The word Laser actually stands for "Light Amplification by Stimulated Emission of Radiation." It is a form of electromagnetic radiation the same as radio and microwaves. The difference is that light has a much higher frequency than radio or microwaves. The light emitted by a laser is no different than any other source except that it has a unique method of generating light. The type of laser used is an infrared semiconductor laser diode. The generated light energy has a wavelength of approx. 900 nanometers, with a beam divergence of 3 millenarians, equal to a beam width of about 3 m (or ft) at 1000 m (ft). Target acquisition times range from 0.3 to 0.7 seconds. This laser is completely eye safe, meeting FDA Class 1 specifications. This means that you could stare directly into the laser for 3 hours without any harm to your eyesight. The radiated light power on MOST lasers is in the order of 50 microwatts, or in other terms, it outputs only one twentieth the light power of a typical TV remote control, and far less than a flashlight. This is why laser jammers using industry standard laser LED diodes are effective against laser guns. The products calculate distance by measuring the time of flight of very short pulses of infrared light. This method is different from the traditional surveying instrument method of measuring phase shifts by comparing the incoming wavelength with the phase of the reflected light. Any solid object will reflect back a certain percentage of the emitted light energy - it need only be small for the sensitive detector to pick it up. The guns measure the time it takes a laser pulse to travel to the target and back with a precision, crystal-controlled time base. Knowing the speed of light, you then calculate the distance travelled. To increase accuracy, the laser measures as many as sixty pulses, utilizing a least squares method of determining the range. Sophisticated error trapping algorithms are in place to ensure a reliable reading. However laser jammers generate an off phase pulse which infills the phasing cycle of the laser guns making them easy to defeat. |
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