EP4038417A1

EP4038417A1 - Device for a satellite laser distance measurement, and method for a satellite laser distance measurement

Info

Publication number: EP4038417A1
Application number: EP20780168.9A
Authority: EP
Inventors: Paul Wagner; Daniel Hampf
Original assignee: Deutsches Zentrum fuer Luft und Raumfahrt eV
Current assignee: Deutsches Zentrum fuer Luft und Raumfahrt eV
Priority date: 2019-09-30
Filing date: 2020-09-23
Publication date: 2022-08-10
Also published as: DE102019126336A1; US20220342043A1; WO2021063775A1

Abstract

The invention relates to a device (500) for a satellite laser distance measurement, comprising a base segment (520) and an optical segment (522) which is supported by the base segment (520) and has a telescope mounting (510) with an azimuth axis (506) and an elevation axis (508), wherein a transmitter telescope (120), a receiving telescope (200), and a laser (100) coupled to the transmitter telescope (120) are arranged on the telescope mounting (510). The invention also relates to a method for operating such a device (500).

Description

Description title

Device for satellite laser distance measurement and method for satellite laser distance measurement prior art

The invention relates to a device for satellite laser distance measurement and a method for satellite laser distance measurement.

Satellite laser rangefinding (SLR) technology has evolved from a geodetic tool to a widely used mission support tool. Currently, about eighty satellite missions rely on continuous laser ranging data for accurate position information, including several earth observation satellites and many navigation satellites. Even more satellites have used SLR measurements in their early orbit phase to calibrate or verify their on-board navigation. In the future, the demand for satellite laser rangefinding could continue to grow as more and more operators of

Small satellites or even the proposed mega-constellations recognize the potential of this technology to obtain centimeter-accurate orbit information during and also after the mission. Only a small and lightweight retroreflector is required on board the satellites. A worldwide network of around forty stations is available for localization on site (International Laser Ranging Service, ILRS). Currently, the ILRS tracking list contains about thirty missions in low orbit (LEO) and about fifty targets in higher orbits from 19,000 to 24,000 km altitude, mostly GNSS satellites ("Global Navigation Satellite System"). Typically, a good SLR station today achieves an accuracy of approx. 1 cm in the

Distance measurement and is able to work day and night.

However, many existing ILRS stations are reaching their limits in terms of the number of satellites observed. In addition, worldwide coverage is quite inhomogeneous, with many stations in

Europe and Asia, only a few in Africa and America and none in very high northern and southern latitudes. Some new stations are under construction, others are being planned worldwide. These stations are integrated in their own buildings, which often occupy an observatory and adjoining laboratory rooms. Both the investment for the construction and the

Installations as well as operating costs are significant and represent a serious obstacle to expanding the network.

In the publication by F. Pierron et al. "Status and New Capabilities of the French Transportable Laser Ranging Station," Proceedings 11th

International Workshop on Laser Ranging, Deggendorf, Germany, September 21-25, 1998, describes a transportable system with a total weight of 300 kg in 8 containers.

Disclosure of the invention

The object of the invention is to create an inexpensive device for satellite laser distance measurement.

Another object is to specify a method for operating such a device. The tasks are achieved by the features of the independent claims. Favorable configurations and advantages of the invention emerge from the further claims, the description and the drawing.

A device for satellite laser distance measurement is proposed, with a base segment and an optics segment supported by the base segment. The optics segment has a telescope mount with an azimuth axis and an elevation axis. A transmitter telescope, a receiver telescope and a laser coupled to the transmitter telescope are arranged on the telescope mount.

The receiving telescope can be, for example, a Newton telescope with an aperture diameter of 20 cm.

By arranging the laser on the telescope mount, the beam guidance between the laser and the transmitter telescope can be provided outside the axes of rotation. This arrangement of the laser on the telescope mount advantageously eliminates the need for an expensive and complex Coude beam guide, in which a beam feed-through for the laser beam has to be guided through the axes of rotation of the telescope mount. In this way, the telescope mount and the overall construction can be reduced considerably in terms of size and weight. As a result, the costs for such a device can be reduced significantly, since a commercially available telescope mount can be used.

Small, powerful and robust lasers make it possible to place the laser on the telescope mount. Lasers with relatively low pulse energies and high repetition rates can be used which, with the same average power, are smaller and more cost-effective than the high-energy lasers usually used in satellite distance measurement. The device can advantageously be designed to be transportable. The dimensions and weight allow the device to be manufactured at one location and transported to another location. It is therefore advantageously possible to dispense with operating the telescope mount on a foundation, as is otherwise customary. Instead, any technique of the device can be mounted in the transportable device. Any inaccuracies that may result from this can be compensated for using a suitable method, such as so-called closed-loop tracking and the creation of a so-called pointing model.

