As we all know, metal detectors serve a wide range of utilitarian functions all around the world. However, at the very beginning, there were some incredible stories about the invention of metal detectors.
A summer day in 1881, one bullet aimed at James A. Garfield who was the President at that time. He was shot and doctors couldn’t find the bullet lodged inside his chest. A man named Alexander Graham Bell made a device to aid in searching the bullet but he failed. At the time, there was a newly invented mattress with coil spring. It was a rarity and much sought after by upper-class. The White House was one of them. Ordinary people had never even heard of it. Since the President was lying on a metal coil spring bed which made the machine confused. That’s why the device didn’t succeed in finding out the bullet. Unfortunately, Bell and his workmates didn’t know the reason after a long time. It was not a happy ending for the President who died later but Bell's device became the very first metal detector. As a common application of metal detectors in modern society, walk through metal detector was invented to find out would-be thieves in the 1920s as well.
Early hand metal scanner were used to find treasures left behind by unknown explorers. Then they were used after World War I to locate unexploded bombs. In the 1920s, hand-held metal detectors appeared. That was the period when the modern development of those new devices began. Nowadays, different types of metal detectors are manufactured to meet the increasing needs of market. With a variety of features, they are intended to detect successfully in hunting buried metals and they are widely used in mining, archaeology, military, security services, and other industries.
According to the technology system that the detectors used, there are mainly four types of them: VLF, PI, BFO and RCD. However, the most obvious component of a compact hand held metal detector is the transmitter coil with different sizes. Other parts of the equipment are control box, shaft and stabilizer. The transmitter coil (a coil of wire) can create an electromagnetic field around it. When it met a target metal, the electromagnetic field comes from the coil can cause another field around the metal. Then the receiver detects the metal. Some of security screening system can be operated in different modes. For example, all-metal mode is used for detecting many kinds of metals, such as gold, relics and so on. Tone discriminate mode is mainly used to search coins, jewelry or bombs. Their capabilities in detecting depth help the metal detectors become the most valuable and fascinating tools in historic research.
Besides, there are many metal detecting clubs worldwide. The members of these clubs are fond of using metal detectors for some mini project like beachcombing, coin tracking and treasure hunting. With the rapid development of technology, some coils of wire are waterproof and you can use them even in shallow water or in mud. Thanks to such applications of this high-tech device, science becomes more approachable.
- See more at: http://www.eastimagesecurity.com/IndustryNews/How-Metal-Detectors-Invented-and-What-They-Are-Used-for.shtml
