This work studies the spatial propagation of the four-wave mixing signal of a molecular system with two electronic levels immersed in a thermal bath. Using the optical Bloch-Maxwell equations, we present three approximations, two of them are analytical solutions and the other is a numerical approach, where the effects of the variation of pump intensity through the optical path are considered. Also, we compare these results with the analogous in absence of the thermal reservoir and it is shown that the stochastic effect induced by the solvent, due to the experimental conditions as relaxation times, concentration of the solution and optical frequencies of the pumps, diminishes the intensity responses compared with the same in absence of the bath.
{"title":"Propagation of the four-wave mixing signal immersed in a thermal bath","authors":"M. Izquierdo, A. Mastrodoménico, J. L. Paz","doi":"10.1117/12.2021376","DOIUrl":"https://doi.org/10.1117/12.2021376","url":null,"abstract":"This work studies the spatial propagation of the four-wave mixing signal of a molecular system with two electronic levels immersed in a thermal bath. Using the optical Bloch-Maxwell equations, we present three approximations, two of them are analytical solutions and the other is a numerical approach, where the effects of the variation of pump intensity through the optical path are considered. Also, we compare these results with the analogous in absence of the thermal reservoir and it is shown that the stochastic effect induced by the solvent, due to the experimental conditions as relaxation times, concentration of the solution and optical frequencies of the pumps, diminishes the intensity responses compared with the same in absence of the bath.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129880786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. T. Mendonça, H. Crespo, A. A. Amorim, L. Bernardo
We present an alternative description of nonlinear cross-phase modulation based on the kinetic equation for photons. The most relevant feature of this new approach is that phase itself is completely ignored. Formal exact solutions and approximate analytical solutions are discussed. Experimental measurements of cross-phase modulation of two-color ultrashort laser pulses propagating in a highly nonlinear photonic crystal fiber reveal a good agreement with the analytical results.
{"title":"Photon kinetic description of nonlinear cross-phase modulation","authors":"J. T. Mendonça, H. Crespo, A. A. Amorim, L. Bernardo","doi":"10.1117/12.2026316","DOIUrl":"https://doi.org/10.1117/12.2026316","url":null,"abstract":"We present an alternative description of nonlinear cross-phase modulation based on the kinetic equation for photons. The most relevant feature of this new approach is that phase itself is completely ignored. Formal exact solutions and approximate analytical solutions are discussed. Experimental measurements of cross-phase modulation of two-color ultrashort laser pulses propagating in a highly nonlinear photonic crystal fiber reveal a good agreement with the analytical results.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128558981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Campos-García, F. Granados-Agustin, E. Percino-Zacarías, Amilcar Estrada-Molina, V. Moreno-Oliva, A. Santiago-Alvarado, M. Avendaño-Alejo
We report the qualitative testing of a spherical concave surface with deformation coefficients based on the null-screen principles. The design of cylindrical null screen with curved grid is described; its image, which is formed by reflection on the test surface, becomes an exact square grid if the surface is perfect. Any departure from this geometry is indicative of defects on the surface. In contrast to others tests, here the whole surface is tested at once. The surface under test is 140 mm in diameter and a radius of curvature of 97 mm. The surface is testing during the manufacturing process; departures from the design surface will be analyzed and discussed.
{"title":"Accuracy of the optical testing of a fast aspheric concave surface through null-screens","authors":"M. Campos-García, F. Granados-Agustin, E. Percino-Zacarías, Amilcar Estrada-Molina, V. Moreno-Oliva, A. Santiago-Alvarado, M. Avendaño-Alejo","doi":"10.1117/12.2025722","DOIUrl":"https://doi.org/10.1117/12.2025722","url":null,"abstract":"We report the qualitative testing of a spherical concave surface with deformation coefficients based on the null-screen principles. The design of cylindrical null screen with curved grid is described; its image, which is formed by reflection on the test surface, becomes an exact square grid if the surface is perfect. Any departure from this geometry is indicative of defects on the surface. In contrast to others tests, here the whole surface is tested at once. The surface under test is 140 mm in diameter and a radius of curvature of 97 mm. The surface is testing during the manufacturing process; departures from the design surface will be analyzed and discussed.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123743584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Juarez-Salazar, C. Robledo-Sánchez, C. Meneses-Fabian, G. Rodríguez-Zurita, Fermin Guerrero Sanchez, A. Barcelata-Pinzón
A faster and robust generalized phase-shifting interferometry suitable to automatic real-time applications is presented. The proposal is based on the parameter estimation by the least squares method. The algorithm can retrieve the wrapped phase from two or more phase shifted interferograms with unknown phase steps between 0 and π rad. Moreover, by the multiple or single parameter estimation approach of this algorithm, interferograms with variable visibility both spatial and temporally can be processed, overcoming the restrictions and drawbacks from usual variable spatial visibility approaches. By both computer simulation and a optical experiment, the algorithm's feasibility is illustrated.
