Optical coherence tomography(OCT) is an optical imaging modality that performs high-resolution,cross-sectional,subsurface tomographic imaging of the microstructure of tissues.The physical principle of OCT is similar t...Optical coherence tomography(OCT) is an optical imaging modality that performs high-resolution,cross-sectional,subsurface tomographic imaging of the microstructure of tissues.The physical principle of OCT is similar to that of B-mode ultrasound imaging,except that it uses infrared light waves rather than acoustic waves.The in vivo resolution is 10-25 times better(about 10 μm) than with high-frequency ultrasound imaging,but the depth of penetration is limited to 1-3 mm,depending upon tissue structure,depth of focus of the probe used,and pressure applied to the tissue surface.In the last decade,OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice,including the gastrointestinal(GI) tract and pancreatic-biliary ductal system.OCT imaging from the GI tract can be done in humans by using narrow-diameter,catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope,for investigating the epithelial structure of the GI tract,or a side-view endoscope,inside a standard transparent ERCP catheter,for investigating the pancreatico-biliary ductal system.Esophagus and the esophago-gastric junction has been the most widely investigated organ so far;more recently,also duodenum,colon and pancreatico-biliary ductal system have been extensively investigated.OCT imaging of the gastro-intestinal wall structure is characterized by a multiple-layer architecture that permits an accurate evaluation of the mucosa,lamina propria,muscularis mucosae,andpart of the submucosa.The technique may be,therefore,used to identify pre-neoplastic conditions of the GI tract,such as Barrett's epithelium and dysplasia,and evaluate the depth of penetration of early-stage neoplastic lesions.OCT imaging of the pancreatic and biliary ductal system could improve the diagnostic accuracy for ductal epithelial changes and the differential diagnosis between neoplastic and non-neoplastic lesions.展开更多
To sharpen the imaging of structures, it is vital to develop a convenient and efficient quantitative algorithm of the optical coherence tomography (OCT) sampling. In this paper a new Monte Carlo model is set up and ho...To sharpen the imaging of structures, it is vital to develop a convenient and efficient quantitative algorithm of the optical coherence tomography (OCT) sampling. In this paper a new Monte Carlo model is set up and how light propagates in bio-tissue is analyzed in virtue of mathematics and physics equations. The relations,in which light intensity of Class 1 and Class 2 light with different wavelengths changes with their permeation depth,and in which Class 1 light intensity (signal light intensity) changes with the probing depth, and in which angularly resolved diffuse reflectance and diffuse transmittance change with the exiting angle, are studied. The results show that Monte Carlo simulation results are consistent with the theory data.展开更多
In this paper,a digital holography system with short-coherence light source is used to record a series of holograms of a micro-object.The three dimensional reconstruction is completed by the least-square-polynomial-fi...In this paper,a digital holography system with short-coherence light source is used to record a series of holograms of a micro-object.The three dimensional reconstruction is completed by the least-square-polynomial-fitting with a series of two dimensional intensity images which are obtained through holographic reconstruction.This three dimensional reconstruction method can be used to carry out three-dimensional reconstruction of a micro-object with strong laser speckle noise,which can not be obtained from the conventional method.展开更多
Using the technique of integration within an ordered product of nonlinear Bose operators and by composing the nonlinear coherent state's over-completeness relation, we construct the corresponding P-representation ...Using the technique of integration within an ordered product of nonlinear Bose operators and by composing the nonlinear coherent state's over-completeness relation, we construct the corresponding P-representation theory. The generalized P-representation for some nonlinear Bose operators can be established.展开更多
The original idea of quantum optical spring arises from the requirement of quantization of the frequency of oscillations in the Hamiltonian of harmonic oscillator. This purpose is achieved by considering a spring whos...The original idea of quantum optical spring arises from the requirement of quantization of the frequency of oscillations in the Hamiltonian of harmonic oscillator. This purpose is achieved by considering a spring whose constant （and so its frequency） depends on the quantum states ofanother system. Recently, it is realized that by the assumption of frequency modulation of ω to ω √1＋ μα＋α the mentioned idea can be established. In the present paper, we generalize the approach of quantum optical spring with particular attention to the dependence or trequency to the intensity of radiation field that naturally observes in the nonlinear coherent states, from which we arrive at a physical system has been called by us as nonlinear quantum optical spring. Then, after the introduction of the generalized tlamiltonian of nonlinear quantum optical spring and it＇s solution, we will investigate the nonclassical properties of the obtained states. Specially, typical collapse and revival in the distribution functions and squeezing parameters, as particular quantum features, will be revealed.展开更多
