Patent ID: 7321121

Claim:
A portable radiation detector for homeland security comprising: a battery-powered light intensity measuring device having an active portion for measuring light intensity; a scintillating fiber having a first end and a second end; coupling means for optically coupling the first end of the scintillating fiber to the active portion of the light intensity measuring device; light shielding means surrounding the scintillating fiber and the active portion of the light intensity measuring device for shielding the scintillating fiber and the active portion of the light intensity measuring device from ambient light; wherein the light intensity measuring device produces an output signal in accordance with an amount of light generated in the scintillating fiber; wherein the output signal of the light intensity measuring device is fed through a low-pass filter to an electrical system which includes a voltage-to-frequency converter that produces a variable-frequency output signal; and wherein the variable-frequency output signal is employed to drive a sound generating means for producing an audible output with a frequency related to the radiation dose-rate absorbed by the scintillating fiber, and wherein the light shielding means comprises a substantially rigid tube which surrounds the scintillating fiber.