The device can have a modular structure in order to meet customer-specific requirements. The complete device can contain only a minimal set of easily replaceable components, so that on-site maintenance is facilitated. The components used in the device are advantageously commercially available components. The device can be adapted for different requirements with practically no further development effort.

The entire structure, including all of the control and data acquisition electronics, can be housed in a small container, for example an aluminum container. Favorable dimensions are, for example, 1.80 mx 1.20 mx 1.60 m.

The base segment carries the telescope mount and is correspondingly stable and torsion-resistant. Control electronics and control computers can be protected from the weather and temperature-controlled or air-conditioned. The control software can advantageously be designed to operate the device in a practically completely automated manner, in particular the control of the hardware components in the device. This allows the device, from recording the weather to the

Measurement planning, control of the telescope mount, recording of the images, controlling the laser, beam alignment, recording of the distance data and the evaluation of the distance data and images to carry out all the necessary process steps independently. The operating and maintenance effort can advantageously be reduced.

Corrections with the pointing model or closed loop tracking can also be carried out automatically.

According to a favorable embodiment of the device, the telescope mount can have a swivel base with the azimuth axis and a

Have rotary shaft with the elevation axis, around which the telescopes synchronously with each other and the laser synchronously with the

Transmitter telescope are pivotable. The laser can therefore advantageously be arranged on the counterweight axis of the receiving telescope, namely the elevation axis, as a result of which the telescope mount can be balanced in terms of weight.

Objects such as satellites and missile bodies can advantageously be equipped with small retroreflectors. Such reflectors are usually smaller than 20 mm x 20 mm, weigh only a few grams and do not require any energy. Using the device according to the invention, the distance measurement to these objects can be a routine task for every existing or future SLR station. The distance to a satellite can be determined with an accuracy in the centimeter range, and its trajectory can usually be predicted with uncertainties of a few meters. In addition, when using several retroreflectors, the orientation of the satellite can be determined with a resolution of up to 1 degree. During the life of a mission, this can support many position sensitive tasks that might otherwise require heavy, bulky, and energy consuming on-board position sensors.

According to a favorable embodiment of the device, a carrier plate of a carrier unit can extend at a distance from the elevation axis between the two telescopes. In particular, the

Carrier unit comprise the carrier plate, which is arranged parallel to the elevation axis, and at least one further carrier plate, which is arranged parallel to the azimuth axis. The two carrier plates can advantageously be rigidly connected to one another, in particular via one or more angle elements. The transmitter telescope and the other

Carrier plates can be connected to one another. The rigid support unit stabilizes the structure on the telescope mount and offers stable positioning of the components. The carrier plates can advantageously be designed in the manner of a breadboard, also known as a breadboard. This enables flexible arrangement and alignment of the components on the respective carrier plate as well as modularization.

According to a favorable embodiment of the device, the telescope mount can have a transmitter optics coupled to the transmitter telescope and one coupled to the receiving telescope

Have receiving optics. In particular, the transmitter optics can be fastened to the one carrier plate and the receiving optics can be fastened to the further carrier plate. This facilitates the modular structure of the device. According to a favorable embodiment of the device, the transmitter optics can comprise one or more of the following components: (i) a laser energy control unit, in particular with a beam attenuation unit; (ii) a laser energy control unit, in particular with a beam splitter and / or a measuring head for energy and / or power; (iii) a diaphragm, in particular a mechanical diaphragm; (iv) a variable beam expansion unit; (v) a beam direction control unit; in particular a moving mirror; (vi) a beam splitter; (vii) a transmitter camera, especially one

Transmitter camera with imaging optics; (viii) a starting diode, (ix) at least one mirror; (x) at least one retroreflector.

The components can be mounted compactly on one of the carrier plates of the carrier unit. The transmitter optics are used for expansion and

Collimation of the laser beam. A diameter of at least 30 mm, for example at most 100 mm, is favorable. Furthermore, energy regulation can take place and the laser pulse energy can be monitored.

According to a favorable embodiment of the device, the receiving optics can comprise one or more of the following components: (i) a beam splitter for splitting the radiation received by the receiving telescope into visible light and infrared light; (ii) a tracking camera in the focus of the receiving telescope; (iii) a relay

Optics unit, which is provided as further imaging optics; (iv) a band pass filter; (v) a detector and / or an optical fiber for feeding the received signals. In the receiving optics, the received by the receiving telescope

Radiation can be divided into the visible spectrum and the infrared spectrum. According to a favorable embodiment of the device, the laser can have near infrared (NIR) radiation, in particular IR-B with a wavelength between 1500 nm to 1750 nm. In particular, the laser of laser class I according to DIN EN 60825-1 from the year

2004, according to which the accessible laser radiation is harmless under reasonably foreseeable conditions, in particular harmless to the eye as long as the cross-section is not reduced by optical instruments (magnifying glasses, lenses, telescopes) Public.

