The invention relates to a field of artificial illumination, in particular, to methods of light emission control, as well as to a field of optical receiving devices, in particular, to methods of reducing light pollution that affects optical receiving devices.
Outdoor illumination is one of main sources of atmosphere light pollution near cities, motorways and industrial sites. Light pollution substantially complicates operations of different optical receiving devices, in particular, optical devices such as astronomical instruments. Light pollution also affects life and labor activities of people.
Known methods of generating light fluxes, e.g., by directing outdoor illumination to particular areas do not reduce light pollution substantially, inter alia, since the light fluxes are reflected by soil, snow or water and still enter atmosphere freely.
In addition to outdoor illumination, moving objects having illumination devices also contribute light pollution a lot.
Therefore, there is a need for new methods of reducing effect of light pollution on optical receiving devices.
There is a known illumination system of international application WO2007008283, publ. on Jan. 18, 2007, which is intended for optimizing object visibility at night. The system sets a base level of lighting and adds a variable light to that base level of lighting. Timing and sequence of the base level of lighting and the variable lighting are synchronized. The system varies light by intensity, color, direction, or a combination thereof. The system includes a detector for detecting motion or noise. The system can be implemented as a fixed lighting source, a movable lighting source, or a vehicle mounted lighting source. The system improves visibility at night and reduces occurrence of accidents. The system also saves energy and enhances quality of life by reducing light pollution.
U.S. Pat. No. 9,615,066, publ. on Apr. 4, 2017, discloses a system of smart lighting and a city sensor. An IoT device for a city includes a light source, sensors comprising a camera and a microphone; a processor coupled to the light source and the sensors; and a wireless transceiver coupled to the processor. The device, in particular, minimizes light pollution by illuminating just an area in vicinity of the light source, where a person or a vehicle moves. This is provided by detecting motion near each lamppost and switching on just a few lights in the motion area, while other light sources remain switched off.
The closest prior art is a method of prevention of light pollution that affects astronomical instruments of patent RU2662907, publ. on Jul. 31, 2018. The method includes separation of operation periods of time for lighting devices and astronomical instruments. Pulsed light flux of lighting devices is generated with frequency that is not imperceptible for human vision and with a certain duty cycle, and suppressing light flux to photosensitive matrix of an astronomical instrument is provided in pulsed mode with the same frequency but in counter-phase to the generated light flux. This solution allows improving protection of astronomical instruments against light pollution. However, it does not provide protection against moving or movable light sources, as substantial change of distance between an illumination device and an astronomical instrument affects time of propagation of light pulse, which, in turn, causes loss of synchronization.
Patent RU2662907 also discloses a system for control of light sources. Synchronization of power pulses of all power sources is ensured by adjustable synchronization and delay devices. As the synchronization signal, either a periodical signal having accuracy of not less than 10 microseconds, preferably not less than 1 microsecond from a special source, or a standard time signal received via GPS, GLONASS or other publicly available system providing standard time signals may be used.
Patent RU2662907 also discloses a device for control of a shatter of a photo receiver in an astronomical instrument. The control device includes adjustable synchronization and delay devices. The synchronization signal may be either a periodic signal from a special source or a standard time signal.
An advantageous effect of the claimed inventions is reducing effect of light pollution on at least one optical receiving device caused by fixed or movable light sources. The claimed method and system provide protection of not only stationary astronomical instruments, but also other kinds of optical receiving devices including moving or movable optical receiving devices.
A first aspect of the invention is a method of reducing effect of light pollution, which includes the following.
A method of reducing effect of light pollution on at least one optical receiving device includes that at least some of light sources provided in form of pulsed light sources causing light pollution are switched on periodically with time duration tem, time period T and time shift d, depending on position of the light sources relative to the optical receiving device. Light flux from the pulsed light sources is suppressed in the optical receiving device, and the time shift d is changed depending on current location of the pulsed light sources, when they move. At least one area is defined around the optical receiving device that is most important to be protected against light pollution at a particular distance from the optical receiving device. The pulsed light sources located within the area are switched on based on the constant time shift d, defined for this area.