{"title":"Automatic real-time generalized phase-shifting interferometry to process interferograms with spatio-temporal visibility","authors":"R. Juarez-Salazar, C. Robledo-Sánchez, C. Meneses-Fabian, G. Rodríguez-Zurita, Fermin Guerrero Sanchez, A. Barcelata-Pinzón","doi":"10.1117/12.2026103","DOIUrl":"https://doi.org/10.1117/12.2026103","url":null,"abstract":"A faster and robust generalized phase-shifting interferometry suitable to automatic real-time applications is presented. The proposal is based on the parameter estimation by the least squares method. The algorithm can retrieve the wrapped phase from two or more phase shifted interferograms with unknown phase steps between 0 and π rad. Moreover, by the multiple or single parameter estimation approach of this algorithm, interferograms with variable visibility both spatial and temporally can be processed, overcoming the restrictions and drawbacks from usual variable spatial visibility approaches. By both computer simulation and a optical experiment, the algorithm's feasibility is illustrated.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123765485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. L. Velazquez, A. Ferrero, M. López, A. Pons, A. Villamarín, J. Campos, A. Sperling
A goniophotometer to characterize the angular distribution of the averaged luminous intensity of LEDs has been developed at Optics Institute of CSIC. Distributions of for four low-power LEDs transfer standards (red, blue, green and white) for luminous flux and luminous intensity are shown. A proper characterization of the angular luminous intensity distribution allows measurement uncertainties to be better determined. The instrument has got a photometer placed on a ruled optical bench to vary the source-detector distance and a CCD camera to carry out the alignment of the LEDs respect to the centre of geometrical reference system. Measurements were taken at a distance of 316 mm (condition A of the CIE) to different LEDs by varying the polar angle between 0° and 90° with a step of 5° and the azimuth angle between 0° and 180° with a step of around 11°. The red LED is the most Lambertian, whereas the blue, green and white LEDs have a different behavior. Finally, to identify systematic errors, a comparison with the measurements of a similar goniophotometer in Physikalisch-Technische Bundesanstalt (PTB) was carried out.
{"title":"Angular distribution of the averaged luminous intensity of low power LEDs transfer standards","authors":"J. L. Velazquez, A. Ferrero, M. López, A. Pons, A. Villamarín, J. Campos, A. Sperling","doi":"10.1117/12.2027039","DOIUrl":"https://doi.org/10.1117/12.2027039","url":null,"abstract":"A goniophotometer to characterize the angular distribution of the averaged luminous intensity of LEDs has been developed at Optics Institute of CSIC. Distributions of for four low-power LEDs transfer standards (red, blue, green and white) for luminous flux and luminous intensity are shown. A proper characterization of the angular luminous intensity distribution allows measurement uncertainties to be better determined. The instrument has got a photometer placed on a ruled optical bench to vary the source-detector distance and a CCD camera to carry out the alignment of the LEDs respect to the centre of geometrical reference system. Measurements were taken at a distance of 316 mm (condition A of the CIE) to different LEDs by varying the polar angle between 0° and 90° with a step of 5° and the azimuth angle between 0° and 180° with a step of around 11°. The red LED is the most Lambertian, whereas the blue, green and white LEDs have a different behavior. Finally, to identify systematic errors, a comparison with the measurements of a similar goniophotometer in Physikalisch-Technische Bundesanstalt (PTB) was carried out.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"408 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115864751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Gutierrez-Arroyo, C. Sánchez Pérez, N. Alemán-García, C. Piña-Barba
In this work we utilize heat conduction measurements trough the photothermal beam deflection technique to characterize thermal properties of biological tissue. We design a heat flux sensor based on the phenomenon of photothermal laser beam deflection within a thermo-optic slab (acrylic), where the deflection is quantified by an optical fiber angle sensor. We analytically model the heat flux sensor response based on heat wave propagation theory that well agree with experimental data. We present heat conduction measurements on different tissues applying a heat pulse. Hence we obtain the thermal effusivity coefficient of bovine tendon and chicken liver and heart. It has been shown that thermal conduction depends on the tissue´s chemical composition as well on their structural arrangements, so any modification in tissue will affect on heat conduction rendering this method potentially useful as an auxiliary in biomedical studies. Nowadays there are several thermal effusivity and diffusivity measurement techniques with classic calorimetry (using thermistors) for research and industrial applications. However there are only few integrated optical devices already proposed, turning this optical technique in an innovative and alternative sensing system for thermal properties characterization.