According to a favorable embodiment of the device, the laser can have laser pulses with a pulse length in the picosecond range to nanosecond range, in particular in the range from 0.5 picoseconds to 100 nanoseconds, with a pulse energy of 1 pJ to 1 mJ. Diode-pumped solid-state lasers are advantageous.

A high pulse repetition frequency is advantageous in order to be able to record a large number of measured values. A pulse repetition frequency much greater than 10 kHz, in particular greater than 30 kHz, is advantageous.

According to a favorable embodiment of the device, the basic segment can contain one or more of the following components: (i) a control computer; (ii) control electronics, in particular with an event timer and a trigger generator. The control computer can advantageously control any hardware, such as lasers, telescope mounts, cameras, detectors, sensors, laser beam direction, laser energy. The control computer advantageously has a network connection for remote control of the device.

According to a favorable embodiment of the device, the optics segment can have at least one cover. In particular, the transmitter telescope, the receiver telescope and the carrier unit can have separate covers. A separate

Covering the telescopes and the carrier unit reduces contamination of the components if individual components have to be exposed for maintenance purposes. According to a favorable embodiment of the device, an interior of the at least one cover of the optics segment can be air-conditioned. In particular, a climate control unit can be arranged in the base segment. Problems with humidity or strong temperature fluctuations can be avoided.

According to a further aspect of the invention, a method for operating a device according to the invention is proposed. The method can be used for satellite laser range measurement with a device. The device comprises a base segment and an optics segment supported by the base segment, the one

Has telescope mount, with azimuth axis and elevation axis, wherein a transmitter telescope and a receiving telescope and a laser coupled to the transmitter telescope are arranged on the telescope mount. When the transmitter telescope moves, the laser is moved synchronously with the transmitter telescope. The synchronous movement of the laser with the

Transmitter telescope, a stable transmission of the laser pulse can take place without complex, variable beam guidance. This makes it possible to reduce the weight and installation space of the device. In addition, the system's susceptibility to errors can be reduced in this way.

According to a favorable embodiment of the method, a distance measurement of an object can take place with the following steps: (i) calibration of a tracking camera of the receiving optics; (ii) Measurement of the position of the object to be measured on the camera image of the

Tracking camera; (iii) Alignment of the telescope mount using coordinates converted from the measurement of the image; (iv) Repeating steps (ii) and (iii) as long as the converted coordinates have a predetermined deviation from a nominal position. This procedure enables very precise alignment of the

Receiving telescope on the object to be measured can be achieved in a favorable manner.

According to a favorable embodiment of the method, a laser beam can be aligned on an object with the following steps:

(i) checking the focusing of the transmitter camera on the laser beam and determining the focus position of the laser beam reflected back by a retroreflector in the transmitter camera;

(ii) determining a motor position in relation to the focus position; (iii) Observing a position of at least one object and determining the

Object position of the imaged object in the transmitter camera after removing the retroreflector and temporarily blocking the laser beam; (iv) Converting the object position into the motor position. In this way it can advantageously be determined which motor position correlates with which camera position. When checking the focusing of the transmitter camera, at least one retroreflector is placed in front of the exit aperture of the transmitter telescope and is removed after the calibration procedure.

According to a favorable embodiment of the method, a

Object distance can be determined with the following steps: (i) determining a point in time of an emission of a laser pulse onto an object by means of an event timer; (ii) determining a point in time upon detection of a photon, in particular the laser pulse reflected back from the object to be measured, by an assigned detector; (iii) transferring the times to an evaluation unit, in particular a control computer; (iv) Correlation of the measured values of emission and detection. In this way, an object distance can be determined with great accuracy.

According to a favorable embodiment of the method, a

Data evaluation takes place with the following steps: (i) Calibration of the device by measuring the distance to an object with a known distance; (ii) Correlation of times when

Laser pulses and received signals; (iii) comparing an expected transit time to an object to be examined to a transit time measured thereon; (iv) extracting correlated data; (v) Averaging the distance measurements on the object to be examined. In this way, an object distance can be determined with great accuracy. Control software can thus be able to record data in a fully automated manner. This includes any control of the hardware components in the system. As a result, the system can independently carry out all the necessary process steps from recording the weather situation to measurement planning, controlling the mount, recording the images, controlling the laser, beam alignment, recording the distance data and evaluating the distance data and images, so that no additional operation is necessary. Possible corrections with a pointing model or closed-loop tracking can also be carried out automatically.

