Measuring device with scanning functionality and adjustable receiver reception areas

Description

[0001] The invention relates to a measuring device with scanning functionality for the optical measurement of an environment.

[0002] To capture objects or surfaces in an environment, methods are frequently used that involve scanning with a laser scanner. The spatial position of a surface point is determined by measuring the distance to the targeted point with the laser and combining this measurement with angular information from the laser emission. From this distance and angular information, the spatial location of the captured point can be determined, allowing, for example, a surface to be continuously measured. Often, in parallel with this purely geometric surface capture, an image is also captured by a camera, which provides not only the overall visual view but also additional information, such as details about the surface texture.

[0003] 3D scanning is a highly effective technology for generating millions of individual measurement data points, particularly 3D coordinates, within minutes or seconds. Typical measurement tasks include capturing objects and their surfaces, such as industrial plants, building facades, or historical buildings, as well as accident scenes and crime scenes. Surveying instruments with scanning functionality include total stations and theodolites, which are used to measure and create 3D coordinates of surfaces. For this purpose, they must be able to guide the measuring beam—usually a laser beam—of a distance measuring device across a surface or along an edge, thereby successively capturing the direction and distance to the respective measurement points in different directions at a predetermined sampling or measurement rate. Direction and distance are relative to a measurement reference point, such as...The location or zero point of the surveying instrument, in other words, lies in a common reference or coordinate system, so that the individual measurement directions and thus the individual measurement data are linked to each other via the local coordinate system. From the distance measurement value and the correlated measurement direction for each point, a so-called 3D point cloud can then be generated from the multitude of scanned points, for example, using an integrated or external data processing system.

[0004] Measuring devices with scanning functionality are also used, for example, as LiDAR systems, such as for aerial landscape surveying. In this process, laser pulses from a moving platform, particularly an aircraft or drone (UAV, "unmanned aerial vehicle"), are directed towards the surface according to a defined scanning grid via a rapidly adjustable deflection element, such as a scanning mirror ("sweeping mirror") or a refracting optical component. Based on the returning portions of the radiation emitted towards the surface and the platform's own movement, detected, for example, by a global navigation satellite system (GSNS) and / or an inertial measurement unit (IMU), an accurate surface model of the area to be surveyed can be derived.

[0005] Other measurement tasks of scanning measuring devices include, for example, monitoring an environment, such as within the framework of a warning or control system for an industrial manufacturing plant, or use in driver assistance systems.

[0006] Other applications of scanning measuring devices include, for example, determining the shape and area of ​​tunnel cross-sections or determining the volume of building pits or gravel piles.

[0007] In the field of autonomous vehicles, the roads to be traveled are typically mapped beforehand and represented in a model. This is done, for example, using vehicles equipped with scanners that scan and map the relevant region. A LiDAR module used in this process must meet specific requirements, particularly regarding field of view and acquisition rate. For instance, the horizontal field of view should encompass approximately 80 degrees, while the required vertical field of view is typically much smaller, e.g., around 25 degrees. The acquisition rate for scanning the entire field of view is, for example, around 25 Hz.

[0008] In principle, such scanning measuring devices are designed, for example, with an electro-optical laser-based distance meter to determine the distance to an object point as a measuring point, and also include a measurement direction deflection unit to vary the transmission direction of the distance measuring beam, for example with respect to one or more independent spatial directions, thereby enabling the detection of a spatial measurement or scanning area.

[0009] Various principles and methods are known in the field of electronic and electro-optical distance measurement. One approach involves emitting pulsed electromagnetic radiation, such as laser light, at a target to be measured and subsequently receiving an echo from that target as a backscattering object. The distance to the target can then be determined, for example, based on the travel time, shape, and / or phase of the pulse. Such laser distance meters have now become standard solutions in many areas.

[0010] To detect the backscattered pulse or a pulse sequence, two different approaches or a combination thereof are usually used.

[0011] In the so-called threshold method, a light pulse is detected when the intensity of the radiation incident on a detector of the distance measuring device exceeds a certain threshold. This threshold prevents background noise and interference from being falsely detected as the useful signal, i.e., as backscattered light from the emitted pulse.

[0012] However, a problem arises because weak backscattered pulses, such as those caused by larger measurement distances, can no longer be detected if the pulse intensity falls below the detection threshold. The main disadvantage of this threshold method is therefore that the amplitude of the measurement signal must be sufficiently larger than the noise amplitude of optical and electrical noise sources in the signal path to adequately minimize false detections. Consequently, the threshold method is only conditionally suitable for measurements over relatively large distances.

[0013] The other approach is based on sampling the backscattered pulse. This approach is typically used for weak backscattered signals (e.g., pulse signals), such as those caused by larger measurement distances. This method can also be considered holistic signal acquisition, where sampling captures both the entire signal and the essential noise information, leading to increased measurement accuracy. An emitted signal is detected by sampling the radiation captured by a detector, identifying a signal within the sampled area, and finally determining the signal's position in time. By using a large number of samples and / or summing the received signal synchronously with the emission rate, a useful signal can be identified even under unfavorable conditions, thus enabling detection over larger distances or in noisy or congested environments.Background scenarios fraught with disturbances can be managed.

[0014] Nowadays, the entire waveform of the analog signal of the radiation detected by a detector is often sampled using the waveform digitization method ("Waveform Digitizing", WFD). After identifying the encoding of the corresponding transmitted signal (ASK, FSK, PSK, also called distance or interval modulation, etc.) of a received signal, a signal propagation time ("pulse propagation time") is determined very precisely, for example, by means of a Fourier transform or from a defined point in the course of the sampled, digitized and reconstructed signal, such as the inflection points, the curve maxima, or integrally using an optimum filter known from time interpolation.

[0015] Alternatively or in addition to determining the pulse transit time, (fast) sampling is often also performed with regard to pulses or pulse trains encoded or modulated in amplitude, phase, polarization, wavelength and / or frequency.

[0016] For example, in the approach of highly precise temporal sampling of the backscattered signal, the electrical signal generated by the detector is converted into a digital signal sequence using an analog-to-digital converter (ADC). This digital signal is then usually processed further in real time. In a first step, this signal sequence is decoded—that is, recognized—by special digital filters (ASK, FSK, PSK, etc.), and finally, the position of a signature describing a time interval within the signal sequence is determined. Examples of time-resolved signatures include center of gravity, sine-cosine transform, or, for example, amplitude-normalized finite impulse response (FIR) filters with a weighting coefficient set derived from the pulse shape. To eliminate any distance drift, a corresponding time-resolved signature is also compared with an internal start signal.To avoid irreversible sampling errors, additional digital signal transformations known to experts are applied.

[0017] One of the simplest modulation methods is the identification of individual pulses or pulse sequences by distance coding, as described, for example, in EP 1 832 897 B1. This is used, for instance, for the purpose of re-identification. This re-identification is necessary when ambiguity arises, which can occur during pulse transit-time measurements due to various situations, such as when more than one pulse or pulse group is located between the measuring instrument and the target object. Pulse coding is particularly advantageous in multi-beam systems consisting of several laser beams and associated receiving sensors.

