RU2143108C1 - Remote laser method of detection of oil film on water surface - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: invention can be employed for proximate test of spreads of oil and oil products in seas and internal water basins. Remote laser method of detection of oil film on water surface includes sounding of examined water surface by pulse optical beam, recording of energy and duration of echo pulse reflected from water surface and comparison of energy and duration of echo pulse reflected from examined and clean water surfaces. Presence of oil film on water surface is evaluated by simultaneous realization of two relations: W>W₀, τ < τ₀, where W, W₀ and τ,τ₀ are correspondingly energy and duration of echo pulse recorded by detector from examined and clean water surfaces. EFFECT: increased authenticity of detection. 1 dwg

Description

 The invention relates to measuring equipment and can be used for express control of oil spills and oil products in the seas and inland waters.

 A known method of detecting an oil film on a water surface, which consists in the fact that the test surface is irradiated with optical radiation and register the intensity of the reflected radiation in different spectral ranges [1].

 The disadvantage of this method is its low efficiency and, as a result, poor suitability for remote measurements designed to control large areas of water.

Closest to the invention in technical essence is a method [2] for detecting an oil film on a water surface, in which the studied water surface is irradiated with a pulsed beam of optical radiation, a reflected signal is received, and signals reflected from the surface of pure and test water are compared, choosing as a parameter comparing the number of pulsed signals N that exceeded the analyzer threshold. For N ≥ N _b, the presence of an oil film is judged, and for N <N _b , its absence (where N _b is the number characterizing the probability of receiving reflected signals under waves).

 The disadvantage of this method of detecting an oil film is the low reliability of detection.

This disadvantage can be avoided by the fact that, according to a method for detecting an oil film on the surface of water bodies, which includes irradiating the water surface with a pulsed beam of optical radiation, receiving a reflected signal and then comparing the signals reflected from the surface of the pure and test water, choose the energy W and the duration of the echo pulse τ recorded by the receiver, and the presence of an oil film is judged by the fulfillment of two ratios simultaneously:
W> W ₀ ,
τ <τ _o ,
where W, W ₀ and τ, τ _o are the energy and duration of the echo pulse recorded by the receiver from the studied and clean water surfaces, respectively.

 The presence of distinctive features indicates compliance with the criterion of "novelty."

 These distinguishing features are known in the scientific, technical and patent literature only partially [2-4] (there are known options for using the intensity of reflected radiation, which is the energy characteristic of reflected radiation, as well as the energy of an echo pulse), their combination is unknown in scientific technical and patent literature, and therefore, the proposed technical solution meets the criterion of "inventive step".

 The drawing schematically shows a device that implements the proposed method.

 The device comprises a pulsed laser source 1, a photodetector 2, a unit 3 for calculating the energy W and the duration τ of the echo pulse detected by the receiver, a unit 4 for comparing the energy and duration of the echo pulse reflected from the test surface 5 and from a clean water surface.

 The device operates as follows.

 The probe pulsed laser radiation is reflected by the studied water surface, the intensity of the reflected radiation is detected by the photodetector 2, the signal from the photodetector is fed to the unit 3 for calculating the energy W and the duration τ of the echo pulse. Then, the calculated energy W and the duration τ of the echo pulse reflected from the investigated water surface are compared in the comparison unit 4 with the energy and duration of the echo pulse reflected from the clean water surface, which are stored in the memory of the said comparison block.

 Theoretical calculations and experimental studies show that the physical basis for the remote detection of oil films on a water surface by laser sensing is the contrast of the brightness of the reflected radiation from a clean water surface and a water surface covered with an oil film. The contrast is due to two reasons: the oil film has a different reflection coefficient than the air-water interface, and the oil film smoothes the excitement of the water surface. Monitoring only one of these effects reduces the reliability of detection of oil pollution: an area with smoothed wind waves can be a glare on the water surface or a wind shadow behind an island or a high shore; the reflection coefficient from the water surface can vary not only due to oil pollution, but also due to the presence of foam on the water surface, films of biological origin, algae, etc. To increase the reliability of detection of oil pollution, it is necessary to control the presence of two effects simultaneously - smoothing wind waves and changing the reflection coefficient of the water surface. This is achieved by choosing the statistical energy parameters W (to control the change in the reflection coefficient of the water surface) and the duration τ of the echo pulse recorded by the receiver (to control the smoothing of wind waves).

 Thus, the choice of statistical parameters of the energy W and the duration τ of the echo pulse recorded by the receiver can significantly increase the reliability of the detection of an oil film on the water surface during remote measurements.

 The invention is aimed at solving the problem of increasing the reliability of detection of oil pollution on the water surface. Known methods for detecting an oil film on a water surface may erroneously identify areas of a water surface with smooth wind waves (such as glare on a water surface, a wind shadow behind an island or a high shore) and areas with a high reflection coefficient (for example, due to the presence of foam on the water surface, films of biological origin, algae, etc.).

 The developed detection algorithm makes it possible to identify oil pollution on the water surface with high reliability, as it distinguishes oil pollution from areas with smoothed wind waves and areas with a high reflection coefficient.

 This device can be assembled at the enterprises of the Russian Federation from components and assemblies manufactured in the Russian Federation, and meets the criterion of "industrial applicability".

Sources of information
1. Krylova T.V. Interference coatings. - L .: Engineering, 1973, p. 174-190.

 2. USSR copyright certificate N 1354073, cl. G 01 N 21/55, 1987.

 3. Radiophysical monitoring of environmental pollution / Belov M. L., Gorodnichev V. A., Kozintsev V. I. et al. - M.: Argus, 1994, 107 pp.

 4. Kropotkin M.A. and other applications for the detection of surface oil pollution of inland water bodies of an optical locator based on a visible light projector. // Water resources, 1980, N 6, p. 167-171.

Claims (1)

A remote method for detecting an oil film on a water surface by irradiating the water surface with a pulsed beam of optical radiation and receiving a reflected signal, followed by comparing the signals reflected from the surface of pure and test water, characterized in that the energy W and the duration of the echo pulse are selected as parameters of the reflected radiation τ, and the presence of an oil film is judged by the fulfillment of two ratios simultaneously
W> W ₀ ,
τ <τ _o ,
where W, W ₀ and τ, τ _o are the energy and duration of the echo pulse recorded by the receiver from the investigated and clean water surfaces, respectively.