Analytical Sciences

Fundamental Imaging Properties of Transillumination Laser Computed Tomography Based on Coherent Detection Imaging Method

Tetsuya YUASA, *¹ Shinji TANOSAKI,*² Yoshiaki SASAKI,*¹ Michiaki TAKAGI,*³ Akira ISHIKAWA,*³ Hiroshi TANIGUCHI,*⁴ Balasigamani DEVARAJ,*⁵ and Takao AKATSUKA*¹

*1 Faculty of Engineering, Yamagata University, 4-3-16 japan, Yonezawa 992-8510, Japan
*2 I. T. Research Co., Ltd., 2-1-40 Takamori, 2lst Century Plaza, Izumi, Sendai 981-3203, Japan
*3 School of Medicine, Yamagata University, 2-2-2 Iida, Yamagata 990-0031, Japan
*4 Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551, Japan
*5 New Focus Corp., 5215 Hellyer Avenue, San Jose, CA 95138-1001, USA

The coherent detection imaging (CDI) method the optical heterodyne detection technique. CW and single frequency lasers having long coherence lengths are used to exploit the maximum advantages of heterodyne detection, such as high directionality, selectivity and sensitivity. The CDI method based on optical heterodyne detection enables selective filtering of the directional coherence-retaining emergent photons, which leads to image reconstruction from projections, similar to X-ray computed tomography (CT). So far we have demonstrated the advantages and capabilities of the measurement technique for transillumination optical computed tomography in biomedicine. Here, we investigate the fundamental imaging properties of CDI method, such as its high directionality and quantitativeness, with preliminary physical phantom experiments. The results show that the CDI method satisfies the requirements for CT reconstruction under the first order approximation, and enables quantitative measurements in the sense that the relationship between estimated and actual concentration retains a satisfactory linearity.

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