DE102012015238A1 - Device for optical scanning of surfaces or objects for use as remote sensing system for gas, particularly for hydrocarbons, has light source and optical element rotated around rotational axis by first output for deflecting light rays - Google Patents

Abstract

The device has a light source and optical element (5) rotated around a rotational axis (19a,19b) by a first output (11) for deflecting light rays (2,12). The optical element has a first light-transmissive optical wedge plate (6) and a second light-transmissive optical wedge plate (7), where each wedge plate has an entry surface (8,8') and an exit surface (9,9') for the light rays.

Description

The invention relates to a device for optically scanning surfaces or objects, comprising a light source and an optical element rotating in a plane of rotation about a rotation axis by means of a first output for deflecting light radiation for optically scanning surfaces or objects.

A device of the type mentioned is from the WO 2004/092803 A1 known. The known device has a deflection mirror for deflecting light radiation. The deflecting mirror is connected to a drive and rotatable, wherein the mirror normal is tilted with respect to the axis of rotation. The deflection mirror is in a mounted version and is provided with at least one leveling element.

An important field of application for the aforementioned device is the remote sensing or remote location of gases, in particular of hydrocarbons, such as methane in the airspace or the atmosphere above the ground. The device may be part of a mobile optical remote sensing system and be installed in an aircraft, in particular in a helicopter. By flying over the route of a natural gas network, this can be monitored for leaks or leaks.

In remote sensing of gases, light emanating from the ground or atmosphere due to radiation emission or due to scattering or reflection of light from a light source is analyzed. For this purpose, the light radiation is focused with a telescope on a detector. It may be light radiation in the ultraviolet, visible or infrared spectral range.

If a high sensitivity is to be achieved and / or the amounts of light emitted from the atmosphere or a surface are relatively small, telescopes or receiving systems with large optical apertures must be used, whose diameter can be up to several 10 cm.

In order to be able to scan a surface quickly, either the receiving system has to be moved correspondingly quickly, or the field of view of the telescope must be continuously reoriented by means of a suitable device.

For receiving systems or telescopes with large optical apertures, the movement of the receiving system or the telescope due to the size and the resulting drive problems is out of the question.

Devices of the type mentioned, which are to be used for detecting gas, in particular for the purpose of monitoring natural gas pipelines, must be able to scan the largest possible area. Consequently, the deflection or the deflection angle for the light radiation must be as large as possible.

At the time of the WO 2004/092803 A1 known device there is a risk that at larger deflection or deflection angles the annular balance mass is tilted into the light radiation. For higher rotational speeds beyond the mechanical complexity is high.

The object of the invention is therefore to provide a structurally simple device of the type mentioned, can be scanned quickly and flexibly with the large areas.

This object is achieved by a device having the features of claim 1.

The device for optically scanning surfaces or objects with a light source and an optical element rotating in a plane of rotation about a rotation axis by means of a first output for deflecting light radiation for optically scanning surfaces or objects is characterized in that the optical element has a first translucent optical wedge plate and at least one second translucent optical wedge plate, that each wedge plate has an entrance surface and an exit surface for the light radiation that the entrance surface and the exit surface of each wedge plate are not parallel to each other, so that the light radiation upon entry and / or exit due to refraction is deflected, that the first and the second wedge plate in the path of the light radiation are arranged one behind the other and that the position of the first and the second wedge plate about the axis of rotation relative to each other is adjustable to the deflection angle to change the light radiation.

A beam of light passing through the translucent optical wedge plates is deflected according to the law of refraction. Since it is wedge-shaped plate-shaped optical elements, changes in the passage of a light beam through the wedge plates whose angle or its direction.

Optical wedge plates for deflecting light radiation are known per se. The disadvantage is that the deflection angle, d. H. the deviation of the light beam from its original direction due to refraction at the front side or the light entry side and the rear side or the light exit side is only dependent on the properties of the optical material (refractive index).

The invention is based on the recognition that the deflection angle of the light beam is variable, if one arranges at least two wedge plates in succession and allows the adjustment of the first relative to the second wedge plate in the circumferential direction relative to each other.

Since the first and second wedge plates have different thicknesses across the cross section, the light beam will be deflected at different angles from the original beam direction, depending on the angular position in which the first wedge plate is in relation to the second wedge plate.

Preferably, the axes of rotation of the first wedge plate and the second wedge plate are coaxial with each other. The plane of rotation is perpendicular to the axes of rotation. Alternatively, the axis of rotation of the first wedge plate can be tilted with respect to the axis of rotation of the second wedge plate. The axes of rotation are merely imaginary geometrical axes around which the wedge plates rotate. The wedge plates are mounted and driven from the outside.

Preferably, both wedge plates rotate with the same direction of rotation. Alternatively, the direction of rotation of the first wedge plate may be different to the direction of rotation of the second wedge plate.

