An explosives vapor detector is usually a portable instrument composed of two parts: a collecting device, known as a sampler, and an analyzer. Although no two detectors work in the same manner, they operate on the same principle. The collector sucks in the contaminated air and absorbs it onto some type of surface, such as a platinum wire, which is specifically designed for that detector. Flash hearing removes the vapors from the wire and transports them as a stream of gas to the analyzer. The analyzer determines whether explosives are present in the sample. An alarm or light display indicates the results. In the mid-1980's, a private company began work on an explosives detector based on a technology called "chemluminescence." This technology involves a specific chemical reaction that occurs with most nitrogen-based explosives, but with very few other compounds. The first detector that used this technique showed great promise with a wide range of explosives, including plastic explosives, because it improved sensitivity capabilities for detecting those with low vapor pressures. In early 1990, a second-generation explosives detector, made by the same company, could identify the wide range of explosives of interest to law enforcement with even greater sensitivity. This new-generation detector is referred to as a vapor/particle detector, because it has the capability to detect small particles of explosives. Explosives detectors can serve law enforcement in several areas, including security, in laboratories, and at crime scenes.