{"title":"Optical characterization of thermal properties of biological tissue","authors":"A. Gutierrez-Arroyo, C. Sánchez Pérez, N. Alemán-García, C. Piña-Barba","doi":"10.1117/12.2025877","DOIUrl":"https://doi.org/10.1117/12.2025877","url":null,"abstract":"In this work we utilize heat conduction measurements trough the photothermal beam deflection technique to characterize thermal properties of biological tissue. We design a heat flux sensor based on the phenomenon of photothermal laser beam deflection within a thermo-optic slab (acrylic), where the deflection is quantified by an optical fiber angle sensor. We analytically model the heat flux sensor response based on heat wave propagation theory that well agree with experimental data. We present heat conduction measurements on different tissues applying a heat pulse. Hence we obtain the thermal effusivity coefficient of bovine tendon and chicken liver and heart. It has been shown that thermal conduction depends on the tissue´s chemical composition as well on their structural arrangements, so any modification in tissue will affect on heat conduction rendering this method potentially useful as an auxiliary in biomedical studies. Nowadays there are several thermal effusivity and diffusivity measurement techniques with classic calorimetry (using thermistors) for research and industrial applications. However there are only few integrated optical devices already proposed, turning this optical technique in an innovative and alternative sensing system for thermal properties characterization.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125515109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eye models to test intraocular lenses (IOLs) in an optical bench are commonly designed in agreement with the ISO 11979-2 and 11979-9 standard requirements. However, modifications to the ISO eye model have been proposed to test IOLs in conditions closer to real human eye. Wavefront analysis and aberration characterization, wavelength dependence, efficiency, off-axis performance and imaging degradation under certain amount of misalignment can thus be measured in vitro. The main parts of the system to test IOLs are: the illumination system and object test, the eye model including the IOL immersed in a wet cell and a microscope assembled to a sensor that magnifies and captures the aerial image of the object formed by the eye model. A problem concerning the simultaneous variation of defocus and magnification arises when using the microscope to capture out-of-focus images in a through-focus study. Using the eye model, we study the problem of implementing a through-focus measurement of the imaging quality of an IOL. We find a solution based on geometrical optics and compare it with other proposals reported in the literature. The effects on the measurement of the Modulation Transfer Function and the Point Spread Function are predicted. Experimental results are obtained and discussed.
