Laser self-mixing interferometry of absolute distances is represented by the method of frequency modulation of supply current of the laser diode (FMCW technique). The advantages of the triangular wave modulation method in combination with the use of the frequency of the self-mixing signal spectrum have been shown. The advantages of the harmonic wave modulation method in combination with the use of the some various amplitudes of the self-mixing signal spectrum have been shown were shown also. The advantages of the harmonic wave modulation method in combination with the use of different amplitudes of the spectrum of self-mixing signals are shown. The equipment includes a frequency-modulated semiconductor self-mixing laser diode RLD-650 on quantum-size structures with a diffraction-limited single spatial mode with a wavelength of 654 nm. The results of computer simulation showed that the accuracy of determining the distance at the harmonic wave modulation decreases with increasing the distance to the measured object. But at small distances, its value is much smaller than at the triangular wave modulation of laser radiation.
The possibilities of self-mixing interferometry for measuring nanodisplacement of a probe included in a near-field scanning microwave microscope have been considered. The features of the formation of a laser interference signal at current modulation of the wavelength of laser radiation have been investigated. Experimental responses of a semiconductor laser system included in scanning microwave microscope to control nanodisplacement of the probe have been demonstrated.To register the nanodisplacement of the probe, it is proposed to use the method of determining the stationary phase of a laser interference signal by low-frequency spectrum of a semiconductor laser. The change of the amplitudes of the spectral components in the spectrum of the interference signal due to creation of the standing wave in the external resonator of the laser self-mixing system has been shown. The form of the interference signal at current modulation of the radiation wavelength was experimentally obtained when the probe moves with a step of 80 nm. The results of measuring nanodisplacements of an electromagnetic translator STANDA 8MVT40-13 have been demonstrated. Deviation of the nanodisplacement of the proposed method does not exceed 15%.
The essence of the phenomenon of ischemic preconditioning is increasing myocardium resistance to long periods of ischemia that occurs after several short ischemia-reperfusion periods. The aim of this pilot study was to determine the temperature and vascular response in double brachial occlusions and to assess the prospects of using this maneuver for remote ischemic preconditioning. Infrared thermography-based measurements were used to assess hemodynamics both left and right hands during the baseline, ischemia and hyperemia periods. Double ischemia with a period of 2 min was implemented by a cuff compression of the brachial artery of the right hand. A study group was constituted of eight men and six women without cardiovascular abnormalities at the age of 22 to 35 years. As a result, we have determined that a temperature and vascular response to ischemia of right hand is accompanied by the vascular reaction of the contralateral left hand, especially after the inflation and deflation of the cuff. These vascular reactions are reproducible, systemic and appear to be at least neurological in nature. An experimental confirmation of the systemic vascular «training effect» after multiple brachial ischemia-reperfusion periods is a subject of further investigations.
Application of thermometry as a method of blood flow estimation in hands is limited by the differences in
waveform of the skin temperature and blood flow oscillations. In addition, there is the delay time between
simultaneously registered blood flow and temperature signals. We offer the method of blood flow estimation in
hands based on the analysis of skin temperature dynamics.
Simplification of the Shitzer's temperature dynamics model in hands allowed us to express the relation between
the temperature and blood flow oscillations. As it turns out, within using model the skin blood flow is
proportionally to the first time derivative of the skin temperature, in other words, the blood flow oscillations
determine the rate of skin temperature alterations. We also derived relation between spectral components of the
blood flow and temperature oscillations. To extract spectrum of the blood flow oscillations from temperature
spectrum it is necessary using frequency dependent multiplication factor and time shift of each of temperature
spectral component.
In this study the skin temperature was registered by infrared camera and blood flow was estimated by
photoplethysmography. First time derivation of the temperature increases correlation between processed signal
and blood flow oscillations from ~0.3 to ~0.7 on average. Thus, derived relations between temperature and blood
flow in fingertips provide the basis for the application of thermometry in the field of analysis of low-frequency
peripheral blood flow oscillations.
Interrelation of skin temperature and blood flow oscillations of fingers under normal conditions in healthy subjects has
been investigated. Oscillations of a blood flow were measured by means of photoplethysmography; oscillations of a
temperature were registered by means of thermal imaging camera.
The method of blood flow reconstruction by temperature oscillations with the use of the Pennes bioheat transfer equation
and a definition of delay time of a temperature in relation to blood flow signal has been described. Temperature oscillations
have a lag in relation to blood flow oscillations of approximately 10-20 seconds. Delay time of temperature waves
can be used for the definition of an effective thickness of a tissue layer separating blood vessels and skin surface.
