Rongguang Liang - Academia.edu (original) (raw)

Papers by Rongguang Liang

We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-F... more We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-Fluorescence Imaging (AFI), Infra-Red Imaging (IRI) and Endo-Cytoscopy System (ECS). The purpose of these imaging techniques is to emphasize the important tissue features associated with early stage of lesions. We have already launched the new medical endoscope system including NBI, AFI and IRI (EVIS LUCERA SPECTRUM, OLYMPUS MEDICAL SYSTEMS Co., Ltd., Fig. 1). Moreover ECS, which has enough ...

We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-F... more We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-Fluorescence Imaging (AFI), Infra-Red Imaging (IRI) and Endo-Cytoscopy System (ECS). The purpose of these imaging techniques is to emphasize the important tissue features associated with early stage of lesions. We have already launched the new medical endoscope system including NBI, AFI and IRI (EVIS LUCERA SPECTRUM, OLYMPUS MEDICAL SYSTEMS Co., Ltd., Fig. 1). Moreover ECS, which has enough ...

Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences)... more Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

... Multiphoton imaging for deep tissue penetration and clinical endoscopy. Author(s): Chris Xu. ... more ... Multiphoton imaging for deep tissue penetration and clinical endoscopy. Author(s): Chris Xu. Optical coherence tomography using bessel beams. Author(s): Kye-Sung Lee; Sophie Vo; Jannick P. Rolland. ...

A multimodal imaging system has been developed for tooth tissue imaging. This imaging system is d... more A multimodal imaging system has been developed for tooth tissue imaging. This imaging system is designed to obtain one or more two-dimensional images of the tooth tissue, and those two-dimensional images are rendered with advanced algorithms to provide a high-contrast image. This system combines polarized reflectance imaging, fluorescence imaging, and optical coherence tomography (OCT) imaging. The imaging system design, as well as some experimental results, will be discussed in the presentation.

Dental caries is a disease in which minerals of the tooth are dissolved by surrounding bacterial ... more Dental caries is a disease in which minerals of the tooth are dissolved by surrounding bacterial plaques. A caries process present for some time may result in a caries lesion. However, if it is detected early enough, the dentist and dental professionals can implement measures to reverse and control caries. Several optical, nonionized methods have been investigated and used to detect dental caries in early stages. However, there is not a method that can singly detect the caries process with both high sensitivity and high specificity. In this paper, we present a multimodal imaging system that combines visible reflectance, fluorescence, and Optical Coherence Tomography (OCT) imaging. This imaging system is designed to obtain one or more two-dimensional images of the tooth (reflectance and fluorescence images) and a three-dimensional OCT image providing depth and size information of the caries. The combination of two- and three-dimensional images of the tooth has the potential for highly sensitive and specific detection of dental caries.

Optics & Photonics News, 2009

Applied Optics, 2000

We describe a method of measuring the relative optical phase on reflection between amorphous and ... more We describe a method of measuring the relative optical phase on reflection between amorphous and crystalline regions of the phase-change media of optical data storage. With a red He-Ne laser ͑wavelength, 632.8 nm͒ the relative phases on two quadrilayer optical disk stacks were measured and found to be ϳ40°. The results are in good agreement with the calculated values based on the known layer thicknesses and refractive indices of the stacks. For calibration purposes the height of a known step on an otherwise flat silicon substrate was measured with the same apparatus. The proposed method is fairly simple to set up, can measure both front-surface and through-substrate types of optical disk, and can be used with any laser that has long coherence length.

Optics & Photonics News, 2000

P hotolithography is the technolo gy of reproducing patterns using light. Developed originally fo... more P hotolithography is the technolo gy of reproducing patterns using light. Developed originally for repro ducing engravings and photographs, and later used to make printing plates, photolithography was found ideal in the 1960s for mass-produc ing integrated circuits. 1 Projection exposure tools, which are now used routinely in the semiconductor in dustry, have continually improved over the past several decades to satis fy the insatiable demand for reduced feature size, increased chip size, im proved reliability and production yield, and lower overall cost. High numerical aperture lenses, shortwavelength light sources, and com plex photoresist chemistry have been developed to achieve fabrication of fine patterns over fairly large areas. Research and development efforts in recent years have been directed at improving the resolution and depth of focus of the photolithographic process by using phase-shifting masks (PSMs) in place of the con ventional binary intensity masks (BIMs). In this article we describe briefly the principles of projection photolithography and explore the range of possibilities opened up by the introduction of PSMs.

