0000000000033370
AUTHOR
Gunta Papelba
Liquid crystal goggles for vision science applications
Spectral and switching characteristics of two manufacturer liquid crystal goggles are tested, and a contrast ratio for the computer display phosphors wavelengths is determined. Goggles are used in vision science experiments for random dot stereo stimuli phase separation. The human stereovision acuity and threshold was studied for case, when one eye random dot stereo stimulus simulated on the display is cotinuously blurred or the stimulus contrast is decreased.
Eye Cataract Simulation Using Polymer Dispersed Liquid Crystal Scattering Obstacles
Polymer dispersed liquid crystals with electrically induced variations of light scattering extent similar to that of transparent PLZT ceramics are used for simulation of different development stages of eye cataract. Wavelength dependencies of scattering are determined in the visible spectral range, and human visual response looking through the scattering obstacle to the onset of various spatial frequency stimuli is determined psychophysically and electrophysiologically in order to find correlation between the scattering extent, visual acuity and visual evoked potential VEP chromatic characteristics.
<title>Polarization-optical visualization of eye inhomogeneities</title>
Polarization sensitive technique is reported for visualization of eye scattering and birefringent inhomogeneities using digital subtracting of eye images captured by a CCD camera for two orthogonal polarizations of light forming images in the CCD camera. For fast capturing of images the polarization plane of the backscattered light is periodically switched at 90 degrees by an electro-optical PLZT phase plate. This plate is placed close to the CCD camera together with a sheet polarizer inserted between camera and the phase plate. Polarization plane is switched applying the voltage 1200 V to the phase plate at a rate of 7.5 Hz. The technique improves visualization due to diminishing of the im…
<title>Stereoacuity determination at changing contrast of colored stereostimuli</title>
Studies are focused on design and appraisal of an objective test for assessment of the stereovision quality in unfavorable conditions. Stereostimuli of different colors are used while the contrast of one of the stimulus being varied. Tests are based on principles of black-and-white and two primary color random dot stereotests. Experiments are divided by the method of stimuli display and separation: 1) stereoeffect is obtained haploscopically - by use of spectacles with color filters (blue and red) or prisms, 2) stimuli separation is obtained by liquid crystal shutters when both eye stimuli are demonstrated with a different delay. The stereovision threshold is determiend at different stimuli…
<title>Stereovision studies by disbalanced images</title>
Studies are focused on design and appraisal of an objective test of the quality of stereovision depending on optical stimuli blurring and detecting of the stereovision threshold at various stimuli blur degree. The method is based on the principles of grayscale and color random dot stereotests. Experiments may be divided with respect to the principle of demonstration: 1) the blur is modeled by defocusing an optical lens - the strength of the optical system is varied at a constant quality of the stimulus, or 2) the blur is simulated on the computer screen - here the quality of the stimulus varies. To obtain an independent description and to measure blurring the experimentally demonstrated ima…