For third harmonic generation in cubic-nonlinear media, the influence of intensity-dependent parts of the refractive index must be taken into account because the corresponding susceptibilities for the parametric process and the process of self-action are of the same order. The intensity dependence of the index of refraction may destroy the phase matching and therefore lower the efficiency. It is well known that at low efficiencies (in the parametric approximation) it is easy to compensate the nonlinear mismatch by a proper linear one. The problem is more complicated beyond the parametric approximation. We present numerical results concerning this question. The maximum efficiency and the dependence of the harmonic on the (normalized) length of the nonlinear medium were calculated for different cases. Neglecting the dispersion of the third-order nonlinear susceptibility, the efficiency is determined only by one parameter Δk · l nl /2, where Δk is the usual linear mismatch Δk = K3 − 3k1, and l nl is the nonlinear interaction length (which is inversely proportional to the input intensity of the fundamental wave and the effective third-order nonlinearity). Whereas for Δk = 0 the maximum efficiency (defined here as ratio of the amplitudes) is 0.55, one gets for an optimum mismatch of (Δk)opt = −0.27 (2/lnl) a maximum attainable efficiency of 0.92; i.e., also in the case including pump depletion it is possible nearly to compensate the nonlinear mismatch. However, as we also show, the dispersion of the nonlinear susceptibility can lower the maximum possible efficiency.
{"title":"Third harmonic generation with high efficiency","authors":"R. Fischer","doi":"10.1063/1.36844","DOIUrl":"https://doi.org/10.1063/1.36844","url":null,"abstract":"For third harmonic generation in cubic-nonlinear media, the influence of intensity-dependent parts of the refractive index must be taken into account because the corresponding susceptibilities for the parametric process and the process of self-action are of the same order. The intensity dependence of the index of refraction may destroy the phase matching and therefore lower the efficiency. It is well known that at low efficiencies (in the parametric approximation) it is easy to compensate the nonlinear mismatch by a proper linear one. The problem is more complicated beyond the parametric approximation. We present numerical results concerning this question. The maximum efficiency and the dependence of the harmonic on the (normalized) length of the nonlinear medium were calculated for different cases. Neglecting the dispersion of the third-order nonlinear susceptibility, the efficiency is determined only by one parameter Δk · \u0000 l\u0000 nl\u0000 /2, where Δk is the usual linear mismatch Δk = K3 − 3k1, and \u0000 l\u0000 nl\u0000 is the nonlinear interaction length (which is inversely proportional to the input intensity of the fundamental wave and the effective third-order nonlinearity). Whereas for Δk = 0 the maximum efficiency (defined here as ratio of the amplitudes) is 0.55, one gets for an optimum mismatch of (Δk)opt = −0.27 (2/lnl) a maximum attainable efficiency of 0.92; i.e., also in the case including pump depletion it is possible nearly to compensate the nonlinear mismatch. However, as we also show, the dispersion of the nonlinear susceptibility can lower the maximum possible efficiency.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130255666","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 detailed description of a corner-cube laser trap concept inside the cavity of a cw alexandrite laser operating in the TEM 01 * mode and using 4He cooling (at temperature ≲ 1.5 K) for trapping neutral potassium atoms is given in a recent paper.1 We report recent progress made toward the implementation of this trap concept: in optimization of the design of the laser cavity, in the understanding of the thermal lensing effects in the alexandrite laser, and in the status of the cryogenic apparatus.