{"title":"Experiment design for through-focus testing of intraocular lenses","authors":"M. S. Millán, F. Alba-Bueno, F. Vega","doi":"10.1117/12.2025474","DOIUrl":"https://doi.org/10.1117/12.2025474","url":null,"abstract":"Eye models to test intraocular lenses (IOLs) in an optical bench are commonly designed in agreement with the ISO 11979-2 and 11979-9 standard requirements. However, modifications to the ISO eye model have been proposed to test IOLs in conditions closer to real human eye. Wavefront analysis and aberration characterization, wavelength dependence, efficiency, off-axis performance and imaging degradation under certain amount of misalignment can thus be measured in vitro. The main parts of the system to test IOLs are: the illumination system and object test, the eye model including the IOL immersed in a wet cell and a microscope assembled to a sensor that magnifies and captures the aerial image of the object formed by the eye model. A problem concerning the simultaneous variation of defocus and magnification arises when using the microscope to capture out-of-focus images in a through-focus study. Using the eye model, we study the problem of implementing a through-focus measurement of the imaging quality of an IOL. We find a solution based on geometrical optics and compare it with other proposals reported in the literature. The effects on the measurement of the Modulation Transfer Function and the Point Spread Function are predicted. Experimental results are obtained and discussed.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"23 12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126118689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. García-Resúa, Hugo Pena-Verdeal, M. Lira, M. G. Penedo, M. .. Giraldez, E. Yebra-Pimentel
The lipid layer plays a major role in limiting evaporation of the tear film. Based on interference phenomena, there is a test directed to lipid layer pattern (LLP) evaluation, but is affected by subjective interpretation of the patterns. The aim of this study is to compare the LLP evaluation between two experienced observers on a group of healthy patients. Furthermore, the observers re-evaluated the same images in order to check their individual repeatability. LLP was examined using a Tearscope-plus (Keeler, Windsor, UK) attached to a slit lamp. Tear film was recorded by a Topcon DV-3 digital camera video and LLP images were captured. This yielded 124 LLP images that were categorized (based on Guillon’s schema) by two expert observers in two sessions separated by one month. Interobserver repeatability and intraobserver repeatability between both sessions were studied by using Cohen’s kappa coefficient. Comparing LLP categorization between both observers, Cohen's kappa coefficient was 0.615 and 0.633 for first and second session, respectively. When comparing LLP categorization by the same observer between both sessions, Cohen's kappa coefficient was 0.770 and 0.812 for Observer 1 and Observer 2. These results indicate substantial correlation in all cases [range of 0.61–0.80]. The most frequent misinterpretations were between open and closed meshwork and Wave and closed meshwork patterns. Although substantial correlation was found between categorizations of experienced observers, misinterpretation of the patters may appear even in the same observer. Some misinterpretations between adjacent patterns could be palliated by including intermediate patterns between those categories.
{"title":"Interobserver and intraobserver repeatability of lipid layer pattern evaluation by two experienced observers","authors":"C. García-Resúa, Hugo Pena-Verdeal, M. Lira, M. G. Penedo, M. .. Giraldez, E. Yebra-Pimentel","doi":"10.1117/12.2030432","DOIUrl":"https://doi.org/10.1117/12.2030432","url":null,"abstract":"The lipid layer plays a major role in limiting evaporation of the tear film. Based on interference phenomena, there is a test directed to lipid layer pattern (LLP) evaluation, but is affected by subjective interpretation of the patterns. The aim of this study is to compare the LLP evaluation between two experienced observers on a group of healthy patients. Furthermore, the observers re-evaluated the same images in order to check their individual repeatability. LLP was examined using a Tearscope-plus (Keeler, Windsor, UK) attached to a slit lamp. Tear film was recorded by a Topcon DV-3 digital camera video and LLP images were captured. This yielded 124 LLP images that were categorized (based on Guillon’s schema) by two expert observers in two sessions separated by one month. Interobserver repeatability and intraobserver repeatability between both sessions were studied by using Cohen’s kappa coefficient. Comparing LLP categorization between both observers, Cohen's kappa coefficient was 0.615 and 0.633 for first and second session, respectively. When comparing LLP categorization by the same observer between both sessions, Cohen's kappa coefficient was 0.770 and 0.812 for Observer 1 and Observer 2. These results indicate substantial correlation in all cases [range of 0.61–0.80]. The most frequent misinterpretations were between open and closed meshwork and Wave and closed meshwork patterns. Although substantial correlation was found between categorizations of experienced observers, misinterpretation of the patters may appear even in the same observer. Some misinterpretations between adjacent patterns could be palliated by including intermediate patterns between those categories.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131406446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
U. Rivera-Ortega, C. Meneses-Fabian, G. Rodríguez-Zurita
A new method to generate inhomogeneous spatial phase variation and phase retrieval is proposed. This method is based under the scheme of three beams forming two Mach-Zehnder interferometers in series, where one arm is considered as the probe beam, while the other two will compose the reference beam where a phase difference within the range of (0,π ) is kept and this remains spatially variable in opposition to the classical PSI method. The generation of phase-shifts is done by on-off nonquadrature amplitude modulation. Although the phase difference between the reference beams are spatially variable having as a consequence that the visibility and phase variations are inhomogeneous, it will be demonstrated that it is still possible to retrieve the phase of the object and also to measure the phase variation. An analytic discussion and experimental results will be shown to sustain the proposed method.
