Photon-measurement density functions Part 2: Finite-element-method calculations

This paper presents a method to calculate photon-measurement density functions (PMDF's), which were introduced in Part 1 [Appl. Opt. 34, 7395-7409 (1995), for near-infrared imaging and spectroscopy in complex and inhomogeneous objects through the use of a finite-element model. PMDF's map the sensitivity of a measurement on the surface of an object to the perturbations of the optical parameters within the object. Data are presented for homogeneous and layered circular objects and for a complex two-dimensional model of a head. In particular the influence of the optical parameters on the shape of the PMDF and the distortions caused by boundary layers and complex inhomogeneties are investigated.