The method provides reducing light pollution caused by both fixed and movable light sources, most of all, for the optical receiving device that is most important to be protected against light pollution. To do that, the light sources are provided in form of pulsed light sources, which are switched on periodically.
It means that at least one area is formed around this optical receiving device at a particular distance therefrom, where the light sources are switched on based on the constant time shift d. Depending on distance between a given area and the optical receiving device (e.g., an observatory telescope), the time shift d may vary. Therefore, the light flux from light sources that induces light pollution is suppressed, when it comes from distant defined areas, not only from the nearest defined area.
Predefining areas (at a predefined distance from the optical receiving device) with the constant time shift d for switching on the light sources allows providing protection of not only the optical receiving device that is most important to be protected against light pollution, but also all other optical receiving devices located within areas covered by this method.
This allows obtaining the claimed advantageous effect, i.e., reducing light pollution caused by both fixed and movable light sources and induced in both fixed and moving optical receiving devices located in the areas. Light pollution of the optical receiving device that is most important to be protected against light pollution may be almost eliminated. Thus, a simple and effective system for reducing effect of light pollution may be provided.
In one embodiment of the invention, current positions of light sources are determined using signals of a satellite-based navigation system.
In another embodiment of the invention, current positions of light sources are determined by receiving signals of terrestrial stations.
Additionally, operation of the pulsed light sources is synchronized by coordinated universal time signals.
Further, an area is defined, where the light sources are switched on based on the constant time shift dN at a distance Z=ND, where D is equal to 30 to 70 km, and N is a sequential number of the area by distance D. In particular, light flux of the pulsed light sources is generated in form of periodical pulses having frequency of 50 to 1000 Hz and duty ratio of 1.05 to 20.
In one embodiment, the optical receiving device that is protected against light pollution is an astronomical instrument.
A second aspect of the invention is a system for providing control of light sources.
At least some of light sources provided in form of pulsed light sources in the system for control of light sources have control devices configured to periodically switch on the light sources, with time duration tem, time period T and time shift d, depending on position thereof relative to the optical receiving device that is protected against light pollution. The control devices of light sources are configured to receive synchronization signals and signals for determination of their locations.
A third aspect of the invention is a control device of optical receiving device.
The control device of optical receiving device includes a unit for receiving and processing synchronization signals and signals for determination of the optical receiving device location relative to the pulsed light sources configured to be periodically switched on, with time duration tem, time period T and time shift d, depending on position thereof relative to the optical receiving device that is protected against light pollution.
The control device includes a unit for generating signals for suppressing light flux from the pulsed light sources. Input of the unit for generating signals is connected to output of the unit for receiving and processing signals.
An optical receiving device is a device used for research, exploration and observation of objects in a visible light/optical spectrum, which needs to be protected against external light pollution impeding observation, in particular, against outdoor illumination.
Light sources causing light pollution are outdoor illumination devices of various kinds, outdoor light emitting advertising devices, outdoor light emitting information devices, illumination of building facades and other architectural structures, as well as other kinds of outdoor lighting.
Area at a certain distance from the optical receiving device is an area located at a distance within a predefined range of distances therefrom, where the same time shift d is applied for earlier switching on the light sources located in this area, both fixed and movable.
Additional features and advantages of the claimed solution are described in the following disclosure, as well as proved by the actual practice of the invention. These advantages and improvements can be achieved by neural networks that have been constructed and trained in accordance with the claimed method, specifically, following the disclosure, along with the accompanying claims and drawings.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
The method and system for providing control of light sources to protect against light pollution ensure reducing effect of light pollution on optical receiving devices and people performing observation functions in a comparatively small area or in a large area.
The method is based on a principle of primarily protecting one main optical receiving device that is most important to be protected against light pollution. For example, such an optical receiving device may be an observatory telescope or a set of optical devices of the observatory.
