Our study discovered that light at certain near-infrared (NIR) regions would significantly increase the tissue imaging depth. Specifically, the highest imaging depth is reached at the “Golden Window” (window III, 1600-1870 nm), with the maximum transmittance (percentage of light passes through the tissue) and minimum absorbance (percentage of light absorbed in the tissue), which is superior to windows I (650-950 nm), II (1100-1350 nm) and IV (centered at 2200 nm).