Katarzyna Komar

Katarzyna Komar
Nicolaus Copernicus University | umk · Faculty of Physics, Astronomy and Informatics

PhD

About

37
Publications
3,136
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271
Citations

Publications

Publications (37)
Article
Full-text available
The recently introduced term “two-photon vision” relates to the visual perception resulting from a simultaneous absorption of two photons by photoreceptors. In this study, we determined two-photon retinal sensitivity in age-related macular degeneration (AMD) and compared it that in normal aging. Microperimetry was performed with visible (white) lig...
Article
Full-text available
We report the development of a widely-tunable femtosecond fiber laser system and its application for two-photon vision studies. The source is based on an Er-doped fiber laser with spectral shift up to 2150 nm, followed by a second harmonic generation module to generate a frequency-doubled beam tunable from 872 to 1075 nm. The source delivers sub-23...
Article
Full-text available
Glaucoma causes irreversible neuropathy, which, untreated, may lead to blindness. In this case–control study, we measured two-photon infrared (IR) light sensitivity in glaucomatous eyes to propose a new method to quantify the visual loss. In total, 64 patients were recruited with an equal distribution between glaucoma and control groups. Retinal se...
Article
Full-text available
Purpose: Two-photon vision relies on the perception of pulsed infrared light due to two-photon absorption in visual pigments. This study aimed to measure human pupil reaction caused by a two-photon 1040-nm stimulus and compare it with pupil responses elicited by 520-nm stimuli of similar color. Methods: Pupillary light reflex (PLR) was induced o...
Article
Full-text available
Background: Noninvasive assessment of metabolic processes that sustain regeneration of human retinal visual pigments (visual cycle) is essential to improve ophthalmic diagnostics and to accelerate development of new treatments to counter retinal diseases. Fluorescent vitamin A derivatives, which are the chemical intermediates of these processes, a...
Conference Paper
Pulsed near-infrared (NIR) light sources can be successfully applied for both imaging and functional testing of the human eye, as published recently. These two groups of applications have different requirements. For imaging applications, the most preferable is invisible scanning beam while efficiently visible stimulating beam is preferable for func...
Article
Full-text available
Two-photon vision is a phenomenon associated with the perception of short pulses of near-infrared radiation (900-1200 nm) as a visible light. It is caused by the nonlinear process of two-photon absorption by visual pigments. Here we present results showing the influence of pulse duration and repetition rate of short pulsed lasers on the visual thre...
Article
Full-text available
Purpose: The eye can see pulsed near-infrared (IR) radiation with the color corresponding to half of the wavelength used. Until recently, the technology required for measuring IR vision was confined to optical laboratories and was not studied clinically. The current investigation sought to determine the values for IR thresholds in a healthy popula...
Article
Full-text available
Microperimetry is a subjective ophthalmologic test used to assess retinal function at various specific and focal locations of the visual field. Historically, visible light has been described as ranging from 400 to 720 nm. However, we previously demonstrated that infra-red light can initiate visual transduction in rod photoreceptors by a mechanism o...
Conference Paper
The aim of this paper is to present a novel method, called Adaptive Edge Detection (AED), of extraction of precise pupil edge coordinates from eye image characterized by reflections of external illuminators and laser beams. The method is used for monitoring of pupil size and position during psychophysical tests of two-photon vision performed by ded...
Article
Full-text available
Two-photon vision arises from the perception of pulsed infrared (IR) laser light as color corresponding to approximately half of the laser wavelength. The physical process responsible for two-photon vision in rods has been delineated and verified experimentally only recently. Here, we sought to determine whether IR light can also be perceived by ma...
Article
Full-text available
Two-photon absorption occurring in photoreceptors of human eye is responsible for perception of pulsed infrared laser beams. Color of perceived light corresponds to about half of wavelength of stimulating beam. This recently discovered phenomenon is called two-photon vision. However it is yet not clear how such phenomena could impact an ophthalmic...
Article
Full-text available
Humans can detect infrared light at wavelengths over 1000 nm, perceived as visible light of the corresponding half wavelength. This is due to a two-photon (2P) absorption process, which requires sufficiently large amounts of luminous energy. For safety reasons, this energy must be delivered by pulsed light sources well focused in the retina. Althou...
Conference Paper
Light sensation relies on photoisomerization of chromophores in rod and cone photoreceptor cells. Spectral sensitivity of these photoreceptor cells in the retina is determined by the absorption spectra of their pigments which covers a range from 400 nm to above 700 nm. Regardless the mechanism leading to visual pigment isomerization, light sensatio...
