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Photoplethysmography (PPG) is a noninvasive optical method accepted in the clinical use for measurements of arterial oxygen saturation. It is widely believed that the light intensity after interaction with the biological tissue in vivo is modulated at the heartbeat frequency mainly due to pulsatile variations of the light absorption caused by arterial(More)
We present novel experimental method for estimation of the light penetration depth (LPD) in turbid media based on the analysis of the speckle pattern structure. Under the certain illumination conditions this structure is strongly dependent on the penetration depth. Presented theoretical model based on the Bragg diffraction from the thick holograms allows(More)
Diffraction-limited accuracy is estimated for measuring systems exploiting dynamic speckles. Statistical properties of the signal in the systems with spatial filtering are used to evaluate the signal frequency with precision sufficient to achieve the diffraction-limited accuracy. The results of the analysis allow for designing an optimal measuring system in(More)
Noncontact methods of distance measurements to a moving surface using laser light are relevant for many industrial applications, such as surface profile and position monitoring, thickness measurements, and wear estimation. Application of existing methods (e.g., triangulation) is limited especially for nonhomogeneous, semitransparent and rough materials(More)
We present a novel method for small surface defect detection based on the spatially filtered dynamic speckles. This method possesses high fidelity and versatility. Factors defining resolution of the proposed method is estimated and it is shown that resolution depends solely on the geometrical parameters of the optical system. Experimental results(More)
We recently pointed out the important role of dermis deformation by pulsating arterial pressure in the formation of a photoplethysmographic signal at green light. The aim of this study was to explore the role of this novel finding in near-infrared (NIR) light. A light-emitting diode (LED)-based imaging photoplethysmography (IPPG) system was used to detect(More)
Assessment of the cardiovascular parameters using noncontact video-based or imaging photoplethysmography (IPPG) is usually considered as inaccurate because of strong influence of motion artefacts. To optimize this technique we performed a simultaneous recording of electrocardiogram and video frames of the face for 36 healthy volunteers. We found that signal(More)
Imaging photoplethysmography (IPPG) is a recently developed technique for noncontact assessment of cardiovascular function. However, its wide use is limited by low signal-to-noise ratio due to motion artifacts. The aim of this work is to estimate the polarization-filtration impact on discriminating artifacts in IPPG measurements. Experiments were carried(More)
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