Deep imaging in highly scattering media by combining reflection matrix measurement with Bessel-like beam based optical coherence tomography

• Published in: Applied physics letters 2018-07, Vol.113 (1), p.011106-011106
• Main Authors: Yang, Qiang, Miao, Yusi, Huo, Tiancheng, Li, Yan, Heidari, Emon, Zhu, Jiang, Chen, Zhongping
• Format: Article
• Language: English
• Subjects: Photonics and Optoelectronics
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5036661

Multiple scattering in biomedical tissue limits the imaging depth within a range of 1–2 mm for conventional optical imaging techniques. To extend the imaging depth into the scattering medium, a computational method based on the reflection matrix measurement has been developed to retrieve the singly back-scattered signal light from the dominant detrimental multiple-scattered background. After applying singular value decomposition on the measured matrix in the post-process, the target image underneath the turbid media is clearly recovered. To increase the depth of focus of the incident light by elongating the focal spot along the optical axis, a digital grating pattern is specially designed and displayed on a phase-only spatial light modulator to generate the Bessel-like beam for lateral point scanning. According to the results, the depth of focus is increased up to 2.4 mm which is much longer than the value of ∼50 μm obtained by using the conventional focused Gaussian beam, leading to a deeper penetration depth due to the self-healing feature of the Bessel-like beam. In addition, generation of the Bessel-like beam simplifies the axial scanning process by getting rid of the need to mechanically translate the focal zone along the optical axis of an objective with a high numerical aperture. By combining this method with an optical coherence tomography system with a low coherence light source, a depth-resolved optical image is obtained underneath a highly turbid medium.