The control software can thus have a modular structure and use open source software as far as possible. This enables every user to independently expand the system according to their needs.

drawing

Further advantages emerge from the following description of the drawings. Exemplary embodiments of the invention are shown in the figures. The figures, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

It shows by way of example:

1 shows a schematic structure of essential components of a transmitter optics of a device for satellite laser distance measurement according to an embodiment of the invention; 2 shows a schematic structure of essential components of a receiving optics of a device for satellite laser distance measurement according to an embodiment of the invention;

3 shows a schematic side view of a device for satellite laser range measurement according to a

Embodiment of the invention;

FIG. 4 shows a plan view of the transmitter optics of the device for satellite laser range measurement according to FIG. 3;

FIG. 5 shows a plan view of the receiving optics and the laser of the device for satellite laser distance measurement according to FIG. 3;

6 shows an isometric representation of the receiving optics with telescope mounting;

7 shows an isometric representation of the device for satellite laser range measurement according to FIG. 3 with a cover;

8 shows an isometric representation of transmitter optics and receiving optics with telescope mounting according to a further exemplary embodiment of the invention;

9 shows a flow diagram of a method for measuring the distance of an object according to an exemplary embodiment of the invention; 10 shows a flow diagram of a method for aligning a laser beam onto an object according to an exemplary embodiment of the invention; 11 shows a flow chart of a method for determining an object distance according to an exemplary embodiment of the invention; and

12 shows a flow diagram of a method for data evaluation according to an exemplary embodiment of the invention.

EMBODIMENTS OF THE INVENTION In the figures, components of the same type or having the same effect are numbered with the same reference symbols. The figures show only examples and are not to be understood as restrictive.

Directional terminology used in the following with terms such as “left”, “right”, “up”, “down”, “in front of” “behind”, “after” and the like serves only for a better understanding of the figures and is in no way intended to restrict the Representing the general public. The components and elements shown, their design and use can vary according to the considerations of a person skilled in the art and can be adapted to the respective applications.

Figure 1 shows a schematic structure of essential components of a transmitter optics 150 of a device 500 for satellite laser range measurement according to an embodiment of the invention. The device can advantageously be mobile and suitable for road transport. The transmitter optics 150 consists of the laser 100 as the actual laser radiation source, the transmitter unit with various components for beam conditioning and the transmitter telescope 120 as the final beam expansion unit. A pulsed laser beam is generated in the laser 100 and can be collimated using an optional laser collimator.

Favorable lasers 100 have laser pulses with a pulse length in the picosecond range to nanosecond range, in particular in the range from 0.5 picoseconds to 100 nanoseconds, with a

Pulse energy from 1 pJ to 1 mJ and with a wavelength between 1500 nm and 1750 nm. A high pulse repetition frequency is advantageous in order to be able to record a large number of measured values. A pulse repetition frequency much greater than 10 kHz, in particular greater than 30 kHz, is advantageous.

Suitable, commercially available lasers are, for example, pulsed erbium fiber lasers with a central wavelength of 1550 nm and pulse energies up to 50 mJ, which are available for example from IPG Photonics Corporation, Oxford, USA, under the name ELPN 1550, with pulse lengths from 1 to 100 ns and pulse repetition rates in the range 10 kHz to 100 MHz. A pulsed erbium laser in the same wavelength range is also available under the designation ELPF-10-500-10-R with a pulse energy of up to 10 mJ, pulse lengths of 500 fs and pulse repetition rates in the range from 100 kHz to 2 MHz.

The transmitter optics 150 are used to expand and collimate the laser beam, preferably to a diameter of less than 100 mm. Furthermore, the transmitter optics 150 are used for energy regulation and control of the laser pulse energy, as well as for beam direction regulation and control of the laser beam direction. The optical axis of the transmitter telescope 120 should be arranged as parallel as possible to the optical axis of the receiving telescope 200. A starting diode 102 is arranged adjacent to the laser 100 and detects a rising edge of the laser pulse and forwards it to an event timer of control electronics 514 of the device 500. By comparing the edges of outgoing laser pulses and the

The distance to the object can be determined on flanks of laser pulses reflected back from an object to be tracked, for example a satellite. The starting diode 102 only needs to receive a very small portion of the laser light for pulse detection, so scattered light or transmission through an imperfect mirror is sufficient.

Appropriately, the diode should always receive the same pulse energy.

Suitable, commercially available event timers are available, for example, from PicoQuant GmbH, Berlin, Germany. A device called the HydraHarp 400 can process trigger pulse widths of 0.5 to 30 ns with a rising edge of 2 ns. The time accuracy achieved is less than 12 ps rms. The maximum count rate is 12.5 x 10 ⁶ events / s.

