A method and device for optically measuring throat area in a vane ring for a gas turbine engine, the method according to one aspect of the invention following the steps of: placing the vane ring on a fixture with the periphery of each throat within an optical measuring field of view; positioning a primary radiation source to cast an area of shadow on the vane ring delineating the throat as a dark area surrounded by an area of reflectance; capturing an image of the dark area with a radiation detector; analyzing the image to acquire a dimensional data of the dark area, proportional to the absolute value of throat dimensions; progressively capturing and analyzing images from each of the individual throats; then processing and calibrating the dimensional data of each image to account for scaling and viewing direction (perspective distortion) to acquire an absolute value for the composite throat area of the vane ring.