[0018] The deflection unit can be implemented as a moving mirror or alternatively by other elements suitable for controlled angular deflection of optical radiation, such as rotatable prisms, movable optical fibers, refractive optical elements, deformable optical components, etc. The measurement is usually performed by determining distance and angles, i.e., in spherical coordinates, which can also be transformed into Cartesian coordinates for representation and further processing.

[0019] A scanning measuring device can, in particular, have two separate beam paths for the transmitted and received radiation, or the beam paths of the transmitting and receiving channels can overlap at least partially. Specifically, the beam paths can be configured such that the deflection unit acts only on the transmitted radiation, meaning that the imaging effect of the receiving channel is essentially independent of the control of a beam steering element of the deflection unit; that the transmitting and receiving channels each have their own deflection unit, which can be controlled separately; or that a single deflection unit acts on both the transmitted and received radiation.

[0020] If the deflection unit only affects the transmitted radiation, this has the disadvantage that the varying angle of incidence causes the image position of the received radiation to vary on the receiver, thus requiring a larger receiver area than if, for example, the image position were stabilized by appropriate optics. However, the larger receiver area also increases the background light component, which, for example, leads to a deteriorated signal-to-noise ratio due to shot noise. Such measuring instruments are therefore typically used for measurement tasks where only a small solid angle needs to be scanned, allowing the receiver area to be kept small.

[0021] The background light component can be reduced, for example, by appropriately selecting the wavelength of the transmitted radiation and incorporating suitable filters in the receiving path. However, this typically increases the complexity of the light source, as it must have a defined and stable wavelength. This is complex, requires special stabilization measures, and also prevents, for example, a more compact design of the measuring device.

[0022] Especially for measurement tasks where larger solid angle areas need to be scanned, the deflection unit is often arranged such that the image position of the received radiation on the receiver is stabilized by the same beam steering element in both the transmitting and receiving channels, or by separate beam steering elements in each channel. This allows the receiver area to be optimized, for example, with respect to the beam diameter of the central received beam, and thus kept relatively small.

[0023] Particularly in airborne LiDAR systems, the measurement distance to the Earth's surface can be several kilometers (up to 5 km), with a relatively high angular rate of the deflection unit (e.g., 200-300 rad / s). This means, for example, that the setting of the deflection unit, e.g., the position of a single deflection mirror in a common beam path for the transmit and receive signals, is different for an outgoing transmit signal and a corresponding incoming receive signal.

[0024] For example, the travel time for a pulse traveling at the speed of light (approx. 300,000 km / s) at an altitude of 5 km is 33 µs. With an angular adjustment rate of 200 rad / s for the deflection element shared by the transmit and receive channels, this results in an aiming error of 6.6 mrad. This means that the receiver is looking 6.6 mrad away from the position where the laser beam hits the ground. If the laser beam has a diameter of, for example, 0.2–0.5 mrad, the receiver's field of view—in order to collect all the light returning from the laser beam—must therefore cover ten to twenty times the diameter of the laser beam. If the LiDAR scanner can also perform a complex two-dimensional scanning pattern, the aiming error occurs in all directions of the laser beam, thus doubling the required field of view for the receiver.

[0025] To keep the receiver small and thereby, for example, reduce the background light component, various methods are known in the prior art to compensate for the aiming error due to the finite propagation time as a function of the measurement distance, for example by means of distance-dependent control of complex optical compensation elements in the receive path. However, each of the individual solutions always requires a compromise with regard to device parameters such as device size, system complexity, measurement accuracy, measurable distance range, or flexibility with regard to adjustable scanning patterns.

[0026] EP 3 182 159 A1 describes both optical and sensor-based solutions for distance-dependent compensation of the aiming error to reduce the background light component in airborne distance measurement.

[0027] The object of the invention is to provide a measuring method or a measuring device which avoids the disadvantages known from the prior art, in particular enabling fast and precise measurements over an extended distance measuring range.

[0028] This problem is solved by realizing the characterizing features of the independent claims. Features that further develop the invention in an alternative or advantageous way are to be found in the dependent claims.

[0029] The invention relates to a measuring device for the optical measurement of an environment, comprising a radiation source for generating a transmitting radiation, e.g. pulsed laser measurement radiation, a transmitting channel for emitting at least a part of the transmitting radiation, a beam steering element in the transmitting channel which is configured to deflect the transmitting radiation and to set a time-varying transmitting direction of the transmitting radiation from the transmitting channel, and a receiving channel with a receiver which is configured to detect a received signal based on at least a part of the returning transmitted radiation, hereinafter referred to as received radiation.The measuring device also includes control electronics configured to control the device based on a pre-programmed measurement process, an angle determiner for acquiring angle data relating to the direction of transmission, and a processing unit for deriving distance measurement data based on the received signal. The measurement process involves a scanning scan of the transmitted radiation, based on a defined, continuous control of the beam steering element to continuously change the direction of transmission, a continuous transmission of the radiation, a continuous acquisition of the received signal, and the derivation of the distance measurement data.

[0030] According to the present invention, the receiver for detecting the received signal comprises an optoelectronic sensor based on an array of microcells, in particular wherein the sensor is configured as an array of single-photon avalanche photodiodes, wherein the sensor has a plurality of microcells and is configured such that the microcells can be read out individually and / or in groups of microcells, and thereby individually readable active sub-areas of the receiver can be set. Readable means that the microcells or the groups of microcells have a signal output that allows the determination of the transit time in picoseconds or sub-picoseconds.During the measurement process, the control of the beam steering element and the acquisition of the received signal are synchronized in such a way that the acquisition of the received signal is based on an active sub-area of ​​the receiver, whereby the active sub-area is set based on the angle data defining the direction of transmission of the transmitted radiation and / or based on distance measurement data, in particular distance measurement data relating to an immediately preceding control of the beam steering element.

[0031] According to the present invention, the receiver has a total detector area, wherein a sub-area of ​​the total detector area is set as an active detection area / an active sub-area, wherein the active detection area is adjustable with respect to its position on the total detector area, in particular wherein the active detection area is further adjustable in its shape and / or its extent, and wherein a receiver signal dependent on the setting of the active detection area is generated by received radiation incident on the total detector area.

[0032] On the one hand, if the beam steering element, for example, only affects the transmitted radiation, a separate compensation must typically be provided on the receiving channel side with respect to the varying angle of incidence of the returning beam in the receiving channel caused by the movement of the beam steering element. According to the invention, this compensation is therefore performed on the detector side, based on the sensor according to the invention and depending on the direction of transmission of the transmitted radiation.

[0033] On the other hand, if, for example, the image position of the received radiation on the receiver is stabilized by the same beam-guiding element in the transmitting and receiving channels, or by separate beam-guiding elements in the transmitting and receiving channels, an angular difference arises between the outgoing and received radiations due to the finite signal propagation time and the movement of the beam-guiding element. This difference is relative to the respective angles of incidence on the beam-guiding element, resulting in the receiver looking away from the position where the laser beam hits the illuminated surface, depending on the distance. This distance-dependent offset is compensated for by the inventive use of the sensor.