The laser beam then passes through a laser energy control unit 104, in which the laser beam energy is controlled via a beam attenuator, which can preferably be reflective. A notch filter in one over one can be advantageous for this

Electric motor driven filter wheel can be used.

The energy of the laser beam is then measured in a laser energy control unit 106 which has an energy or power measuring head. The laser pulse is decoupled into the laser energy control unit 106 via a beam splitter 105, for example in the form of a 90:10 or 99:01 beam splitter. The laser beam is guided via a mirror 108 into a diaphragm 110, for example a mechanical diaphragm 110, by means of which the laser beam can be interrupted.

This is optionally followed by a variable beam expansion and focusing unit 112. The beam expansion unit 112 is, for example, an afocal optical system which has a collimated beam as input and output. This allows the diameter and angular translation of the laser beam to be changed and is determined by the magnification of the optical system.

The direction of the laser beam can be set electronically by means of a movable mirror 114 that follows, which can be adjusted by a motor via two mutually perpendicular axes.

The subsequent IRA / IS beam splitter 118 can separate radiation in the infrared spectrum, which is used to determine the distance, and radiation in the visible spectrum. The outgoing infrared laser light is directed via the beam splitter 118 into the transmitter telescope 120 for the final beam expansion. The transmitter telescope 120 images from infinity to infinity.

Incident visible light can be guided from the transmitter telescope 120 via the beam splitter 118 into the transmitter camera 116. The transmitter camera 116 with its imaging optics is focused on the laser wavelength. The image sensor is arranged in the focal point of the optics.

Retroreflectors 122 can be arranged temporarily in front of the exit aperture of the transmitter telescope 120. The laser light is reflected back in the same direction. Through the imperfect IRA / IS Beam splitter 118 reaches the transmitter camera 116, on which the laser beam is focused, enough light. A plurality of retroreflectors 122 or movement of the retroreflector 122 perpendicular to the optical axis can be used to check whether the transmitter camera 116 is focused for the laser light. The ray is always seen as a point on the same

Position focused on the transmitter camera 116 and must not move. When the direction of the beam is changed by the movable mirror 114, it can now be determined which beam direction corresponds to which focus position on the transmitter camera 116.

FIG. 2 shows a schematic structure of essential components of a receiving optics 250 of a particularly mobile device 500 for satellite laser range measurement according to an exemplary embodiment of the invention.

Incident light 230, which includes both the backscattered laser beam and visible light from the object that is irradiated by the sun, is implemented by means of the receiving telescope 200 via the imaging receiving optics, for example the concavely curved primary mirror 202, which in particular is spherically or parabolically curved can, and the output mirror 204 is directed to an IRA / IS beam splitter 206, which transmits the visible spectrum. The receiving telescope 200 is designed as an imaging system. The visible light is directed to a tracking camera 210, which in the

Focus of the receiving telescope 200 is arranged. The tracking camera 210 records the object to be measured and measures its position relative to the optical axis of the receiving telescope 200. A suitable, commercially available tracking camera is offered, for example, by Andor from the Oxford Instruments Group under the name ZYLA 5.5. The camera tells you 2560x2160 (5.5 megapixel) CMOS sensor and works with readout rates of up to 560 MHz.

The infrared portion of the incident light is directed via the beam splitter 206 into a relay optical unit 212, which has a second optical

Imaging to make the field of view in front of the following detector 218 as large as possible. The relay optical unit 212 can focus the incident light directly on the detector 218 if this is directly connected. Alternatively, the relay optics unit 212 can route the incident light into an optical fiber 216, which in turn directs the light into the detector 218.

A bandpass filter 214 can expediently be arranged in the relay optics unit 212. To filter unwanted radiation, the bandpass filter 214 can be designed so that it only

Spectral range that the laser emits, lets through and blocks other areas as well as possible. This filtering can also be carried out in several steps, for example. The detector 218 can advantageously be designed as a single photon detector and is used to detect the received laser pulses.

Suitable, commercially available detectors are NIR single photon detectors for the wavelength range from 900 to 1700 nm, which are available, for example, under the name SPD_A_NIR from Aurea

Technology SAS, Besangon, France.

Further suitable, commercially available detectors are nanowire detectors, which are available, for example, from ID Quantique SA, Geneva, Switzerland, under the designation ID281 and which operate in the wavelength range from 780 to 1625 nm and have detection rates of up to 50 MHz. FIG. 3 shows a schematic side view of a particularly mobile device 500 for satellite laser range measurement according to an exemplary embodiment of the invention.

