表面增强拉曼散射（SERS）光谱具有高灵敏性及高选择性，它已被用于科学研究及生产实践的多个领域。本文阐述了近几年来SERS 技术在检测重金属离子、多环芳烃、微生物、农药等环境污染物中的发展状况，并分析了该技术在这些应用领域的优点与不足。最后，预测了SERS 的发展趋势。

光声成像是一种以光声效应为物理基础的新型、非电离和非侵入式的成像技术。作为一种纯光学成像与超声成像相结合的混合式成像技术，它的检测图像具有高光学对比度、高超声分辨率的特点。光声成像技术在生物医学检测中具有非常广阔的应用前景。阐述了光声成像的基本原理，对比了当前光声成像的各种系统结构形式、优缺点以及每种技术的应用领域。最后，预测了光声成像系统的发展趋势，并讨论了一些提升系统性能参数的方法。

A position sensor based on grating projection with spatial filtering and polarization modulation is presented. A grating is projected onto the object to be measured through a 4f optical system with a spatial filter. After reflected by the object, the grating projection is imaged on a detection grating through another 4f optical system to form moire fringes. The polarization modulated moire signal is detected to obtain the position information of the object. In the position sensor, the moire signal varies sinusoidally with the position of object. The measurement is independent of the incident intensity on the projection grating and the reflectivity of the object to be measured. In experiments, the effectiveness of the position sensor is proved, and the root mean square (RMS) error at each measurement position is less than 13 nm.