The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

The paper presents the results of in situ studies of marine particles of different nature using a submersible digital holographic camera (DHC) during the Arctic expedition. It also describes the features, performance specifications, and possibilities of the DHC and the DHC technology. The DHC technology can be used for noninvasive automatic evaluation of spatial and temporal characteristics of plankton, including the distribution of plankton concentrations. The comparison of quantitative analysis of zooplankton net samples and classification results using the DHC revealed that the error of the DHC classification of mesoplankton at the level of the main systematic orders was about 30%. The results of determining the data on the medium, such as water turbidity, according to the radiation shielding factor (degree) by the particles of the Suspension taxon using the DHC technology are presented; the prospects for studying the size of gas bubbles and their volume content according to the Bubble taxon data are shown. The use of holographic data for in situ point estimates is considered.

This paper discusses the features of determining the coordinates of biological particles when digital holographic video is used. Experimental results are presented that show that it is possible to take into account rotational motion of a particle. The possibility of refining the coordinates of a particle by using a two-aspect holographic layout is experimentally investigated, taking into account the influence of the water–glass–air optical system.

In this work, the method of IR digital holography intended for detection of volumetric defects in ZnGeP₂ single crystals has been tested. The holographic method is verified by a comparison of the results obtained with the data obtained by other methods. The spatial resolution of the experimental setup is ~15–20 µm. The volumetric defects of the ZnGeP₂ crystal structure (in samples with thickness up to 50 mm) such as growth striations, dislocation chain, and inclusions of the second phase (Zn₃P₂) shaped as needles up to ~100 µm long and ~10 µm wide have been visualized by the method of IR digital holography.