[0034] The sensor can, for example, be an array of single-photon avalanche photodiodes. Single-photon avalanche photodiode arrays (SPADs) are typically arranged in a matrix structure on a chip. These arrays or chips, with photosensitivity in the visible and near-infrared spectral range, are also known as silicon photomultipliers (SiPMs). SiPMs are gradually replacing the photomultiplier tubes used previously, particularly in the visible and near-ultraviolet spectral range. SiPMs have high spectral sensitivity in the visible wavelength range. For example, silicon-based SPAD arrays manufactured using CMOS technology are available in the prior art, which are sensitive well into the near-infrared range, extending to wavelengths well beyond 900 nm.

[0035] The special feature of these SPAD arrays is their high gain, which is why they have so far been used for very weak optical signals, where only 1 to 50 photons reach the sensor. Such sensors, for example airborne ones, are also called SPL lidar (SPL = "single photon lidar"). With only a few photons, however, the distance noise is considerable and typically ranges from 10 mm to 100 mm. Furthermore, the absolute distance measurement accuracy is affected by the signal strength, especially with SPAD arrays containing few microcells. Through special measures, such as range walk compensation, a distance noise of far less than 1 mm can be achieved, resulting in a measurement accuracy of 0.1 mm. This corresponds to a typical time resolution of one picosecond or less.

[0036] Commercial SPAD arrays are also available for wavelengths between 800 nm and 1800 nm. These sensors consist primarily of the semiconductor material InGaAs. Depending on the design, these sensors also feature an external or internal matrix structure across the photosensitive area. Distance measurement systems using SPAD arrays in this spectral range have the advantage that the solar background light (daylight) is significantly lower compared to the visible wavelength range, and therefore this interfering luminous flux has less of an impact on the SPAD arrays.

[0037] The special feature of these SPAD array sensors is their very high photosensitivity, with SPAD arrays primarily designed to reliably detect individual photons. Therefore, they are also referred to as "Multi Pixel Photon Counters" (MPPCs). SPAD arrays consist of hundreds, thousands, or even tens of thousands of microcells and are thus capable of receiving pulses with thousands or hundreds of thousands of photons simultaneously. Furthermore, due to the parallel connection of the many microcells into cell groups (domains), even in solar background light, there are still enough free cells available for the signal photons.

[0038] Another special feature of SPAD arrays is that individual microcells or subsets of microcells can be addressed and / or read separately. The microcells can therefore be activated sequentially, for example, for reading the receiver row by row or column by column (e.g., as a "rolling shutter" or "rolling frame"). In particular, this allows for the definition of individually readable sub-areas of the receiver, dependent on the transmission direction.

[0039] For example, the sub-areas can be defined such that they each represent a spatial sequence of adjacent microcells. However, the sub-areas can also be defined by spaced-apart regions of the receiver, meaning that the individual sub-areas do not represent a continuous sequence of microcells.

[0040] In particular, the individual sub-areas can be defined in such a way that they overlap each other, at least partially.

[0041] For example, the sub-areas can be coordinated in such a way that, through a sequence of signal acquisitions by individual sub-areas, individual microcells or microcell groups (domains) of the SPAD array are alternately directed to the output, for example, alternating even and odd rows (with respect to the SPAD array) within the sub-areas. Such temporally alternating activation of microcells or microcell groups leads, for example, to a reduction in the recovery time of the SPAD array, thereby enabling faster laser modulation or firing rate.

[0042] Instead of activating the microcells or microcell groups (domains) of the SPAD array, they can, for example, remain activated in a stationary state to capture and evaluate the outputs of the microcells or microcell groups (domains) synchronously with the transmitter's scanning movement for the "rolling shutter" or "rolling frame" function. An electronic circuit, integrated, for example, on the SPAD array, connects precisely those microcells or microcell groups (domains) to the signal output that are oriented synchronously with the surface of the object illuminated by the transmitter laser. If the laser's scanning movement is vertical, the effective receiving domain shifts synchronously in the same direction, ensuring that the (effective) field of view (FoV) of the active receiving unit can detect the laser points on the object in a timely manner.The active field of view (FoV) of the receiving unit is designed to be so small in the angular range that the backscattered received pulses can be fully seen and received while receiving as little interfering ambient light as possible.

[0043] According to the invention, direction-dependent active sub-areas of the receiver are defined depending on the direction of transmission of the transmitted radiation in order to adjust the receiver area to a varying imaging position of the received radiation, for example, to compensate for an aiming error due to the finite transit time and a rapidly rotating deflecting mirror as a function of the measurement distance. This allows the receiver area used in each case to be optimized with respect to the incident received beam. For example, the active received area can be essentially matched to the beam diameter of the respective received beam. Thus, even with a receiver that is inherently oversized with respect to the beam diameter, the background light component can be kept low for a single measurement.

[0044] In contrast to the comparatively expensive photomultiplier tubes with high time jitter, modern SiPM sensors are cost-effective and exhibit time jitter in the picosecond to sub-picosecond range. Furthermore, SiPM arrays are manufactured using a conventional CMOS technology process, which also allows for the integration of electronic components and circuits. Similar advantages apply to SPAD arrays made from the semiconductor material InGaAs.

[0045] The high photosensitivity is due to the avalanche mechanism, whereby the individual microcells of the array are operated, for example, in the overvoltage range ("reverse voltage beyond the break voltage"), that is, above the breakdown voltage at which a single photon triggers an avalanche of electrons, thereby greatly amplifying the signal, depending on the setting, e.g., by a factor of up to one million. Because of its magnitude, the current associated with the photon is easily converted into a voltage signal and fed to a signal processing unit without significant amplification.

[0046] A SPAD array is capable of receiving multiple photons simultaneously, whereby the currents of the many microcells on the sensor chip can be added and then converted into a voltage signal, for example, via a resistor or a transimpedance amplifier. The SPAD array can be configured, for example, with more than ten thousand microcells, so that it behaves like an analog photosensor, with its characteristic curve being approximately proportional to the intensity of the incident laser pulse, especially for weak received signals.

[0047] The literature distinguishes between SPAD array operations in linear mode, Geiger mode and SPL mode (SPL, "Single Photon Lidar").

[0048] In linear mode below the breakdown voltage, a reverse voltage and temperature-dependent gain occurs, and SPAD arrays can be used, for example, to build highly sensitive photodetectors with radiation power-proportional output voltage.

[0049] In Geiger mode and SPL mode, i.e., operating above the breakdown voltage, SPADs and SPAD arrays can be used for single-photon counting. With SPADs, in Geiger mode, each individual pixel generates an output signal, with the electron avalanche being triggered by exactly one photon. If a photon packet containing multiple photons arrives, no larger signal is measured; therefore, no amplitude information is available.

[0050] In Geiger mode, an incident photon packet only generates a (binary) event signal, which is not proportional to the number of photons in the photon packet.

[0051] SPL mode refers to a SPAD array operating in Geiger mode, where many microcells are connected in parallel to an output signal. When photon packets containing only a few photons arrive, the individual avalanches add up practically linearly, and the amplitude of the output signal is therefore proportional to the number of photons detected.