We report results of measurements of the optical constants of the dielectric layer, reflecting la... more We report results of measurements of the optical constants of the dielectric layer, reflecting layer, and phase-change layer used as the media of phase-change optical recording. The refractive index and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.

Applied Optics, 2001

Polarization dependence of signals from periodic one-dimensional arrays of magnetic domains in ma... more Polarization dependence of signals from periodic one-dimensional arrays of magnetic domains in magneto-optical (MO) media and crystalline domains in amorphous phase-change (PC) media has been studied by theoretical calculation and experiment. The MO signal in the small-period regime depends on the direction of incident polarization. The relative strength of the E(?) and E(?) signals changes depending on the period of the pattern, the wavelength of the light, and the numerical aperture of the objective lens. For PC media, the reflected signal has similar polarization dependence, but this dependence is weak.

Applied Optics, 2000

We describe the design, construction, and testing of a variant of Zernike's phase-contrast micros... more We describe the design, construction, and testing of a variant of Zernike's phase-contrast microscope. The sample is illuminated with a white-light source through an annular aperture, which is projected onto the entrance pupil of the objective lens. In the return path the light diffracted by the sample and appearing in the interior of the objective's aperture ͑i.e., the test beam͒ is separated from the light returning in the annular region near the rim of the objective ͑i.e., the reference beam͒. The separated beams are relatively phase shifted and then combined to create an interferogram of the sample's surface on a CCD camera. It is fairly straightforward to use this system as a conventional bright-field or dark-field microscope, but its most interesting application is as a Zernike phase-contrast microscope with adjustable amplitude ratio and phase shift between test and reference beams. The ability to continuously adjust the phase of the reference beam also enables quantitative measurement of the phase imparted by the sample to the incident beam.

Applied Optics, 2002

We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), re... more We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), reflecting layer (aluminum-chromium alloy), and phase-change layer (GeSbTe, AgInSbTe) used as the media of phase-change optical recording. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.

Applied Optics, 2002

Digital information in optical data storage systems can be encoded in the intensity, in the polar... more Digital information in optical data storage systems can be encoded in the intensity, in the polarization state, or in the phase of a carrier laser beam. Intensity modulation is achieved at the surface of the storage medium either through destructive interference from surface-relief features (e.g., CD or DVD pits) or through reflectivity variations (e.g., alteration of optical constants of phase-change media). Magneto-optical materials make use of the polar magneto-optical Kerr effect to produce polarization modulations of the focused beam reflected from the storage medium. Both surface-relief structures and material-property variations can create, at the exit pupil of the objective lens of the optical pickup, a phase modulation (this, in addition to any intensity or polarization modulation or both). Current optical data storage systems do not make use of this phase information, whose recovery could potentially increase the strength of the readout signal. We show how all three mechanisms can be exploited in a scanning optical microscope to reconstruct the recorded (or embedded) data patterns on various types of optical disk.

Applied Optics, 2001

Using measurements of reflectance, transmittance, and the ellipsometric parameter ⌬, we have dete... more Using measurements of reflectance, transmittance, and the ellipsometric parameter ⌬, we have determined the thickness, refractive index, and the absorption coefficient of various thin films and thin-film stacks. ͑⌬, the relative phase between the p-and s-polarized components, is measured for both reflected and transmitted light.͒ These optical measurements are performed with a specially designed system at the fixed wavelength of ϭ 633 nm over the 10°-75°range of angles of incidence. The examined samples, prepared by means of sputtering on fused-silica substrates, consist of monolayers and trilayers of various materials of differing thickness and optical constants. These samples, which are representative of the media of rewritable phase-change optical disks, include a dielectric mixture of ZnS and SiO 2 , an amorphous film of the Ge 2 Sb 2.3 Te 5 alloy, and an aluminum chromium alloy film. To avoid complications arising from reflection and transmission losses at the air-substrate interface, the samples are immersed in an index-matching fluid that eliminates the contributions of the substrate to reflected and transmitted light. A computer program estimates the unknown parameters of the film͑s͒ by matching the experimental data to theoretically calculated values. Although our system can be used for measurements over a broad range of wavelengths, we describe only the results obtained at ϭ 633 nm.

Optical Engineering, 2000

The exercise given demonstrates the construction of a diffraction-limited transmission sphere for... more The exercise given demonstrates the construction of a diffraction-limited transmission sphere for interferometry in a geometrical ray-tracing program, followed by an analysis of its performance in a physical-optics program.

