RU223233U1 - Lidar for sensing aerosol atmospheric formations - Google Patents

Abstract

The utility model relates to lidars for sensing aerosol atmospheric formations. Essence: lidar includes a laser (1), an optical plate (2), a photosensor (3), a receiving telescope (4), a plane-parallel glass plate (5), an interference filter (6), a video camera (7), a photoreceiving module (8) and registration system (9). Moreover, the wavelength of the interference filter (6) corresponds to the wavelength of the laser (1). Technical result: increasing the contrast of the image of the radiation spot on the sensing object. 1 ill.

Description

The utility model belongs to the field of technologies of optical methods for monitoring optical-physical parameters of the atmosphere and is intended for simultaneous remote determination of the speed of movement and optical-microphysical parameters of dense aerosol formations (clouds and smoke plumes) in the atmosphere. The model can also be used to solve environmental problems of the atmosphere, in particular, when monitoring the spread of forest fires and emissions from industrial enterprises.

The method of laser sounding of the atmosphere is based on the effects of light scattering on molecules and aerosol particles of the atmosphere, including in the opposite direction in the direction of the radiation source. The optical backscatter signal is received by the receiving optical telescope and then sent to a photodetector, where it is converted into an electrical signal. The electrical signal is converted into digital form using analog-to-digital converters or photon counters and sent for processing to a PC, where information about atmospheric parameters is extracted in accordance with signal processing algorithms.

The most promising means of laser sensing of the atmosphere are devices that combine the reception of signals both at the transmitted wavelengths of radiation and using the effects of Raman scattering of light. In most known systems, the vibrational-rotational spectrum of Raman scattering on nitrogen and oxygen molecules is used for this purpose. Since the cross section for light scattering on these gases is known, this makes it possible to determine the optical parameters of the medium directly from Raman scattering signals without any a priori assumptions about the properties of the atmosphere.

An analogue of a lidar for atmospheric sensing is the lidar of the Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences [1]. This device consists of a laser radiation source that simultaneously generates light pulses at three wavelengths: 1064, 532 and 355 nm, a receiving telescope with a set of interference filters that allows the selection of these optical signals, as well as Raman signals, photodetectors connected through electrical recording units signals to the PC.

The disadvantage of this and similar lidars is that, based on the results of measuring lidar signals, it is impossible to record the movement of a scattering object in a plane perpendicular to the direction of sensing, and to determine whether changes in signals are a consequence of changes in the object itself or a consequence of its movement at a certain speed. Similar problems can be solved when observing a scattering object using an additionally installed video camera.

There are known lidars on which video cameras were installed to control the pointing of the lidar to a specific object. As an example, let us take a lidar [2], which uses a television viewfinder, the image on which is formed using a rotating mirror, which is inserted, if necessary, into the receiving channel of the lidar. The disadvantage of such a device is the impossibility of simultaneously monitoring the movements of an object and recording lidar signals from it.

The closest analogue of the proposed lidar is a lidar for sensing aerosol formations (clouds and smoke plumes) in the atmosphere [3]. The lidar for probing dense aerosol formations includes a laser radiation source with a photosensor that produces an electric start pulse, a receiving optical telescope, at the output of which there is a photoreceiving module connected to the signal input of the lidar signal registration system, and a video camera, the optical axis of which is parallel to the axis telescope, while on the optical axis of the telescope, after the formation of a quasi-parallel beam of radiation, a glass plate is installed in front of the photodetector, dividing the radiation into two beams, in the path of one of which there is a video camera, the synchronization input of which is also connected to the output of the photosensor.

Lidar allows you to study the dynamics of aerosol formations in real time: spatial position, speed of movement and structure of the formation.

The disadvantage of this device is that when probing objects in the daytime, due to the low contrast, it is difficult to visually observe the laser radiation spot on the object against the background of scattered solar radiation through a video camera.

The proposed utility model eliminates this drawback, providing increased image contrast of the laser radiation spot on the sensing object.

The solution to this problem is achieved by installing an interference filter in front of the optical input of the video camera, which transmits radiation at the wavelength of the laser source and cuts off background solar radiation, thereby increasing the contrast of the laser spot image.

In fig. Figure 1 shows a schematic block diagram of a lidar for atmospheric sensing.

The lidar contains a common platform on which a laser (1), an optical plate (2) is rigidly connected to each other, and removes part of the probing laser radiation to a photosensor (3), which generates an electrical start pulse that is supplied to the synchronization inputs of the video camera (7) and the system registration (9).

In the immediate vicinity of the laser (1) a receiving telescope (4) is located in such a way that their optical axes are directed in one direction, and the angle of view of the telescope (4) covers the probing beam of the laser (1) directed into the atmosphere.

In the receiving channel of the lidar, after the receiving telescope (4) that forms a quasi-parallel beam of radiation, a plane-parallel glass plate (5) is installed, dividing the radiation into two beams, on the path of one of which there is a photodetector module (8) and a registration system (9), and in On the other side there is an interference filter (6) and a video camera (7), the observation axis of which coincides with the optical axis of the lidar.

The lidar works as follows. The laser radiation (1) is directed into the atmosphere, the radiation backscattered by a dense aerosol formation is collected by the receiving telescope (4) and is directed in the form of a parallel beam to the separation plate (5). Part of the received radiation is transferred by a plane-parallel plate (5) to an interference filter (6), and then to a video camera (7), on which an image of an aerosol object with a laser radiation spot in the center of the camera’s field of view can be observed. Part of the laser radiation is directed to a photosensor (3), which generates a starting pulse at the moment the laser pulse is released. This pulse is fed to the synchronization input of the lidar recording system (9), triggering the digitization of the lidar signal from the photodetector (8). At the same time, the starting pulse is supplied to the external synchronization input of the video camera (7), as a result of which the image of the object is recorded at the moment the laser pulse arrives at it.

Thus, the object being studied is observed with a laser spot on it, while the background solar radiation illuminating the object is cut off by an interference filter (6), thereby increasing the contrast of the image of the laser spot on the object recorded by the video camera (7).

Literature

1. Balin Yu.S., Bayrashin G.S., Kokhanenko G.P., Klemasheva M.G., Penner I.E., Samoilova S.V. Patent (Russia) No. 106966 Multi-wavelength lidar complex for monitoring the optical state of the atmosphere. Patent holder: IOA SB RAS. Registered in the State Register of Utility Models of the Russian Federation on July 27, 2011.

2. Kozyrev A.V., Shargorodsky V.D. Lidar complex for air pollution control. Patent of the Russian Federation No. 2022251, publication date 10.30.1994.

3. Balin Yu.S., Kokhanenko G.P., Klemasheva M.G., Penner I.E., Samoilova S.V., Novoselov M.M., Tchaikovsky A.P. Lidar complex for sensing dense aerosol formations // Patent (Russia), No. 155857 dated September 28, 2015. Patent holder: IOA SB RAS. Registered in the State Register of Utility Models of the Russian Federation on September 28, 2015.

Claims (1)

A lidar for probing aerosol atmospheric formations, including a laser radiation source rigidly interconnected on a common basis with a photosensor generating an electric start pulse, a receiving optical telescope, on the optical axis of which a glass plate is installed, dividing the radiation into two beams, in the path of one of which there is a video camera connected to the output of the photo sensor, and on the path of the other beam there is a photo receiver connected to the signal input of the lidar signal registration system, characterized in that an interference filter corresponding to the wavelength of the laser radiation source is installed in front of the optical input of the video camera.