Yuriy Vashpanov

Image Light Distribution in the Multiview 3-D Imaging System

The light intensity distributions in the front space of a contact-type multiview 3-D imaging system are measured to estimate the effects of the differences in real and nominal values of parameters and alignment errors on the quality of 3-D images. The distributions clearly reveal how the viewing zone cross section is formed and how the mixed images are formed. For these measurements, a 1×4 Fresnel lens array and a projector are used as the viewing zone forming optics and image source, respectively. The results are graphically represented in terms of crosstalk. Both the misalignments and the inaccuracies greatly increase the crosstalk.

Photo-EMF Sensitivity of Porous Silicon Thin Layer–Crystalline Silicon Heterojunction to Ammonia Adsorption

A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

Optical absorption and photoelectron collection properties of silicon wafers with conical quantum nanocrystals structure

A conical form of nano-sized quantum cluster was formed on the surface of p-type crystalline silicon [111] wafer by anode electrochemical etching in HF-based solution. The conical surface is highly effective in absorbing sunlight and transporting photoelectrons to semiconductor material. These are because each cone has a graded band gap with the energy level in the range from 1.1 to 3 eV which can be considered as consisting of quantum dots in different sizes. Since the boron concentration on the surface of each cone gradually decreases from top to bottom, a continuously varying electrical field is created along the cone height. This electric field is forcing photoelectrons generated in the cone to move rapidly to the direction perpendicular to wafer surface. Hence the drift time of photoelectrons can be less than their recombination time within the thin layer close to the bottom of the cone.

Electronic Parameters of Mesoporous Silicon Upon Adsorption of Plant Viruses

Changes in the electronic parameters of mesoporous silicon upon adsorption of nematodetransmitted polyhedral (NEPO) viruses of plant [tomato ringspot virus (TORSV), grapevine virus A (GVA), and grapevine fan leaf virus (GFLV)] measured at room temperature are investigated. The adsorption of these viruses affected essentially on the electronic characteristic of the porous material. The measurement of the electronic characteristics of porous silicon can be applied to the creation of detectors for the presence of viruses in a given environment.

Polarized Light for Measuring a Human Skin Feature Indicating Aging

The textures of skin on the back of the hand of many men of different ages are analyzed to determine their changes with age. The analysis shows that the textures are segmented by many lines of different lengths and orientations, and the size and number of segments in the skin surface change with age; that is the size increases while the number decreases. As a result, the texture becomes less complex with age. However, the addition of wrinkles from the age of 50 onwards for certain groups of people makes the texture appear somewhat complex.

Stereo camera model of feed horns in focal plane array

The equivalent camera model of two feed horns in millimeter wave imaging system is a radial type stereo camera with diverging axes. The stereo image characteristics of the camera are analyzed. This camera model allows minimizing the distance between cameras.