[0052] The recovery time of the microcells after a photonic trigger is not zero, but rather, for example, between 5 and 50 nanoseconds, which reduces the apparent sensitivity of the SPAD array to subsequently arriving photons. However, this has the advantage that the sensor can detect a signal strength range with high dynamics. This nonlinearity is monotonic in SPAD arrays with a large number of microcells (>1000) and leads, on the one hand, to amplitude compression between the input and output signals, and on the other hand, to a weakened increase in the output signal as the input signal increases. Interestingly, the output signal of SPAD arrays with a high number of microcells (>1000) does not fully saturate, so that even with a received pulse containing a very high number of photons, well over a million, an amplitude change is measurable.

[0053] A SPAD array with a sufficient number of cells captures the received signal amplitude over a large dynamic range and effectively compresses the input amplitude of signals ranging from very small to very large. The SPAD array never overloads, even with very strong signals, for example, even when the radiation is reflected back by an angle-precise retroreflector. At a photon count of < 10⁹, the output signal of the SPAD array asymptotically approaches a maximum threshold voltage. This threshold voltage is matched to the subsequent amplifier circuit and ensures that the electronics downstream, up to the timing circuit, are not overloaded. This is what makes precise distance measurement over a high dynamic range possible.

[0054] When measuring laser distances over different distances and varying surfaces, the number of photons can vary, for example, from less than 10⁻⁹ to more than 10⁻⁹. In contrast, SPAD arrays exhibit a compression factor of the measured signal amplitude that is at least 10⁻⁴, typically 10⁻⁸, compared to the actual signal amplitude. SPAD arrays can therefore be used to measure both black diffuse targets and retroreflectors without requiring signal control in the receiving unit. Due to their high gain, SPAD arrays also exhibit low noise, and SPAD arrays with a high fill factor show a signal-to-noise ratio (SNR) suitable for distance measurements. The more microcells a SPAD array has, the higher the SNR.

[0055] The laser signals from a distance meter are typically pulse-encoded. Typical pulse rates range from kHz to GHz. Experiments have shown that SPAD arrays can reliably receive such signals at overbreak voltages. Pulse packets (bursts) can also be received clearly and with virtually no noise using SPAD arrays. This is true even when the recovery time of the microcells is quite long, at ten nanoseconds. Due to the quasi-analog structure of SPAD arrays, a photocurrent present, for example, from ambient light, can also be received. The laser signal is then superimposed on the electrical photocurrent of the ambient light. For example, the current pulse generated by the laser pulse is high-pass filtered at the output of the SPAD array to shorten the slow trailing edge of the signal. This results in a short signal pulse, e.g., with a pulse duration of less than one nanosecond.Such short pulses with steep edges are suitable for precise time and therefore also distance measurement. However, the use of a high-pass filter (differentiator) has no effect on the recovery time of the SPAD array.

[0056] Furthermore, initial attempts have already been made to integrate more electronic functionality into SPAD arrays. For example, timing circuits ("TOF circuits") have been assigned to each microcell. These measure the time-of-flight (TOF). SPAD array implementations exist, for instance, where precise photon counting is integrated close to the microcells, eliminating the need for a downstream analog-to-digital converter (ADC). Additionally, each microcell can, for example, have its own time-to-digital converter (TDC). A digital interface is used as the output of the SPAD array. Such components are fully digital and do not require mixed-signal processing during CMOS fabrication.

[0057] The receiving channel according to the invention allows the measuring device to be designed for high scanning speeds by means of a rapid movement of the beam steering element. On the receiver side, a measure is required that synchronously tracks the field of view (FoV) of the receiving unit with the scanning on the transmitter side.

[0058] This measure consists, for example, of connecting only one domain—that is, a subset of microcells of the SPAD array—to the signal output at any given time, precisely aligned with the light spot on the object. Since the light spots are scanned across the object being measured by the beam-guiding element, the active domain of the SPAD array is synchronously shifted across the object purely through circuitry. This active domain of the SPAD array forms the active field of view of the receiver. This active field of view of the receiver is intentionally designed to be narrow to minimize the amount of sunlight captured and to minimize the number of microcells of the active domain being falsely triggered.The activated sections of the receiver move synchronously with the light spot across the surface of the SPAD array, such that the active microcells partially or completely enclose the light spot. This electronic scanning, also known as "solid-state scanning," eliminates the need for moving parts on the receiving side, such as MEMS scanners, wedge scanners, polygon prism wheels, or polygon mirror wheels.

[0059] According to the invention, the measuring device has an inertial meter configured to acquire inertial data relating to an intrinsic movement of the measuring device, namely a tilt (6 degrees of freedom, 6DoF), and wherein the active sub-area used in the measurement process is selected based on the inertial data.

[0060] In particular, according to one embodiment, the measuring device is configured, for example, to capture a temporal progression of the measuring device's own movement and to estimate the measuring device's own movement in advance based on the temporal progression, wherein the active sub-area used in the measurement process is selected based on the estimated own movement of the measuring device, in particular taking into account a temporal progression of initially derived distance measurement data.

[0061] For example, vibrations of the measuring device can be compensated for, such as residual vibration of a measuring instrument gimbal-mounted in an aircraft.

[0062] The angular data regarding the direction of transmission of the transmitted radiation are derived, for example, from control signals for the control of the beam steering element and / or based on angular measurement data, which are provided, for example, by one or more angle sensors present in the measuring device.

[0063] According to another embodiment, the measuring device is configured to derive an impact position of the received radiation on the sensor, in particular by means of determining the center of gravity or maximum of the detected received signal, and to derive correction information regarding the angle data based on the impact position and the distance measurement data.

[0064] For example, this allows for precise referencing of distance measurement data for the creation of a point cloud, eliminating the need for an angle sensor in the measuring device. For instance, it may be sufficient if the (initially) derived angle data is based solely on control signals for the beam guidance element and then corrected for referencing in a point cloud based on the impact position.

[0065] In a further embodiment, the measuring device is configured to estimate, based on the angle data, a first imaging information for a beam shape and / or position of the received radiation imaged on the receiver, in particular based on a defined fixed focus optic of the receiving channel, wherein the active sub-area used in the measurement process is selected based on the estimated first imaging information.

[0066] In particular, according to a further embodiment, the measuring device can be configured to estimate a second imaging information for a beam shape and / or position of the received radiation imaged on the receiver based on feedback from the receiver regarding a previously acquired received signal, wherein the active sub-area used in the measurement process is selected based on the estimated second imaging information.

[0067] According to another embodiment, the measuring device is configured to estimate a third imaging information for a beam shape and / or position of the received radiation imaged on the receiver based on the distance measurement data, wherein the active sub-area used in the measurement process is selected based on the estimated third imaging information.

[0068] In one embodiment, the receiving channel is configured such that its imaging effect is essentially independent of the control of the beam-guiding element, particularly in that the beam-guiding element is arranged to act only on the transmitted radiation. This means that the receiving channel has a static optical axis, i.e., no optical directional correction of the incident received beam takes place.

[0069] Alternatively, according to a further embodiment of the invention, the receiving channel can be configured, for example, such that the imaging effect of the receiving channel depends on the control of the beam-guiding element, which is arranged such that it also acts on the received radiation, so that, depending on the control of the beam-guiding element, a first deflection angle of the transmitted radiation and a second deflection angle of the received radiation are given. The measuring device is configured to estimate an angular difference between the first and second deflection angles, based on an estimate of the time difference between the time the transmitted radiation passes the beam-guiding element and the time the corresponding received radiation passes the beam-guiding element, wherein the active sub-area used in the measurement process is set based on the estimated angular difference.