The basic structure of the device 500 has a base segment 520 which carries an optics segment 522 with the telescope mount 510 and is therefore designed to be sufficiently stable and torsion-resistant. Furthermore, the control electronics 514 and the control computer 512 are arranged in the base segment 520, which are located in the base segment 520

Are protected from the elements. Optionally, the interior of the base segment 520 can be designed in a temperature-controlled manner and / or air-conditioned. The telescope mount 510 has two motorized, mutually perpendicular axes, namely a swivel base 507 for the azimuth axis 506 and a rotary shaft 509 for the elevation axis 508 and thereby enables the alignment of the transmitter telescope 120 and receiver telescope 200 to be electronically controlled over the entire half-space of the sky perform. The telescope mount

510 carries the receiving optics 250, the laser 100, the receiving telescope 200, the transmitter optics 150 and the transmitter telescope 120. The components are mounted on support plates 124, 220 of a support unit 518, which is mounted on the rotary shaft 509 representing the elevation axis 508. The carrier plates 124, 220 are shown in FIGS. 4 and 5 with the corresponding components.

The carrier unit 518 comprises the carrier plate 124, which is arranged parallel to the elevation axis 508, and at least one further carrier plate 220, which is arranged parallel to the azimuth axis 506, the two carrier plates 124, 220 being rigidly connected to one another. In particular, the transmitter telescope 120 and the further carrier plate 220 are connected to one another.

The base segment 520 furthermore has an antenna carrier 516 on which sensors and antennas are arranged. For example, a weather station with sensors for clouds, pressure, humidity, temperature can be provided. A GPS antenna (GPS = Global Positioning System), and optionally an ADSB antenna (ADSB = Automatic Dependent Surveillance) and / or a cellular antenna, for example according to the LTE standard (LTE = Long Term

Evolution), be provided for remote control of the device 500.

The optics segment 522 is provided to protect the components on the telescope mount from environmental influences and optionally to provide air conditioning. The optics segment 522 can have viewing windows, for example, so that light can enter the

Receiving telescope 200 arrive and light can be emitted and received by the transmitter telescope 120. The optics segment 522 can be designed as one part that can protect all components or can be designed in several parts so that the receiving telescope 200,

Transmitter optics 150 and receiving optics 250 can be housed and air-conditioned separately.

The control computer 512 controls hardware components such as laser 100, telescope mount 510, tracking camera 210, detectors 218,

Sensors, laser beam direction, laser beam energy and can have a network connection for remote control.

The control electronics 514 have, for example, GPS-synchronized time servers. The control electronics 514 include the event timer, which is available via high-precision GPS signals, which are available via the PPS (Precise Positioning Service) class, with a clock rate of 10MHz is synchronized, and records the time at an event, triggered by the start diode 102 and the single photon detector 218. The control electronics 514 can further optionally include an LTE router for remote control, a trigger generator for controlling the laser pulse emission and the single photon detector.

Suitable, commercially available reference units for time and frequency synchronization based on GPS signals are offered, for example, by Meinberg Funkuhren, Bad Pyrmont, Germany, under the name RD / GPS.

FIG. 4 shows a plan view of the transmitter optics 150 of the particularly mobile device 500 for satellite laser range measurement according to FIG. 3.

The components shown in FIG. 1 are arranged in a modular and space-saving manner on the carrier plate 124 of the transmitter optics 150. The laser beam is coupled in via the mirror 103 and passed on via the laser energy control unit 104, the beam splitter 105, the laser energy control unit 106 to the mirror 108. From there, the laser beam runs via the diaphragm 110 to the mirrors 109, 111 and is guided to the movable mirror 114 via an optional variable beam expansion unit 112. From there, the laser beam reaches the transmitter telescope 120 via the beam splitter 118 or the transmitter camera 116.

FIG. 5 shows a top view of the receiving optics 250 as well as the laser 100 of the particularly mobile device 500 for satellite laser range measurement according to FIG. 3.

The receiving telescope 200 with a covered aperture is mounted on the right end face of the carrier plate 220 in the viewing direction. The Received light passes from the receiving telescope 200 into the beam splitter 206, from which the visible spectrum is passed into the tracking camera 210, while the infrared spectrum is passed into the detector 218 via the relay optical unit 212 with an optional bandpass filter 214.

The laser 100 is also mounted on the carrier plate 220, from which the laser light is guided via the laser collimator 101 and the mirrors 107, 103 into the transmitter optics 150, which are mounted on the carrier plate 124 arranged perpendicular thereto.

In FIG. 6, an isometric illustration of the receiving optics 250 with telescope mount 510 is shown separately. The arrangement of the carrier plate 220 with the receiving telescope 200 mounted on the side on the rotating shaft 509 of the telescope mount 510 can be clearly seen.

FIG. 7 shows an isometric view of the device 500 for satellite laser distance measurement according to FIG. 3 with a cover 536. The cover 536 arranged on the optics segment 522 has a viewing window 538 through which the laser light can be emitted and received.

