0000000000637038
AUTHOR
Anna Maslobojeva
Vadošās acs stabilitāte un binokulārā konkurence
Bakalaura darbs ir uzrakstīts latviešu valodā , tā apjoms 27 lapas. Darbs satur 27 attēlus, 3 tabulas un 28 atsauces uz literatūras avotiem. Pētījuma mērķis ir noskaidrot motorās vadošās acs un sensorās vadošās acs ietekmi uz dominances ilgumu binokulārās konkurences laikā. Noskaidrot, kā binokulārās konkurences attēlu maiņu ietekmē vadošā acs un tās stabilitāte. Novertēt vadošās acs un vadošās sensorās acs sakritību un to ietekmi uz dominances ilgumu binokulārās konkurences laikā, kā attēlu maiņu ietekmi binokulārās konkurences laikā.
Towards combined multispectral, FLIM and Raman imaging for skin diagnostics
To explore challenges for further improvement of diagnostic performance, a project aimed at development of technology for tri-modal skin imaging by combining multispectral, fluorescence lifetime and Raman band imaging was initiated. In this study, each of the mentioned imaging modalities has been preliminary tested and updated. Four different multispectral imaging devices were tested on color standards. Picosecond laser-excited fluorescence lifetime imaging equipment was examined on ex-vivo skin samples. Finally, a new Raman spectroscopy setup with 785 nm laser was launched and tested on cell cultures and ex-vivo skin. Advantages and specific features of the tri-modal skin imaging are discu…
Agar-based phantoms for skin diagnostic imaging
Agar-based skin phantoms with different thicknesses and hemoglobin concentration were evaluated for diagnostics of skin lesions by RGB imaging. Scattering properties of the phantoms were simulated using intralipid, absorption properties – using lyophilized powder of human hemoglobin. RGB images of phantoms were captured by self-developed laboratory made devices. The algorithm for calculation of chromophore concentrations are based on Beer-Lambert law and includes the photon path length evaluated from the measured photon-time-of-flight signals. Optical properties and chromophore concentration maps of phantoms obtained from RGB images were analyzed. The influence of chromophore concentration …
Skin-remitted photon path lengths: experimental study
Skin-remitted picosecond laser pulses were detected at four input-output fiber distances in the spectral range 560-800 nm. After deconvolution procedures, distributions and mean values of the remitted photon path lengths in forearm skin were analyzed.
Towards direct measurements of remitted photon path lengths in skin: kinetic studies in the range 520-800 nm
Skin-remitted picosecond laser pulses have been detected at variable input-output fiber distances (8 … 20 mm) in the spectral range 520-800 nm, with subsequent analysis of the pulse shape changes. Transfer functions representing the temporal responses of remitted photons to infinitely narrow δ-pulse excitation have been calculated. Parameters related to the photon path length in skin – input-output pulse peak delays, pulse FWHM, travel times of the “initial” photons and distributions of the remitted photon path lengths – are presented and analyzed. The measurement results are in general agreement with the photon propagation model expectations
Remitted photon path lengths in human skin: in-vivo measurement data
The remitted photon path lengths in human skin can be estimated by modelling; however, there are very few experimental data available to validate the simulations. This study exploited the photon time of flight method where picosecond laser pulses at seven wavelength bands in the spectral range 560-800 nm were launched into in-vivo forearm skin of 10 volunteers via an optical fiber. The pulses of back-scattered light were detected via another optical fiber placed at variable distance (1, 8, 12, 16 or 20 mm) from the input fiber, with subsequent analysis of their shapes for all 35 spectral-spatial combinations. Using a deconvolution algorithm, the distribution functions of remitted photon arr…
Remitted photon path length in human skin, skin phantoms and cell cultures
An experimental method for remitted photon path length measurements in scattering media has been developed and tested on human skin and skin neoplasms, skin phantoms and cell cultures. The photon time-of-flight (PTOF) measurement method was used in this study, where the photon travel time was converted into path length. Remitted light signals were obtained using a picosecond broadband laser and a set of narrowband interference filters in spectral rang 520 – 760 nm. Five different distances of 1, 8, 12, 16 and 20 mm between the source and detector fibers were used. Measurements were performed at different wavelengths and distance combinations; they were taken from human skin and skin malform…
Skin chromophore mapping from multi-spectral laser line images
Skin chromophore maps can be used for assessment of various skin malformations and early cancer diagnostics. Commercially available devices are bulky and expensive. We present two portable proof-of-concept device prototypes for multi-spectral laser line imaging with three (448 nm, 532 nm and 659 nm) and four (450 nm, 523 nm, 638 nm and 850 nm) wavelength laser illumination. Laser modules and special optics that ensure uniform light distribution over the region of interest have been exploited. Skin chromophore maps were calculated using Beer-Lambert law, considering light scattering properties in the skin and including photon path length evaluated from the directly measured photon-time-of-fl…