A method and a system for free space optical tomography provides one or more light source and one or more light sensors spaced, which in one embodiment are spaced apart from and object to be imaged. A first cooling passage includes radially spaced legs extending laterally from one side of the leading edge toward another side of the leading edge and interconnecting to form a loop with one another. The OLS operating in the APSM provides a level shifter output having a configurable voltage, thereby providing output isolation. A vertical slice image is constructed based upon the horizontal slice image data falling within the vertical region of interest.