Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.qonc44
J. C. Erdmann, J. S. Saint Clair
The applicability of digital correlators to LIDAR is investigated for the special case of a subsurface lidar probing optical depth of the water column in the ocean. The correlator is assumed to operate in the signal averaging mode. For generality a bi-static configuration is analyzed which has advantages under lowest light level conditions. Multiple scattering in the ocean is simulated by a Monte Carlo method. Analysis is included to derive the number density of photons arriving at the detector and the expected arrival time distribution in relation to the lidar pulse energy. Optical depth is obtained by logarithmic display of the correlator channel contents. It is concluded that actual experiments should be possible with existing fast digital correlators and pulsed dye lasers of 1 mJ pulse energy or less.
{"title":"Range Gating of Photons Multiply Scattered in a Stratified Ocean","authors":"J. C. Erdmann, J. S. Saint Clair","doi":"10.1364/pcta.1988.qonc44","DOIUrl":"https://doi.org/10.1364/pcta.1988.qonc44","url":null,"abstract":"The applicability of digital correlators to LIDAR is investigated for the special case of a subsurface lidar probing optical depth of the water column in the ocean. The correlator is assumed to operate in the signal averaging mode. For generality a bi-static configuration is analyzed which has advantages under lowest light level conditions. Multiple scattering in the ocean is simulated by a Monte Carlo method. Analysis is included to derive the number density of photons arriving at the detector and the expected arrival time distribution in relation to the lidar pulse energy. Optical depth is obtained by logarithmic display of the correlator channel contents. It is concluded that actual experiments should be possible with existing fast digital correlators and pulsed dye lasers of 1 mJ pulse energy or less.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133262401","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}
Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.dsopp203
John Bortz
A performance model is developed for an angular frequency measurement technique based on photon correlation. The purpose of the technique is to measure the rate of rotation of a remote diffusely reflecting target. Coherent illumination of the target produces a speckle pattern that is sampled temporally and spatially by an array of photodetectors. The collected data are processed to obtain an estimate of the spatiotemporal cross correlation function for the speckle irradiance. The position of the correlation peak for a particular time delay provides a measure of the speckle velocity, which, combined with the known range and transverse velocity of the target, allows the transverse component of the target's angular frequency (i.e., rotation rate) vector to be calculated. The performance model includes the effects of atmospheric turbulence, clear-weather atmospheric attentuation, dark count, background radiation, dead time, spatiotemporal integration, photon noise, and classical measurement noise. Expressions for the signal-to-noise ratio, signal biasing, angular frequency resolution, and the maximum measurable angular frequency are derived.
{"title":"Remote Angular Frequency Measurement Through Turbulence","authors":"John Bortz","doi":"10.1364/pcta.1988.dsopp203","DOIUrl":"https://doi.org/10.1364/pcta.1988.dsopp203","url":null,"abstract":"A performance model is developed for an angular frequency measurement technique based on photon correlation. The purpose of the technique is to measure the rate of rotation of a remote diffusely reflecting target. Coherent illumination of the target produces a speckle pattern that is sampled temporally and spatially by an array of photodetectors. The collected data are processed to obtain an estimate of the spatiotemporal cross correlation function for the speckle irradiance. The position of the correlation peak for a particular time delay provides a measure of the speckle velocity, which, combined with the known range and transverse velocity of the target, allows the transverse component of the target's angular frequency (i.e., rotation rate) vector to be calculated. The performance model includes the effects of atmospheric turbulence, clear-weather atmospheric attentuation, dark count, background radiation, dead time, spatiotemporal integration, photon noise, and classical measurement noise. Expressions for the signal-to-noise ratio, signal biasing, angular frequency resolution, and the maximum measurable angular frequency are derived.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116872859","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}
Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.pcs137
B. Chu, R. Xu
A prism-cell laser light-scattering (PCLLS) spectrometer capable of measuring the angular distribution of time-averaged scattered intensity at small scattering angles (2°≲ θ ≲ 13° at λo = 632.8 nm and n = 1.33, corresponding to 4600 cm" ≲ K ≲ 30000 cm-1, with K, λo and n being the magnitude of the scattering vector, the wavelength of light in vacuo and the refractive index of the scattering medium, respectively) by means of a linear intensified photodiode array (PDA) detector and simultaneous determination of intensity-intensity time correlation functions at two different scattering angles using two photomultiplier tube (PMT) detectors and associated digital photon correlators is described. The unique prism light-scattering cell also permits measurements of the refractive index of the scattering medium to better than one part in 106. The use of high quality optical glass in the entrance window and in the exit prism of the light-scattering cell for the incident laser beam, together with an aperture after the entrance window and in the scattering medium, results in a substantial reduction of the parasitic scattering along the light path. With the PDA and one of the PMTs mounted on a rotating arm, the angular ranges of our PCLLS spectrometer are limited mainly by optical geometry. For typical dilute aqueous solutions or suspensions, self-beating light-scattering measurements down to a scattering angle of 2° have been achieved. Measurements of self-beating linewidths for a polymer solution undergoing coil-to-globule transition are reviewed and some signal-to-noise ratio considerations for particle sizing in polymer solutions are presented.
