2.1 Holographic Microscopy for the Study of Phase, Diffusive …
69
low spatial coherence. In the works [153, 154], the scheme of holographic microscope for phase object studies is proposed. In this microscope, the coherent noises
suppression is achieved with the help of including in light beam of revolving glass
parallelepiped. During the studies of phase microobjects, which can change polarization state of scattered on them radiation, for coherent background elimination, the
method of polarizing filtration can be quite effective [155]. It is possible that overcoherence of laser radiation also influences the quality of the microobject holographic
image. Taking into consideration low holographing microobject volume (depth is
20 μm), it is reasonable to record reflecting holograms of phase and diffusely scattered microobjects in incoherent light source radiation (for example, lamps similar to
DAC-50 with glowing body of 1 mm can be used as such sources). Attempts of holographing in incoherent light were carried out in the works [156, 157]. It also should
be noticed that the latest developed recording media have resolving power up to
several thousand lines/mm, which is enough for the recording of high space frequencies produced during microobject structures scattering. But, light sensitivity of such
media is quite low. That is why it is very important, in particular during holographic
study of biological microobjects, to reach compromise between maximum allowed
microobject raying energy, light sensitivity of recording holographing medium and
its resolving power.
2.1.3 Peculiarities of Microobject Holographic
Interferograms Formation Connected
with the Dependence of Interference Pattern Contrast
on Defocusing
In holographic interferometry, which allows “remembering” and comparing wave
fronts in different periods of time and of complicated forms up to random fields,
there are a lot of possibilities. Using holographic interferometry in solving biomedical tasks, it is necessary to take into consideration object mobility and the presence
of magnification optics. Though, at the moment, it can be said that principal problems
of holography and holographic interferometry are solved. There are only actual problems such as the search of the best technical decision and the schemes of holographic
devices, more effective media and radiation sources, the decrease of the laboriousness and the cost of holographic recording, the development of algorithms, which
lower the laboriousness and improve the precision of holographic interferograms
processing and searching new and effective fields of their application.
In different schemes of holographic and speckle-interferometry, there is an object
longitudinal shift. Defocusing produced by axial shift leads to a considerable transformation of the wave spread through the optical scheme and influences the interference pattern characteristics, results and measurement range. Holographic interference microscopy with its possibility of interfering comparison of mirror-reflecting
69
low spatial coherence. In the works [153, 154], the scheme of holographic microscope for phase object studies is proposed. In this microscope, the coherent noises
suppression is achieved with the help of including in light beam of revolving glass
parallelepiped. During the studies of phase microobjects, which can change polarization state of scattered on them radiation, for coherent background elimination, the
method of polarizing filtration can be quite effective [155]. It is possible that overcoherence of laser radiation also influences the quality of the microobject holographic
image. Taking into consideration low holographing microobject volume (depth is
20 μm), it is reasonable to record reflecting holograms of phase and diffusely scattered microobjects in incoherent light source radiation (for example, lamps similar to
DAC-50 with glowing body of 1 mm can be used as such sources). Attempts of holographing in incoherent light were carried out in the works [156, 157]. It also should
be noticed that the latest developed recording media have resolving power up to
several thousand lines/mm, which is enough for the recording of high space frequencies produced during microobject structures scattering. But, light sensitivity of such
media is quite low. That is why it is very important, in particular during holographic
study of biological microobjects, to reach compromise between maximum allowed
microobject raying energy, light sensitivity of recording holographing medium and
its resolving power.
2.1.3 Peculiarities of Microobject Holographic
Interferograms Formation Connected
with the Dependence of Interference Pattern Contrast
on Defocusing
In holographic interferometry, which allows “remembering” and comparing wave
fronts in different periods of time and of complicated forms up to random fields,
there are a lot of possibilities. Using holographic interferometry in solving biomedical tasks, it is necessary to take into consideration object mobility and the presence
of magnification optics. Though, at the moment, it can be said that principal problems
of holography and holographic interferometry are solved. There are only actual problems such as the search of the best technical decision and the schemes of holographic
devices, more effective media and radiation sources, the decrease of the laboriousness and the cost of holographic recording, the development of algorithms, which
lower the laboriousness and improve the precision of holographic interferograms
processing and searching new and effective fields of their application.
In different schemes of holographic and speckle-interferometry, there is an object
longitudinal shift. Defocusing produced by axial shift leads to a considerable transformation of the wave spread through the optical scheme and influences the interference pattern characteristics, results and measurement range. Holographic interference microscopy with its possibility of interfering comparison of mirror-reflecting