Abstract: In a pulse laser drilling process having a machine control for controlling a laser, an apparatus is provided to detect when a hole is drilled through a workpiece. The apparatus detects a laser pulse, where the laser pulse emits a laser light upon drilling impact with the workpiece. A second detection step detects sparks emitted by the workpiece, and a spark signal amplitude representative thereof is produced. The sparks produce visible wavelength light. A filter blocks the laser light and transmits the visible wavelength light. A photosensor associated with the filter senses when the spark signal amplitude diminishes below a predetermined threshold level. An output signal, responsive to the photosensor indicates when a through hole is complete and indicates to the machine control to stop any further laser pulse.

Abstract: A method for quality assurance of a laser shock peening process that quantitatively analyzes a single laser shock peened dimple or spot. The method measures a first interior surface of the first dimple to obtain height data and the processes the height data to obtain production volumetric data of the dimple. The volumetric data may then be compared to a predetermined correlation of test volumetric data and high cycle fatigue failure based on high cycle fatigue tests of test pieces that were laser shock peened in the same or similar laser shock peening apparatus as the production workpieces. The test pieces may each have a failure precipitating flaw within a laser shock peened area of the test piece that was laser shock peened in the same or similar laser shock peening apparatus. Preferably, the measuring is performed using a profilometer such as an interferometric optical profilometer.

Abstract: An apparatus and method for monitoring material removal from a workpiece by a beam of energy during a material processing operation are disclosed. A detector is positioned for sensing optical emissions from the workpiece caused by removal of material when an energy beam pulse is incident upon the surface of the workpiece. A computing circuit, algorithm or artificial neural network is provided for determining a quantity of material removed from the sensed optical emissions in real-time during the material processing operation. Analysis of the optical emission pulses caused by the material removal provides an indication of the efficiency of the material processing system and provides feedback for manual or automatic adjustment of material processing parameters during the material processing operation.

Abstract: A laser apparatus is disclosed which is capable of protecting the laser slab or rod crystal within the laser from damage due to overheating when the laser malfunctions in a manner such that laser output ceases while optical pumping of the laser crystal continues. The laser apparatus includes a laser crystal situated within a laser cavity. The apparatus also includes an excitation lamp for pumping the crystal to generate a laser beam to project along a desired main path. A first sensor senses the cessation of the projection of the laser beam along the desired main path and a second sensor senses the continuing excitation of the excitation lamp. The apparatus further includes a extinguishing circuit for extinguishing the excitation lamp a predetermined amount of time after the cessation of the laser beam such that damage to the laser apparatus due to overheating is avoided.

Abstract: An apparatus and method for detecting when a hole has been drilled through a workpiece by way of a pulse laser drilling process having a machine control for controlling whether the pulse laser drill emits laser pulses. The apparatus detects the laser pulse and produces an output signal representative thereof. The output signal is clipped and compared to a first reference signal for producing a compared output signal when the clipped output signal is greater than the first reference signal. The compared output signal triggers an enabling output signal representative of a pulse having a predetermined interval. The apparatus also detects reflected radiation from an entrance of the hole being drilled to produce an output signal which is then clipped and compared to a second reference signal to produce a disabling output signal when the output signal representative of the reflected radiation is greater than the second reference signal.

Abstract: A non-contacting sensing method and apparatus is disclosed for positioning a surface, such as the surface of a workpiece. A collimated light beam is projected through a lens having a known focal length onto the surface. Suitable means such as a television camera is positioned to receive light reflected from the surface and provide a series of video pulses, wherein the number of pulses produced per television frame scan corresponds to the size of the light image focused onto the photosensitive element within the camera. The position of the surface relative to the lens is varied until the number of pulses produced per scan is at a minimum.

Abstract: A non-contacting sensing system for measuring dimensions or determining the position of an object, such as a workpiece in an automated machining process. A small diameter light beam is projected and focused at a predetermined location. A television camera, positioned to view the location, receives light reflected from the location and generates a video signal. This signal is provided to a circuit which detects changes in signal magnitude indicative of a change in position of the object relative to the predetermined location.

Abstract: In the invention, a light beam is scanned along a surface bearing data, such as a serial number. Reflected light is measured and processed for character recognition. The invention wobbles or dithers the light beam during the scan, and takes reflectivity measurements several times within a region on the surface, the region being called a pixel. This procedure enhances the reflectivity signature of edges, thus improving the ability to recognize characters.