4.3 Statistical Properties of Dynamic Speckle-Field Scattered …
333
4.3 Statistical Properties of Dynamic Speckle-Field
Scattered by the Diffuser Oscillating
in the Longitudinal Direction
The case of rotation of diffusely scattering object, which was examined in Sect. 4.1,
concerned the movement of the diffuser in its plane, i.e., transverse movement. And
conditions of object illumination and formation of the speckle-field were constant
in time. Oscillations of the diffuser illuminated with coherent radiation along the
optical axis lead to changes of medium sizes of speckles of dynamic speckle-field
in registration plane, as well as of parameters, which characterize the illuminating
beam and the conditions of observation. As a result of this, correlation and spectral
properties of dynamic speckle-field considerably differ depending on the movement
of the object. But due to considerable difficulties connected with the presentation in
analytical form of the results of theoretical calculations of statistical characteristics of
intensity fluctuations of dynamic speckles under longitudinal oscillations of diffuser
[107], only periodical oscillations and vibrations of diffuse objects in longitudinal
direction are rather fully examined [108, 109].
We investigate statistical characteristics of dynamic speckle-field scattered by the
diffuser, which oscillates in longitudinal direction using the approach applied while
studying longitudinal movement of the object at a constant velocity [110].
We examine the model of oscillating diffusing face with the amplitude h along the
z-axis at the frequency ω illuminated by coherent Gaussian beam with the wavelength
λ focused by the lens with waist W 0 in the plane of oscillations equilibrium (Fig. 4.12).
The observation plane is situated at a distance R 0 from the focus and the position of
equilibrium of diffuser oscillation. Speckle-image is formed in the far-field region
of diffraction at a distance R 0 from the beam waist. The structure of the speckleimage is altered in time as a result of longitudinal oscillations of the object. Variable
Fig. 4.12 Scheme of the diffuser model under consideration. Reprinted from [2] with permission
333
4.3 Statistical Properties of Dynamic Speckle-Field
Scattered by the Diffuser Oscillating
in the Longitudinal Direction
The case of rotation of diffusely scattering object, which was examined in Sect. 4.1,
concerned the movement of the diffuser in its plane, i.e., transverse movement. And
conditions of object illumination and formation of the speckle-field were constant
in time. Oscillations of the diffuser illuminated with coherent radiation along the
optical axis lead to changes of medium sizes of speckles of dynamic speckle-field
in registration plane, as well as of parameters, which characterize the illuminating
beam and the conditions of observation. As a result of this, correlation and spectral
properties of dynamic speckle-field considerably differ depending on the movement
of the object. But due to considerable difficulties connected with the presentation in
analytical form of the results of theoretical calculations of statistical characteristics of
intensity fluctuations of dynamic speckles under longitudinal oscillations of diffuser
[107], only periodical oscillations and vibrations of diffuse objects in longitudinal
direction are rather fully examined [108, 109].
We investigate statistical characteristics of dynamic speckle-field scattered by the
diffuser, which oscillates in longitudinal direction using the approach applied while
studying longitudinal movement of the object at a constant velocity [110].
We examine the model of oscillating diffusing face with the amplitude h along the
z-axis at the frequency ω illuminated by coherent Gaussian beam with the wavelength
λ focused by the lens with waist W 0 in the plane of oscillations equilibrium (Fig. 4.12).
The observation plane is situated at a distance R 0 from the focus and the position of
equilibrium of diffuser oscillation. Speckle-image is formed in the far-field region
of diffraction at a distance R 0 from the beam waist. The structure of the speckleimage is altered in time as a result of longitudinal oscillations of the object. Variable
Fig. 4.12 Scheme of the diffuser model under consideration. Reprinted from [2] with permission