{"title":"Progress toward an alexandrite laser trap for potassium atoms","authors":"Kuo-Ho. Yang, X. Zeng, W. Stwalley","doi":"10.1063/1.36787","DOIUrl":"https://doi.org/10.1063/1.36787","url":null,"abstract":"A detailed description of a corner-cube laser trap concept inside the cavity of a cw alexandrite laser operating in the \u0000 \u0000 \u0000 \u0000 \u0000 TEM\u0000 \u0000 \u0000 01\u0000 \u0000 *\u0000 \u0000 \u0000 \u0000 mode and using 4He cooling (at temperature ≲ 1.5 K) for trapping neutral potassium atoms is given in a recent paper.1 We report recent progress made toward the implementation of this trap concept: in optimization of the design of the laser cavity, in the understanding of the thermal lensing effects in the alexandrite laser, and in the status of the cryogenic apparatus.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129132286","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 highly sensitive and selective laser-based circular dichroism detector for flowing liquid systems, specifically liquid chromatography (LC), is presented. This detector is quite useful for the analysis of biologically related molecules, since optical activity is detected for low nanogram (ng) quantities of samples. Both transmission detected (TDCD) and fluorescence detected circular dichroism (FDCD) were developed for LC. For LC-TDCD, an argon ion laser is operated at 488 nm and 20 mW, with high-frequency polarization modulation employed to reduce laser amplitude noise to1 part in 106, i.e., a signal-to-noise ratio of 106. This is in contrast to a signal-to-noise ratio of 102 for an argon-ion laser before any effort is made to stabilize the power fluctuations. Also, detection selectivity is demonstrated since optically inactive, yet absorbing, molecules do not produce an appreciable detector response. Presently, the optimum modulation frequency range is from 500 to 700 kHz for our system. Similarly, for LC-FDCD, a He-Cd laser is operated at 325 nm, with ~8-mW power, at 150 kHz. Specifically, riboflavin is detected in LC-FDCD at subnanogram levels with optical activity information.
{"title":"Laser-based circular dichroism detection of molecules in flowing liquid systems using high-frequency polarization modulation","authors":"R. Synovec, E. Yeung","doi":"10.1063/1.36832","DOIUrl":"https://doi.org/10.1063/1.36832","url":null,"abstract":"A highly sensitive and selective laser-based circular dichroism detector for flowing liquid systems, specifically liquid chromatography (LC), is presented. This detector is quite useful for the analysis of biologically related molecules, since optical activity is detected for low nanogram (ng) quantities of samples. Both transmission detected (TDCD) and fluorescence detected circular dichroism (FDCD) were developed for LC. For LC-TDCD, an argon ion laser is operated at 488 nm and 20 mW, with high-frequency polarization modulation employed to reduce laser amplitude noise to1 part in 106, i.e., a signal-to-noise ratio of 106. This is in contrast to a signal-to-noise ratio of 102 for an argon-ion laser before any effort is made to stabilize the power fluctuations. Also, detection selectivity is demonstrated since optically inactive, yet absorbing, molecules do not produce an appreciable detector response. Presently, the optimum modulation frequency range is from 500 to 700 kHz for our system. Similarly, for LC-FDCD, a He-Cd laser is operated at 325 nm, with ~8-mW power, at 150 kHz. Specifically, riboflavin is detected in LC-FDCD at subnanogram levels with optical activity information.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"328 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134324361","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}
Characteristics of backward, stimulated light pulses are analyzed in the limit where rate equation approximation breaks down, and fluctuation dynamics (oscillator displacements for Raman and phonon amplitudes for Brillouin) must beconsidered. In this limit, the scattered photon flux N s is N s = a(dN l /dt), (d/dt + γ f )A f = bN l /Af,(d/dt + γ l ) = dN l /Af, where f,/referto fluctuations and pump, respectively; A f the fluctuation intensity, and constants a, b, and d depend on the medium characteristics. An analytical solution to this set of equations has been given by Maier et al.1 in the limit γ f →0 and γ l = 0. With these restrictions removed, analytical solution is difficult. Here, we are considering an analytical solution by reducing the set of equations to that of the cubic Schrodinger equation with real amplitude and by using Backlund transform. Preliminary calculations show that the solitary wave solutions are possible (a purely soliton solution is not admissible2 in the form of hyperbolic secant square).
