To increase efficiency, H7 halogen bulbs in car headlights are fitted with one or more infrared-reflecting layers. This reflects the heat radiation back onto the filament, which means that less electrical energy is required to maintain the operating temperature. This measure increases the efficiency and significantly extends the service life of the lamp. Exact positioning and precise alignment of the reflective surfaces is of considerable importance. This production step is prone to errors because the small lamps are only fixed to their thin connecting wires during this process.

The Thuringian coating specialist GBneuhaus therefore relies on image processing systems from Vision & Control for quality control. The lamps are x-rayed after coating and the edges of the reflective surfaces are measured. At the heart of the inspection system is the intelligent Pictor M58/E camera. The hardware and software for image acquisition and evaluation are already integrated in it. Thanks to its LAN connection and browser-based user interface, quality control can be set up and carried out with practically any PC or tablet in the same network.

The images are provided by the telecentric Vicotar T151/0.26L measuring lens. Due to its parallel beam path on the object side, this lens images objects without perspective distortion. Slight fluctuations in the position of the test specimen therefore have no influence on the measurement result. The diffuse area light FDL06-R633/C provides the transillumination. At 633 nanometers, its wavelength is in the near infrared range. As a result, the infrared-reflecting layers appear as a high-contrast black surface in the image.

The test sequence is created in just a few steps using the vcwin graphical parameterization software. Using the "STRAIGHT PROBING" function, the inspection program first detects the glass edges and then, in the next step, the layer transitions. By combining the detected edges, a vector can be calculated that precisely indicates the position and alignment of the vapor-deposited layers. This ensures that only flawless H7 lamps leave the production line.