点衍射干涉检测技术

本文介绍了点衍射干涉仪不同发展阶段的特点和应用。点衍射干涉仪由波长量级的针孔产生高质量的球面波作为参考波前,能够得到衍射极限性能的分辨率。按照不同的光路特点,点衍射干涉仪可分为点衍射共路干涉和点衍射非共路干涉两种结构,主要应用于高精度波前检测和面形检测。共路干涉结构简单紧凑,对环境振动不敏感,对光源相干度要求不高,可利用光束偏振态及光栅衍射分束的特性对传统点衍射板进行改造,在全共路点衍射干涉仪中引入时间相位调制技术和干涉对比度可调技术,可进一步提高波前检测精度。采用反射式针孔和各种光纤结构发展了非共路点衍射干涉仪,实现了大口径、高精度球面反射镜面形的测量。本文重点阐述了用于极紫外光刻投影物镜中高精度球面反射镜面形检测的反射式针孔点衍射干涉仪,并展望了点衍射检测技术在生物检测等领域的应用前景和发展趋势。

Point diffraction in terference detection technology

In this paper, several characteristics and applications of point diffraction interferometer at different development stages are introduced. In interferometers, high quality spherical wave as a reference wave is produced by pinhole with wavelength scale, which can achieve diffraction limited resolution. According to different light path characteristics, interferometers used for high-precision wavefront testing and surface shape testing are mainly divided into point diffraction common path interferometer and noncommon path interferometer. The former has the advantages of simple structure, low sensitivity to ambient vibration and low requirement for coherence light source. Based on beam polarization and diffraction grating characteristics, the traditional point diffraction splitter plate is improved. Moreover, the temporal phase modulation technology and adjustable interference contrast technology introduced to common path point diffraction interferometer can further improve the measurement accuracy of wavefront. In addition, reflex pinhole and various kinds of fiber structures are employed to develop noncommon point diffraction interferometer, realizing the high-accuracy measurement of large aperture spherical surface. Especially, the reflex pinhole point diffraction interferometer for high-accuracy spherical surface testing in extreme ultraviolet lithography is illustrated in detail. Finally, the wide prospects of application and development of point diffraction interference detection technology are forecasted in many fields, such as biological detection.