograms has been suggested. Possibilities of increasing the accuracy of measuring the phase shift have been considered.

Local tomographic phase microscopy from differential projections

It is proposed to use local tomography for optical studies of the internal structure of transparent phase microscopic objects, for example, living cells. From among the many local tomography methods that exist, the algorithms of back projection summation (in which partial derivatives of projections are used as projection data) are chosen. The application of local tomography to living cells is reasonable because, using optical phase microscopy, one can easily obtain projection data in the form of first-order derivatives of projections applying the methods of differential interference contrast and shear interferometry. The mathematical fundamentals of local tomography in differential projections are considered, and a computer simulation of different local tomography methods is performed. A tomographic phase microscope and the results of reconstructing a local tomogram of an erythrocyte from a set of experimental differential projections are described.

Synthesis of three-dimensional phase images of nanoobjects: Numerical simulation

A way to synthesize three-dimensional phase-diffraction images of nanoobjects is proposed based on the numerical method of backward propagation of a field from the best focusing plane. The obtained phase images are used for solving the applied problem of object defect finding by methods of pattern recognition. The probability of defect detection by phase images is shown to be higher than for amplitude images.