著者

Ju Myeong Jin Hong Young-Joo Makita Shuichi Lim Yiheng Kurokawa Kazuhiro Duan Lian Miura Masahiro Tang Shuo Yasuno Yoshiaki

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.21, no.16, pp.19412-19436, 2013-08

被引用文献数

95

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An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced JMT achieves a sufficiently long depth measurement range for clinical cases of posterior eye disease. Furthermore, a fine spectral shift compensation method based on the cross-correlation of calibration signals was devised for stabilizing the phase of OCT, which enables a high sensitivity Doppler OCT measurement. In addition, a new theory of JMT which integrates the Jones matrix measurement, Doppler measurement, and scattering measurement is presented. This theory enables a sensitivity-enhanced scattering OCT and high-sensitivity Doppler OCT. These new features enable the application of this system to clinical cases. A healthy subject and a geographic atrophy patient were measured in vivo, and simultaneous imaging of choroidal vasculature and birefringence structures are demonstrated.

著者

Duan Lian Hong Young-Joo Yasuno Yoshiaki

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.21, no.13, pp.15787-15808, 2013-06

被引用文献数

25

---

An automated choroidal vessel segmentation and quantification method for high-penetration optical coherence tomography (OCT) was developed for advanced visualization and evaluation of the choroidal vasculature. This method uses scattering OCT volumes for the segmentation of choroidal vessels by using a multi-scale adaptive threshold. The segmented choroidal vessels are then processed by multi-scale morphological analysis to quantify the vessel diameters. The three-dimensional structure and the diameter distribution of the choroidal vasculature were then obtained. The usefulness of the method was then evaluated by analyzing the OCT volumes of normal subjects.

著者

Hoshino Tetsuya Yatagai Toyohiko Itoh Masahide

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.20, no.4, pp.3954-3966, 2012-02

被引用文献数

8

---

We found that the distances between isolated scatterers with similar columnar shapes could be measured by taking a single Fourier transform of their diffraction intensity. If the scatterers have different shapes, the distances between similar shapes can be selected from the distances between all the shapes. The distance from a specific scatterer can be measured with a resolution of 0.8 wavelengths and a precision of 0.01 wavelengths. This technique has the potential to be used in a novel optical memory that has a memory density as high as that of holographic memory, while can be fabricated by simple transfer molding. We used rigorous coupled-wave analysis to calculate the diffraction intensity. Some of the results were verified by nonstandard finite-difference time-domain simulations and experiments.

著者

Tomioka Satoshi Nishiyama Shusuke

出版者

Optical Society of America

雑誌

Applied Optics (ISSN:1559128X)

巻号頁・発行日

vol.51, no.21, pp.4984-4994, 2012-07-20

被引用文献数

23

---

Phase unwrapping for a noisy image suffers from many singular points. Singularity-spreading methods are useful for the noisy image to regularize the singularity. However, the methods have a drawback of distorting phase distribution in a regular area that contains no singular points. When the singular points are confined in some local areas, the regular region is not distorted. This paper proposes a new phase unwrapping algorithm that uses a localized compensator obtained by clustering and by solving Poisson's equation for the localized areas. The numerical results demonstrate that the proposed method can improve the accuracy compared with other singularity-spreading methods.

著者

Sakurai Yoko Kakushima Kuniyuki Ohmori Kenji Yamada Keisaku Iwai Hiroshi Shiraishi Kenji Nomura Shintaro

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.22, no.2, pp.1997-2006, 2014-01

被引用文献数

3

---

Low-temperature photoluminescence (PL) spectra of electron-hole systems in Si nanowires (NWs) prepared by thermal oxidization of Si fin structures were studied. Mapping of PL reveals that NWs with uniform width are formed over a large area. Annealing temperature dependence of PL peak intensities was maximized at 400 °C for each NW type, which are consistent with previous reports. Our results confirmed that the micro-PL demonstrated here is one of the important methods for characterizations of

著者

Obara Yuki Katayama Tetsuo Ogi Yoshihiro Suzuki Takayuki Kurahashi Naoya Karashima Shutaro Chiba Yuhei Isokawa Yusuke Togashi Tadashi Inubushi Yuichi Yabashi Makina Suzuki Toshinori Misawa Kazuhiko

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.22, no.1, pp.1105-1113, 2014-01-13

被引用文献数

47

---

世界で初めて、X線自由電子レーザーを用いたフェムト秒領域でのX線直接吸収分光測定に成功 -極短時間に起こる化学反応の追跡手法をSACLAで実証-. 京都大学プレスリリース. 2014-01-13.