Use of the described technique of comparison of finger blood flow and temperature oscillations allows to raise correlation
coefficient of the signals from 0.35 to 0.63 on average, which testifies of high degree of conditionality of temperature
oscillations by blood flow oscillations.
The considered method of non-contact restoration of blood flow oscillations by means of temperature oscillation measurements
might find practical application in skin thermal lesions research, research of influence of physical and chemical
factors on a skin microcirculation.
The algorithm of analysis of videoirnage of tread pattern trace has been presented. The videoimage comparison is carried out with the help of image subtraction method. Realization of method of recognition of tire tread pattern has been described. The experimental results are given.
The possibility of the reconstruction of a complex non-harmonic function of the moving object by means of autodyne interference system is represented in this work. The results of the experiment show the possibility to determine the parameters of complex nonharmonic movements of the reflector. It is obvious that the use of multistage digital filtering in the course of autodyne experiment allows us to reduce the influence of the noise distortion on restored signal.
The development of methods of quantitative registration of movement character is actually to research of biophysical effects, which are specific for different forms of biological movements, for example, eye movement of human. These methods are based on use of new experimental foundation including high-resolution video techniques and computer analysis of big data arrays.
KEYWORDS: Wavelets, Signal processing, Wavelet transforms, Digital signal processing, Numerical modeling, Homodyne detection, Integration, Smoothing, Signal attenuation, Solid state physics
The possibility of using wavelet transforms for reconstruction of complex nonperiodic motion in optical homodyne in-terferometrie is presented. The numerical simulation of object motion function reconstruction using Fourier and wavelet transforms is performed, and results comparative analysis is examined.
Determination method of the mechanical vibration amplitudes by the spectrum of the autodyne signal of the semiconductor laser for the sphericity of the light wave front is described. The relation between the focusing of the laser beam and form of the autodyne signal was obtained. Measurements of the vibration amplitude of the piezoelectric plate were carried out with the help of the semiconductor laser autodyne system.
The research results of autodyne signal formed under reflection of semiconductor laser radiation from vibrating reflector have been presented. The influence of feedback coefficient and distance to vibrating object on an autodyne signal form has been shown. The method of reverse problem solution in autodyne interferometry of nonharmonical vibrations has been described. The suggested method allows us to restore the amplitude and form of mechanical vibrations for autodyne system developed for interference system separated from the light source. A method of amplitude determination of mechanical vibrations from the spectrum of autodyne signal of semiconductor laser is described. The relation between the vibration amplitude of an object and the frequency of spectral component with the maximum amplitude in the spectrum of the autodyne signal has been obtained. The least-squares method was used to obtain the approximation coefficient. Measurements of vibration of micron amplitude of piezoelectric plate were carried out with the help of a semiconductor laser autodyne system. A method for the quantitative monitoring of nanometer vibrations based on the autodyne detection effect in a semiconductor laser has been developed. It is shown that the semiconductor laser autodyne can be used for measuring vibration amplitudes in the range from one nanometer to 10 μm in the frequency band from a few hertz to several hundred megahertz. With the aid of a lock-in amplifier, the lower threshold of measured vibration amplitudes has been reduced to angstrom.
The method based on autodyne effect of detection in the semiconductor laser is offered for registration of heart and eye movements of fresh-water crawfish-Daphnia. With the help of laser autodyne system amplitude and the shape of Daphnia's heartbeats which used to determine the degree of toxicity of the water environment has been registered. In this work the dependence of frequency and amplitude of heartbeats of Daphnia from a degree of toxicity of the water environment has been presented. Oscillograms of movements of Daphnia's eye and their spectrums have been received both for a case of own movements of an eye, and for occurrence of the phenomenon of synchronization of these movements by an external electric field. Occurrence of the phenomenon of synchronization at which character of movement of an eye becomes close to harmonious has been shown. We show the research results of influence of a magnetic field on Daphnia, placed in the water environment. It is shown, that at frequencies close to Daphnia's heartbeat frequency the frequency of its heartbeat substantially increases. We also discovered great increase in heartbeat frequency of a Daphnia placed in water that was preliminary influenced with a magnetic field. It can be understood as a "magnetization" of water. Under the influence of magnetic field of higher frequency the "magnetization" effect disappears.
A method of amplitude determination of mechanical vibrations from the spectrum of autodyne signal of semiconductor laser is described. The relation between the vibration amplitude of an object and the frequency of spectral component with the maximal amplitude in the spectrum of the autodyne signal is obtained. The least-squares method is used to obtain the approximation coefficient. Measurements of vibration amplitude of piezoelectric plate were carried out with the help of a semiconductor laser autodyne system.