在速率方程近似失效的极限下分析反向受激光脉冲的特性，必须考虑波动动力学(拉曼振荡位移和布里渊声子振幅)。在此极限下，散射光子通量N s为N s = a(dN l /dt)， (d/dt + γ f) a f = bN l /Af，(d/dt + γ l) = dN l /Af，其中f、/分别指波动和泵浦;波动强度和常数A、b和d取决于介质特性。Maier et al.1给出了这组方程在极限γ f→0和γ l = 0下的解析解。除去这些限制条件后，解析解是困难的。在这里，我们考虑一个解析解，通过将方程组简化为具有实振幅的三次薛定谔方程，并使用Backlund变换。初步计算表明孤波解是可能的(双曲正割平方形式的纯孤子解是不允许的)。
{"title":"Steady-state light pulses in stimulated backward scattering","authors":"D. Roy, D. Rao","doi":"10.1063/1.36757","DOIUrl":"https://doi.org/10.1063/1.36757","url":null,"abstract":"Characteristics of backward, stimulated light pulses are analyzed in the limit where rate equation approximation breaks down, and fluctuation dynamics (oscillator displacements for Raman and phonon amplitudes for Brillouin) must beconsidered. In this limit, the scattered photon flux N\u0000 s\u0000 is N\u0000 s\u0000 = a(dN\u0000 l\u0000 /dt), (d/dt + γ\u0000 f\u0000 )A\u0000 f\u0000 = bN\u0000 l\u0000 /Af,(d/dt + γ\u0000 l\u0000 ) = dN\u0000 l\u0000 /Af, where f,/referto fluctuations and pump, respectively; A\u0000 f\u0000 the fluctuation intensity, and constants a, b, and d depend on the medium characteristics. An analytical solution to this set of equations has been given by Maier et al.1 in the limit γ\u0000 f\u0000 →0 and γ\u0000 l\u0000 = 0. With these restrictions removed, analytical solution is difficult. Here, we are considering an analytical solution by reducing the set of equations to that of the cubic Schrodinger equation with real amplitude and by using Backlund transform. Preliminary calculations show that the solitary wave solutions are possible (a purely soliton solution is not admissible2 in the form of hyperbolic secant square).","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115938529","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}
The availability of zirconium fluoride fibers with improved midinfrared transmission has extended the range of remote thermography. One application is measurement of the internal temperature of biological tissue during and after exposure to laser energy. Such measurements are important for verification and calibration of predictive thermal models allowing rational selection of such parameters as power, wavelength, pulse duration, and total fluence. This technique may also help to determine when vaporization will occur with a minimum zone of thermal injury. The infrared signal can be sensed by circuitry to terminate the exposure automatically when the selected tissue temperature is reached. This scheme should be more accurate than visual interpretation of the degree of blanching. We report predictions of the signal level as a function of tissue temperature for detection through the fiber by a thermoelectrically cooled lead selenide photodetector. We also explore the resolution limits in space, time, and temperature, and compare our measured values with results of modeling calculations performed at USCI.
{"title":"Internal biological tissue temperature measurements using zirconium fluoride IR fibers","authors":"E. Sinofsky, Gary Gofstein","doi":"10.1063/1.36806","DOIUrl":"https://doi.org/10.1063/1.36806","url":null,"abstract":"The availability of zirconium fluoride fibers with improved midinfrared transmission has extended the range of remote thermography. One application is measurement of the internal temperature of biological tissue during and after exposure to laser energy. Such measurements are important for verification and calibration of predictive thermal models allowing rational selection of such parameters as power, wavelength, pulse duration, and total fluence. This technique may also help to determine when vaporization will occur with a minimum zone of thermal injury. The infrared signal can be sensed by circuitry to terminate the exposure automatically when the selected tissue temperature is reached. This scheme should be more accurate than visual interpretation of the degree of blanching. We report predictions of the signal level as a function of tissue temperature for detection through the fiber by a thermoelectrically cooled lead selenide photodetector. We also explore the resolution limits in space, time, and temperature, and compare our measured values with results of modeling calculations performed at USCI.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125556444","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}
S. Jackel, R. Lalluz, E. Yarkoni, M. Givon, B. Arad, S. Eliezer, A. Zigler