Y and inverted Y-type four-level schemes for optical quantum coherence systems,which may be intuitivelyconsidered to be very simple,have not been studied intensively till now.In this paper,we present the multiformity ...Y and inverted Y-type four-level schemes for optical quantum coherence systems,which may be intuitivelyconsidered to be very simple,have not been studied intensively till now.In this paper,we present the multiformity ofthese two types of schemes by considering that they can be classified into nine possible level styles as the second-ordersub-schemes using laser fields.Further we point out the complexity of their more than one hundred realistic configurationsas the third-order four-level sub-schemes that may appear in the optical quantum coherence experiments.Throughoutthis paper we review which configurations have been studied in some research aspects and which ones not,accordingto our knowledge,in order to be propitious to next steps of theoretical and experimental investigations,especially forapplications in the fields of quantum optics,quantum information science,laser spectroscopy,and so on.展开更多
The partially coherent beams propagating through random media have been used in the past to enhance effect of nonlinear optical interaction. Moreover, after propagation through a random （or turbulent） medium the coh...The partially coherent beams propagating through random media have been used in the past to enhance effect of nonlinear optical interaction. Moreover, after propagation through a random （or turbulent） medium the coherent beam becomes a partially coherent one. In this research, the analytical formula for the average intensity of Gaussian beam propagating through random medium is derived and the influence of coherent partiality on optical gradient force acting on dielectric particle rounded by a random media is investigated.展开更多
Laser phase noise （LPN） plays an important role in optical coherent systems. Based on the algorithm of Viterbi-Viterbi cartier phase estimation （CPE）, the effects of LPN imposed on the coherent receivers are inves...Laser phase noise （LPN） plays an important role in optical coherent systems. Based on the algorithm of Viterbi-Viterbi cartier phase estimation （CPE）, the effects of LPN imposed on the coherent receivers are investigated for quadrature phase shift keying （QPSK）, 8 phase shift keying （SPSK） and 16-quadrature amplitude modulation （16-QAM） optical coherent systems, respectively. The simulation results show that the optimal block length in the phase estimation algorithm is a tradeoffbetween LPN and additive white Gaussian noise （AWGN）, and depends on the level of modulation formats. The resolution requirements of analog to digital converter （ADC） in the coherent receivers are independent of LPN or the level of modulation formats. For the bit error rate （BER） of 10-3, the required bit number of ADC is 6, and the gain is marginal for the higher resolution.展开更多
文摘Optical coherence tomography(OCT) is an optical imaging modality that performs high-resolution,cross-sectional,subsurface tomographic imaging of the microstructure of tissues.The physical principle of OCT is similar to that of B-mode ultrasound imaging,except that it uses infrared light waves rather than acoustic waves.The in vivo resolution is 10-25 times better(about 10 μm) than with high-frequency ultrasound imaging,but the depth of penetration is limited to 1-3 mm,depending upon tissue structure,depth of focus of the probe used,and pressure applied to the tissue surface.In the last decade,OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice,including the gastrointestinal(GI) tract and pancreatic-biliary ductal system.OCT imaging from the GI tract can be done in humans by using narrow-diameter,catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope,for investigating the epithelial structure of the GI tract,or a side-view endoscope,inside a standard transparent ERCP catheter,for investigating the pancreatico-biliary ductal system.Esophagus and the esophago-gastric junction has been the most widely investigated organ so far;more recently,also duodenum,colon and pancreatico-biliary ductal system have been extensively investigated.OCT imaging of the gastro-intestinal wall structure is characterized by a multiple-layer architecture that permits an accurate evaluation of the mucosa,lamina propria,muscularis mucosae,andpart of the submucosa.The technique may be,therefore,used to identify pre-neoplastic conditions of the GI tract,such as Barrett's epithelium and dysplasia,and evaluate the depth of penetration of early-stage neoplastic lesions.OCT imaging of the pancreatic and biliary ductal system could improve the diagnostic accuracy for ductal epithelial changes and the differential diagnosis between neoplastic and non-neoplastic lesions.
