Determination of subpixel microdisplacements of speckle structure using the phase shift of spatial spectrum field

An experimental method for measurement of subpixel microdisplacements of speckle structure based on the parameters of the linear phase shift in the field of the complex spatial spectrum of the displaced structure is proposed and experimentally implemented. The phase shift is determined when a phase shift of spectrum is numerically added and the correlation analysis of the resulting linear phase shift in the spatial spectrum of specklegrams is performed. The method provides additional possibilities in the measurements using digital speckle photography when the period of interference fringes formed in the total spatial spectrum of specklegrams is significantly greater than the spectral width.

     

Formation of a quasi-regular interference pattern in a speckle-modulated laser beam reflected from a transparent optically nonuniform layer

Conditions for the formation of a quasi-regular interference pattern in the speckle-modulated radiation reflected from a rough transparent layer irradiated by a focused laser beam are found. A laser method for determining the optical thickness of the transparent coating deposited onto the rough surface is proposed.     

Numerical correction of coherence gate in full-field swept-source interference microscopy

A big problem in low-coherence interference microscopy is the degradation of the coherence signal caused by shift of the angular and temporal spectrum gates. It limits the depth of field in confocal optical coherence microscopy and degrades images of sample inner structure in most interference microscopy techniques. To overcome this problem we propose numerical correction of the coherence gate in application to full-field swept-source interference microscopy. The proposed technique allows three-dimensional sample imaging without mechanical movement of the microscope components and is also capable of determining separately the geometrical thickness and the refractive index of the sample layers, when the sample contains a transversal pattern. The applicability of the proposed technique is verified with numerical simulation.     

Manifestation of longitudinal correlations in scattered coherent fields in an interference experiment

The processes of formation of interference signals in the scattered coherent field with a wide angular spectrum in a scanning Michelson interferometer are considered. The effect of longitudinal correlation properties of the light-field complex amplitude on parameters of the interference oscillation envelope, upon detection of the signal in the image space and in the near-field region of diffraction, is studied.     

Erratum to: The Influence of the Numerical Aperture of a Beam Probing an Object on the Determination of the Thickness of a Layered Object in Confocal Microscopy

Optics and Spectroscopy - erratum     

The influence of the spectral properties of human skin on the resolution of a Linnik interference microscope

We have studied the Zeeman structure of the 3p5f configuration of SiI and revealed its particular features in the range of variation of the magnetic field from 0 to 60 kOe. In this range, we have found 71 crossings of Zeeman sublevels with ΔM = ±1 and ±2 (M is the magnetic quantum number) and 4 anticrossings of lower F levels with j ₁ = 1/2 (j ₁ is the total angular momentum of the p electron). From splittings of levels in the assured linear range up to 40 Oe, we have calculated gyromagnetic ratios and compared them with their counterparts in the absence of the field.     

The Nonaberrational Width of the Angular Spectrum of a Field Probing a Layered Object in Confocal Microscopy

Optics and Spectroscopy - The influence of the numerical aperture of a light beam that probes a layered object on the magnitude of the quantity measured with a confocal interference microscope upon...     

Instantaneous Speckle-Modulated Interference Images and Coherent Effects in Optical Microscopy of Thin Layers

Optics and Spectroscopy - We consider the formation of instantaneous speckle-modulated interference images of thin transparent layers in an optical microscope under their illumination of either...     

Study of polymer dissolution and diffusion by laser interferometry

A Mickelson laser interferometer is used to study the polymer dissolution and diffusion in the system of cellulose diacetate fiber and nitromethane solvent. Digital interferograms at different stages of the diffusion mixing are obtained. The kinetics of the diffusion parameters (refractive index distribution and concentration of the medium) is considered. The diffusion coefficients of the polymer in the mass transfer process are determined, and their temperature dependences are constructed.     

Longitudinal purely spatial coherence of a light field

The effects of longitudinal purely spatial coherence of light and the results of observation of these effects in an interference experiment are considered under the condition that the length of temporal coherence l _c is considerably smaller than the length of longitudinal spatial coherence ρ_‖ of the field. It is shown that, for l _c ? ρ_‖, the longitudinal purely spatial coherence of the light field in fact governs the coherence of the wave train in the process of its propagation. The length and the time of coherent (“free”) path of the wave train are considered as new spatial and temporal scales of a partially coherent light field.