The first and second wedge plates usually rotate at the same angular velocity. As a result of the rotation of both wedge plates at the same angular velocity, the light beam is guided on a circle on the target or on the ground.

In order to adjust the position of the first and the second wedge plate relative to each other about the axis of rotation in a preferred embodiment, the rotational speeds of the first wedge plate and the second wedge plate differ for at least a predetermined period of time.

Alternatively, the adjustment of the position of the first wedge plate and the second wedge plate about the axis of rotation relative to each other by means of a second drive. This can have an electronic control and be controlled.

In the simplest case, the position of the first wedge plate relative to the second wedge plate and thus the size of the deflection angle is fixed. Alternatively, the deflection angle can also be changed continuously. Advantageously, the adjustment of the first wedge plate relative to the second wedge plate and thus the adjustment of the deflection angle and the deflection angle is infinitely variable.

The angles, with the front and back are inclined to each other, may be the same size in the first and the second wedge plate. But it is also possible to use two wedge plates with different wedge angle and / or of different material.

The wedge plates may be sapphire or zinc sulfide. It has proved favorable in tests in the infrared spectral range if the first and the second wedge plate consist of germanium.

The cross section of the wedge plates can be circular. But it can also be used other forms, which are installed in a holder whose outer enclosure is circular.

Preferably, each one of the two surfaces of each wedge plate, d. H. in each case the entrance surface or the exit surface, parallel to the plane of rotation.

In the context of the invention, the entry surface of the first wedge plate and the exit surface of the second wedge plate preferably run parallel to the plane of rotation. The exit surface of the first wedge plate and the entry surface of the second wedge plate then run as a rule not parallel, but at an angle to each other.

Alternatively, the exit face of the first wedge plate and the entry face of the second wedge plate may be parallel to the plane of rotation.

A further advantageous embodiment is that the entry surfaces of both wedge plates are parallel to the plane of rotation. The exit surface of both wedge plates extend in this case usually at an angle to each other.

In the context of the invention, it is also possible that the exit surface of both wedge plates extend parallel to the plane of rotation. The entry surfaces of both wedge plates are then usually at an angle to each other.

Finally, it is possible that none of the entry and exit surfaces of both wedge plates is parallel to the plane of rotation.

The choice of one of the aforementioned variants depends on the requirements of the particular application. For example, a variant may be required in which certain residual reflections are avoided back into the light source.

Since large aperture telescopes can be used, the device is particularly suitable as part of an optical remote sensing system for gases, particularly for hydrocarbons such as methane or natural gas. It is special for such applications advantageous if the light radiation originates from a laser light source. Within the scope of the invention, the light radiation can also be sunlight. It may also be the light radiation, z. B. heat radiation emitted by objects or surfaces.

In the context of the invention, the device is characterized in that the device comprises a light receiving system with a telescope and a detector for backscattered light and that the optical element in the path of the transmitted light from the light source and in the way of a surface or an object in the direction on the receiving system reflect light radiation is arranged such that the deflection of the transmitted and the reflected light radiation takes place synchronously.

It is advantageous if the axes of rotation of the first and the second wedge plate with the telescopic axis extend coaxially.

Alternatively, the axes of rotation of the first and / or the second wedge plate relative to the telescopic axis can be tilted.

Preferably, the light source is designed as a laser light transmitting device. The device is designed as part of a mobile optical remote sensing system for gases, in particular for hydrocarbons such as methane.

The light beam describes a circle on the target surface. As a result, the scanning speed can be large. If you move the device in a linear direction, the beam on the ground describes a cycloid.

Preferably, the device is installable in an aircraft and provided with a navigation device. Since the drive for the rotational movement does not have to apply large acceleration forces, a low-cost drive with low power can be used. The navigation device may be a known Global Positioning System (GPS).

The device according to the invention can be particularly advantageous for the monitoring of underground gas pipelines by means of an aircraft, z. B. a helicopter can be used. In this way, leaks in a pipeline network can be quickly detected by flying over the route, in particular a helicopter.

The invention will be explained below with reference to an embodiment.

The drawing shows in

1 schematically a device according to the invention as part of a mobile optical remote sensing system for gases, in particular for hydrocarbons with an optical element having a first and a second wedge plate;

2 the configuration of the two wedge plates as in 1 wherein the first and second wedge plates are in a position with respect to one another that does not deflect the light beam;

3 further configuration of the first and second wedge plates;

4 another configuration of the first and second wedge plate;

5 another configuration of the first and the second wedge plate;

6 a final configuration of the first and second wedge plates.

In the 1 shown schematically device is part of a mobile optical remote sensing system or remote sensing system for methane or natural gas for detecting a leak in underground gas pipelines. The remote sensing system is installed in a helicopter, not shown, and connected to a navigation system, not shown. The helicopter flies at a speed of about 80 to 100 km / h over the route of the natural gas pipeline.

