BROADBAND FOCUSING FOR EXTREME MULTIMODAL MICROSCOPY

项目摘要 几乎所有用于生物成像的光学显微镜都是基于折射物镜的。 这些镜片的性能接近理论极限，然而它们的使用是有限的。 到可见光到近红外光谱范围。即使在这个范围内，他们的表现也只是 保证在相对较窄的范围内使用，而宽带使用总是受到 色差。另一个问题是这些透镜的群延迟色散 引入了降低非线性光(NLO)信号效率的短光脉冲 显微镜下的世代。综上所述，这些缺点严重损害了 三光子激发等几种非线性光学成像方式的成像特性 荧光和三次谐波的产生。此外，折射物镜根本不能 用于在中红外(MIR)范围内结合激发光的NLO技术，如 作为光热成像和和频产生，基于MIR的有前途的技术 分子对比。唯一可行的替代方案是全反射施瓦茨柴尔德-卡塞格伦 (SC)目标，其固有的消色差但遭受非理想点扩散函数的影响 以及限制吞吐量的中心模糊。由于这些限制，SC镜片具有 在生物成像应用中未发现广泛使用。这种表现的缺乏也是 令人兴奋的基于MIR的NLO成像技术取得进展的原因是 令人窒息：根本没有高性能的高数值对焦选项可供选择 支持这些新兴的成像技术。 在这个项目中，我们开发了一种新型的全反射大数值孔径透镜，该透镜 克服了SC调焦镜头的所有限制。基于非同心设计，这款新的 设计功能从紫外线到中红外都有完美的色彩校正，展示了广泛的 视场，显著减少群延迟色散并显著提高吞吐量 通过一起消除中心遮挡。这种透镜不仅使现有的NLO 依赖宽带辐射的模式，但也支持新技术，如 到目前为止性能低下的光热成像和SFG显微镜 聚焦光学。

Project Summary Virtually all optical microscopes for biological imaging are based on refractive objective lenses. The performance of these lenses approaches the theoretical limit, however, their use is limited to the visible to near-infrared spectral range. Even within this range, their performance is only guaranteed over a relatively narrow range, and broadband use is invariably affected by chromatic aberrations. Another problem is the group delay dispersion that these lenses introduce to short optical pulses, which reduces the efficiency of nonlinear optical (NLO) signal generation in the microscope. Taken together, these shortcomings seriously compromise the imaging properties of several NLO imaging modalities such as three-photon excited fluorescence and third-harmonic generation. In addition, refractive objectives simply cannot be used for NLO techniques that incorporate excitation light in the mid-infrared (MIR) range, such as photothermal imaging and sum-frequency generation, promising technologies based on MIR molecular contrast. The only viable alternative is the all-reflective Schwarzschild-Cassegrain (SC) objective, which is inherently achromatic but suffers from a non-ideal pointspread function and a center obscuration that limits throughput. Because of these limitations, SC lenses have not found widespread use in biological imaging applications. This lack of performance is also the reason why advances in exciting new MIR-based NLO imaging technologies have been stifled: there simply are no high-performance high numerical focusing options available to support these emerging imaging technologies. In this project, we develop a novel all-reflective high numerical aperture lens that overcomes all limitations of the SC focusing lens. Based on a non-concentric design, this new design features perfect color correction from the ultra-violet to the mid-infrared, exhibits a wide field of view, dramatically reduces group delay dispersion and significantly improves throughput by eliminating the center obscuration all together. This lens not only advances existing NLO modalities that rely on broadband radiation, but also enables new technologies such as photothermal imaging and SFG microscopy that have thus far suffered from low performance focusing optics.