FIG. 8 shows an isometric illustration of transmitter optics 150 and receiving optics 250 with telescope mounting 510 according to another

Embodiment of the invention shown. The arrangement of the individual components arranged on the carrier plates 124 and 220, the transmitter telescope 120, the transmitter optics 150, the receiver optics 250 and the receiver telescope 200 corresponds to the arrangement on the telescope mount 510 shown so far Components from mechanical damage, Protect from the effects of weather and from scattered light from laser radiation and also be able to control the temperature if necessary. The cover 534 of the transmitter optics 150 is shown open on the side opposite the carrier plate 124, but can also be designed to be closed.

FIG. 9 shows a flow diagram of a method for measuring the distance of an object according to an exemplary embodiment of the invention. In step S100, the tracking camera 210 of the receiving optics 250 is calibrated, followed by step S102, in which an image of the object to be measured is measured on the camera image of the tracking camera 210. The telescope mount 510 is aligned thereupon in step S104 on the basis of coordinates converted from the measurement of the image. Steps S102 and S104 are then repeated as long as the converted coordinates do not fall below a predefined deviation from a target position.

FIG. 10 shows a flow diagram of a method for aligning a laser beam on an object according to an exemplary embodiment of the invention. In step S200, the focusing of the transmitter camera 116 on the laser beam 130 is checked and the focus position of the laser beam 130 reflected back by a retroreflector 122 is determined in the transmitter camera 116. A motor position in relation to the focus position is then determined in step S202. A position of at least one object is then observed in step S204 and the object position of the imaged object is determined in the transmitter camera 116 after removing the retroreflector 122 and temporarily blocking the laser beam 130, followed by converting the object position into the motor position in step S206.

FIG. 11 shows a flow diagram of a method for determining an object distance according to an exemplary embodiment of the invention shown. In step S300, a point in time of emission of a laser pulse onto an object is determined by an event timer. Thereafter, in step S302, a point in time when a photon is detected, in particular the laser pulse reflected back from the object to be measured, is determined by an assigned detector 218.

The times are then transmitted to an evaluation unit, in particular a control computer 512, step S304. Finally, the measured values of emission and detection are correlated. FIG. 12 shows a flow diagram of a method for data evaluation according to an exemplary embodiment of the invention. In step S400, the device 500 is calibrated by means of distance measurement to an object with a known distance. In step S402, times when laser pulses are emitted and signals are received are correlated. Thereafter, in step S404, an expected transit time to an object to be examined is compared to a transit time measured thereon, followed by the extraction of correlated data in step S406. Finally, in step S408, the distance measurements on the object to be examined are averaged.

laser

Laser collimator

Start diode

mirror

Energy control unit

Beam splitter

Energy control unit

mirror

cover

mirror

Beam expansion unit Movable mirror T ransmitter camera beam splitter

Transmitter telescope / beam expander

Retroreflector

Carrier plate

Broadside

laser beam

Transmitter optics

Receiving telescope

Primary mirror

Outcoupling mirror

Beam splitter

mirror

Tracking camera

Relay optical unit

Band pass filter optical fiber

detector

Carrier plate incident light beam

Receiving optics

contraption

Azimuth axis

Swivel base

Elevation axis

Rotating shaft

Telescope mount

Tax calculator

Control electronics Antenna carrier carrier unit (with breadboards) basic segment optics segment cover cover cover cover viewing window

Claims

Expectations

1. Device (500) for satellite laser distance measurement, with a base segment (520) and an optics segment (522) supported by the base segment (520) and having a telescope mount (510) with an azimuth axis (506) and an elevation axis (508), wherein a transmitter telescope (120) and a receiver telescope (200) as well as a laser (100) coupled to the transmitter telescope (120) are arranged on the telescope mount (510).

2. Device according to claim 1, wherein the telescope mount (510) has a swivel base (507) with the azimuth axis (506) and a rotary shaft (509) with the elevation axis (508) around which the telescopes (120, 200) synchronously with each other and the laser (100) can be pivoted synchronously with the transmitter telescope (120).

3. Device according to claim 1 or 2, wherein a carrier plate (124) of a carrier unit (518) extends at a distance from the elevation axis (508) between the two telescopes (120, 200).

4. The device according to claim 3, wherein the carrier unit (518) comprises the carrier plate (124) which is arranged parallel to the elevation axis (508), and at least one further carrier plate (220) which is arranged parallel to the azimuth axis (506), wherein the two carrier plates (124, 220) are rigidly connected to one another, in particular wherein the transmitter telescope (120) and the further carrier plate (220) are connected to one another.