Other optical receiving devices (which may constitute a plurality by kinds of the devices and by number thereof in this area or in adjacent areas) may also be protected against light pollution with the same effectiveness as the main optical receiving device or, possibly, with lower effectiveness, when they are located far from the main optical receiving device.
As shown in
Light emitters mounted on fixed or movable objects, which cause light pollution, are equipped with light sources operating in pulsed mode and include the system for providing control of light sources.
As shown in
The system for providing control of light sources includes control devices configured to periodically switch on the light sources with time duration tem, time period T and time shift d, depending on position of the light sources relative to the optical receiving device that is most important to be protected against light pollution. The control devices of light sources are configured to receive synchronization signals and signals for determination of their locations. The control devices may be provided for individual light sources or for groups of light sources or for entire regions. Examples of control devices for fixed and movable light sources are shown in
The optical receiving devices shall be equipped with devices for suppressing light flux, e.g., electromechanical shutters, electronic shutters, devices for fast switching the optical receiving devices from receiving mode to idle mode, or devices for rejecting components of output electric signal formed by the light flux in the optical receiving devices.
In this context, optical receiving devices mean, in addition to astronomical optical devices, any devices receiving or passing optical radiation and having devices configured to suppress light flux or reduce light flux intensity. In particular, they include eyeglasses wearable by people, windows of buildings and other facilities equipped with illumination control systems, aircraft passenger cabin windows, aircraft crew cabin windows, etc.
For example,
Control devices of light sources and control devices of optical receiving devices operate based on standard time signals and positioning signals. These signals may be received from satellites 4 (
Block diagrams of control devices of light sources and control devices of optical receiving devices are shown in
Value d2 corresponds to time of propagation of a light pulse travelling from region N2 to region N1. With average extent of each region of 50 km, this time is about 165 μs. Value d3 corresponds to time of propagation of a light pulse travelling from region N3 to region N1. Since this distance is 100 km in average, the time is about 330 μs. Value d4 corresponds to time of propagation of a light pulse travelling from region N4 to region N1, which distance is 150 km in average, so the time is about 495 μs.
When the pulsed light source operates with the lowest frequency in the range, which is equal to 50 Hz, and with the highest duty cycle of 20, duration of the light pulse is equal to 1 ms and duration of a gap between the pulses is equal to 19 ms. This mode of operation means that the optical receiving device may be in open state for almost 19 ms. So a photosensitive array of the optical receiving device may receive light flux for a long time with no interruption. Such a long time interval allows providing observation of objects of low brightness (e.g., telescopes may survey faint stars). To ensure this operation mode, it is necessary to use light sources capable of withstanding substantial peak load, as strength of a short light pulse shall be high enough so that an average level of illumination remains sufficient despite long time periods between the pulses.
In another case, when the pulsed light source operates with frequency of 50 Hz and with the lowest duty cycle of 1.05, duration of the light pulse is equal to 19 ms and duration of a gap between the pulses is equal to 1 ms. In this mode of operation, optical receiving devices may receive payload light signals during time of 1 ms or less. This means that they are able to survey bright objects only. Since time of emission of the light sources may be of 95% of pulse period, then the light sources not configured for a high peak load may be used to maintain a sufficient average level of illumination. This allows substantially reducing cost of the illumination system.
Operation of pulsed light sources in the upper portion of the frequency range, at 5000 to 1000 Hz, facilitates better reducing adverse effect of light flicker on people.
The control device of optical receiving device includes a unit for receiving and processing synchronization signals and signals for determination of the optical receiving device location relative to the pulsed light sources. It also includes a unit for generating signals for suppressing light flux from the pulsed light sources, where input of this unit is connected to output of the unit for receiving and processing signals.
The discussed configuration of the control devices 20 is just an example, and all control functions may be implemented in a single device.