From a laser light source 1 becomes a laser light beam 2 sent on the surface to be scanned or the ground 3 distributed.

In the way of the transmitted laser light beam 2 in the manner known per se by means of mirrors 4 is deflected, there is an optical element 5 with a first wedge plate 6 and a second wedge plate 7 , Each wedge plate has an entrance surface 8th respectively. 8th' and an exit surface 9 respectively. 9 ' for the light radiation, which are not parallel to each other, to redirect the light radiation due to refraction.

The entrance area 8th the first wedge plate 6 and the exit surface 9 ' the second wedge plate are parallel to a plane of rotation 10 ,

The first wedge plate 6 and the second wedge plate 7 rotate uniformly and relatively quickly by means of a first drive 11 , The rotational speed is, for example, 300 rpm.

The light beam directed at the ground 2 is called light radiation 12 scattered back and kicked through the optical element 5 , The light radiation 12 will be at the back 9 ' and the front 8th' the second wedge plate 7 and the back 9 and the front 8th the first wedge plate 6 synchronous to the light beam 2 diverted. The one from the ground 3 or the atmosphere located above scattered light radiation is applied to a light receiving system 13 with a telescope 14 derived. The telescope has a large optical aperture. The light radiation is with the telescope 14 collected and on the detector 15 focused.

The configuration of the two wedge plates 6 . 7 is chosen so that unwanted residual reflections back into the light source 1 and in the light receiving system 13 be avoided.

The rotational angle position of the first wedge plate 6 may be in relation to the rotational angle position of the second wedge plate 7 by means of a second drive 16 be adjusted continuously. In this way, the deflection angle of the transmitted and the backscattered light beam 2 . 12 adjusted and adjusted to the width of the surface to be scanned and the requirement due to the topography of the target area. The transmitted light beam 2 describes a circular path. By superimposing the scanning with the flight movement of the helicopter, the measuring points lie on a cycloid.

The axes of rotation 19a and 19b the first and the second wedge plate 6 . 7 are coaxial with each other and coaxial with the telescopic axis 17 ,

The light beam emitted by the laser light source 2 becomes parallel to the telescope axis 17 sent. In the event of a leak, the methane content in the atmosphere above the ground is increased because natural gas consists mainly of methane. Methane absorbs the emitted light at certain wavelengths, so that the concentration of methane in the atmosphere can be determined by evaluating the returning light.

2 can be seen that the entrance surface 8th the first wedge plate 6 and the exit surface 9 ' the second wedge plate 7 parallel to the plane of rotation 10 run. The axes of rotation 19a and 19b the two wedge plates 6 . 7 are coaxial. In the illustrated position of the first wedge plate 6 in relation to the second wedge plate 7 about the axis of rotation relative to each other extend the exit side 9 the first wedge plate 6 and the entry side 8th' the second wedge plate 7 parallel to each other. In this position the wedge plates 6 . 7 (About the axis of rotation relative to each other) is the light beam, not shown 2 not distracted.

3 shows the same configuration as 2 , where the wedge plates 6 . 7 take a different position about the axis of rotation relative to each other. The entrance area 8th the first wedge plate 6 and the exit surface 9 ' the second wedge plate 7 run parallel to the plane of rotation 10 and at a right angle to the sidewall 18 , The exit surface 9 the first wedge plate 6 and the entrance area 8th' the second wedge plate 7 are at an angle to each other. In 1 is shown as in the in 3 shown position of the wedge plates 6 . 7 about the axis of rotation relative to each other the light beam 2 is diverted.

In 4 another configuration is shown where the exit surface 9 the first wedge plate 6 and the entrance area 8th' the second wedge plate 7 parallel to the plane of rotation 10 run. The rotary axes, not shown 19a and 19b the two wedge plates 6 . 7 are coaxial. The entrance area 8th the first wedge plate 6 and the exit surface 9 ' the second wedge plate 7 are at an angle to each other.

When configuring 5 run the entrance surface 8th the first wedge plate 6 and the entrance area 8th' the second wedge plate 7 parallel to the plane of rotation 10 , The rotary axes, not shown 19a and 19b the two wedge plates 6 . 7 are coaxial. The two exit surfaces 9 . 9 ' run at the position shown here, the two wedge plates 6 . 7 about the axis of rotation relative to each other in parallel.

6 shows a configuration in which the two exit surfaces 9 . 9 ' the first wedge plate 6 and the second wedge plate 7 parallel to the plane of rotation 10 run. The rotary axes, not shown 19a and 19b the two wedge plates 6 . 7 are coaxial. The entrance area 8th the first wedge plate 6 and the entrance area 8th' the second wedge plate 7 run at the position shown here, the two wedge plates 6 . 7 in the direction of rotation relative to each other in parallel.

