Ultrafast Radiative Transfer Characteristics in Multilayer Inhomogeneous 3d Media Subjected to a Collimated Short Square Pulse Train

The advent of ultrafast lasers has brought many new applications, in particular in biomedicines and material processing, such as laser tissue ablation (Huang and Guo, 2010; Jiao and Guo, 2011), laser tissue soldering and welding (Kim and Guo, 2004), protein shock (Sajjadi et al., 2013), thermal response (Jiao and Guo, 2009), and the detection of tumors by using an exogenous fl uorescence agent and ultrashort near-infrared laser pulses (Quan and Guo, 2004). The development of optical computed tomography (optical-CT) has been proceeding vigorously, as the optical-CT is expected to obtain imaging information on the physiology as well as morphology inside living bodies (Yamada, 1995; Hebden et al., 2001). To realize a fully functional optical-CT, better understanding of the characteristics of laser radiative transfer of scattered signals in highly scattering and weakly absorbing biological tissues is needed. It is important that accurate solutions be obtained for the equation of radiative transfer. There have been many proposed numerical methods to solve the hyperbolic equation of ultrafast radiative transfer accurately as recently reviewed by Guo and Hunter (2013). The solution based on the frequency-domain diffusion approximation was also considered (Liu and Liu, 2012). Some prior numerical studies relevant to the present study are reviewed as follows. Muthukumaran and Mishra (2008b,c,d) concentrated on numerical studies for elucidating the radiative transfer characteristics in a homogeneous medium and a participating medium consisting of local inhomogeneity subjected to a diffuse or a collimated pulse train consisting of 1–4 pulses with a step or Gaussian temporal variation, using the fi ULTRAFAST RADIATIVE TRANSFER CHARACTERISTICS IN MULTILAYER INHOMOGENEOUS 3D MEDIA SUBJECTED TO A COLLIMATED SHORT SQUARE PULSE TRAIN