In light of the recent kerfuffle regarding airport strip searches, I was quite surprised to discover this little gem from the dark ages of 1974. Written by Paul Wahl, it appeared in the May 1974 issue of Science and Mechanics magazine, on pages 77 and 93.
Nude air travel has been proposed as probably the best way to eliminate the skyjacking menace. Concealing a weapon would be difficult and certainly uncomfortable! This idea isn’t feasible – travelers aren’t ready for it yet- but The Stripper, Tetron’s (sic) new passenger screening device (PSD) might be the next best way of discouraging air pirates.
When a passenger carrying a weapon-size metal object, ferrous or non-ferrous, walks through the Stripper’s free form arch which contains the search coils, a red light flashes and a beeper sounds off – gotcha!
Don’t let this system’s name and the naked lady in the picture fool you. The suspect’s clothing isn’t dematerialized – no, science hasn’t advanced that far as yet. The name “Stripper” is intended to suggest that this PSD is as effective as a strip search in finding concealed weapons.
Here’s how this detector works: It operates on the principle of measuring the decay time of a magnetic field. A low-value magnetic field is established by a transmitter coil. A receiver unit samples this field with a similar coil. Then the transmitter is turned off, causing the field to decay rapidly. The rate of decay is measured by the receiver and a normal value is established for the rate. When extra metal is introduced into the field, this rate of decay changes, upsets the balance of the normal value, and the receiver produces an alarm condition. Removing the metal from the field produces the same effect in the opposite direction, providing a second chance for detection.
A totally solid state device, the Tectron PSD employs computer-like logic cirsuits (sic) to control the entire sequence of operation. The weapon sensitivity adjustment can be set so that the Stripper will detect a small pocket handgun such as a .25 automatic, but will reject a bunch of keys or other metal objects of lesser mass.
This PSD is a takeoff from Tectron’s Tramp Metal Detector used extensively in ore mines and in the aggregate industry for the protection of crusher equipment.
Currently, the Stripper is under consideration by Canada’s Department of Transport. Manufacturer of this anti-skyjacking device is Tectron Engineering, Santa Ana, California.