Texas A&M University, College Station, TX 77843 USA.
Engility, Joint Base San Antonio, Fort Sam Houston, TX 78227, USA.
Sci Rep. 2017 Mar 15;7:44572. doi: 10.1038/srep44572.
Optical imaging of fast events and processes is essential for understanding dynamics of complex systems. A bright flash of illuminating light is required to acquire sufficient number of photons for superior image quality. Laser pulses can provide extreme brightness and are typically employed to achieve high temporal resolution; however, the high degree of coherence associated with the lasing process degrades the image quality with speckle formation. Random lasers are low-coherence sources of stimulated emission and do not suffer from speckle, but are rather broadband and have a relatively low output power limiting the scope of their potential applications. In this report, we demonstrate the use of random Raman lasing as a novel imaging light source with unprecedented brightness for a speckle-free and narrowband light source. We showcase the advantages of a random Raman laser to image the nanosecond scale dynamics of cavitation formation in water and quantitatively compare these images to those taken with incoherent fluorescent emission and coherent laser light as illumination source.
快速事件和过程的光学成像是理解复杂系统动态的关键。为了获得更高质量的图像，需要有足够数量的光子，因此需要明亮的闪光照明。激光脉冲可以提供极高的亮度，通常用于实现高时间分辨率；然而，与激光过程相关的高度相干性会导致散斑形成，从而降低图像质量。随机激光是受激辐射的低相干光源，不会产生散斑，但它们是宽带光源，输出功率相对较低，限制了它们的潜在应用范围。在本报告中，我们展示了将随机拉曼激光用作一种新型成像光源的用途，这种光源具有前所未有的亮度，可用于无散斑的窄带光源。我们展示了随机拉曼激光在成像水中空化形成的纳秒级动力学方面的优势，并将这些图像与使用非相干荧光发射和相干激光作为照明源获得的图像进行定量比较。
