A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation in photonic crystal fiber

Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

Objective: To demonstrate optical coherence tomography for high-resolution, noninvasive imaging of the human retina. Optical coherence tomography is a new imaging technique analogous to ultrasound B scan that can provide cross-sectional images of the retina with micrometer-scale resolution. Design: Survey optical coherence tomographic examination of the retina, including the macula and optic nerve head in normal human subjects. Settings Research laboratory. Participants: Convenience sample of normal human subjects. Main Outcome Measures: Correlation of optical coherence retinal tomographs with known normal retinal anatomy. Results: Optical coherence tomographs can discriminate the cross-sectional morphologic features of the fovea and optic disc, the layered structure of the retina, and normal anatomic variations in retinal and retinal nerve fiber layer thicknesses with 10- μm depth resolution. Conclusion: Optical coherence tomography is a potentially useful technique for high depth resolution, cross-sectional examination of the fundus.

Optical Coherence Tomography of the Human Retina

Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

In Vivo Endoscopic Optical Biopsy with Optical Coherence Tomography

PROBLEM TO BE SOLVED: To provide a dimension measuring device for measuring the surface height of a measurement object at high speed and high accuracy. SOLUTION: This dimension measuring device 1 includes a light division element 3 which divides light emitted from a white light source 2 into a measurement light flux having an optical path length according to the surface height of the measurement object and a reference light flux, a reference light scanning optical system 5 which changes the optical path length of the reference light flux, a detector 6 which detects the interference signals of both the light fluxes, and a controller 7 which determines the surface height of the measurement object from the optical path length of the reference light flux corresponding to the maximum of the interference signals. The reference light scanning optical systems 5 includes a rotation member 51, first and second reflection elements (53, 55) arranged to the rotation shaft 52 of the rotation member 51 so as to be center-point-symmetrical to each other, and beam direction change members (57-66) which guide the reference light flux so that when the reference light flux enters into either of the reflection elements, the reference light flux reflected by the reflection element enters the other reflection element in parallel with and reversely to the incidence direction for the former reflection element. COPYRIGHT: (C)2010,JPO&INPIT

Dimension measuring device

In conclusion, we have demonstrated the generation of 1.18-2.10 /spl mu/m ultra-widely broadened SC and 1.46-1.68 /spl mu/m linearly chirped SC using only 5 m long two different kinds of highly nonlinear fibers and only 600 pJ pulse. This system is constructed with all the fiber devices and it is useful for practical application. The generated SC is experimentally analyzed using X-FROG technique. It is observed that the anti-Stokes pulse is overlapped with the trailing edge of the soliton pulse in PM-HN-DSF. It is considered that, after the a few meter propagation, the soliton pulses are redshifted due to the soliton self-frequency shift and the anti-Stokes components are gradually blueshifted due to the effect of pulse trapping by the soliton pulse in PM-HN-DSF.

Generation and characterization of widely broadened super continuum using highly nonlinear fibers and fiber laser

Fiber based optical frequency comb was developed using polarization maintaining Er-doped ultrashort pulse fiber laser using polyimide film dispersed with single wall carbon nanotube. f ceo was stable and locked with EO modulator and LD driver.

Optical frequency comb using polarization maintaining Er-doped ultrashort pulse fiber laser with carbon-nanotube polyimide film

PROBLEM TO BE SOLVED: To provide a wavelength dispersion measuring apparatus and a method capable of measuring wavelength ranges longer than 17 μm in a short time without being affected by vibration or temperature variations SOLUTION: The wavelength dispersion measuring apparatus comprises an ultra short optical pulse light source 1 for generating ultra short optical pulses; a medium 2 to be measured for propagating the ultra short optical pulses generated from the ultra short optical pulse light source 1; and a two-photon absorption detecting means 3 for receiving the ultra short optical pulses propagated through the medium 2 to be measured and outputting two-photon absorption signals and measures the wavelength dispersion of the medium 2 to be measured on the basis of the two-photon absorption signals output from the two-photon absorption detecting means It is possible to perform highly accurate measurements without being affected by vibration or temperature variations by a principle of measurement different from those of a conventional optical pulse method, an interference method, and phase shift method Since there is no need for time difference adjustments, it is possible to perform high-speed measurements Since the propagation distance (z) of the medium to be measured may be short, it is possible to measure a short medium to be measured Since wavelength dispersion is measured on the basis of the two-photon absorption signals, it is possible to measure the wavelength dispersion of long wavelength ranges of ≥17 μm COPYRIGHT: (C)2005,JPO&NCIPI

Wavelength dispersion measuring apparatus and measuring method

1.6-1.9 um wavelength tunable comb with spectral width of 4 nm was demonstrated using wavelength tunable soliton pulse and comb profile fiber. High SNR of 37 dB was confirmed for generated comb by beat measurement.

Norihiko Nishizawa

Papers

Dimension measuring device

Generation and characterization of widely broadened super continuum using highly nonlinear fibers and fiber laser

Optical frequency comb using polarization maintaining Er-doped ultrashort pulse fiber laser with carbon-nanotube polyimide film

Wavelength dispersion measuring apparatus and measuring method

Wavelength Tunable Narrow Linewidth Comb Using Soliton Self-frequency Shift and Spectral Compression Technique