With confocal laser scanning technology, a laser scans a specimen, which has been injected with fluorescent dyes. When scanned, these dyes emit light of specific wavelengths. This light passes through a pinhole aperture, which rejects unfocused light, before being detected by a camera. The focused light comes from an extremely thin layer, allowing scientists to optically slice the specimen. Computer software then combines the layers to produce a high-resolution, clearly focused 3D image.