Guo Cuixia, Yang Xiaojie, Wu Jian-Ping, Guo Xiaorui, He Yonghong, Shen Zhiyuan, Sun Zhan, Guan Tian, Chen Fangyi
Appl Opt. 2019 Mar 1;58(7):1606-1613. doi: 10.1364/AO.58.001606.
Vibrometry using optical coherence tomography (OCT) can provide valuable information for investigating either the mechanical properties or the physiological function of biological tissues, especially the hearing organs. Real-time imaging of the measured tissues provides structure imaging and spatial guidance for and is thus highly demanded by such vibrometry. However, the traditional time-domain OCT (TD-OCT) systems, although capable of subnanometric vibrometry at large ranges of frequencies, are unable to offer an imaging speed that is high enough to acquire depth-resolved images for guidance. The spectral-domain OCT (SD-OCT) systems, although allowing image-guided vibrometry, are challenged in measuring vibration at high frequencies, particularly for scattering tissue specimens that require longer exposure time to ensure imaging and vibrometry performance. This is because of their limit in the line-scan rate of the CCD, in which the maximum resolvable frequency measured by the SD-OCT is about 1/4 of the CCD line-scan rate in practice. In the present study, we have developed a dual-mode OCT system combining both SD-OCT and TD-OCT modalities for image-guided vibrometry, as the SD-OCT can provide guiding structural images in real-time and, moreover, the TD-OCT can guarantee vibrometry at large ranges of frequencies, including high frequencies. The efficacy of the developed system in image-guided vibrometry has been experimentally demonstrated using both piezoelectric ceramic transducer (PZT) and ex vivo middle-ear samples from guinea pigs. For the vibrometry of PZT, the minimum detectable vibration amplitude was reached at ∼0.01 nm. For the vibrometry of the sound-evoked biological samples, both real-time two-dimensional imaging and subnanometric vibrometry were performed at the frequency ranging from 1 to 40 kHz. These results indicate that our dual-mode OCT system is able to act as an excellent vibrometer enabling image-guided high-frequency measurement.
利用光学相干断层扫描（OCT）进行振动测量可为研究生物组织（尤其是听觉器官）的力学特性或生理功能提供有价值的信息。对被测组织进行实时成像可为振动测量提供结构成像和空间引导，因此这种振动测量对实时成像有很高的要求。然而，传统的时域OCT（TD - OCT）系统虽然能够在大范围频率下进行亚纳米级的振动测量，但无法提供足够高的成像速度来获取用于引导的深度分辨图像。光谱域OCT（SD - OCT）系统虽然允许进行图像引导的振动测量，但在高频振动测量方面面临挑战，特别是对于需要更长曝光时间以确保成像和振动测量性能的散射组织样本。这是因为其电荷耦合器件（CCD）的线扫描速率有限，实际上SD - OCT测量的最大可分辨频率约为CCD线扫描速率的1/4。在本研究中，我们开发了一种结合SD - OCT和TD - OCT模式的双模式OCT系统用于图像引导的振动测量，因为SD - OCT可以实时提供引导结构图像，而且TD - OCT可以保证在包括高频在内的大范围频率下进行振动测量。已使用压电陶瓷换能器（PZT）和豚鼠中耳离体样本通过实验证明了所开发系统在图像引导振动测量中的有效性。对于PZT的振动测量，最小可检测振动幅度达到约0.01 nm。对于声诱发生物样本的振动测量，在1至40 kHz的频率范围内进行了实时二维成像和亚纳米级振动测量。这些结果表明，我们的双模式OCT系统能够作为一种出色的振动计，实现图像引导的高频测量。
