The possibility of using a multi-modal approach in the clinical practice of a dermatologist for psoriasis, which includes 3 optical non-invasive technologies: laser Doppler flowmetry, video capillaroscopy, and laser speckle-contrast imaging, is demonstrated. The dynamics of changes in the main microhemodynamic parameters of the microcirculatory bed of patients with psoriasis during conservative therapy was studied, and the effectiveness of treatment of patients suffering from psoriasis was evaluated.
Videocapillaroscopy (VCS) and laser Doppler flowmetry (LDF) are non-invasive methods for evaluating microcirculation parameters. The VCS method is based on a high-speed video recording of capillaries in the nailfold. The recorded video frames are processed using a specialized algorithm to determine the red blood cells velocity. The LDF technique is based on the analysis of the Doppler shift of back-scattered laser radiation from moving red blood cells. In this work, simultaneous measurements of VCS and LDF have been performed in healthy volunteers and rheumatic patient. The study was conducted using a cold pressor test. Changes were recorded in response to cold exposure in rheumatic diseases.
Advanced processing of high-speed video-capillaroscopy data revealed that
erythrocytes speed follows variations of arterial blood pressure, whereas intensity of light returned
from a single capillary is almost unmodulated at the heartbeat frequency.
An optical instrument for nailfold fluorescence capillaroscopy and image registration has been developed. With this
instrument, an effect of increasing fluorescence intensity in the spectral range of NADH fluorescence during ischemia
was detected.
A multi-view scanning method is suggested to assess a complicated surface relief by white light interferometer.
Peculiarities of the method are demonstrated on a special object in the form of quadrangular pyramid cavity, which is
formed at measurement of micro-hardness of materials using a hardness gauge. An algorithm of the joint processing of
multi-view scanning results is developed that allows recovering correct relief values. Laser ablation craters were studied
experimentally, and their relief was recovered using the developed method. It is shown that the multi-view scanning
reduces ambiguity when determining the local depth of the laser ablation craters micro relief. Results of experimental
studies of the multi-view scanning method and data processing algorithm are presented.
Peculiarities of optical design for optical coherence tomography (OCT) system with illumination by a swept-source in the spectral range 1.26-1.36 μm are considered. In the OCT system, an object is illuminated by light intensity distribution in the form of line providing high power efficiency of the light source when evaluating micro structure of objects. A linearray photo detector with the frame acquisition rate of a few tens of kilohertz is utilized that allows obtaining B-scans without mechanical lateral scanning. The illumination power density at each point of investigated object is much less with respect to conventional "flying spot" methods that is important when studying biological objects not resistant to intensive light. Results of experimental investigations utilizing the Linnik micro interferometer optical scheme are given. Experimental tomograms of different objects are presented.
Laser Doppler flowmetry (LDF) is widely used for diagnosing blood microcirculation diseases. It is well known that the Doppler shift of laser radiation scattered by moving red blood cells (RBC) can be assessed through analyzing photocurrent produced by a photodetector. LDF signal contains information about regulating blood flow rhythms: myogenic, cardiac, nervous and endothelial. The method of videocapillaroscopy (VCS) allows local capillary blood flow velocity evaluation and, using video data processing algorithms, is able to assess RBC velocity changes into capillary. We present the results of simultaneous investigations of changes in tissue perfusion of the distal phalanx of human finger by the LDF as well as changes in capillary blood flow velocity in the nail bed evaluated by the VCS method during arterial occlusion test. The experimental results confirmed the correspondence between blood perfusion and blood flow velocity.
High-resolving full-field OCT method is considered that provides increased resolution and interferometric data acquisition speed due to high optical magnification and electronic lateral scan provided by video camera. OCT data processing algorithm based on signal squaring with subsequent low-pass filtering is considered. Experimental results obtained when evaluating samples of paper material are presented and discussed.
Testing the condition of art subjects plays important role in reservation of Cultural Heritage. Optical Coherence
Tomography (OCT) is a promising tool for nondestructive cross-sectional evaluating internal structure of material
samples like varnish layer of paintings. It is important to use high-speed OCT systems for testing subsurface structure of
objects with large area. In the paper, comparison of OCT systems from viewpoint of information capacity is given to
select the most appropriate OCT system variant for evaluating 3D multilayer and random tissues. The method of sub-
Nyquist sampling of OCT signals is considered that is used to decrease sampling speed in a few times. To provide high
noise-immunity and stability when processing OCT signals with randomly variable parameters, the Kalman filtering
method has been applied for evaluating sub-Nyquist sampled OCT signals. Experimental results of evaluating materials
like varnish layer of paintings are presented and discussed.
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