Holographic interference microscopy

Holographic interference microscopy (HIM) is holographic interferometry applied for microscopy for visualization of phase micro-objects. Phase micro-objects are invisible because they do not change intensity of light, they insert only invisible phase shifts. The holographic interference microscopy distinguishes itself from other microscopy methods by using a hologram and the interference for converting invisible phase shifts into intensity changes.

Other related microscopy method to holographic interference microscopy are phase contrast microscopy, holographic interferometry.

Holography was born as "new microscopy principle". D. Gabor invented holography for electron microscopy.For some reasons his idea is not applied in this branch of microscopy. But invention of holography opened up new possibilities in imaging of phase micro-objects due to the application of the holographic interference methods in microscopy that allow not only qualitative, but quantitative study. Combining the holographic interference microscopy with methods of numerical processing has solved the problem of 3D imaging of untreated, native biological phase micro-object.>

In the holographic interference method the images appear as the result of the interference of two object waves passed the same path through the microscope optical system but in different points of time: the reconstructed from the hologram “empty” object wave, and the object wave disturbed by the phase micro-objects under study. The hologram of the "empty" object wave is recorded using a reference beam, and it is used as an optical element of the holographic interference microscope. In the dependence on conditions of the interference two methods of the holographic interference microscopy can be realized: the holographic phase-contrast method and the holographic interference-contrast method. In the first case, the phase shifts inserted by the phase micro-object into the light wave passing through it are converted into intensity changes in its image; and in the second case – into deviations of interference fringes.

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