Automated Thickness Measurement of Nacreous Layer of Seawater Pearls Based on Optical Coherence Tomography

The nondestructive optical coherence tomography measurement can show the shell-nucleus features, quantify the nacre thickness and thus has the potential to identify or grade the pearls [1]. However, the automated thickness measurement of nacreous layer based on OCT has not been reported. In this article, an automated approach is first time proposed to measure the thickness of nacreous layer using OCT raw data. This approach made use of the signal characteristic of OCT scan line, integrated with support vector machine (SVM), hidden markov model (HMM) and circle fitting technologies to measure the thickness of the nacreous layer of seawater pearls. The experimental results show this approach is accurate and adaptable.