[0070] Thus, for example, an aiming error due to the finite runtime as a function of the measurement distance can be compensated, while at the same time the complexity of the optical setup can be kept low.

[0071] In particular, according to a further embodiment, the angular difference is estimated based on at least one element from a distance to a target object in the environment, in particular based on initially acquired distance measurement data, a setting rate of the time-varying transmission direction, a scanning pattern defined by the measurement process for scanning by means of the beam guidance element, and the intrinsic movement of the measuring device.

[0072] For example, the angle difference can also be estimated based on a continuous trend estimation based on previously estimated angle differences, in particular based on the last three immediately preceding angle differences.

[0073] Furthermore, according to another embodiment, the receiver can have multiple sensors, wherein the multiple sensors are arranged one-dimensionally or two-dimensionally relative to each other, in particular wherein each sensor has separate control electronics and / or evaluation electronics. Often, in such arrangements of sensors, for example SPAD arrays, the individual arrays are referred to as pixels, although each of these pixels itself consists of hundreds to tens of thousands of microcells.

[0074] Furthermore, according to another embodiment, the receiver is configured such that a set of active sub-areas that can be read out in parallel can be defined, in particular wherein the radiation source is configured to generate a bundle of parallel, differently directed and / or spaced-apart laser measurement beams, wherein the sub-areas of the set of active sub-areas are defined such that they are each assigned to a laser measurement beam of the bundle of laser measurement beams. This allows, for example, multibeam scanning with several parallel and / or diverging laser measurement beams.

[0075] According to a further embodiment, the receiver has a blocking element on the receiving radiation side that is opaque to the received radiation, wherein the blocking element is configured such that a time-variable adjustable pass-through area is set to allow the received radiation to pass through to the total detector area of ​​the receiver, wherein the position of the pass-through area with respect to the total detector area is adjustable, in particular wherein the pass-through area is further adjustable with respect to its shape and / or its extent.

[0076] For example, the blocking element can be designed based on an adjustable, rotatable disk made of radiation-impermeable material, arranged essentially parallel to the overall detector surface, and featuring an opening that is transparent to the received radiation. For instance, the openings and rotational speeds of two interlocking disks can be designed and adjusted such that the transmission range is adjustable to define a two-dimensional virtual movement across the detector surface.

[0077] The measuring device according to the invention is described in more detail below with reference to exemplary embodiments schematically depicted in the drawings. Identical elements are marked with the same reference numerals in the figures. The described embodiments are generally not drawn to scale and are not to be understood as limiting the scope of the invention.

[0078] In detail, they show Fig. 1a-d: Exemplary application areas for the inventive measuring instrument, e.g., a) airborne LiDAR surveying, b) terrestrial LiDAR or scanner surveying, c) autonomous vehicle, d) total station; Fig. 2: Schematic illustration of the generation of a targeting error due to the rapid movement of a deflection element and the finite transit time of the transmitted signal; Fig. 3a-d: Schematic illustration of a beam path of an inventive use of a SPAD array as a photosensitive surface of a receiver in a measuring instrument; Fig. 4a,b: Inventive embodiment ("rolling shutter window") with respect to the definition of the individual sub-areas of the SPAD arrangement dependent on the transmission direction, e.g., a) one-dimensional, b) two-dimensional; Fig. 5: Coordinate measuring instrument with a two-stage scanning mechanism based on a receiver-side SPAD array; Fig. 6a-b: Linear multipixel arrangement consisting of several SPAD arrays for a wide-angle scan area. ...

[0079] The Figures 1a to 1d show exemplary application areas for measuring instruments according to the invention with scanning functionality, for detecting objects or surfaces in an environment by means of scanning with a laser measuring beam.

[0080] Figure 1a Figure 1 shows a typical airborne survey based on a LiDAR system on board an airborne platform 1, e.g., an aircraft. A transmitted beam 2 is generated, for example, by short laser pulses, which is deflected towards the surface according to a defined scan pattern 3, for example, by means of a movable mirror or an adjustable refractive optical element. The surface is mapped, and for each target direction of the transmitted beam 2, the distance between the measuring device 4 and the corresponding surface points 5 is recorded, for example, using the pulse time-of-flight method.

[0081] The measuring device 4 according to the invention can, for example, access further data to determine a relative or absolute position of the measuring device 4, such as inertial sensors 6 provided by the carrier 1, height measurement data, or data from a global positioning system 7. The measuring device 4 also has its own inertial sensors for recording inertial data relating to its own movement, e.g., a relative displacement and tilting of the measuring device 4. In addition, the measuring device 4 records, for example, at least the angles of the transmitter-side laser beam deflection units, thus making the relative or absolute position of the surface points 5 on the object to be measured known.

[0082] The additional data can be partially processed by a computing unit 8 of the carrier, or the computing unit 9 of the measuring device can be configured to directly process the provided (raw) data, e.g., where the computing unit 9 of the measuring device continuously derives the position and orientation of the measuring device 4 based on the data and, for example, generates a time series of the self-movement of the measuring device 4.

[0083] The scan pattern on the object to be measured can be generated, for example, based on a simple "zigzag" scan, e.g., using a sweeping mirror and the forward movement of the airborne carrier 1. However, as shown in the figure, scan patterns 3 based on a circular scan ("Palmer scan") are often used, e.g., using a rotating inclined deflecting mirror or a refractive scanning unit. The flight movement thus creates a spiral scan pattern 3 on the surface to be measured. This has the advantage, for example, that each surface point 5 to be measured can be captured from two different angles in a single pass. This minimizes shadow effects and allows a large area to be scanned simultaneously.In this embodiment, the optical receiving channel and the transmitting channel are guided over the same scanning elements such as deflection mirrors or polygon wheels.

[0084] According to the invention, the measuring device 4 has a receiver, for example based on a SPAD array, wherein direction-dependent sub-areas of the receiver are defined depending on the transmission direction of the transmitting radiation 2 in order to adjust the active receiver area to a varying imaging position of the received radiation 10, for example to compensate for an aiming error due to the finite transit time and a rapidly rotating deflection mirror as a function of the measuring distance.

[0085] Figure 1bshows a terrestrial application of a LiDAR system designed for medium to large measurement distances, for example in the field of construction monitoring, e.g. for monitoring or checking the integrity of a dam 11 by detecting the smallest movements of the dam 11 due to varying water pressure.

[0086] In terrestrial applications, the measurement distances are often shorter compared to airborne surveying, whereas the sampling rate can be significantly higher, e.g. due to the improved mechanical stability of the support 1 or due to the knowledge of existing 3D models of the surface to be measured, which allows, for example, the use of already optimized sampling patterns.

[0087] For example, the measuring device can be configured to scan a relatively small surface 12 of the dam with high scanning speed and high resolution, for example based on the pulse time-of-flight principle, wherein a rapidly rotating mirror deflects the transmitting beam 2 along a first direction, for example to adjust the height, and the entire measuring system 4 is pivoted laterally (comparatively slowly) back and forth about the axis of rotation 13.