Small, medium, and large solid-state rod amplifiers have typical diameters d and gains g of: l,d = 0.5-3cm, g = 15-50; II, d = 3-7cm, g = 5-15; lll, d = 7-12 cm, g = 2-5. Many applications require overall rod system gains of g = 103-106, terminating in class II or III sized beams. Conventional laser systems achieve this required gain using chains of increasingly larger amplifiers. A new generation laser would use only one or two multiple-pass amplifiers. We have successfully built multiple-pass (and multiple-beam) amplifiers with large fill factors, high coupling efficiency, nonresonant geometry, and using passive optics for polarization and angularly controlled beam steering. Gains of > 103 with output intensities in the saturated region were routinely achieved with triple-pass units. Diffraction-limited 100-GW, 1-4-ns temporally shaped laser pulses in one or two beams were obtained with only two multiple-pass amplifiers at half the cost of a conventional laser. Frequency conversion was successfully accomplished. Phase conjugation (Brillouin in organic liquid) and polarization compensation are being incorporated into an ultrahigh performance unit with good preliminary results. Ring laser configurations are being adapted to substantially improve intra amplifier and inter amplifier isolation. These additional improvements will yield multipass systems at a quarter of the cost of conventional lasers. (Poster paper)
小型，中型和大型固态棒放大器的典型直径d和增益g为:1,d = 0.5-3cm, g = 15-50;II, d = 3-7cm, g = 5-15;ll, d = 7-12 cm, g = 2-5。许多应用要求总体杆系统增益g = 103-106，终止于II级或III级尺寸的梁。传统的激光系统使用越来越大的放大器链来实现所需的增益。新一代激光器将只使用一个或两个多通道放大器。我们已经成功地构建了多通(和多光束)放大器，具有大填充因子，高耦合效率，非谐振几何形状，并使用被动光学器件进行偏振和角度控制光束转向。在饱和区域输出强度达到bbbb103的增益通常是通过三通装置实现的。仅用两个多通放大器，以传统激光器一半的成本获得了一个或两个光束中衍射受限的100吉瓦，1-4纳秒的瞬时成形激光脉冲。频率转换成功完成。相位共轭(有机液体中的布里渊)和极化补偿被整合到一个超高性能单元中，并取得了良好的初步结果。环形激光器的配置被用于大幅度提高放大器内部和放大器之间的隔离。这些额外的改进将使多通道系统的成本仅为传统激光器的四分之一。(广告纸)
{"title":"New generation of high power laser systems based on multiple-pass amplifiers","authors":"S. Jackel, R. Lalluz, E. Yarkoni, M. Givon, B. Arad, S. Eliezer, A. Zigler","doi":"10.1063/1.36711","DOIUrl":"https://doi.org/10.1063/1.36711","url":null,"abstract":"Small, medium, and large solid-state rod amplifiers have typical diameters d and gains g of: l,d = 0.5-3cm, g = 15-50; II, d = 3-7cm, g = 5-15; lll, d = 7-12 cm, g = 2-5. Many applications require overall rod system gains of g = 103-106, terminating in class II or III sized beams. Conventional laser systems achieve this required gain using chains of increasingly larger amplifiers. A new generation laser would use only one or two multiple-pass amplifiers. We have successfully built multiple-pass (and multiple-beam) amplifiers with large fill factors, high coupling efficiency, nonresonant geometry, and using passive optics for polarization and angularly controlled beam steering. Gains of > 103 with output intensities in the saturated region were routinely achieved with triple-pass units. Diffraction-limited 100-GW, 1-4-ns temporally shaped laser pulses in one or two beams were obtained with only two multiple-pass amplifiers at half the cost of a conventional laser. Frequency conversion was successfully accomplished. Phase conjugation (Brillouin in organic liquid) and polarization compensation are being incorporated into an ultrahigh performance unit with good preliminary results. Ring laser configurations are being adapted to substantially improve intra amplifier and inter amplifier isolation. These additional improvements will yield multipass systems at a quarter of the cost of conventional lasers. (Poster paper)","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125770685","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}
Atomic strontium vapor in a thermionic diode is irradiated by the light from a tunable dye laser at two-photon resonance on the 5s5d1D2 state. At a laser intensity of ~ 108 W/cm2 and a vapor pressure of several torrs, not only three-photon ionization occurs but also the generation of new frequencies due to a nonlinear polarization is observed. Simultaneously, strong and strictly directed beams are generated which are resonantly enhanced by the 5s5p1P1 and 5s6p1P1 states, respectively. Close to the first resonance, four-wave mixing causes braodband two-photon emission, the bandwidth of which is determined by the region of negative dispersion due to phase matching. On the other hand the process via the 6p state is exactly resonant as can be shown by comparison in every case with the respective fluorescence light. At higher pressures (~ 10Torr), however, a second line appears, which is also shifted to the side of negative dispersion.