We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-F... more We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-Fluorescence Imaging (AFI), Infra-Red Imaging (IRI) and Endo-Cytoscopy System (ECS). The purpose of these imaging techniques is to emphasize the important tissue features associated with early stage of lesions. We have already launched the new medical endoscope system including NBI, AFI and IRI (EVIS LUCERA SPECTRUM, OLYMPUS MEDICAL SYSTEMS Co., Ltd., Fig. 1). Moreover ECS, which has enough ...

We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-F... more We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-Fluorescence Imaging (AFI), Infra-Red Imaging (IRI) and Endo-Cytoscopy System (ECS). The purpose of these imaging techniques is to emphasize the important tissue features associated with early stage of lesions. We have already launched the new medical endoscope system including NBI, AFI and IRI (EVIS LUCERA SPECTRUM, OLYMPUS MEDICAL SYSTEMS Co., Ltd., Fig. 1). Moreover ECS, which has enough ...

Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences)... more Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

... Multiphoton imaging for deep tissue penetration and clinical endoscopy. Author(s): Chris Xu. ... more ... Multiphoton imaging for deep tissue penetration and clinical endoscopy. Author(s): Chris Xu. Optical coherence tomography using bessel beams. Author(s): Kye-Sung Lee; Sophie Vo; Jannick P. Rolland. ...

A multimodal imaging system has been developed for tooth tissue imaging. This imaging system is d... more A multimodal imaging system has been developed for tooth tissue imaging. This imaging system is designed to obtain one or more two-dimensional images of the tooth tissue, and those two-dimensional images are rendered with advanced algorithms to provide a high-contrast image. This system combines polarized reflectance imaging, fluorescence imaging, and optical coherence tomography (OCT) imaging. The imaging system design, as well as some experimental results, will be discussed in the presentation.

Dental caries is a disease in which minerals of the tooth are dissolved by surrounding bacterial ... more Dental caries is a disease in which minerals of the tooth are dissolved by surrounding bacterial plaques. A caries process present for some time may result in a caries lesion. However, if it is detected early enough, the dentist and dental professionals can implement measures to reverse and control caries. Several optical, nonionized methods have been investigated and used to detect dental caries in early stages. However, there is not a method that can singly detect the caries process with both high sensitivity and high specificity. In this paper, we present a multimodal imaging system that combines visible reflectance, fluorescence, and Optical Coherence Tomography (OCT) imaging. This imaging system is designed to obtain one or more two-dimensional images of the tooth (reflectance and fluorescence images) and a three-dimensional OCT image providing depth and size information of the caries. The combination of two- and three-dimensional images of the tooth has the potential for highly sensitive and specific detection of dental caries.

Optics & Photonics News, 2009

Applied Optics, 2000

We describe a method of measuring the relative optical phase on reflection between amorphous and ... more We describe a method of measuring the relative optical phase on reflection between amorphous and crystalline regions of the phase-change media of optical data storage. With a red He-Ne laser ͑wavelength, 632.8 nm͒ the relative phases on two quadrilayer optical disk stacks were measured and found to be ϳ40°. The results are in good agreement with the calculated values based on the known layer thicknesses and refractive indices of the stacks. For calibration purposes the height of a known step on an otherwise flat silicon substrate was measured with the same apparatus. The proposed method is fairly simple to set up, can measure both front-surface and through-substrate types of optical disk, and can be used with any laser that has long coherence length.

Optics & Photonics News, 2000

P hotolithography is the technolo gy of reproducing patterns using light. Developed originally fo... more P hotolithography is the technolo gy of reproducing patterns using light. Developed originally for repro ducing engravings and photographs, and later used to make printing plates, photolithography was found ideal in the 1960s for mass-produc ing integrated circuits. 1 Projection exposure tools, which are now used routinely in the semiconductor in dustry, have continually improved over the past several decades to satis fy the insatiable demand for reduced feature size, increased chip size, im proved reliability and production yield, and lower overall cost. High numerical aperture lenses, shortwavelength light sources, and com plex photoresist chemistry have been developed to achieve fabrication of fine patterns over fairly large areas. Research and development efforts in recent years have been directed at improving the resolution and depth of focus of the photolithographic process by using phase-shifting masks (PSMs) in place of the con ventional binary intensity masks (BIMs). In this article we describe briefly the principles of projection photolithography and explore the range of possibilities opened up by the introduction of PSMs.

