One of the methods to determine vehicle speed at impact is to examine the speedometer. The laboratory examination of the speedometer consists of observation, microscopical analysis under normal lighting conditions and ultraviolet light, and micro-photography. A very important factor to be determined in any accident investigation is the speed of the vehicle at impact. It can be established in a few different ways, among them, an examination of the vehicle and estimation of the damages it sustained from the collision is used frequently. In some instances, head-on or fixed-object collisions may be so severe that the speedometer needle makes a mark on the dial as it pushes against the face of the speedometer during impact. This stamp or mark sometimes can be seen with the naked eye. Examination under binocular stereoscopical microscope in some instances could reveal some indentations or scratches on the dial of the speedometer.