5. Device according to one of the preceding claims, wherein the telescope mount (510) has a transmitter optics (150) coupled to the transmitter telescope (120) and a receiver optics (250) coupled to the receiver telescope (200), in particular wherein the transmitter optics (150) are connected the one support plate (124) is attached and the receiving optics (250) is attached to the further support plate (220).

6. The device of claim 5, wherein the transmitter optics (150) comprises one or more of the following components

(i) a laser energy control unit (104), in particular with a beam attenuation unit;

(ii) a laser energy control unit (106), in particular with a beam splitter (105) and / or a measuring head for energy and / or power;

(iii) a screen (110), in particular a mechanical screen (110);

(iv) a variable beam expansion unit (112);

(v) a beam direction control unit (114); in particular a movable mirror (114);

(vi) a beam splitter (105);

(vii) a transmitter camera (116), in particular a transmitter camera (116) with imaging optics;

(viii) a starting diode (102)

(ix) at least one mirror (107, 108, 111);

(x) at least one retroreflector (122).

7. Apparatus according to claim 5 or 6, wherein the receiving optics (250) comprises one or more of the following components

(i) a beam splitter (206) for splitting the radiation received by the receiving telescope (200) into visible light and infrared light;

(ii) a tracking camera (210) in the focus of the receiving telescope

(200);

(iii) a relay optics unit (212) which is provided as further imaging optics;

(iv) a band pass filter (214);

(v) a detector (218) and / or an optical fiber (218) for feeding the received signals. 8. Device according to one of the preceding claims, wherein the

Laser (100) has radiation in the near infrared, in particular IR-B with a wavelength between 1500 nm to 1750 nm.

9. Device according to one of the preceding claims, wherein the laser (100) has laser pulses with a pulse length in the picosecond range to nanosecond range, in particular in the range from 0.5 picoseconds to 100 nanoseconds, with a pulse energy of 1 pJ to 1 mJ. 10. Device according to one of the preceding claims, wherein the

Base segment (520) includes one or more of the following components

(i) a control computer (512);

(ii) Control electronics (514), in particular with an event timer and a trigger generator.

11. Device according to one of the preceding claims, wherein the optics segment (522) has at least one cover (530, 532, 534, 536); in particular wherein the transmitter telescope (120), the receiving telescope (200) and the carrier plate (124) are separate

Have covers (530, 532, 534).

12. The device according to claim 11, wherein an interior of the at least one cover (530, 532, 534, 536) of the optics segment (522) is air-conditioned, in particular with a climate control unit in the

Base segment (520) is arranged.

13. A method for satellite laser range measurement with a device (500), which comprises a base segment (520) and an optical segment (522) supported by the base segment (520), which has a

Telescope mount (510), with azimuth axis (506) and elevation axis (508), a transmitter telescope (120) and a receiver telescope (200) as well as a laser (100) coupled to the transmitter telescope (120) being arranged on the telescope mount (510) , in particular according to one of the preceding claims, wherein the laser (100) is moved synchronously with the transmitter telescope (120) when the transmitter telescope (120) moves.

14. The method of claim 13, wherein a distance measurement one

Object is done with the steps

(i) calibration of a tracking camera (210) of the receiving optics (250);

(ii) measuring an image of the object to be measured on the camera image of the tracking camera (210);

(iii) Alignment of the telescope mount (510) on the basis of coordinates converted from the measurement of the image;

(iv) Repeating steps (ii) and (iii) as long as the converted coordinates have a predetermined deviation from a nominal position.

15. The method of claim 13 or 14, wherein an orientation of a

Laser beam (130) on an object takes place with the steps

(i) checking the focusing of the transmitter camera (116) on the laser beam (130) and determining the focus position of the laser beam (130) reflected back by a retroreflector (122) in the transmitter camera (116);

(ii) determining a motor position in relation to the focus position;

(iii) observing a position of at least one object and determining the object position of the imaged object in the transmitter camera (116) after removing the retroreflector (122) and temporarily blocking the laser beam (130);

(iv) Converting the object position into the motor position.

16. The method according to any one of claims 13 to 15, wherein a

Object distance is determined with the steps

(i) determining a point in time of emission of a laser pulse onto an object by means of an event timer;

(ii) determining a point in time upon detection of a photon, in particular the laser pulse reflected back from the object to be measured, by an assigned detector (218);

(iii) transferring the times to an evaluation unit, in particular a control computer (512);

(iv) Correlation of the measured values of emission and detection.

17. The method according to any one of claims 13 to 16, wherein a

Data evaluation takes place with the steps

(i) calibration of the device (500) by means of distance measurement to an object of known distance;

(ii) Correlation of times when laser pulses are emitted and when signals are received;

(iii) comparing an expected transit time to an object to be examined to a transit time measured thereon;

(iv) extracting correlated data;

(v) Averaging the distance measurements on the object to be examined.