{"title":"Spatially inhomogeneous phase-modulating interferometry by non-quadrature amplitude modulation","authors":"U. Rivera-Ortega, C. Meneses-Fabian, G. Rodríguez-Zurita","doi":"10.1117/12.2025664","DOIUrl":"https://doi.org/10.1117/12.2025664","url":null,"abstract":"A new method to generate inhomogeneous spatial phase variation and phase retrieval is proposed. This method is based under the scheme of three beams forming two Mach-Zehnder interferometers in series, where one arm is considered as the probe beam, while the other two will compose the reference beam where a phase difference within the range of (0,π ) is kept and this remains spatially variable in opposition to the classical PSI method. The generation of phase-shifts is done by on-off nonquadrature amplitude modulation. Although the phase difference between the reference beams are spatially variable having as a consequence that the visibility and phase variations are inhomogeneous, it will be demonstrated that it is still possible to retrieve the phase of the object and also to measure the phase variation. An analytic discussion and experimental results will be shown to sustain the proposed method.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128142437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hugo Pena-Verdeal, C. García-Resúa, L. Ramos, A. Mosquera, E. Yebra-Pimentel, M. .. Giraldez
Tear film breakup time (BUT) test only examines the first break in the tear film, but subsequent tear film events are not monitored. We present a method of measuring the area of breakup after the appearance of the first breakup by using open source software. Furthermore, the speed of the rupture was determined. 84 subjects participated in the study. 2 μl volume of 2% sodium fluorescein was instilled using a micropipette. The subject was seated behind a slit-lamp using a cobalt blue filter together with a Wratten 12 yellow filter. Then, the tear film was recorded by a camera attached to the slit lamp. 4 frames of each video was extracted, the first rupture (BUT_0), breakup after 1 second (BUT_1), rupture after 2 seconds (BUT_2) and breakup before the last blink (BUT_F). Open source software of measurement based on Java (NIH ImageJ) was used to measure the number of pixels in areas of breakup. These areas were divided by the area of exposed cornea to obtain the percentage of ruptures. Instantaneous breakup speed was calculated for second 1 as the difference between BUT_1 - BUT_0, whereas instant speed for second 2 was BUT_2 - BUT_1. Mean area of breakup obtained was: BUT_0 = 0.26%, BUT_1 = 0.48%, BUT_2 = 0.79% and BUT_F = 1.61%. Break speed was 0.22 area/sec for second 1 and 0.31 area/sec for second 2, showing a statistical difference between them (p = 0.007). Post BUT analysis may be easily monitoring with the aid of this software.
{"title":"Measuring the area of tear film break-up by image analysis software","authors":"Hugo Pena-Verdeal, C. García-Resúa, L. Ramos, A. Mosquera, E. Yebra-Pimentel, M. .. Giraldez","doi":"10.1117/12.2030431","DOIUrl":"https://doi.org/10.1117/12.2030431","url":null,"abstract":"Tear film breakup time (BUT) test only examines the first break in the tear film, but subsequent tear film events are not monitored. We present a method of measuring the area of breakup after the appearance of the first breakup by using open source software. Furthermore, the speed of the rupture was determined. 84 subjects participated in the study. 2 μl volume of 2% sodium fluorescein was instilled using a micropipette. The subject was seated behind a slit-lamp using a cobalt blue filter together with a Wratten 12 yellow filter. Then, the tear film was recorded by a camera attached to the slit lamp. 4 frames of each video was extracted, the first rupture (BUT_0), breakup after 1 second (BUT_1), rupture after 2 seconds (BUT_2) and breakup before the last blink (BUT_F). Open source software of measurement based on Java (NIH ImageJ) was used to measure the number of pixels in areas of breakup. These areas were divided by the area of exposed cornea to obtain the percentage of ruptures. Instantaneous breakup speed was calculated for second 1 as the difference between BUT_1 - BUT_0, whereas instant speed for second 2 was BUT_2 - BUT_1. Mean area of breakup obtained was: BUT_0 = 0.26%, BUT_1 = 0.48%, BUT_2 = 0.79% and BUT_F = 1.61%. Break speed was 0.22 area/sec for second 1 and 0.31 area/sec for second 2, showing a statistical difference between them (p = 0.007). Post BUT analysis may be easily monitoring with the aid of this software.","PeriodicalId":135913,"journal":{"name":"Iberoamerican Meeting of Optics and the Latin American Meeting of Optics, Lasers and Their Applications","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134366680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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