A diagram of our near-infrared HRI system, which was described briefly by Wang et al.,22 is shown in Fig. 2. It uses a 100 W quartz tungsten–halogen fiber-optic light source (Oriel Instruments, Stratford, Connecticut) for illumination. The illumination light was delivered through a liquid light guide (Newport Corporation, Irvine, California) of 5 mm diameter, collimated and expanded to a beam diameter of 15 mm, and homogenized using a diffuser before applying to the sample. The reflected light from the sample was collected through a macrovideo zoom lens (18–108 mm focal length, , Edmund Optics, Barrington, New Jersey), collimated by a 5 mm lens, then filtered by a liquid crystal tunable filter (LCTF, CRI Varispec, Perkin Elmer, Waltham, Massachusetts), working in the range of 650 to 1000 nm, with bandwidths of 7 to 10 nm. Filtered light was detected by a Peltier-cooled, high-sensitivity, visible–near-infrared CCD camera (Pixis 1024, Princeton Instruments, Trenton, New Jersey). A LabView interface was used to control the LCTF and the camera (wavelength range, wavelength step size, and exposure time).