[0088] According to the invention, the measuring device 4 has a receiver, for example based on a SPAD array, wherein direction-dependent active sub-areas of the receiver are defined depending on the direction of transmission of the transmitted radiation in order to tune the receiver area to a varying imaging position of the received radiation 10.

[0089] For example, the receiver can be configured in such a way that the sub-areas used for capturing the received signal function like a "rolling shutter window" (see, for example, also Fig. 4 ) with the respective set height of the associated transmitting beam 2 on the receiver along the first direction "up and down".

[0090] Figure 1c Figure 4 shows a further application of the measuring device 4 according to the invention in the field of autonomously driving vehicles, wherein, for example, the roads to be driven on are first driven by means of a vehicle 1 equipped with the measuring system 4, in order to record the roads and to map the roads in a model.

[0091] Such systems typically require a robust and durable design for the measuring device 4, typically aiming for the most compact design possible and largely eliminating moving parts where feasible. Furthermore, the measurement process must meet specialized requirements, e.g., regarding field of view and acquisition rate. For example, the horizontal field of view 14 should encompass approximately 80 degrees, while the required vertical field of view 15 is typically considerably smaller, e.g., approximately 25 degrees. The acquisition rate for scanning the entire field of view is, for example, approximately 25 Hz.

[0092] Therefore, MOEMS components ("micro-opto-electro-mechanical system") or adjustable or deformable refractive optical elements, such as liquid lenses, are often used as deflection elements.

[0093] The use of a receiver based on a SPAD array according to the invention has the advantage, for example, that the optomechanical design of the receiving channel can be simplified by having the SPAD array's field of view cover the entire transmitter-side scan area of ​​80 degrees x 25 degrees. As already described, however, only a small portion of the receiver-side field of view is activated, namely the domain (activated group of microcells) that surrounds the received light spot on the SPAD array. Alternatively, the slow horizontal movement of the measuring device 4 can also be guided on the receiver side via the transmitter-side directional deflection unit, with the fast vertical scan movement being performed virtually on the receiver side, i.e., with a one-dimensional vertical activation of the domain on the SPAD array.

[0094] Figure 1dFigure 1 shows a use of the measuring device 4 according to the invention as a total station 16. Total stations are used, for example, to record the properties of defined points in a measurement environment, in particular to record data with spatial reference, i.e., direction, distance, and angle to measurement points. Typically, total stations therefore have alignment means for aligning the aiming axis 17 of the total station 16 with a target.

[0095] Total stations can also be designed for automatic target tracking, for example, by actively illuminating a target with emitted tracking radiation and identifying and tracking it based on the returning radiation, for example by detecting the placement of the detected tracking beam on a position-sensitive diode.

[0096] A total station 16 of the prior art, for example, has a base 18 and a support 19, wherein the support 19 is rotatably mounted on the base 18 about a first axis of rotation 20. Furthermore, the total station 16 has, for example, a carrier 21, which is rotatably mounted on the support about a second axis of rotation 22 that is substantially orthogonal to the first axis of rotation 20. The carrier 21 has an optical distance meter for measuring a distance to the target by means of a distance-measuring beam 2. The carrier 21 also has, for example, a common output and input optics 23 for the emitted distance-measuring beam 2 (transmit beam) and associated returning parts of the distance-measuring beam 10 (receive beam). Alternatively, the carrier can also have separate input optics and separate output optics.

[0097] Typically, for the two-dimensional alignment of the distance measuring beam 2 to a target, both the support 19 and the beam 21 are moved, whereby for a specific surveying task, for example, at least one movement of the support 19 or the beam 21 is necessary for each measurement operation. The support 19, in particular, but also the beam 21, are often comparatively heavy and therefore inert components, which is why the scanning speed is correspondingly limited within the scope of a surveying task.

[0098] To increase the sampling rate, the carrier 21 therefore has, for example, an additional fast deflection element for the rapid deflection 24 of the outgoing distance measuring beam 2 relative to the carrier 21. Thus, a rapid movement of the beam bundle of the distance measuring beam 2 required for measurement can be achieved within the detection range of the inlet optics 23, without requiring the otherwise necessary movement of the larger (inert) components. Points outside the detection range of the inlet optics 23 are detected by means of a combined movement sequence. The slow or inert movements with low acceleration are achieved by means of support 19 and carrier 21, while the fast movements with high acceleration are achieved on the transmitter side by known means such as a polygon (prism or mirror), laser array, or MEMS deflection means, and on the receiver side by means of the inventive device.

[0099] According to the invention, the receiver of the distance meter is, for example, based on a SPAD array, wherein the control of the additional fast deflection element in the carrier 21 and the acquisition of the received signal are synchronized such that, based on the transmission direction of the distance measurement radiation 2 (transmitted radiation), the received signal is acquired based on a set active sub-area of ​​the receiver. On the receiver side, the fast scan movement is again carried out virtually, that is, with a one- or two-dimensional activation of the domain on the SPAD array assigned to the light spot.

[0100] Figure 2 Figure 1 shows a schematic illustration of the origin of an aiming error due to the rapid movement of a deflection element 25, here a rapidly moving (e.g. "sweeping") deflection mirror, and the finite travel time of the transmitted signal.

[0101] The transmit channel includes a laser source 26, wherein the transmit radiation 2 generated by the laser source 26 is coupled into a common transmit and receive channel by means of a first fixed deflection element 27. Furthermore, a moving (e.g., "sweeping") deflection mirror 25 is located in the common transmit and receive channel, the moving deflection mirror 25 acting on both the transmit radiation 2 and the receive radiation. The receive channel also includes a second fixed deflection element 28, an imaging optic 29, and a LiDAR receiver 30 with a photosensitive receiving surface 31.

[0102] Furthermore, optical principal rays 32 are indicated with respect to a current targeting direction, i.e., a current setting 33 of the moving deflection mirror 25, and principal rays 34 with respect to a previous setting 35 of the moving deflection mirror 25. For both orientations of the deflection mirror 25, the optical path between the LiDAR receiver and the deflection mirror 25 is static.

[0103] Due to the finite travel time of an emitted and returning signal and the fast sampling rate using the movable deflection mirror 25, e.g., 300 rad / s, the orientation of the deflection mirror 25 changes between the time of emission of the transmitted radiation 2 and the time of return of the received radiation. This means that the received radiation is directed into the remaining (fixed) receiving optics at an angular offset (depending on the distance). This means that the receiver, with a deflection dependent on the measurement distance, is positioned away from where the laser beam strikes the surface to be scanned. The field of view of the receiver 30, or rather the receiver area 31, must therefore cover, for example, a multiple of the diameter of the laser beam.If the LiDAR scanner can also perform a complex two-dimensional scanning pattern, the aiming error occurs in all directions of the laser beam, thus further increasing the field of view requirement for the receiver 30. However, the larger receiver area 31 also increases the background light component, which, for example, leads to a deteriorated signal-to-noise ratio.

[0104] According to the invention, the receiver area 31 is designed, for example, as a SPAD array, wherein only the part which includes the reflected laser spot is forwarded to the lidar receiving and evaluation unit.

[0105] The Figures 3a to 3d Figure 1 schematically shows an inventive use of a SPAD array 36 as a photosensitive surface of a receiver. Figures 3a,3bThese refer to a first transmission direction 37, set by a deflection element 38, which essentially only acts on the transmission radiation 2, i.e. the optical axis of the receiving channel is essentially static, and the Figures 3c,3d refer to a second transmission direction 39, set by the deflection element 38.

