PROCEEDINGS ARTICLE | February 20, 2008
Proc. SPIE. 6861, Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XV
KEYWORDS: Microscopes, Holograms, Holography, Optical signal processing, Digital holography, Microscopy, Wavefronts, CCD cameras, Phase imaging, Phase shifts
Different interferometric techniques were developed last decade to obtain full field, quantitative, and absolute
phase imaging, such as phase-shifting, Fourier phase microscopy, Hilbert phase microscopy or digital holographic
microscopy (DHM). Although, these techniques are very similar, DHM combines several advantages. In contrast,
to phase shifting, DHM is indeed capable of single-shot hologram recording allowing a real-time absolute phase
imaging. On the other hand, unlike to Fourier phase or Hilbert phase microscopy, DHM does not require to record
in focus images of the specimen on the digital detector (CCD or CMOS camera), because a numerical focalization
adjustment can be performed by a numerical wavefront propagation. Consequently, the depth of view of high NA
microscope objectives is numerically extended. For example, two different biological cells, floating at different
depths in a liquid, can be focalized numerically from the same digital hologram. Moreover, the numerical
propagation associated to digital optics and automatic fitting procedures, permits vibrations insensitive full-
field phase imaging and the complete compensation for a priori any image distortion or/and phase aberrations
introduced for example by imperfections of holders or perfusion chamber. Examples of real-time full-field phase
images of biological cells have been demonstrated.
