A system and method for measurement of high aspect ratio through silicon via structures. A preferred embodiment includes a white light source and optical components adapted to provide a measurement beam which is nearly collimated with a measurement spot size of the same order of magnitude as the diameter (or effective diameter) of the TSV. These embodiments include a white light source with a variable aperture and other optical components chosen to control the angular spectrum of the incident light. In preferred embodiments the optical components include an automated XYZ stage and a system controller that are utilized to direct the illumination light so as to illuminate the top and bottom of TSV under analysis.