拉曼光谱是一种用于分析分子化学成分、结构等信息的检测技术，具有信息丰富、制样简单、水的干扰小、非侵入等特点，在生物医学等研究领域中具有广泛应用。拉曼光谱成像作为一种结合拉曼光谱和成像的混合模式，通过采集空间中每个像素处的拉曼光谱信息，将分子信息在空间上展现，并定性、定量与定位地分析物质分子。相对于传统的拉曼光谱测量，拉曼光谱成像可额外提供生物医学应用中极为重要的空间信息，因此，以图像形式观测物质成分与结构等信息的拉曼光谱成像技术在生物样本检测、临床诊断及治疗等生物医学领域中具有重要的应用价值。从拉曼光谱原理出发,介绍了拉曼光谱成像技术及其发展，并综述了近年来拉曼光谱成像技术在生物医学领域中的应用，最后总结并展望了拉曼光谱成像技术及其发展趋势。

As a newly developed lensless imaging technique, PIE (ptychographical iterative engine) does not only maintain the simplicity and convenience of the equipment of traditional coherent diffraction imaging (CDI) methods, but also overcomes the drawbacks such as restricted field of view and slow convergence. With the extensible imaging field, better convergence speed and higher immunization capability to noise, PIE is widely researched and used in optical, X-ray and electron beam imaging fields. PIE is a new method which is possible to replace the current phase imaging methods. The background, development, applications, problems and developing trend of the PIE method are introduced.

作为一种新近发展的无透镜成像技术，PIE(ptychographical iterative engine)不但保持了传统相干衍射成像方法装置简单、使用方便等优点，克服了视场受限和收敛速度慢等缺点，还具有成像范围可扩展、收敛速度快、抗噪声能力强等优势，在光学、X射线和电子束等领域得到了广泛关注并开展了大量研究，是一种有可能在大范围内替代现有相位成像技术的新方法。主要介绍了PIE方法的技术背景、技术现状、相关应用及面临的问题和可能的发展方向。

The physical meaning and essence of Fresnel numbers are discussed, and two definitions of these numbers for offaxis optical systems are proposed. The universal Fresnel number is found to be N=(a2/λz)*C1+C2. The Rayleigh–Sommerfeld nonparaxial diffraction formula states that a simple analytical formula for the nonparaxial intensity distribution after a circular aperture can be obtained. Theoretical derivations and numerical calculations reveal that the first correction factor C1 is equal to cosθ and the second factor C2 is a function of the incident wavefront and the shape of the diffractive aperture. Finally, some diffraction phenomena in off-axis optical systems are explained by the off-axis Fresnel number.

A method to accurately evaluate optical thin-film damage threshold is presented. The poor coherences in time and space of amplified spontaneous emission (ASE) result in a very smooth beam profile in the near-field region and uniform intensity distribution of the focused beamlet in the far-field region. In order to increase the uniformity of the irradiation source and test the damage threshold with a greater precision, ASE beam is used to test the damage threshold. ASE is generated by a rod amplifier of the Ndglass in SG-II high power laser system. The pulse duration is 9 ns after an electro-optical switch with the output energy changing from a few millijoules to tens of joules. The spectral full width at half maximum (FWHM) is 1 nm. According to ISO-11254, the damage threshold of the TiO2 high reflection film using ASE is 15.1 J/cm2, which is higher than that of 7.4 J/cm2 tested by laser with pulse duration of 9 ns. So a more accurate evaluation of the samples damage thresholds can be obtained using ASE as the irradiation source.

The physical meaning and essence of Fresnel numbers are discussed, and two definitions of these numbers for offaxis optical systems are proposed. The universal Fresnel number is found to be N=(a2/λz)*C1+C2. The Rayleigh–Sommerfeld nonparaxial diffraction formula states that a simple analytical formula for the nonparaxial intensity distribution after a circular aperture can be obtained. Theoretical derivations and numerical calculations reveal that the first correction factor C1 is equal to cosθ and the second factor C2 is a function of the incident wavefront and the shape of the diffractive aperture. Finally, some diffraction phenomena in off-axis optical systems are explained by the off-axis Fresnel number.

提出了一种精确评估光学薄膜损伤阈值的方法。放大的自发辐射（ASE）光源由于时间相干性和空间相干性较差，所以在近场区域光场强度分布均匀，聚焦后远场也没有被非均匀调制。采用ASE光束作为光学元件损伤阈值测试的辐照光源，可以提高辐照光源的均匀度，实现对光学薄膜损伤阈值的精确评估。ASE光源由神光II高功率激光装置的一级钕玻璃棒状放大器输出，脉宽经过光电开关调制后为9 ns，能量输出在几毫焦耳到几十焦耳范围内可调节，光谱半峰全宽（FWHM）为1 nm。根据标准ISO-11254，实验获得ASE测试TiO2高反膜的损伤阈值为15.1 J/cm2，高于激光测试样品的损伤阈值7.4 J/cm2（脉宽为9 ns时），更准确地评估了样品的损伤阈值。