{"title":"Prism-Cell Laser Light-Scattering Spectrometer","authors":"B. Chu, R. Xu","doi":"10.1364/pcta.1988.pcs137","DOIUrl":"https://doi.org/10.1364/pcta.1988.pcs137","url":null,"abstract":"A prism-cell laser light-scattering (PCLLS) spectrometer capable of measuring the angular distribution of time-averaged scattered intensity at small scattering angles (2°≲ θ ≲ 13° at λo = 632.8 nm and n = 1.33, corresponding to 4600 cm\" ≲ K ≲ 30000 cm-1, with K, λo and n being the magnitude of the scattering vector, the wavelength of light in vacuo and the refractive index of the scattering medium, respectively) by means of a linear intensified photodiode array (PDA) detector and simultaneous determination of intensity-intensity time correlation functions at two different scattering angles using two photomultiplier tube (PMT) detectors and associated digital photon correlators is described. The unique prism light-scattering cell also permits measurements of the refractive index of the scattering medium to better than one part in 106. The use of high quality optical glass in the entrance window and in the exit prism of the light-scattering cell for the incident laser beam, together with an aperture after the entrance window and in the scattering medium, results in a substantial reduction of the parasitic scattering along the light path. With the PDA and one of the PMTs mounted on a rotating arm, the angular ranges of our PCLLS spectrometer are limited mainly by optical geometry. For typical dilute aqueous solutions or suspensions, self-beating light-scattering measurements down to a scattering angle of 2° have been achieved. Measurements of self-beating linewidths for a polymer solution undergoing coil-to-globule transition are reviewed and some signal-to-noise ratio considerations for particle sizing in polymer solutions are presented.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128870342","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}
An LDA system using photon correlation technique and capable of handling non photon resolved signals is reported. Comparisons with the power spectrum of actual detector signals show that the correlation technique is very efficient. Turbulence production by means of swirl has been tested by making cycle resolved LDA measurements in a motored petrol engine for three different swirl levels. Firing tests of the engine show that the ignition delay (0 - 1% burned) correlates well with the high frequency components (> 1 kHz) of the turbulence at the spark plug location.
{"title":"In-Cylinder LDA Measurements Using a Correlator","authors":"E. Max, I. Denbratt","doi":"10.1364/pcta.1988.efd78","DOIUrl":"https://doi.org/10.1364/pcta.1988.efd78","url":null,"abstract":"An LDA system using photon correlation technique and capable of handling non photon resolved signals is reported. Comparisons with the power spectrum of actual detector signals show that the correlation technique is very efficient.\u0000 Turbulence production by means of swirl has been tested by making cycle resolved LDA measurements in a motored petrol engine for three different swirl levels. Firing tests of the engine show that the ignition delay (0 - 1% burned) correlates well with the high frequency components (> 1 kHz) of the turbulence at the spark plug location.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126019660","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}
Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.nit172
Robert G. W. Brown
Traditional optical systems for photon correlation laser anemometry and spectroscopy have relied upon physically large and fairly expensive lasers, "bulk-optics" such as lenses of a few inches diameter, large mechanical mounts etc and carefully selected, fragile and bulky photon-counting photomultiplier detectors. In some cases experimental fluid dynamics at a desired position in a flow, perhaps deep inside complex machinery, is physically impossible or very difficult. Similar problems exist with photon correlation spectroscopy, eg., heterodyne experiments. We have investigated and characterized various optical and electro-optical components with the aim of replacing existing photon correlation laser anemometry and spectroscopy techniques in miniaturized form, and with significant cost reduction.