文摘To sharpen the imaging of structures, it is vital to develop a convenient and efficient quantitative algorithm of the optical coherence tomography (OCT) sampling. In this paper a new Monte Carlo model is set up and how light propagates in bio-tissue is analyzed in virtue of mathematics and physics equations. The relations,in which light intensity of Class 1 and Class 2 light with different wavelengths changes with their permeation depth,and in which Class 1 light intensity (signal light intensity) changes with the probing depth, and in which angularly resolved diffuse reflectance and diffuse transmittance change with the exiting angle, are studied. The results show that Monte Carlo simulation results are consistent with the theory data.
基金Supported by the National Natural Science Foundation of China(Grant No.60377008)the Natural Science Foundation of Tian-jin,China (Grant No.043800611)the State Key Laboratory of Modern Optical Instrumentations of Zhejiang University,China(Grant No.LMOI-0503)
文摘In this paper,a digital holography system with short-coherence light source is used to record a series of holograms of a micro-object.The three dimensional reconstruction is completed by the least-square-polynomial-fitting with a series of two dimensional intensity images which are obtained through holographic reconstruction.This three dimensional reconstruction method can be used to carry out three-dimensional reconstruction of a micro-object with strong laser speckle noise,which can not be obtained from the conventional method.
文摘Using the technique of integration within an ordered product of nonlinear Bose operators and by composing the nonlinear coherent state's over-completeness relation, we construct the corresponding P-representation theory. The generalized P-representation for some nonlinear Bose operators can be established.
文摘The original idea of quantum optical spring arises from the requirement of quantization of the frequency of oscillations in the Hamiltonian of harmonic oscillator. This purpose is achieved by considering a spring whose constant （and so its frequency） depends on the quantum states ofanother system. Recently, it is realized that by the assumption of frequency modulation of ω to ω √1＋ μα＋α the mentioned idea can be established. In the present paper, we generalize the approach of quantum optical spring with particular attention to the dependence or trequency to the intensity of radiation field that naturally observes in the nonlinear coherent states, from which we arrive at a physical system has been called by us as nonlinear quantum optical spring. Then, after the introduction of the generalized tlamiltonian of nonlinear quantum optical spring and it＇s solution, we will investigate the nonclassical properties of the obtained states. Specially, typical collapse and revival in the distribution functions and squeezing parameters, as particular quantum features, will be revealed.
基金Supported by the Research Starting Funds of Tianjin Polytechnic University under Grant Nos.20080033 and 20070010
文摘Y and inverted Y-type four-level schemes for optical quantum coherence systems,which may be intuitivelyconsidered to be very simple,have not been studied intensively till now.In this paper,we present the multiformity ofthese two types of schemes by considering that they can be classified into nine possible level styles as the second-ordersub-schemes using laser fields.Further we point out the complexity of their more than one hundred realistic configurationsas the third-order four-level sub-schemes that may appear in the optical quantum coherence experiments.Throughoutthis paper we review which configurations have been studied in some research aspects and which ones not,accordingto our knowledge,in order to be propitious to next steps of theoretical and experimental investigations,especially forapplications in the fields of quantum optics,quantum information science,laser spectroscopy,and so on.
文摘The partially coherent beams propagating through random media have been used in the past to enhance effect of nonlinear optical interaction. Moreover, after propagation through a random （or turbulent） medium the coherent beam becomes a partially coherent one. In this research, the analytical formula for the average intensity of Gaussian beam propagating through random medium is derived and the influence of coherent partiality on optical gradient force acting on dielectric particle rounded by a random media is investigated.
基金supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department (No.11JK1006)
文摘Laser phase noise （LPN） plays an important role in optical coherent systems. Based on the algorithm of Viterbi-Viterbi cartier phase estimation （CPE）, the effects of LPN imposed on the coherent receivers are investigated for quadrature phase shift keying （QPSK）, 8 phase shift keying （SPSK） and 16-quadrature amplitude modulation （16-QAM） optical coherent systems, respectively. The simulation results show that the optimal block length in the phase estimation algorithm is a tradeoffbetween LPN and additive white Gaussian noise （AWGN）, and depends on the level of modulation formats. The resolution requirements of analog to digital converter （ADC） in the coherent receivers are independent of LPN or the level of modulation formats. For the bit error rate （BER） of 10-3, the required bit number of ADC is 6, and the gain is marginal for the higher resolution.
