Tuesday, September 19, 2017

Tapio Fabritius 先生 ショートセミナー


University of Oulu (Finlnad) の Tapio Fabritius 教授にショートセミナーをして頂きました。

Fabritus 氏は2007-2008年にかけ Oulu 大学 からの訪問研究者として筑波大学で光干渉断層計の研究をされていました。現在は Oulu大学で printing electronics (印刷型電子回路)とその光学評価など幅広く研究をされています。

今回のセミナーでは、印刷技術を用いた微小光学素子の作成、そこで用いられる粘弾性材料の光学評価手法、作成した微小阻止の形状計測手法についてレクチャーをおこなっていただきました。



2019-09-19

Friday, September 8, 2017

論文出版: Superpixels for Jones matrix tomography

技術補佐員・博士候補の宮澤氏がアメリカ光学会の論文誌 Biomedical Optics Express に論文を発表しました。これは私達が開発を進めているマルチコントラスト ジョーンズ行列トモグラフィー(JM-OCT)の新たな画像処理方である「superpixel」に関するものです。この superpixel 法は JM-OCT 画像のピクセルを、光学特性と空間的な類似性によってグルーピングしていきます。このグルーピングされたピクセル (superpixel) をさらなる画像処理の局所的な処理領域(kernel)として用いることで、画像の分解能を落とすことなる、統計処理にもとづいたJM-OCT信号の定量解析が可能になります。

興味のある方は以下の論文を御覧ください。
>> Full length article (open access)
A. Miyazawa, Y.-J. Hong, S. Makita, D. Kasaragod, and Y. Yasuno "Generation and optimization of superpixels as image processing kernels for Jones matrix optical coherence tomography," Biomed. Opt. Express 8, 4396-4418 (2017).

Joschi, Yoshiaki Yasuno



Publication: Superpixels for Jones matrix tomography

Our colleague Miyazawa recently reported a sophisticated method to analyze the pixel-by-pixel characteristic of multi-contrast Jones matrix optical coherence tomography (JM-OCT) images. This method makes groups of pixels based on its similarlity in optical properties and its spatial proximity. It can provide smart "kernels" to compute local statistics of OCT without sacrificing its resolution.

The details of the method is reported in Biomedical Optics Express.
Citation: A. Miyazawa, Y.-J. Hong, S. Makita, D. Kasaragod, and Y. Yasuno "Generation and optimization of superpixels as image processing kernels for Jones matrix optical coherence tomography," Biomed. Opt. Express 8, 4396-4418 (2017).

Joschi, Yoshiaki Yasuno


Wednesday, May 31, 2017

論文出版: 偏光OCT レビュー

当研究グループの安野がアムステルダム自由大学の Prof. Johannes de Boer、ウィーン医科大学の Prof. Christoph Hitzenberger と共同で偏光感受型光コヒーレンストモグラフィー (偏光OCT)のレビュー論文を発表しました。

この論文は、偏光OCTの原理、ハードウェア実装、信号処理、臨床応用までを広く解説しています。偏光OCTの作成、利用に興味のある方には最初に読む教科書として最適なものになっていると思います。また、偏光OCTにまずは興味がある、という方にも 最初に読む文献として適切なものに仕上がっていると思います。

>> Full length article (open access)

Citation: J. F. de Boer, C. K. Hitzenberger, and Y. Yasuno "Polarization sensitive optical coherence tomography – a review [Invited]," Biomed. Opt. Express 8, 1838-1873 (2017).

Publication: Review article for polarization sensitive optical coherence tomography

Our colleague Yasuno recently published an review article of "polarization sensitive optical coherence tomography (PS-OCT)," which is co-authored with Prof. Johannes de Boer (VU University of Amsterdam) and Prof. Christoph Hitzenberger (Medical University of Vienna).

This article provides a comprehensive overview of PS-OCT principle, hardware implementation, signal processing, and clinical applications. If you are interested in building or using PS-OCT, this article can be a good textbook. For beginners of OCT, this article can be a good introduction of
a functional extension of OCT.

>> Full length article (open access)

Citation: J. F. de Boer, C. K. Hitzenberger, and Y. Yasuno "Polarization sensitive optical coherence tomography – a review [Invited]," Biomed. Opt. Express 8, 1838-1873 (2017).

Tuesday, December 16, 2014

研究室紹介

COGでの研究活動に興味のある皆様へ。
Computational Optics Group の研究紹介スライドを公開します。

Tuesday, July 1, 2014

Publication: Accurate Quantification of Tissue Birefringence

Microstructures support the mechanical property of a tissue. And hence, investigating tissue microstructure has been a great interest both in the biomechanical research and for investigation of diseases associated with biomechanics, such as glaucoma. However, there was no way for in vivo quantification of tissue biomechanics. One promising approach, as we believe, is quantifying tissue birefringence for quantifying biomechanics. This approach is based on the fact that both the tissue biomechanics and birefringence are based on the same aspect of the tissue, i.e., microstructure. Our group has been working for polarization sensitive optical coherence tomography (PS-OCT) for the quantification of the biomechanics through quantitative measurement of tissue birefringence.

Since its innovation in 1997, PS-OCT was nice to qualitatively visualize the tissue birefringence. However, its quantification ability was low. It was mainly because its non-linear and complex effects of measurement noise into the birefringence values to be measured. To be honest, the raw birefringence value measured by PS-OCT has not been reliable at all.

Our colleagues Deepa Kasaragod recently developed a mathematical framework to accurately estimate the tissue birefringence from the raw birefringence values measured by PS-OCT. She first numerically characterized the relationship between the measurement noise and measured birefringence values. And then, she designed a mathematical frame work, by using a Bayesian rule together with the numerically obtained property, to obtain a “maximum likelihood estimation” of the tissue birefringence.

Both numerical and experimental validations proved that this framework has high ability to quantitate the birefringence. This method was recently published in Optics Express (full citation is shown below). In this paper, some in vivo human eye results including a pathologic case (anterior eye of trabeculectomy bleb) are presented.

Currently, a clinical study with this method is ongoing. I believe we can present impressive clinical results soon. The details of the technology are now available on the following paper.

Full length article (open access)
D. Kasaragod, S. Makita, S. Fukuda, S. Beheregaray, T. Oshika, and Y. Yasuno, Optics Express 22, 16472-16492 (2014), http://dx.doi.org/10.1364/OE.22.016472

Joschi, Yoshiaki Yasuno