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PROJECT PROPOSAL FOR INTERNATIONAL COOPERATION
Russian R&D Institute "Platan" seeks partners for realization of investment projects, based on different applications of electron-beam-pumped-semiconductor laser (EBPL)
Mobile Laser Three-Color Transit and Course Beacons
The project is aimed at development of the new-generation equipment supporting navigation in narrows and in sea and river ports with an intricate terrain under conditions of low visibility and impeding outside lighting.
The laser beacon enables:
- forming of light orientation sectors of tree different colors (for a course beacon);
- forming a central transit as a fixed-width corridor in case of two color beacons installed (for a transit beacon);
- visual and instrumental information on the ship position about the transit axis and on distances to beacons to be presented to a navigator.
A special feature of the project is in production of a beacon based on a unique multicolor nanosecond light pulse electron-beam-pumped semiconductor laser emitter (EPSL) and an optical system forming light zones of different configurations. The emitter offers increased visibility under extreme weather conditions and impeding outside lighting.
A laser distinctive feature is a possibility to form several red-, yellow-, green-color zones in one emitting surface. Spatial distribution of optical system's emitting zones is transformed into an angular one: a central beam is yellow, edge beams are green and red. By changing a configuration of emitting areas one can select a laser beam aperture angle, with an angular emission density being conserved. The laser emitter ensures the following features of the laser beacon:
- As the optical system forms disjoint and adjacent different-color zones, the laser course beacon (LCB) has two additional different-color edge orientation zones that enable one to determine a direction of a ship deviation from a course.
- A narrow spectral emission band resulted from the laser effect provides for accurate identification on the background of the other port lights and increases visibility under extreme weather conditions.
- Pulse operation conditions make it possible to inform a port service of a ship position.
All the light-signal transit beacons commonly used have a serious drawback: increase of the central light zone and consequently a possible ship deviation from the transit axis with increase of a ship distance to a beacon.
A multicolor semiconductor laser permits development of a transit beacon (LTB) which forms a central transit as a corridor with a width specified by concrete requirements. Such transit beacon includes two EPSL-based two-color LTB's spatially separated by a corridor width. One LTB forms yellow and red, another-yellow and green sectors. The LTB's are arranged so that their beams coinciding wavelengths (yellow) overlap one another and the rest of beams are on the outsides of the corridor. If edge beams of LTB's yellow zones are parallel one another, the yellow zone is formed as an h-width corridor. Moreover, if the geometry provides that edge beams of the yellow zones to be parallel to those of the red and green ones, edge zones (red, green) also are formed as the fixed-width corridors in the horizontal plane. Between the red and yellow color zones there is an intermediate zone in the form of a sector in which both this colors are observed. A like zone (but yellow-green) is observed between the yellow and green light corridors. The existence of such auxiliary zones ensures further orientation of a ship. To estimate a dead zone, the beacons must be moved at a small distance into the mainland.
LTB's mobility and self-contained power supply make it possible to deploy several LTB's along an intricate and long fairway at any type terrain. Short-pulse operation of the laser transit beacon permits measurements of ship distances. All one has to do is to install a corner reflector on a ship and to complete the LTB with a time interval meter and a data transmission system that presents data on ship's request.
The EPSL-based laser transit and course beacons can be used at sea and river ports with an intricate terrain under extreme weather conditions instead of usual transit and course beacons or as reserve ones when a power supply system of main beacons is failed.
Comparison with analogs. A comparative analysis of available navigation facilities (NF) and visual ones on the basis of customary light sources shows that laser NF's have certain advantages over visual NF's:
- essentially increased visibility on the background of other impeding port lights due to a super-narrow spectral laser emission band,
- large visible distance, especially in the day-time, in the twilight and low visibility,
- high accuracy of forming of transit light sectors due to a narrow directional diagram and precision scanning systems,
- increased efficiency of transit and course beacons with color-separated zones due to the lack of color narrow-band filters.
However, these systems primarily oriented on gas lasers have serious drawbacks:
- color range limited,
- very low efficiency (no more than 0,1%) that calls for a several-kilowatt power source,
- the need for precision optical and scanning systems to form light zones and to ensure uninterrupted transition from one color zone to another (otherwise dark zones arise in which a ship loses orientation),
- high external action sensitivity of both gas lasers themselves, and scanning system that require continuous monitoring of such beacons,
- significant mass and overall dimensions that increase in proportion to a number of light zones, as every wavelength practically needs own laser source or own scanning system if a multicolor source is used.
Moreover, a very high coherence of gas lasers may have a detrimental effect upon human's eyes and a human being on the whole because of secondary effects which are not related with an optical power density directly but contribute to decreasing of blood coagulation.
All the above drawbacks of visual NF's based on gas lasers can be eliminated by using pulse electron-beam-pumped semiconductor lasers (EPSL) as light sources. EPSL's have efficiency close to that of high-efficiency injection lasers (up to 10%), on the one hand, and permit laser emission of up to several tens mW pulse power to be achieved for any wavelength within a spectral range 0,37 μm (near UV) - 0,9 μm (near infrared), on the other hand, that is ensured by the choice of a stoichiometric composition of a semiconducting material. An emission spectrum width of such laser is 10-30 Å, I.e. far less than a corresponding value of a standard light source and two-order of magnitude greater than emission spectrum line width of a gas laser.
Such an intermediate position of EPSL's keeps LTB's advantages of reliable detection on the background of conventional lights, on the one hand, and eliminates side effects that laser emission, produces on a human being because of high coherence, on the other hand. The effect of EPSL emission is almost identical with that of usual light sources because EPSL emission, though monochromatic, is not coherent.
The development and usage of the beacons enables one to increase working efficiency and sea and river transport traffic safety under conditions of mist, snow-fall, strong dust content, and impeding lighting.
Degree of mastering. At present, the main functional units of the laser transit beacon are developed. The laser transit beacon as a system is asserted by the Russian patent. Foreign analogs are not known. A prototype beacon has passed full-scale tests in Klaipeda sea port in the presence of representatives of ports navigation and beacon services.
Patentee's assertion. The key functional units and the laser emitter are asserted by Russian patents. The laser emitter is rewarded with the golden medal and diploma of the "Brussel-Eureca-96" 45-th World Invention Salon.
The most important measures to realize the project.
- Development and production of the laser beacon functional units.
- Production and testing of the laser beacon as a whole.
- Working out and issuance of design and technical documents.
This project is presented by the cooperation of R&D Institute "Platan" and Scientific-Production Firm "Gamma", LTD.
Contact person for this project - Dr. Igor M. Olikhov.
Mail Address: Talsinskaya 20/24, Stchelkovo, Moscow Region, 141100 Russia, Phone: +7 096/ 564-5226. E-mail: email@example.com