All or some of light sources of a particular region (N1, N2, N3, N4) causing light pollution of optical receiving devices are implemented as pulsed light sources, e.g., as LED-based sources, which are able to switch fast to emission mode. For each region (N1, N2, N3, N4), synchronous operation of all light sources of a particular region (N1 or N2, N3, N4) is ensured by the control devices using periodic pulses with frequency of 50 to 1000 Hz and duty cycle of 1.05 to 20, which may be unified for these regions.
As shown is
Emission mode with time shift d2 relative to switch period T of the optical receiving device 2 located in region N1 is defined for region N2, while emission mode with time shift d3 is defined for region N3 (
Time shift d2 for distance of 50 km between regions N1 and N2 is about 165 μs. This is a time of propagation for a light pulse to travel 50 km. Time shift d3 for distance between regions N1 and N3 is about 330 μs.
Defining constant time shift values d for start of emission of all light sources in each region facilitates designing and operating the system. Inaccuracy related to difference of arriving light fluxes from light sources located at different edges of a given region N is compensated by that time of suppressing light fluxes to optical receiving devices located in each region is selected to be longer than duration of the emission pulse.
An example of implementation of light sources and optical receiving devices is shown in
Pulsed light sources installed on fixed and movable objects in region N1 periodically with period T emit light pulses with duration of tem. Standard time and positioning signals comes from GLONASS or GPS system or from terrestrial synchronization devices. These signals are fed into control units 20 (
Optical receiving devices, which shall be protected against light pollution in region N1, also receive time synchronization and positioning signals from GLONASS or GPS system or from terrestrial synchronization devices. Operation of light flux suppressing devices is provided by control devices 30 (
In other regions N2, N3 distant from region N1, the pulsed light sources operate also periodically with period T, but with advance time shifts d2, d3 (
The following mode of operation is defined for optical receiving devices located in other regions N2, N3, not in region N1, which need to be protected against light pollution caused by the light sources (
In some cases, e.g., to protect pedestrians against excessive light of outdoor illumination devices, outdoor advertising lights or artistic external building illumination, various algorithms may be applied for switching on light sources and activating devices for suppressing light flux in optical receiving devices.
Referring to
The examples described in the above do not limit embodiments of the method.
The invention may be implemented for various purposes and for protection of various optical receiving devises installed on various fixed and moving objects.
The method of reducing effect of light pollution implies that the system aimed at attaining this result is implemented around a main object like an astronomical observatory, in particular, around optical receiving devises of an observatory. In such a way of implementation, maximum effect of protection against light pollution is obtained for exactly that object. However, the system is capable of protecting multiple devices against optical pollution near the main object and in adjacent areas.
The method and system for reducing effect of light pollution caused by outdoor illumination systems of living and industrial blocks may be used for optical receiving devices located on satellites and intended for fire surveillance, in particular, regarding urban fires, and for vehicle traffic surveillance.
The method may also be used for reducing light pollution near airports to aid pilots in landing airplanes. Optical receiving devices operating in pulsed mode and suppressing light flux may be implemented in front windows of crew cabin in airplanes or in form of controllable pilot's eyeglasses.
The method may also be used for reducing light pollution near open air cinemas, in sites of performing light or laser show, in sites of displaying video projections, as well as during photo-video- and cinema shooting.
As indicated in the above, the proposed method for reducing effect of light pollution on optical receiving devises and people performing observation functions, and the control system may be implemented instantly. To do that, it is necessary simply to replace old-fashioned light sources and equip luminaries with corresponding control devices. Modification of existing optical receiving devices mainly requires introducing control devices.
Having thus described a preferred embodiment, it should be apparent to those skilled in the art that certain advantages of the described method and system have been achieved.
It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention. The invention is further defined by the following claims.
Number | Date | Country | Kind |
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2019139214 | Dec 2019 | RU | national |
Filing Document | Filing Date | Country | Kind |
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PCT/RU2019/000896 | 12/5/2019 | WO |