{"title":"Multiwave mixing and multiphoton ionization in strontium vapor","authors":"K. Bohmer, J. Reif, E. Matthias","doi":"10.1063/1.36727","DOIUrl":"https://doi.org/10.1063/1.36727","url":null,"abstract":"Atomic strontium vapor in a thermionic diode is irradiated by the light from a tunable dye laser at two-photon resonance on the 5s5d1D2 state. At a laser intensity of ~ 108 W/cm2 and a vapor pressure of several torrs, not only three-photon ionization occurs but also the generation of new frequencies due to a nonlinear polarization is observed. Simultaneously, strong and strictly directed beams are generated which are resonantly enhanced by the 5s5p1P1 and 5s6p1P1 states, respectively. Close to the first resonance, four-wave mixing causes braodband two-photon emission, the bandwidth of which is determined by the region of negative dispersion due to phase matching. On the other hand the process via the 6p state is exactly resonant as can be shown by comparison in every case with the respective fluorescence light. At higher pressures (~ 10Torr), however, a second line appears, which is also shifted to the side of negative dispersion.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126235316","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}
The ultrasensitive and isomerically selective detection of chlorinated aromatic hydrocarbons is currently a problem of particular concern due to the toxic and/or carcinogenic nature of these species and their widespread presence in the environment. In this work laser-induced fluorescence and resonantly enhanced multi photon ionization (REMPI) are applied to a series of mono- and dichloronaphthalenes that are rotationally cooled in a free jet expansion. Both techniques provide isomeric selectivity in the S1-S0 spectral region; however 1 + 2 REMPI is more sensitive. In the REMPI spectra of the dichloronapthalenes (DCNs) the S1-S0 origins of different positional isomers are separated by as much as 424 cm-1. Low resolution time-of-flight (TOF) mass spectra of the DCNs show the REMPI ion fragmentation pattern to be isomer dependent. The additional selectivity that isomer-dependent frag mentation provides is demonstrated by the different relative intensities observed in the parent and fragment ion REMPI spectra of a three-component DCN mixture. Possible extensions of the REMPI technique, including two-color, 1 + 1 REMPI for enhanced sensitivity and high-resolution TOF mass spectrometry for enhanced isomeric selectivy, are discussed.
{"title":"Laser spectroscopy of jet-cooled chlorinated aromatic hydrocarbons","authors":"E. Rohlfing, D. Chandler","doi":"10.1063/1.36871","DOIUrl":"https://doi.org/10.1063/1.36871","url":null,"abstract":"The ultrasensitive and isomerically selective detection of chlorinated aromatic hydrocarbons is currently a problem of particular concern due to the toxic and/or carcinogenic nature of these species and their widespread presence in the environment. In this work laser-induced fluorescence and resonantly enhanced multi photon ionization (REMPI) are applied to a series of mono- and dichloronaphthalenes that are rotationally cooled in a free jet expansion. Both techniques provide isomeric selectivity in the S1-S0 spectral region; however 1 + 2 REMPI is more sensitive. In the REMPI spectra of the dichloronapthalenes (DCNs) the S1-S0 origins of different positional isomers are separated by as much as 424 cm-1. Low resolution time-of-flight (TOF) mass spectra of the DCNs show the REMPI ion fragmentation pattern to be isomer dependent. The additional selectivity that isomer-dependent frag mentation provides is demonstrated by the different relative intensities observed in the parent and fragment ion REMPI spectra of a three-component DCN mixture. Possible extensions of the REMPI technique, including two-color, 1 + 1 REMPI for enhanced sensitivity and high-resolution TOF mass spectrometry for enhanced isomeric selectivy, are discussed.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122195074","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}
Metastable oxygen molecules in the singlet delta state, O2(1Δ), are believed to be the active species that are produced during laser irradiation of hematoporphyrin derivative (HPD), attached to tumors, and are responsible for cancer cell destruction. Although the presence of O2(1Δ) has been inferred by indirect chemical measurements, it has not been detected in real time. In this work, we review the optical characteristics of O2(1Δ) and describe an optical diagnostic procedure for its real-time detection during laser irradiation. In vitro experiments using both pulsed and cw dye lasers are described. Additionally, recent work has been presented whereby repetitively pulsed dye laser radiation can be delivered through a fiber-optic probe to induce fragmentation of kidney stones and gallstones.