[0106] Figure 3aFigure 1 shows a simplified optical path for the first transmission direction 37 in a side view, with a principal axis 40, a common exit / entry optic 41, and a receiver comprising a SPAD array 36. The deflection element 38 can deflect the transmitted radiation 2, in particular in one or two dimensions, i.e., along a first and / or second deflection direction. Furthermore, it is clear to a person skilled in the art that, depending on the type of deflection element 38 used, e.g., mirror element, prism, polygon wheel, double wedge, refractive element, movable light guide, or MOEMS component, and the mode of action of the resulting beam deflection, e.g., displacement / tilting of the deflection element or electro-optical control of optical (e.g., refractive) properties of the deflection element, it can be arranged in both a parallel and a divergent beam path.

[0107] Figure 3bshows the receiver, or rather the SPAD array 36, in a top view. Figure 3a According to the invention, the SPAD array 36 has a plurality of microcells and is configured such that the microcells can be read out individually and / or in groups of microcells (domains), thereby allowing individually readable sub-areas of the SPAD array 36 to be set. The control of the deflection element 38 and the detection of the receiving beam 10 are synchronized such that, based on the transmission direction, here the first transmission direction 37, the receiving beam 10 is detected based on a defined sub-area of ​​the SPAD array 36, here a first sub-area 42.

[0108] Similarly, the Figure 3c (Side view) and 3d (Top view) the optical path with respect to the second transmission direction 39, wherein, based on the second transmission direction 39, a second sub-area 43 is defined for capturing the receiving beam 10.

[0109] In particular, the respective defined active sub-areas 42, 43 can each be optimized with respect to the beam shape of the incident receiving beam 10. For example, the area of ​​the sub-area can be essentially matched to the beam diameter of the respective receiving beam 10, taking into account, for instance, changes in the light spot size due to a fixed-focus optic on the receiver side. Thus, the background light component can be kept low for a single measurement, even with a receiver that is inherently oversized with respect to the beam diameter.

[0110] Figure 4aFigure 1 shows a further inventive embodiment regarding the definition of the individual active sub-areas of a sensor configured as a SPAD array 36, which depend on the transmission direction. Here, the sub-areas are defined similarly to a so-called "rolling shutter" principle, i.e., the position-dependent sub-area, which acts directionally via the optics, is defined by a combination of several SPAD rows. The sub-area, similar to a rolling shutter window 45 with a variable height 44, "rolls" up and down over the SPAD array 36 in a direction perpendicular to the SPAD rows, depending on the current transmission direction. This definition of sub-areas has the advantage, for example, of simplified control electronics, where, for instance, the height 44 of the current sub-area 45 can be further adapted to the beam diameter of the received radiation 10, e.g., as a function of a distance-dependent change in the light spot size.

[0111] A SPAD array configured in this way is suitable, for example, when the beam deflection is achieved by the deflection element 38 (see Fig.3a ) is essentially one-dimensional, i.e., deflected along a deflection direction corresponding to the "rolling direction".

[0112] Furthermore, the measuring device can be configured, for example, to derive an impact position 46 of the received radiation 10 on the receiver, or rather the SPAD arrangement 36, e.g., by determining the center of gravity or the maximum of the received signal. Using the impact position 46 derived in this way, the currently active sub-area 45 can be finely adjusted in real time to the beam diameter of the received radiation 10. In addition, the derived impact position 46 and the corresponding distance measurement data can be used, for example, to derive the associated transmission direction, for instance, to verify angular data with respect to the transmission direction, e.g., based on control signals from the deflection element 38, or to derive correction information regarding the angular data.

[0113] Figure 4bFigure 1 shows the receiving area of ​​a SPAD array 36 with an active sub-area 45 that shifts in a two-dimensional direction and is dependent on the transmission direction. The movement path 48 of the light spot 10 on the SPAD array 36 is shown, and thus the path of the active sub-area 45, i.e., the active microcells, which move as a domain in a scanning path across the surface of the SPAD array 36. Here, too, the respective sub-areas are assigned to a direction of the transmission unit. If the direction of the transmission beam moves, for example, in the form of a serpentine line 48, the active sub-area 45 moves synchronously in a similar manner on the SPAD array 36.

[0114] Figure 5Figure 1 shows a measuring instrument according to the invention as a total station 16. The instrument is equipped here with a two-stage scanning mechanism, based on a first axis of rotation 20 for rotating the support 19 with respect to the base 18, a second axis of rotation 22 for rotating the carrier 21 with respect to the support 19, and at least one fast scanning deflecting element in the carrier, which can additionally deflect the transmitting beam 10 at high angular velocity.

[0115] The figure shows a scan pattern 3 in object space as a motion track 48, where the S-shaped path in a first part T 1 is generated solely by rotations of the support 19 and / or the carrier 21 about the first 20 and second 22 axes. In a second part T 2, the motion track 48 is generated by means of the additional fast-scanning deflection element in the carrier 21, thereby achieving a denser surface coverage. This results, for example, in a more uniform distribution of the point density on the object surface to be scanned, especially at very high distance measurement rates of more than 1 MHz. Without the fast-scanning deflection element, the measurement points 52 would lie close together on a line of the motion track 48, but measurement points would be missing between the lines. Fast tracking of the field of view is also required on the receiver side. Using the inventive sensor, as is shown, for example, with regard to the Figures 4a and 4bdescribed, an active sub-area 45 synchronized in time and space with the direction of transmission ( Fig. 4a,b ) shifted in a one-dimensional or two-dimensional direction so that the signal of the associated laser emission from a group of microcells can be transmitted to a distance measuring device with time resolution.

[0116] Figures 6a and 6b Two further inventive embodiments of a photosensor unit suitable for so-called "solid state scanning" are shown. Figure 6aThe photosensor unit consists of several SPAD arrays 36 arranged in a line. This arrangement is suitable, for example, for scanning larger angular areas in object space. The received laser spot 10 moves across the multiple SPAD arrays. The active sub-area 45 is moved in time and space synchronous with the received light spot 10, so that the measurement signal is received efficiently, but at the same time as little ambient light as possible is detected per microcell. The displacement of the sub-area 45 appears as a virtual movement 47 and is indicated in the direction of the arrow. The achievable field of view 50 of the receiving unit can be easily dimensioned by the number of SPAD arrays 36.

[0117] In Figure 6bSeveral SPAD arrays 36 are represented in a two-dimensional multipixel arrangement. Each pixel is its own SPAD array 36. The achievable field-of-view 50a,b is shown here as an example based on a 3x3 arrangement of individual SPAD arrays 36. To ensure that the overall detection area has no gaps, SPAD arrays without border regions can be used, for example. In this example, the movement of the received laser spot 10 describes a circular path 48, with the active sub-area 45 enclosing the laser spot 10 and being controlled such that it moves with the laser spot 10 along a virtual scan direction 47.If the microcell domain 45 is located entirely on a SPAD array, then the received signal of all microcells within domain 45 is output to a single output signal line. However, if the microcell domain 45 covers two adjacent SPAD arrays, then two output signal lines are activated, which can then be combined outside the multipixel SPAD array arrangement via a multiplexer circuit. This signal merging electronics can also be implemented directly on the SPAD array pixels 36 (SPAD array chips), for example.

