George Eugene Dovgalenko

Optically induced birefringence in bacteriorhodopsin as an optical limiter

Experimental data are presented, which demonstrates an optical limiter based on a large birefringence which is optically induced in bacteriorhodopsin. The induced birefringence is observed to be a function of incident intensity, but saturates at a value of about 0.454 W/cm2. A measured value of Δn of 6.6×10−4 at a wavelength of 514 nm is reported. The observed birefringence is found to be in good agreement with a proposed model.

Manifestation of circular photogalvanic current by dynamic holography in BaTiO3

We report the first measurement of the photo-galvanic circular current antisymmetric tensor component in BaTiO3: Co. The measurement gives a value of this coefficient, for extraordinary beam amplification, of 4×10−9 A/W using a nonstationary measurement technique at a wavelength of 0.632 μm.

Portable holographic interferometric device for aircraft inspecting

A new single-beam technique for a continuous reconstruction of volume holograms in photorefractive crystals of symmetry 23 is presented. The doped crystal Bi12TiO20 (Fe,P) possessing diffraction efficiency above 70% is used for real-time holographic interferometry. The major advantage of this technique is an automatic self-adjustment of diffraction in volume holograms, continuous reconstruction of volume holograms, high diffraction efficiency without application of external electric field, high resolution (more than 3000 lines/mm), high vibroprotection stability, low cost using of He-Ne or diode lasers, and portability (single-beam device). A 1 mm crack was detected at a depth of 1.5 mm in airplane wings near a rivet zone using protable adaptive holographic interferometer.

Advanced holographic nondestructive testing system for residual stress analysis

The design and operating of a portable holographic interferometer for residual stress analysis by creating a small scratch along with a new mathematical algorithm of calculations are discussed. Preliminary data of the stress investigations on aluminum and steel alloys have been obtained by the automatic processing of the interference pattern using a notebook computer. A phase-shift compensation technique in real-time reflection interferometry is used to measure the out-of-plane stress release surface displacement surrounding a small scratch (25 micrometer depth and 0.5 mm width) in a plate with residual stress of around 50 MPa. Comparison between theoretical models for a rectangular and triangular shaped scratch with the experimental data are presented.

Fast residual stress determination of welded joints using reversible holographic interferometric (RHI) film

A mathematical algorithm is proposed for fast determination of residual stress in blind hold drilling method. Computer simulation of this algorithm has been made. Comparing of theoretical interference pattern with experimental interferogram is presented.

In-situ thin film stress measurement using high-stability portable holographic interferometer

A stress in thin film SiO2 was detected using high stability portable holographic interferometer. A stress relaxation phenomenon in this film thickness of 0.5 micrometers on Si wafer has been observed. This phenomenon does not exist in film with thickness of 1 micrometers . The advantages of the proposed measured technique and results are discussed.

Submicron grating adaptive sensor

An adaptive, selfdiffractive image sensor with space resolution greater than 11,000 lines/mm is presented. Practically unlimited reversibility in continuous hologram registration regime without pretreatment (chemical, temperature, electrical field etc.) allows creation of a new portable interferometers with high Isignal/Inoise ratio. The advantages of proposed systems for diffusely reflected objects are discussed.

Dynamic sensors on subwavelength gratings

A basic conception of an adaptive, remote optical sensor for small angle tilt displacement in 3D space is presented. Sensor is based on high space resolution 11,000 lines/mm adaptive photorefractive gratings has no moving parts is portable, robust and can provide measurement in plane and out-of-plane displacements simultaneously. Resolution of small angle tilt measurement of order of 10-5 Rad has been achieved. Advantages and disadvantages of this sensor are discussed.

Stress measurement of deposited SiO2 films on a silicon wafer using dimensional-stability holographic interferometry test

In quality control nondestructive techniques gain more and more importance. Holographic interferometry has the advantage of being very sensitive and can be used contactless for inspection of technical components. The interferogram contains fringes, whose pattern holds information about the surface deformation of a part subjected to the load. The load in case of deposited silicone oxide film is cased by stress produced different thermal expansion temperature coefficients film and silicone substrate. Change in stress in thin silicon dioxide films was observed using a high stability portable holographic interferometer using dimension stability test. Pattern recognition algorithm for synthesis of stress analyses map is reported. A stress relaxation phenomenon in this film thickness of 0.5 micrometers on Si wafer has been observed. Correlation of differential stress with initial flatness deviation of Si wafer has been discovered. The advantages of the proposed measuring technique and results are discussed.

High-resolution self-diffractive adaptive element for remote displacement sensing

A new conception of adaptive, high resolution, selfdiffractive microsensor for remote displacement measurements is presented. The sensor is sensitive in 3D space and can provide in-plane and out-of-plane displacements simultaneously and separately.