{"title":"Miniature Instrumentation for Photon Correlation Experiments","authors":"Robert G. W. Brown","doi":"10.1364/pcta.1988.nit172","DOIUrl":"https://doi.org/10.1364/pcta.1988.nit172","url":null,"abstract":"Traditional optical systems for photon correlation laser anemometry and spectroscopy have relied upon physically large and fairly expensive lasers, \"bulk-optics\" such as lenses of a few inches diameter, large mechanical mounts etc and carefully selected, fragile and bulky photon-counting photomultiplier detectors. In some cases experimental fluid dynamics at a desired position in a flow, perhaps deep inside complex machinery, is physically impossible or very difficult. Similar problems exist with photon correlation spectroscopy, eg., heterodyne experiments. We have investigated and characterized various optical and electro-optical components with the aim of replacing existing photon correlation laser anemometry and spectroscopy techniques in miniaturized form, and with significant cost reduction.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117348097","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 soot particles generated by a Diesel car exhaust have been sized by P.C.S.in a dilution tunnel for various loads. Due to the very heterogeneous composition of the particles population on-line measurements were not possible. So we have chosen to record a set of successive correlograms. The choice of the correlograms having to be regrouped before processing is based upon the total count number received during an experiment. They are displayed on a histogram or a Henry line. The necessary K 7027 software modifications are briefly described.
{"title":"Measurement of Diesel Exhaust Particles in a Dilution Tunnel by Photon Correlation Spectroscopy","authors":"N. Lhuissier, A. Nazih, M. Weill","doi":"10.1364/pcta.1988.efd84","DOIUrl":"https://doi.org/10.1364/pcta.1988.efd84","url":null,"abstract":"The soot particles generated by a Diesel car exhaust have been sized by P.C.S.in a dilution tunnel for various loads. Due to the very heterogeneous composition of the particles population on-line measurements were not possible. So we have chosen to record a set of successive correlograms. The choice of the correlograms having to be regrouped before processing is based upon the total count number received during an experiment. They are displayed on a histogram or a Henry line. The necessary K 7027 software modifications are briefly described.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123308548","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}
Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.qonc26
M. Silverman
The intensity correlation of fermion beams provides a novel interferometric approach, hitherto largely unexplored, to the investigation of the wave-like attributes, exchange symmetry, and interaction with potentials of multifermion states. Predicted quantum interference effects derive from the indistinguishability of particles as well as from the spatial separation of particle paths.
{"title":"Applications of Photon Correlation Techniques to Fermions","authors":"M. Silverman","doi":"10.1364/pcta.1988.qonc26","DOIUrl":"https://doi.org/10.1364/pcta.1988.qonc26","url":null,"abstract":"The intensity correlation of fermion beams provides a novel interferometric approach, hitherto largely unexplored, to the investigation of the wave-like attributes, exchange symmetry, and interaction with potentials of multifermion states. Predicted quantum interference effects derive from the indistinguishability of particles as well as from the spatial separation of particle paths.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129082577","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}
Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.pcs132
R. Nossal
The possibility of using dynamic light scattering to measure parameters describing the dynamic response of transiently bonded gels is investigated. When a sample is subjected to externally imposed mechanical excitation, a resonance in the frequency dependence of the response will be observed if the relaxation times for bond formation and breakage are long on a timescale determined by the dimensions and the instantaneous shear modulus of the sample. However, if the relaxation is fast on such a timescale, the response does not show resonance behavior and is maximal at zero frequency. Analytical expressions are provided that relate the half-widths of spectral response to kinetic parameters pertaining to the internal restructuring of the gel matrix.
{"title":"Analysis of Dynamic Light Scattering from Transient Gels","authors":"R. Nossal","doi":"10.1364/pcta.1988.pcs132","DOIUrl":"https://doi.org/10.1364/pcta.1988.pcs132","url":null,"abstract":"The possibility of using dynamic light scattering to measure parameters describing the dynamic response of transiently bonded gels is investigated. When a sample is subjected to externally imposed mechanical excitation, a resonance in the frequency dependence of the response will be observed if the relaxation times for bond formation and breakage are long on a timescale determined by the dimensions and the instantaneous shear modulus of the sample. However, if the relaxation is fast on such a timescale, the response does not show resonance behavior and is maximal at zero frequency. Analytical expressions are provided that relate the half-widths of spectral response to kinetic parameters pertaining to the internal restructuring of the gel matrix.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131036396","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}
Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.qonc35
D. Pine, D. Weitz, P. Chaikin, E. Herbolzheimer
Photon correlation spectroscopy is extended to strongly multiply scattering systems by assuming that the transport of light is diffusive. A simple model is developed which accounts for different sample geometries, scattering configurations, absorption, and sample polydispersity. Experimental data are found to be in excellent agreement with the predictions. The dependence on geometry provides an important experimental control over the length and time scales probed.