The method for monitoring of involuntary eye motion on the basis of image processing and analysis technology is posed. The efficiency of the program for the object movement analysis by its trajectory and spectrum is demonstrated. The results of measuring of involuntary eye movements of patients with nystagmus are presented. The measuring results characterizing the nystagmus status changing before and after the squint correction is demonstrated.
Methods of analysis of objects characterized by wide variety of sizes, shapes, color and type of dynamics are described. Application of automatic video control systems for granulometric analysis of various metal powders and grinded materials used in dispenser elements of electrovacuum devices is illustrated. The results of color analysis of millet seeds images having different color shade are given. The features of optoelectronic detection and computer diagnostics of complex movements of the freshwater crayfish Daphnia eye are considered.
The research results of autodyne signal formed under reflection of semiconductor laser radiation from vibration reflector have been presented. The influence of feedback coefficient and distance to vibration object on autodyne signal form has been shown. The method of reverse problem solution in autodyne interferometry of nonharmonical vibrations has been described. The suggested method allows to restore the amplitude and form of mechanical vibrations for autodyne system developed for interference system separated from the light source.
The research results of autodyne signal formation in the interference systems based on the use of external optical feedback have been presented. The possibility of measurements of vibration characteristics with help of laser autodyne interferometry has been proved. The solution method of reverse problem in autodyne interferometry of nonharmonical vibrations has been described. Considered method allows to use for autodyne system the methods of the determination of amplitudes and forms of mechanical vibrations using for interference system separated from the light source.
New coherence methods of microobject parameter measurements are analyzed in connection with the development of the automatic data processing systems, of the phase0shifting holography methods, as well as with the appearance of new active elements permitting to carry out autodyne measurements. The simple method of parameter inspection of microobject vibration is based on usual optical microscope with TV camera is discussed. The method based on the phase- shifting interference pattern consequence analysis using the Fourier transformation is given. For the first time the possibility of the returning of the non-harmonical vibration spectrum of the object in phase-shifting holographic interferometry has been considered. The semiconductor laser autodyne systems have been used to elaborate new technologies of fast-changing processes control. The use of semiconductor laser autodyne for the diagnostics of the microsaccidic eye movements, known as eye tremor, whose amplitude does not exceed several microns has been shown.
The method based on the autodyne effect in semiconductor laser has been described to the analysis of dynamical behavior of biological specimen. The advantage of the method has been shown in comparison with tradition photoelectrical methods. The experimental investigations of the effect of external alternating voltage on the amplitude and frequency of fresh water crawfish - daphnia have been implemented. The synchronization effect of daphnia heart beating by the external electric field has been discovered. The investigation results of the dependence of daphnia heart beating frequency on the water toxicity degree.
The results of interference registration of human eye movements are presented. The semiconductor laser autodyne has been used for the diagnostics of the saccadic eye movements. The frequency and amplitude of the eye tremor was measured.
The effect of autodyne detection in semiconductor lasers generated relaxation oscillations has been investigated. The computer simulation of the experimentally observed blurring of phase trajectories on its certain parts has been made with the help of numerical calculation of the system of differential equations for semiconductor laser with vibrating external reflector. The relation of the blurring of trajectories with generation of relaxation oscillations on these parts has been found. It has been shown that semiconductor laser in the generation regime of relaxation oscillations has the high sensitivity to the fluctuations of parameters of external optical feedback and to the non- stability of power supply.
The article proves the problem of determining the mechanical vibration amplitudes of complicated movements by optical homodyne interferometry to be incorrect. The possibility of its approximate solution by the least-squares method is presented. The above method usage for the restoration of mechanical system vibration spectrum has been verified.
The possibility of determination of the complicated form of the object motion by the homodyne system has been shown. The method is based on the use of Fourier representation of the function of the object motion. The results of the experimental data processing for a nonharmonic vibrating mirror have been presented.
The influence of parameters of external optical feedback on the character of autodyne signal of semiconductor laser has been investigated. For harmonic and non-harmonic mechanical vibrations the possibility of restoration of interference signal function for autodyne system has been shown.
The formation analysis of speckle patterns and the holographic image of vibrating objects has been made in dependence on recording and reconstruction of the object image using a television system. A television speckle interferometer scheme has been proposed by which the speckle pattern images with improved contrast are receiving. The possibility of brightness increase of the interference pattern has been shown when mirror components of recorded and reconstructed waves are focused.
To provide an improvement of vibrotest process of the small-sized units and systems the optic method of determination of resonance frequencies, quality and oscillation amplitudes has been developed. Sensitivity of the method can be compared with the sensitivity properties of the well known interference- holographic-vibration methods. The typical for resonance of oscillation phenomena of amplitude increasing has been used for oscillation parameter determination.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.