Method of reducing light pollution of astronomical instruments by outdoor illumination devices

Abstract

The invention relates to a field of outdoor (street) illumination, in particular, to methods of controlling light emission, as well as to a field of optical devices, in particular, to methods of reducing light pollution that affects astronomical instruments. The method of reducing impact of light of outdoor illumination devices on astronomical instruments consists in generating a light flow of illumination devices in a form of periodical pulses and in blocking the light flow directed to a light-sensitive matrix of an astronomical instrument during arrival of the light flow pulses of the outdoor illumination devices. Thus, light pollution of astronomical instruments by outdoor illumination devices is avoided.

Claims

1. A method of reducing light pollution to an astronomical instrument by outdoor illumination devices, the method comprising: generating a light flow of the outdoor illumination devices in a form of periodical pulses; and interrupting, by a shutter, accumulation of information in a light-sensitive matrix of the astronomical instrument during arrival of the periodical pulses from the outdoor illumination devices, and accumulating information in the light-sensitive matrix only when the shutter permits the light-sensitive matrix to receive light.

2. The method of claim 1, wherein the periodical pulses have a frequency of 300-1000 Hz and a duty ratio of 2 to 10.

3. The method of claim 1, wherein the periodical pulses of each light source of the outdoor illumination devices located at different distances from the astronomical instrument are generated with different time shifts so that the periodical pulses of different light sources arrive simultaneously at the astronomical instrument.

4. The method of claim 1, wherein the light flow is generated using LED light sources.

5. The method of claim 1, wherein the light flow is generated based on synchronization signals using standard time signals received from a public system of broadcasting standard time signals.

6. The method of claim 1, wherein the light flow is generated based on synchronization signals generated by a satellite source.

7. The method of claim 1, wherein the light flow is generated based on synchronization signals transmitted via a wire communication line.

8. The method of claim 1, wherein the light flow is generated based on synchronization signals transmitted via a fiber optic communication line.

9. The method of claim 1, wherein the shutter is controlled based on standard time signals received from a public system of broadcasting standard time signals.

10. The method of claim 1, wherein the shutter is controlled based on synchronization signals generated by a satellite source.

11. The method of claim 1, wherein the shutter is controlled based on synchronization signals transmitted via a wire communication line.

12. The method of claim 1, wherein the shutter is controlled based on synchronization signals transmitted via a fiber optic communication line.

13. The method of claim 1, wherein the shutter is external to the astronomical instrument.

14. The method of claim 1, wherein the shutter is a part of the astronomical instrument.

15. The method of claim 1, wherein the shutter is an electronic shutter.

16. The method of claim 1, wherein the shutter is an electro-optical shutter.

17. The method of claim 1, wherein the shutter is an electromechanical shutter.

18. A system for reducing light pollution to an astronomical instrument, the system comprising: an astronomical instrument including a light-sensitive matrix; a shutter coupled to the astronomical instrument; and a plurality of outdoor illumination devices generating a light flow in a form of pulses; and wherein the shutter interrupts the light flow to the light-sensitive matrix, so that accumulation of information in a light-sensitive matrix when the outdoor illumination devices are turned on by an external synchronization signal, and wherein the information is accumulated in the light-sensitive matrix only when the shutter permits the light-sensitive matrix to receive light.

Description

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

(1) 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.

(2) In the drawings:

(3) FIG. 1 is a timing diagram of emitting a light flow by outdoor illumination devices and blocking the light flow by a photodetector shutter of an astronomical instrument.

(4) FIG. 2 is a block diagram illustrating an embodiment of the claimed method.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(5) Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

(6) The invention uses separation of time of operation of an illumination system and time when a light flow may be passed to a light-sensitive matrix of an astronomical instrument photodetector. It is proposed to provide outdoor illumination by a pulsed light source. When pulses of the light flow arrive from the outdoor illumination devices, accumulation of information in the photodetector is interrupted by a special shutter. The shutter may be external (e.g., electronic, electrooptical or electromechanical) or internal (implemented by feeding corresponding electric potentials to control electrodes of the photodetector).

(7) The Frequency of interruption must exceed 300 Hz, as pulses having frequency of above 300 Hz are not perceived by eyesight of humans.

(8) All illumination devices must be synchronized so that (a) they emit light pulses of the same frequency and the same duration and (b) they are switched on and off with a time shift relative to each other so that their light pulses coincide when coming into the photodetector.

(9) As the illumination devices are located at different distances from the photodetector, time of light travelling from a certain illumination device to the photodetector may differ by tens of microseconds (light travels 1 km in 3.3 microseconds). To provide that, power sources should be equipped with adjustable synchronization and delay devices. Light flow pulses are synchronized by a standard time signal received via GPS, GLONASS or some other publicly available system providing standard time signals.

(10) Power U.sub.1 of the illumination devices is on during time period t.sub.1 (FIG. 1). Duty ratio of the power pulses (i.e., ratio of T to t.sub.1) is in range of 2 to 10. During this time, power U.sub.S of the shatter is off.

(11) After the illumination devices are powered off, the telescope shutter is powered on by U.sub.S. During this time, power U.sub.1 of the illumination devices is off.

(12) A block diagram illustrating an embodiment of the claimed method is represented in FIG. 2. The following components are shown in the diagram. 1 Astronomical instrument 2 Shutter 3 Light-sensitive matrix of astronomical instrument 4 Pulsed power source of shutter 5 Synchronization signal source 6 Pulsed power source of illumination device 7 Illumination device

(13) After the telescope shutter is powered off, the illumination devices are powered on.

(14) Cycle duration T of pulses of the both power sources is the same and it does not exceed 3 milliseconds, preferably 1-2 milliseconds.

(15) Synchronization of power pulses of all power sources is ensured by adjustable synchronization and delay devices. As a source of the synchronization signal, either a special source of a periodical signal having accuracy of not less than 10 microseconds, preferably not less than 1 microsecond, or a standard time signal received via GPS, Glonass or other publicly available system providing standard time signals may be used.

INDUSTRIAL APPLICABILITY

(16) The invention may be implemented in modern astronomical instruments by way of modified control of outdoor illumination devices having LED light sources.

(17) Having thus described a preferred embodiment, it should be apparent to those skilled in the art that certain advantages of the described method and apparatus have been achieved.

(18) 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.