Laser beacon

(autotranslated, could have mistakes)

No. 11, 1999

I. OLIKHOV, L. KOSOWSKY. Mobile laser three-color navigation system. "Electronics: NTB" No. 3, 1999, pp. 46-49.

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A lighthouse is one of the oldest means of navigation. In poor visibility or at night without it, it has always been extremely difficult to navigate a vessel through waters with complex bottom and shore topography. But if before the lighthouse was just a bright lantern, clearly visible at a great distance, then over time, and especially with the advent of aviation, the requirements for it have increased significantly.

Now a lighthouse is not just a source of light, but a source of a narrow beam, within the boundaries of which the sailor leading the ship or the landing pilot must stay. And for the brightness of such a beam to be sufficient, powerful energy-intensive lamps and bulky focusing systems were needed. Therefore, the appearance of lasers, capable of creating a narrow and bright beam in the absence of focusing systems, has become very useful for navigation. But lighthouses usually use gas lasers, which have an efficiency of no more than 0.1% (which means they are also energy-intensive) and have very impressive dimensions. A gas laser also has a more significant drawback: its radiation, due to its high coherence (constancy of the phase shift), is not harmless to human vision and to his health in general.

Another thing is a semiconductor laser, similar to that used in CD players, only much more powerful. This power is achieved by pumping such lasers using an electron beam, for which they are placed in a cathode ray tube. It can accommodate several different lasers at once, which allows you to simultaneously emit several multi-colored beams, for example red, yellow and green, thereby optimizing the navigation system to a large extent. Several beams of different colors give the pilot or sailor the opportunity to see a beam of a certain color, depending on whether it moves exactly along a given path or deviates from it in one direction or another.

The experimental sample of such a laser beacon, called LSNO (laser aids to navigation), shown in the photograph, has the size of a bedside table and weighs only 35 kg. It can be powered from a 220 V network or from a car battery. The compactness and cost-effectiveness of such a system make it possible not only to use it for aviation and sea (river) navigation, but also to quickly deploy and collapse if necessary.

Source: SCIENCE AND LIFE