{"title":"Mechanistic and diagnostic aspects of photodynamic enhancement and stone fragmentation","authors":"D. Rosen, S. Davis, A. Boni, John P. Campbell","doi":"10.1063/1.36808","DOIUrl":"https://doi.org/10.1063/1.36808","url":null,"abstract":"Metastable oxygen molecules in the singlet delta state, O2(1Δ), are believed to be the active species that are produced during laser irradiation of hematoporphyrin derivative (HPD), attached to tumors, and are responsible for cancer cell destruction. Although the presence of O2(1Δ) has been inferred by indirect chemical measurements, it has not been detected in real time. In this work, we review the optical characteristics of O2(1Δ) and describe an optical diagnostic procedure for its real-time detection during laser irradiation. In vitro experiments using both pulsed and cw dye lasers are described. Additionally, recent work has been presented whereby repetitively pulsed dye laser radiation can be delivered through a fiber-optic probe to induce fragmentation of kidney stones and gallstones.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"201 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121113494","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}
Intensity-vs-wavelength spectra of light scattered elastically from suspensions of monodisperse, dielectric microspheres were measured for both parallel and perpendicular polarizations. Whereas previous experimenters have observed sharp resonances in the spectra of single microspheres, the broad peaks observed in the present experiment are a summation of sharp resonances over the range of sizes present in the illuminated region of the suspension. Peak locations in these resonance light scattering (RLS) spectra were then compared with those computed from Mie theory to obtain a precise value for the mean diameter of the microspheres. The RLS-determined mean diameter of 9.90μm agreed to within 0.01 μm with the values measured by optical array sizing and scanning electron microscopy, both high-accuracy techniques. However, the shapes of the RLS spectra calculated for different size-distribution widths gave a standard deviation of 0.035 μm, less than half of the value obtained by array sizing and transmission electron microscopy. Mie scattering calculations for a range of mean diameters and distribution widths showed that the RLS method is useful for microsphere diameters from ~5μm to ~ 25μm, depending on the distribution width. Experimental procedures, computer analysis of the RLS spectra, sources of error, and limitations on the technique for high-accuracy microsphere sizing are discussed.
{"title":"Resonance light scattering from a suspension of microspheres","authors":"T. Lettieri, E. Marx","doi":"10.1063/1.36752","DOIUrl":"https://doi.org/10.1063/1.36752","url":null,"abstract":"Intensity-vs-wavelength spectra of light scattered elastically from suspensions of monodisperse, dielectric microspheres were measured for both parallel and perpendicular polarizations. Whereas previous experimenters have observed sharp resonances in the spectra of single microspheres, the broad peaks observed in the present experiment are a summation of sharp resonances over the range of sizes present in the illuminated region of the suspension. Peak locations in these resonance light scattering (RLS) spectra were then compared with those computed from Mie theory to obtain a precise value for the mean diameter of the microspheres. The RLS-determined mean diameter of 9.90μm agreed to within 0.01 μm with the values measured by optical array sizing and scanning electron microscopy, both high-accuracy techniques. However, the shapes of the RLS spectra calculated for different size-distribution widths gave a standard deviation of 0.035 μm, less than half of the value obtained by array sizing and transmission electron microscopy. Mie scattering calculations for a range of mean diameters and distribution widths showed that the RLS method is useful for microsphere diameters from ~5μm to ~ 25μm, depending on the distribution width. Experimental procedures, computer analysis of the RLS spectra, sources of error, and limitations on the technique for high-accuracy microsphere sizing are discussed.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123337192","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：