A method of laser drilling a hole comprising providing a laser source at a first side of a component to laser drill a hole through the component. A light source is positioned in the path of the laser beam at the opposite side of the component. A camera is provided at the first side of the component. The camera is positioned such that it has a line of sight view of the light source through the laser drilled hole. The laser drilled hole in the component is viewed using the light provided by the light source at the opposite side of the component. The parameters of the laser drilled hole are measured using the view of the laser drilled hole provided by the camera and a flow of gas is provided over the surface of the light source to protect the light source.