Coherence Controlled Holographic Microscopy (CCHM) is a novel holographic technique for quantitative-phasecontrast (QPC) biological observations particularly of living cells. Owing to the ordinary (low coherence) illumination source, the CCHM images are of low noise, deprived of coherence noise (speckles) and the lateral resolution is improved by a factor of 2 compared to classic holographic microscopes. Long-lasting time-lapse experiments require elimination of the CCHM optical system instability in order to achieve precise QPC measurement and to maintain correct CCHM adjustment for its low-coherence operation. The critical part of CCHM is the interferometer, which is very sensitive to temperature fluctuations and air turbulences. The temperature stabilization of the whole microscope without air turbulences is therefore required to provide stability for long-term observations of living cells. Novel heated microscope box and stage designed and constructed for this purpose are described in the paper. The system maintains a constant temperature of both the microscope and of the sample set to 37 °C thus providing optimal living conditions for living human and animal cells. The system is completed with a novel flow-chamber for living-cells accommodation during observation. A service of the system to CCHM is demonstrated by a series of pictures of growing cells.
In the paper a new off-axis achromatic interferometer configuration of a digital holographic microscope is presented.
The proposed configuration uses a reflective diffraction grating and ensures a high-contrast interference pattern in the
output plane of the microscope using illumination of an arbitrary degree of temporal and spatial coherence. The concept
of this optical system brings a significant improvement of microscope parameters, enables implementation of
conventional observing techniques and is more user-friendly in comparison with the previous generation of
the microscope. The functionality of the microscope has been proved experimentally.
The design of 3D optical system for multidirectional phase tomograph is presented in detail. The suggested tomograph uses a multidirectional holographic interferometer with diffusive light. The method of dividing of the laser-beam to object and reference beams is described. The optimisation of geometrical dimensions of the testing area and optical parameters of projection beams was done in order to increase the number of obtainable angular projections. Finally, projecting properties of the scanning system of the tomograph are presented.
A proposed design of the multidirectional holographic interferometer (MHI) with diffusive illumination in 3D dodecagon
geometry for optical tomography is presented. The beam from Nd-YAG laser is divided and transformed to six object
beams that incident to diffusors and illuminate the cross section area. The optical axes of reference beams lie in six
vertical planes that are turned 30 degrees to each other, which is the specific of our design. Next is discussed the
constructional design of mechanical realization of filtering and collimating optics as well as the ways of traction of the
rotationally embedded scanning system of CCD cameras. Finally, optical and mechanical properties of interferometer are
digestedly summarized.
A three-dimensional configuration of multidirectional Mach-Zehnder holographic interferometer with diffusive illumination
is used in novel phase tomograph. The multidirectional tomography setup with diffusive illumination enables to digitize
many times higher number of projections in comparison with other known configurations. This setup doesn't require to
rotate with the object. The resulting resolution of the reconstructed three-dimensional image depends not only on the choice
of computer tomography algorithm, but first of all on the device ability to digitize sufficient number of complete and
equally spaced projections in given angular range with low noise level. The proposed paper is focused on design and
optimization of the optical tomography setup for the three-dimensional non-contact diagnostic of the physical properties of
stationery placed non-symmetric phase objects. Optimization of geometrical configuration design of multidirectional
holographic interferometr, with respect to significant increase of the signal to noise ratio in interferograms is performed.
Characteristic properties of the multidirectional interferograms of investigated phase objects are discussed and presented.
The novel laboratory system for the optical tomography is used to obtain three-dimensional temperature field around a heated element. The Mach-Zehnder holographic interferometers with diffusive illumination of the phase object provide the possibility to scan of multidirectional holographic interferograms in the range of viewing angles from 0 deg to 108 deg. These interferograms form the input data for the computer tomography of the 3D distribution of the refractive index variation, which characterizes the physical state of the studied medium. The configuration of the system allows
automatic projection scanning of the studied phase object. The computer calculates the wavefront deformation for each projection, making use of different methods of Fourier-transform and phase-sampling evaluations. The experimental set-up together with experimental results is presented.
A basic description of the system for optical tomography with diffusive illumination of the phase object is presented. The configuration of the system allows automatic projection scanning of the studied phase object (such as a burner flame or temperature fields around heated elements) in the range of viewing angles from 0 deg to 90 deg. The object’s projections are obtained using multidirectional holographic interferometry and consequently digitized by a CCD camera. A computer then calculates the wavefront deformation for each projection, and the subsequent tomographic reconstruction of each horizontal slice of the object is processed. Finally, all slices are interpolated and displayed. Here we present the experimental setup along with some experimental results.
Multidirectional holographic interferometry (MHI) allows to study characteristics of phase objects using transmission computer tomography. The present paper deals with comparison of various phase-measurement interferometry techniques. On this basis two configurations of holographic interferometers were designed. Both of them can be modified according to the method used for the evaluation of the phase change. Components for MHI for imaging phase object with full and partial asymmetry were constructed.
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