A turbine blade or vane inspection apparatus for use during a manufacturing process, comprising: a mounting for holding a turbine blade or vane; a source of illumination; a camera; a controller; wherein at least two of the source of illumination, the camera, and the mounting are moveable components; and, wherein the controller is configured to: control the movable components to (a) position the turbine blade or vane mounted thereon relative to the illumination source so as to provide a contrast of illumination between a cooling hole in the turbine blade or vane and an adjacent surface of the turbine blade or vane and (b) position the camera so that the optical axis of the camera is directed towards the cooling hole so that the optical axis of the camera is aligned with a centreline of the hole; and measure a size of a profile of the cooling hole at the break-through point as the narrowest point of the cooling hole, the measurement being based on an image obtained by the camera, wherein the illumination source comprises an illumination probe and the controller is configured to control the movable components to position the turbine blade or vane so that the illumination probe enters the internal passage of the turbine blade or vane and radiation from the illumination probe shines out from the internal passage through the cooling hole in the turbine blade or vane.. a mounting for holding a turbine blade or vane; a source of illumination; a camera; a controller; wherein at least two of the source of illumination, the camera, and the mounting are moveable components; and, wherein the controller is configured to: control the movable components to (a) position the turbine blade or vane mounted thereon relative to the illumination source so as to provide a contrast of illumination between a cooling hole in the turbine blade or vane and an adjacent surface of the turbine blade or vane and (b) position the camera so that the optical axis of the camera is directed towards the cooling hole so that the optical axis of the camera is aligned with a centreline of the hole; and measure a size of a profile of the cooling hole at the break-through point as the narrowest point of the cooling hole, the measurement being based on an image obtained by the camera, wherein the illumination source comprises an illumination probe and the controller is configured to control the movable components to position the turbine blade or vane so that the illumination probe enters the internal passage of the turbine blade or vane and radiation from the illumination probe shines out from the internal passage through the cooling hole in the turbine blade or vane.. control the movable components to (a) position the turbine blade or vane mounted thereon relative to the illumination source so as to provide a contrast of illumination between a cooling hole in the turbine blade or vane and an adjacent surface of the turbine blade or vane and (b) position the camera so that the optical axis of the camera is directed towards the cooling hole so that the optical axis of the camera is aligned with a centreline of the hole; and measure a size of a profile of the cooling hole at the break-through point as the narrowest point of the cooling hole, the measurement being based on an image obtained by the camera, wherein the illumination source comprises an illumination probe and the controller is configured to control the movable components to position the turbine blade or vane so that the illumination probe enters the internal passage of the turbine blade or vane and radiation from the illumination probe shines out from the internal passage through the cooling hole in the turbine blade or vane..