the emission of light propagation in one direction

If you do a free pulse waveform, the probe attenuation to add one to three layers of paper; if it is Q-wave, the attenuation of the probe front of the paper than do the more free pulse (to do with lens cleaning paper, attenuation paper). When the measured waveforms are done, do not forget to switch off the probe. Ordinary light is light in all directions. Make the emission of light propagation in one direction, you need to light a certain condenser fitted with devices such as car headlights, and searchlights were installed on the role of the condenser mirror, so that radiation is to bring together in one direction injection. Laser emission of the laser, born in one direction injection, beam divergence is extremely small, only about 0.001 radians, nearly parallel. In 1962, the first human use of laser irradiation the moon, the moon's distance from the Earth about 38 million km, but the laser spot at the lunar surface less than two kilometers. If condenser works well, seemingly parallel light beam searchlight shooting the moon, according to its spot diameter will cover the entire moon. The  laser pointer  company manages to attract more customers with the low cost and expense.
Before the invention of the laser, artificial sources of high-voltage pulsed xenon lamp brightness maximum, comparable with the brightness of the sun, while the ruby laser laser light, xenon lamp can exceed several hundred billion times. Because the laser is extremely bright, they were able to illuminate distant objects. Ruby laser beam emitted illumination produced on the moon is about 0.02 lux (light intensity units), the color red, visible laser spot. If the most powerful searchlight with power moon light, the illumination produced only about a trillionth of Lux, the human eye can not detect. The main reason is the high brightness of laser light directed. A large number of photons concentrated in a very small space within the injection, the natural high energy density. Laser intensity and the ratio between the sun is one million, and it is a human creation. Color of the laser depends on the laser wavelength, the wavelength depends on the laser active material issue, he incurs the laser stimulation can produce the kind of material. Stimulation can produce deep pink ruby laser beam, it is used in medical applications, such as for skin treatment and surgery.