[0118] It is understood that these figures only schematically represent possible embodiments. The various approaches can also be combined with each other and with prior art methods.

Claims

1. Measuring device (4) for optically surveying an environment, comprising - a radiation source (26) for generating transmitted radiation (2), - a transmitting channel for emitting at least a part of the transmitted radiation, - a beam deflection element (38) in the transmitting channel, which is configured to deflect the transmitted radiation (2) and to set a chronologically varying transmission direction (37, 39) of the transmitted radiation (2) out of the transmitting channel, - a receiving channel comprising a receiver (30), which is configured to acquire a reception signal based on at least a part of the returning transmitted radiation, referred to hereafter as received radiation (10), - a control electronics unit, which is configured to control the measuring device (4) based on a preprogrammed measurement procedure, - an angle determining unit for acquiring angle data with respect to the transmission direction (37, 39) of the transmitted radiation (2), and - a computer unit (9) for deriving distance measurement data based on the reception signal, wherein scanning is carried out by means of the transmitted radiation (2) by way of the measurement procedure, based on - a defined ongoing actuation of the beam deflection element (38) for the ongoing change of the transmission direction (37, 39) of the transmitted radiation (2), - an ongoing emission of the transmitted radiation (2) and an ongoing acquisition of the reception signal, and - a derivation of the distance measurement data, wherein - the receiver (30) for acquiring the reception signal has an optoelectronic sensor (36) based on an assembly of microcells, - the sensor (36) has a plurality of microcells and is configured such that the microcells can be read out individually and / or in microcell groups and active sections (42, 43, 45), which can be read out individually, of the receiver (30) are thus settable, and - in the scope of the measurement procedure, the actuation of the beam deflection element (38) and the acquisition of the reception signal are synchronized such that - the acquisition of the reception signal takes place based on an active section (42, 43, 45) of the receiver (30), wherein - the active section (42, 43, 45) is set based on the angle data defining the transmission direction (37, 39) of the transmitted radiation (2) and / or based on distance measurement data, characterized in that - the measuring device (4) has an inertia meter which is configured to acquire inertia data with respect to an intrinsic movement of the measuring device (4) that is a tilt, and - the active section (42, 43, 45) used in the scope of the measurement procedure is selected based on the inertia data.

2. Measuring device (4) according to claim 1, characterized in that the measuring device (4) is configured - to acquire a time curve of the intrinsic movement of the measuring device (4), and - to estimate the intrinsic movement of the measuring device (4) in advance based on the time curve, wherein the active section (42, 43, 45) used in the scope of the measurement procedure is selected based on the estimated intrinsic movement of the measuring device (4), in particular in consideration of a time curve of initially derived distance measurement data.

3. Measuring device (4) according to any one of the preceding claims, characterized in that the measuring device (4) is configured - to derive a position of incidence (46) of the received radiation (2) on the sensor (36), in particular by means of focal point determination or maximum determination of the acquired reception signal, and - to derive an item of correction information with respect to the angle data based on the position of incidence (46) and the distance measurement data.

4. Measuring device (4) according to any one of the preceding claims, characterized in that the measuring device (4) is configured, based on the angle data, to estimate a first item of imaging information for a beam shape and / or location of the received radiation (10) imaged on the sensor (36), in particular based on a defined fixed focus optical unit of the receiving channel, wherein the active section (42, 43, 45) used in the scope of the measurement procedure is selected based on the estimated first item of imaging information.

5. Measuring device (4) according to any one of the preceding claims, characterized in that the measuring device (4) is configured - based on feedback of the sensor (36) with respect to a previously acquired reception signal, to estimate a second item of imaging information for a beam shape and / or location of the received radiation (10) imaged on the sensor (36), wherein the active section (42, 43, 45) used in the scope of the measurement procedure is selected based on the estimated second item of imaging information.

6. Measuring device (4) according to any one of the preceding claims, characterized in that the measuring device (4) is configured - based on the distance measurement data, to estimate a third item of imaging information for a beam shape and / or location of the received radiation (10) imaged on the sensor (36), wherein the active section (42, 43, 45) used in the scope of the measurement procedure is selected based on the estimated third item of imaging information.

7. Measuring device (4) according to any one of the preceding claims, characterized in that the receiving channel is configured such that the imaging effect of the receiving channel is substantially independent of the actuation of the beam deflection element (38), in particular wherein the beam deflection element (38) is arranged such that it acts solely on the transmitted radiation (2) .

8. Measuring device (4) according to any one of claims 1 to 6, characterized in that - the receiving channel is configured such that the imaging effect of the receiving channel is dependent on the actuation of the beam deflection element (38), which is arranged such that it acts on the received radiation (10), and therefore dependent on the actuation of the beam deflection element (38), a first deflection angle of the transmitted radiation (2) and a second deflection angle of the received radiation (10) are provided, and - the measuring device (4) is configured to estimate an angle difference between the first and second deflection angles, based on an estimation of the time difference between the point in time of the passage of the beam deflection element (38) by the transmitted radiation (2) and the point in time of the passage of the beam deflection element (38) by the associated received radiation (10), wherein the active section (42, 43, 45) used in the scope of the measurement procedure is set based on the estimated angle difference.

9. Measuring device (4) according to claim 8, characterized in that the angle difference is estimated based on at least one element of - a distance to a target object in the environment, in particular based on initially acquired distance measurement data, - a setting rate of the chronologically variable transmission direction (37, 39), - a scanning pattern (3) defined by the measurement procedure for the sweeping scanning by means of the beam deflection element (38), and - the intrinsic movement of the measuring device (4) .

10. Measuring device (4) according to any one of claims 8 to 9, characterized in that the angle difference is estimated based on a continuously occurring trend estimation on the basis of previously estimated angle differences, in particular based on the last three immediately preceding angle differences.

11. Measuring device (4) according to any one of the preceding claims, characterized in that the receiver (30) has multiple sensors (36), wherein the multiple sensors are arranged one-dimensionally or two-dimensionally in relation to one another, in particular wherein each sensor (36) has a separate actuation electronics unit and / or analysis electronics unit.

12. Measuring device (4) according to any one of the preceding claims, characterized in that the receiver (30) is designed such that a set of active sections (42, 43, 45) which can be read out in parallel with respect to time is definable, in particular wherein the radiation source (26) is configured - to generate a bundle of differently oriented and / or spaced-apart laser measuring beams generated in parallel, and - the sections (42, 43, 45) of the set of active sections are defined such that they are each associated with a laser measuring beam of the bundle of laser measuring beams.

13. Measuring device (4) according to any one of the preceding claims, characterized in that - the receiver (30) has a radiation-opaque blocking element for the received radiation (10) on the received radiation side, - the blocking element is configured such that a transmission region settable in a chronologically variable manner is set to transmit the received radiation (10) to the overall detector surface of the receiver (30), wherein - the position of the transmission region is settable with respect to the overall detector surface, in particular wherein the transmission region is furthermore settable with respect to its shape and / or its dimensions.