{"title":"Features of Diffusing Wave Spectroscopy","authors":"D. Pine, D. Weitz, P. Chaikin, E. Herbolzheimer","doi":"10.1364/pcta.1988.qonc35","DOIUrl":"https://doi.org/10.1364/pcta.1988.qonc35","url":null,"abstract":"Photon correlation spectroscopy is extended to strongly multiply scattering systems by assuming that the transport of light is diffusive. A simple model is developed which accounts for different sample geometries, scattering configurations, absorption, and sample polydispersity. Experimental data are found to be in excellent agreement with the predictions. The dependence on geometry provides an important experimental control over the length and time scales probed.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130129163","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}
Pub Date : 1900-01-01DOI: 10.1364/pcta.1988.pcmdr14
J. Shaumeyer, R. Gammon
We have performed an experiment to test our understanding of the run time, T, necessary to achieve a specified precision in the value of the intensity coherence time, τc, extracted from correlation functions taken in the strong signal limit, and to test predictions for the values of some experimental parameters that optimize the precision. Using ensembles of 10 correlation functions taken at 5 different choices of sample time, we found that the ensemble estimators for the error in τc were well described by the expression δτ/τ c =4.2/T/τ c , in agreement with the work of Degiorgio and Lastovka (1971). The sample times used were chosen so that the number of coherence times spanned by the 128 channels of the correlator, α, covered the range 1 ≤ α ≤ 16; in this range, we found no evidence of a minimum in δτ/τc to suggest an optimum value of α. These results were independent of whether we used three-parameter or two-parameter least-squares fits to extract τc. However, we did find that the two fits gave systematically different values of τc, and both show a similar dependence on α.
我们进行了一个实验，以测试我们对运行时间T的理解，T是在强信号极限中从相关函数中提取的强度相干时间τc值达到指定精度所必需的，并测试对优化精度的一些实验参数值的预测。使用5种不同采样时间下的10个相关函数的集合，我们发现τc误差的集合估计可以用δτ/τ c =4.2/T/τ c的表达式很好地描述，这与Degiorgio和Lastovka(1971)的工作一致。选取采样次数，使相关器的128个通道所跨越的相干次数α在1≤α≤16范围内;在这个范围内，我们发现没有证据表明δτ/τc有一个最小值来表示α的最佳值。这些结果与我们是否使用三参数或两参数最小二乘拟合来提取τc无关。然而，我们确实发现这两种拟合给出了系统不同的τc值，并且都显示出对α的相似依赖。
{"title":"Optimizing Fitting Statistics in Photon Correlation Spectroscopy","authors":"J. Shaumeyer, R. Gammon","doi":"10.1364/pcta.1988.pcmdr14","DOIUrl":"https://doi.org/10.1364/pcta.1988.pcmdr14","url":null,"abstract":"We have performed an experiment to test our understanding of the run time, T, necessary to achieve a specified precision in the value of the intensity coherence time, τc, extracted from correlation functions taken in the strong signal limit, and to test predictions for the values of some experimental parameters that optimize the precision. Using ensembles of 10 correlation functions taken at 5 different choices of sample time, we found that the ensemble estimators for the error in τc were well described by the expression \u0000δτ/τ\u0000 c\u0000 =4.2/T/τ\u0000 c\u0000 , in agreement with the work of Degiorgio and Lastovka (1971). The sample times used were chosen so that the number of coherence times spanned by the 128 channels of the correlator, α, covered the range 1 ≤ α ≤ 16; in this range, we found no evidence of a minimum in δτ/τc to suggest an optimum value of α. These results were independent of whether we used three-parameter or two-parameter least-squares fits to extract τc. However, we did find that the two fits gave systematically different values of τc, and both show a similar dependence on α.","PeriodicalId":371566,"journal":{"name":"Photon Correlation Techniques and Applications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128002134","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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