Cuticle (outer exoskeleton) of the head of a fruit fly (Drosophila melanogaster). This 3D model is based on confocal laser scanning microscopy data. The fly's proboscis is at left. Parts of each compound eye can be seen on either side of the head at right. Confocal laser scanning microscopy is an imaging technique that focuses a laser beam on or inside a sample, and produces an image from only the point in focus. The focal point can be scanned over the subject, allowing images of very thin layers of an object to be obtained, which can be combined in a computer to form a detailed 3D image.