Modifications are readily possible within the scope of the invention. So it is possible that none of the entrance and exit surfaces ( 8th . 8th' . 9 . 9 ' ) of the first and second wedge plates 6 . 7 parallel to the plane of rotation 10 runs.

LIST OF REFERENCE NUMBERS

1

Laser light source

2

transmitted light beam

3

ground

4

mirror

5

optical element

6

first wedge plate

7

second wedge plate

8th

Entrance area wedge plate

9

Exit surface wedge plate

10

plane of rotation

11

first drive

12

backscattered light steel

13

Light receiving system

14

telescope

15

detector

16

second drive

17

telescopic axis

18

Side wall

19a

first axis of rotation

19b

second axis of rotation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2004/092803 A1 [0002, 0009]

Claims (14)

Device for the optical scanning of surfaces or objects, with a light source and in a plane of rotation ( 10 ) about a rotation axis ( 19a . 19b ) by means of a first output ( 11 ) rotating optical element ( 5 ) for deflecting light radiation, characterized in that the optical element ( 5 ) a first translucent optical wedge plate ( 6 ) and at least one second translucent optical wedge plate ( 7 ), that each wedge plate ( 6 . 7 ) an entrance surface ( 8th . 8th' ) and an exit surface ( 9 . 9 ' ) for the light radiation ( 2 . 12 ), that the entrance surface ( 8th . 8th' ) and the exit surface ( 9 . 9 ' ) each wedge plate ( 6 . 7 ) are not parallel to each other, so that the light radiation ( 2 . 12 ) is deflected on entry and / or exit due to refraction that the first and the second wedge plate ( 6 . 7 ) in the path of light radiation ( 2 . 12 ) are arranged one behind the other and that the position of the first and the second wedge plate ( 6 . 7 ) about the axis of rotation ( 19a . 19b ) is adjustable relative to each other to the deflection angle of the light radiation ( 2 . 12 ) to change. Device according to claim 1, characterized in that the axis of rotation ( 19a ) of the first wedge plate ( 6 ) and the axis of rotation ( 19b ) of the second wedge plate ( 7 ) extend coaxially. Device according to claim 1, characterized in that the axis of rotation ( 19a ) of the first wedge plate ( 6 ) with respect to the axis of rotation ( 19b ) of the second wedge plate ( 7 ) is tilted. Device according to one of claims 1 to 3, characterized in that the direction of rotation of the first wedge plate ( 6 ) equal to the direction of rotation of the second wedge plate ( 7 ). Device according to one of claims 1 to 3, characterized in that the direction of rotation of the first wedge plate ( 6 ) different to the direction of rotation of the second wedge plate ( 7 ). Device according to one of claims 1 to 5, characterized in that the rotational speeds of the first wedge plate ( 6 ) and the second wedge plate ( 7 ) at least for a predetermined period of time to determine the position of the first and second wedge plates ( 6 . 7 ) relative to each other about the axis of rotation ( 19a . 19b ) to adjust. Device according to one of claims 1 to 6, characterized in that the adjustment of the position of the first wedge plate ( 6 ) and the second wedge plate ( 7 ) about the axis of rotation ( 19a . 19b ) relative to each other by means of a second drive ( 16 ) he follows. Device according to one of claims 1 to 7, that the adjustment of the position of the first wedge plate ( 6 ) and the second wedge plate ( 7 ) about the axis of rotation ( 19a . 19b ) takes place continuously relative to each other. Device according to one of claims 1 to 8, characterized in that either the entrance surface ( 8th . 8th' ) or the exit surface ( 9 . 9 ' ) each wedge plate ( 6 . 7 ) parallel to the plane of rotation ( 10 ) runs. Device according to one of claims 1 to 8, characterized in that none of the inlet and outlet surfaces ( 8th . 8th' . 9 . 9 ' ) of the first and second wedge plates ( 6 . 7 ) parallel to the plane of rotation ( 10 ) runs. Device according to one of claims 1 to 10, characterized in that the device is a light receiving system ( 13 ) with a telescope ( 14 ) and a detector ( 15 ) for backscattered light and that the optical element ( 5 ) in the path of the light radiation emitted by the light source ( 2 ) and in the path of a surface or an object towards the light receiving system ( 13 ) reflect light radiation ( 12 ) is arranged such that the deflection of the transmitted and the reflected light radiation ( 2 . 12 ) takes place synchronously. Device according to claim 11, characterized in that the axes of rotation ( 19a . 19b ) of the first and the second wedge plate ( 6 . 7 ) coaxial with the telescopic axis ( 17 ). Device according to one of claims 1 to 12, characterized in that the light source ( 1 ) is designed as a laser light transmitting device and that the device is designed as part of a mobile optical remote sensing system for gases, in particular for hydrocarbons. Apparatus according to claim 13, characterized in that the device is provided with a navigation device and can be installed in an aircraft.

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