珍珠质的内部微观分辨和测量是珍珠产业发展和学术研究的核心难题。光学相干层析(OCT)高清晰深度分辨技术通过探测珍珠质的光学反射散射特性,提供了研究其结构形态和分布规律的新途径。阐述了对珍珠质进行成像扫描的原理和实验装置,以光纤迈克尔逊干涉仪为主体,利用中心波长1310 nm的宽带光源和傅里叶域光学延迟线实现了扫描速度1 frame/s,纵向分辨率15 μm,成像深度3 mm的光学相干层析成像系统。实验结果验证了光学相干层析检测方法适用于珍珠质的定量检测和定性分辨的可行性,初步的报道包括珍珠质层和珠核贝壳层的分辨鉴别,珍珠质层平均测量误差在20 μm以内,珍珠质内部各种反常生长分布信息也清晰可见。

Research on optical coherence tomography (OCT) applied in pearl identification and nacre measurement is represented. Due to the difference of scattering properties for various components, OCT image characteristics can exact the two-dimensional information of subsurface structure of pearls, which could only be previously accomplished by the conventional section. An OCT system mainly composed of fiber Michelson interferometer with wideband source of 1310 nm central wavelength and Fourier-domain optical delay line has been implemented. The system can complete the nondestructive and real time detection, with scanning speed of 1 frame/s, depth resolution of 15 μm and penetration depth of 3 mm. Experimental results included determining the structural identity: nacreous layer or shell nucleus, quantifying the nacre thickness (measuring errors less than 20 μm), and showing abnormal information of shell-nucleous features.