Article
Full-text available
Two-photon microscopy allows visualization of subcellular structures in the living animal retina. In previously reported experiments it was necessary to apply a contact lens to each subject. Extending this technology to larger animals would require fitting a custom contact lens to each animal and cumbersome placement of the living animal head on mi...
Article
Full-text available
Vision relies on photoactivation of visual pigments in rod and cone photoreceptor cells of the retina. The human eye structure and the absorption spectra of pigments limit our visual perception of light. Our visual perception is most responsive to stimulating light in the 400- to 720-nm (visible) range. First, we demonstrate by psychophysical exper...
Conference Paper
Looking for the processes in which 2 photons are involved in human eye autofluorescence intensity, we measured excited state absorption (ESA) in lipofuscin solution. Performing pump and probe experiment, we've found ESA at 850 nm.
Article
Full-text available
In this paper we present a multimodal device for imaging fundus of human eye in vivo which combines functionality of autofluorescence by confocal SLO with Fourier domain OCT. Native fluorescence of human fundus was excited by modulated laser beam (λ = 473 nm, 20 MHz) and lock-in detection was applied resulting in improving sensitivity. The setup al...
Article
Full-text available
Scattering and fluorescence images provide complementary information about the health condition of the human eye, so getting them in a single measurement, using a single device may significantly improve a quality of diagnosis as it has been already demonstrated in Spectralis (Heidelberg Eng.) OCT instrument. There is still challenge to improve qual...
Article
Laser ablation was applied for surface cleaning and spectroscopic diagnostics of historical paper documents and model samples in the framework of the conservation projects. During cleaning the spectra of ablation products were recorded by means of the LIBS technique which allowed for nearly non-destructive identification of surface layers such as c...
Article
Full-text available
Results of the recent application studies of laser-based techniques for conservation practice, carried out in the frames of research and conservation projects are presented and discussed. The Gotland Sandstone Project covers laser cleaning, spectroscopic techniques of the process monitoring and materials analysis. The post-processing effect is inve...
Chapter
The fluorescence spectra of historical and model paper samples, previously irradiated with the laser beam at wavelengths of 1,064, 532, 355, and 266 nm, are recorded under excitation at 266 nm, and the nonirradiated samples are used for reference. The spectral profiles obtained for the laser-treated model papers made of cotton and/or linen only rev...
Chapter
The fluorescence spectra of historical and model paper samples, previously irradiated with the laser beam at wavelengths of 1,064, 532, 355, and 266 nm, are recorded under excitation at 266 nm, and the nonirradiated samples are used for reference. The spectral profiles obtained for the laser-treated model papers made of cotton and/or linen only rev...
Article
Techniques of laser emission spectroscopy such as LIPS and LIF are applied to identify pastels and pigments composition for the use in conservation of historical documents. The question of data reliable for pigment identification by these techniques is considered. For model samples made of the cotton paper of chemical composition corresponding to t...
Chapter
Samples of artificially contaminated model papers were cleaned by the use of pulsed Nd:YAG laser at 1064 nm and 532 nm and the ArF excimer laser 193 nm. The post-processing effects were analysed basing on comparison of DRIFT spectra and colorimetric data obtained before and after accelerated ageing. In the DRIFT spectra measured after the laser sur...
Chapter
The LIPS spectra obtained for the historical samples of Gotlandic sandstone (XVI c) under pulsed laser irradiation at 355 and 1064nm are analysed and applied for monitoring of the surface cleaning process. The spectra are recorded in the range 370 – 760nm upon successive cleaning pulses and depend strongly on the laser wavelength and dose applied....
Article
Results of paper cleaning by means of the 532 nm Nd:YAG laser (pulse length 6 ns, fluency 0.3-0.6 J/cm2) are reported and discussed. Results of the surface cleaning of the paper samples originating among others from the two oldest Polish Bibles (XVI c.) are examined by the SEM technique after laser processing. For the process diagnostic the LIF spe...
Article
The spectra of laser excited surface plasma (LIPS) recorded for historical, originally contaminated paper and also for model samples reveal reach structures which vary strongly for successive excitation pulses. The characteristic bands are ascribed to contaminants (Na I, Ca I) and pigments (e.g. V I, V II, Ti II, Fe I). Results confirm that the app...
Article
Full-text available
The historical paper samples from XIII–XIX c. are characterised by means of techniques of the optical spectroscopy. The influence of pulsed laser cleaning by means of the Q-switched Nd:YAG laser at 532 nm on the spectra and also cleaning results of stained paper documents are reported and considered. In the absorption spectra, the minima around 280...

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