Annual Report 2012 - Latvijas Universitātes Cietvielu fizikas institūts

in terms of colour coordinate dispersion for printing methods used is much higher than
in case of commercially available colour vision deficiency tests.
RAYLEIGH EQUATION ANOMALOSCOPE FROM COMMERCIALLY
AVAILABLE LEDs
R. Trukša, S. Fomins, and M. Ozolinsh
Most precise classification of CVD (color vision deficits) can be provided by using
anomaloscope. Today anomaloscopes are available, which can evaluate red-green
(Rayleigh) and blue-green (Moreland) color defects. Our aim is to create and calibrate
commercially available LEDs based anomaloscope for diagnosis of red-green color
vision defects. Other field of use of anomaloscope is a seasonal and overall variation of
normal color vision in Latvian population.
LED BASED DUAL WAVELENGTH HETEROCHROMATIC FLICKER
METHOD FOR SEPARATE EVALUATION OF LUTEIN AND
ZEAXANTHIN IN RETINA
M. Ozolinsh and P. Paulins
The decrease of density and consequentially optical density of macular pigment serves
as a diagnostic mean for a number of ophthalmological pathologies, particularly as a risk
factor for age related macular degeneration. Macular pigment absorbs light in short
wavelength blue spectral range. Thus the optical density of macular pigment can be
detected by various optical – both objective and subjective psychophysical techniques.
Latter techniques use eye and brain visual pathway as spectral sensitive optical detector
and decision maker, and exploit perception facility to process information flow in a
unique manner to create various perception illusions. The psychophysical methods of
detection of optical density of macular pigment include heterochromatic flicker
photometry and minimum illusory motion photometry. We develop and employ a
heterochromatic flicker photometry method where LEDs are used as visual stimuli. LED
emission maximum wavelengths in blue spectrum region are chosen in range 445-460
nm, that corresponds to spectrally resolved maxima of light absorption for two types of
macula pigments – lutein and zeaxanthin or in spectral range 500-510 nm, where lutein
and zeaxanthin absorption have decay, that for both type of pigments have a detectable
shift. Statistical dispersion of the results allows to use the difference between results of
psychophysical measurements obtained for different LEDs to estimate the concentration
of lutein and zeaxanthin in human retina.
APPLICABILITY OF A BINARY AMPLITUDE MASK FOR CREATING
CORRECTORS OF HIGHER-ORDER OCULAR ABERRATIONS IN A
PHOTORESISTIVE LAYER
V. Karitans, K. Kundzins, E. Laizane, M. Ozolinsh, and L. Ekimane
Ocular aberrations can be corrected with wavefront correctors created in a photoresist
layer. The simplest type of the mask used in optical lithography is a binary amplitude
mask. It is known that such a mask has a periodic hole pattern. The purpose of this
research was to assess applicability of a binary amplitude mask for creating ocular
wavefront correctors. The photoresist was applied to the substrate by using the dipcoating
method. The photoresist layer was illuminated through a mask printed on a
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