We report results of measurements of the optical constants of the dielectric layer, reflecting la... more We report results of measurements of the optical constants of the dielectric layer, reflecting layer, and phase-change layer used as the media of phase-change optical recording. The refractive index and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.

Applied Optics, 2001

Polarization dependence of signals from periodic one-dimensional arrays of magnetic domains in ma... more Polarization dependence of signals from periodic one-dimensional arrays of magnetic domains in magneto-optical (MO) media and crystalline domains in amorphous phase-change (PC) media has been studied by theoretical calculation and experiment. The MO signal in the small-period regime depends on the direction of incident polarization. The relative strength of the E(?) and E(?) signals changes depending on the period of the pattern, the wavelength of the light, and the numerical aperture of the objective lens. For PC media, the reflected signal has similar polarization dependence, but this dependence is weak.

Applied Optics, 2000

We describe the design, construction, and testing of a variant of Zernike's phase-contrast micros... more We describe the design, construction, and testing of a variant of Zernike's phase-contrast microscope. The sample is illuminated with a white-light source through an annular aperture, which is projected onto the entrance pupil of the objective lens. In the return path the light diffracted by the sample and appearing in the interior of the objective's aperture ͑i.e., the test beam͒ is separated from the light returning in the annular region near the rim of the objective ͑i.e., the reference beam͒. The separated beams are relatively phase shifted and then combined to create an interferogram of the sample's surface on a CCD camera. It is fairly straightforward to use this system as a conventional bright-field or dark-field microscope, but its most interesting application is as a Zernike phase-contrast microscope with adjustable amplitude ratio and phase shift between test and reference beams. The ability to continuously adjust the phase of the reference beam also enables quantitative measurement of the phase imparted by the sample to the incident beam.

Applied Optics, 2002

We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), re... more We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), reflecting layer (aluminum-chromium alloy), and phase-change layer (GeSbTe, AgInSbTe) used as the media of phase-change optical recording. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.

Applied Optics, 2002

Digital information in optical data storage systems can be encoded in the intensity, in the polar... more Digital information in optical data storage systems can be encoded in the intensity, in the polarization state, or in the phase of a carrier laser beam. Intensity modulation is achieved at the surface of the storage medium either through destructive interference from surface-relief features (e.g., CD or DVD pits) or through reflectivity variations (e.g., alteration of optical constants of phase-change media). Magneto-optical materials make use of the polar magneto-optical Kerr effect to produce polarization modulations of the focused beam reflected from the storage medium. Both surface-relief structures and material-property variations can create, at the exit pupil of the objective lens of the optical pickup, a phase modulation (this, in addition to any intensity or polarization modulation or both). Current optical data storage systems do not make use of this phase information, whose recovery could potentially increase the strength of the readout signal. We show how all three mechanisms can be exploited in a scanning optical microscope to reconstruct the recorded (or embedded) data patterns on various types of optical disk.

Applied Optics, 2001

Using measurements of reflectance, transmittance, and the ellipsometric parameter ⌬, we have dete... more Using measurements of reflectance, transmittance, and the ellipsometric parameter ⌬, we have determined the thickness, refractive index, and the absorption coefficient of various thin films and thin-film stacks. ͑⌬, the relative phase between the p-and s-polarized components, is measured for both reflected and transmitted light.͒ These optical measurements are performed with a specially designed system at the fixed wavelength of ϭ 633 nm over the 10°-75°range of angles of incidence. The examined samples, prepared by means of sputtering on fused-silica substrates, consist of monolayers and trilayers of various materials of differing thickness and optical constants. These samples, which are representative of the media of rewritable phase-change optical disks, include a dielectric mixture of ZnS and SiO 2 , an amorphous film of the Ge 2 Sb 2.3 Te 5 alloy, and an aluminum chromium alloy film. To avoid complications arising from reflection and transmission losses at the air-substrate interface, the samples are immersed in an index-matching fluid that eliminates the contributions of the substrate to reflected and transmitted light. A computer program estimates the unknown parameters of the film͑s͒ by matching the experimental data to theoretically calculated values. Although our system can be used for measurements over a broad range of wavelengths, we describe only the results obtained at ϭ 633 nm.

Optical Engineering, 2000

The exercise given demonstrates the construction of a diffraction-limited transmission sphere for... more The exercise given demonstrates the construction of a diffraction-limited transmission sphere for interferometry in a geometrical ray-tracing program, followed by an analysis of its performance in a physical-optics program.