著者

Min Eun Jung Shin Jun Geun Lee Jae Hwi Yasuno Yoshiaki Lee Byeong Ha

出版者

Optical Society of America

雑誌

Applied optics (ISSN:1559128X)

巻号頁・発行日

vol.52, no.21, pp.5143-5151, 2013-07

---

We propose a single-step method appropriated for a fiber-optic probe-based full-range spectral domain optical coherence tomography (OCT). The fiber-optic probe was scanned over a sample with a magnetically driven actuator. In the reference arm, a phase shift of π/2 was applied during two neighbor axial scanning, from which the complex spectral interferogram was directly reconstructed. Since the complex-conjugate-free OCT image is obtained by doing just one Fourier transform on the complex interferogram, obtaining the full-range image is simple in algorithm and effective in computation time. Some full-range images of biological samples created with the proposed method are presented and the processing time is analyzed.

著者

Hiramatsu Kotaro Kano Hideaki Nagata Takashi

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.21, no.11, pp.13515-13521, 2013-05

被引用文献数

19 1

---

We demonstrate a method to measure Raman optical activity (ROA) by using coherent anti-Stokes Raman scattering (CARS) spectral interferometry. An extremely weak chirality-induced CARS field is amplified through the interference with a strong CARS field generated from an external reference and is extracted by the Fourier transformation. In this interferometric coherent Raman optical activity (iCROA), both the sign and the magnitude of optical active non-resonant background susceptibility can be directly determined. Measurement of a CARS-ROA spectrum with less artifact is obtained because a broad offset artifact due to optical rotatory dispersion is clearly distinguished in iCROA.

著者

Sasaki Kazuhiro Kurokawa Kazuhiro Makita Shuichi Yasuno Yoshiaki

出版者

Optical Society of America

雑誌

Biomedical Optics Express (ISSN:21567085)

巻号頁・発行日

vol.3, no.10, pp.2353-2370, 2012-10

被引用文献数

30 6

---

We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applying SA, and the direction of extension can be controlled by the sign of applied SA. Finally, we demonstrated in vivo human retinal imaging by altering the applied SA.

著者

Akiyama Suguru Nomura Shintaro

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.20, no.20, pp.21847-21859, 2012-09

被引用文献数

4

---

We investigated the dynamic response of a cascaded-ring-resonator-loaded Mach–Zehnder modulator (CRR-MZM), in which a number of cascaded ring resonators (RRs) are loaded in the interferometer as phase modulators. The analytical form is derived for the small-signal response of CRR-MZM using temporal-coupled-mode (TCM) theory, and its validity is confirmed by numerical calculations. It is revealed that the bandwidth of the CRR-MZM is maximized by setting proper delays in driving signals between neighboring RRs; the optimized delay is twice the photon lifetime of each RR. The calculated performances of CRR-MZMs are compared with those of standard modulators based on a single-ring-resonator (SRR) without interferometer, in terms of the modulation depth and bandwidth. For a given degree of the refractive index change in a waveguide, CRR-MZM can provide a larger modulation depth than a SRR-type modulator in frequency ranges exceeding 25 GHz.

著者

Akiyama Suguru Kurahashi Teruo Morito Ken Yamamoto Tsuyoshi Usuki Tatsuya Nomura Shintaro

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.20, no.15, pp.16321-16338, 2012-07

被引用文献数

14 2

---

A cascaded-ring-resonator-loaded Mach–Zehnder modulator (CRR-MZM) is presented in which a number of cascaded ring resonators (RRs) are loaded in the interferometer as phase modulators. The ability of the design to provide enhanced modulation efficiency at a wide optical bandwidth is demonstrated in comparison with a conventional single-RR-type modulator without an interferometer. The optimization of RRs for the CRR-MZM is investigated experimentally by measuring the transmission spectra in both intensity and group delay of RRs having various structural parameters. Using the optimized parameters, we fabricated a CRR-MZM with 10 cascaded RRs loaded on each arm of the interferometer on a silicon-on-insulate substrate. The RRs had pin-diodes along the waveguides, which were operated with forward bias voltage. Its modulation efficiency was enhanced by a factor of 4.4 at the expense of additional loss of less than 3.5 dB compared with a standard non-resonant MZM. 10 Gb/s-operations of CRR-MZM were successfully demonstrated using pre-emphasized RF signals with amplitude of 1.5 Vpp in a wavelength range of 2 nm.

著者

Jaillon Franck Makita Shuichi Yasuno Yoshiaki

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.20, no.1, pp.385-396, 2012-01

被引用文献数

24 13

---

In this study, we present dual-beam Doppler optical coherence angiography with variable beam separation. Altering beam distance, independently of the scanning protocol, provides a flexible way to select the velocity range of detectable blood flow. This system utilized a one-micrometer wavelength light source to visualize deep into the posterior eye, i.e., the choroid. Two-dimensional choroidal vasculature maps of a human subject acquired with different beam separations, and hence with several velocity ranges, are presented. Combining these maps yields a semi-quantitative visualization of axial velocity of the choroidal circulation. The proposed technique may be useful for identifying choroidal abnormalities that occur in pathological conditions of the eye.

著者

Hong Young-Joo Makita Shuichi Jaillon Franck Ju Myeong Jin Min Eun Jung Lee Byeong Ha Itoh Masahide Miura Masahiro Yasuno Yoshiaki

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.20, no.3, pp.2740-2760, 2012-01

被引用文献数

50

---

A high-penetration swept-source optical coherence tomography (HP-SS-OCT) system based on a 1-μm short cavity laser is developed. Doppler OCT processing is applied, along with a custom-made numerical phase stabilization algorithm; this process does not require additional calibration hardware. Thus, our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. The bidirectional blood flow and vasculature in the deep choroid was successfully imaged via two Doppler modes that use different time intervals for Doppler processing. En face projection image of squared power of Doppler shift is compared to ICGA, and the utility of our method is verified.

著者

Makita Shuichi Jaillon Franck Yamanari Masahiro Yasuno Yoshiaki

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.30, no.2, pp.2681-2692, 2012-01

被引用文献数

6 3

---

Dual-beam-scan Doppler optical coherence angiography (DB-OCA) enables high-speed, high-sensitivity blood flow imaging. However, birefringence of biological tissues is an obstacle to vasculature imaging. Here, the influence of polarization and birefringence on DB-OCA imaging was analyzed. A DB-OCA system without birefringence artifact has been developed by introducing a Faraday rotator. The performance was confirmed in vitro using chicken muscle and in vivo using the human eye. Birefringence artifacts due to birefringent tissues were suppressed. Micro-vasculatures in the lamina cribrosa and nerve fiber layer of human eyes were visualized in vivo. High-speed and high-sensitivity micro-vasculature imaging involving birefringent tissues is available with polarization multiplexing DB-OCA.

著者

Min Eun Jung Shin Jun Geun Lee Jae Hwi Yasuno Yoshiaki Lee Byeong Ha

出版者

Optical Society of America

雑誌

Optics letters (ISSN:01469592)

巻号頁・発行日

vol.37, no.15, pp.3105-3107, 2012-08

被引用文献数

7

---

We present a full range handheld probe type spectral domain optical coherence tomography (SD-OCT) method. Here, the sample arm is composed of a tilted fiber-optic cantilever scanner; thus, the phase shift concurrently occurs while sample scanning. With the phase shift, we could achieve a full range complex-conjugate-free OCT image with no additional phase shifters in the reference arm. To realize this technique, a magnetically actuated probe was adopted. Full range SD-OCT images of a pearl, human fingernail, and human tooth were subsequently obtained using this suggested probe. The scanning range and acquisition speed were 3 mm and 20  frames/s, respectively.

著者

Namura Kyoko Suzuki Motofumi Nakajima Kaoru Kimura Kenji

出版者

Optical Society of America

雑誌

Optics Letters (ISSN:01469592)

巻号頁・発行日

vol.36, no.18, pp.3533-3535, 2011-09-15

被引用文献数

9

---

We have investigated the heat generation from gold nanoparticles resulting from their local plasma resonance. We have demonstrated the self-assembly of Au nanoparticle arrays/dielectric layer/Ag mirror sandwiches, i.e., a local plasmon resonator, using a dynamic oblique deposition technique. The thicknesses of the Au and dielectric layers were changed combinatorially on a single substrate. As a result, local plasmon resonator chips were successfully fabricated. Because of strong interference, their optical absorption can be controlled between 0.0% and 97% in the near-IR region, depending on the thickness of the dielectric layer. We evaluated the heat generation from Au nanoparticles by measuring the temperature of water with which a cell prepared on a chip is filled under laser illumination. The change in the water temperature is proportional to the optical absorption of the local plasmon resonator chips. This suggests that the photothermal conversion efficiency can be controlled by interference. These features make the application of the local plasmon resonator to nanoheaters, which can spatiotemporally control heat generation, suitable.