DE102019135771B4 - Device and method for the scanning distance determination of an object - Google Patents

Abstract

Device for the scanning distance determination of an object, with • at least one light source (110) for emitting an optical signal with a time-varying frequency; • a dispersive element (131) which effects an angular distribution of a measurement signal resulting from the optical signal, partial signals of the measurement signal below • an evaluation device (160) for determining values of the distance of the object (140) on the basis of a superimposition of the partial signals reflected on the object (140) with a partial signal not reflected on the object (140) Object (140) reflected reference signal resulting beat frequencies; and • a memory unit for storing the measurement times of different beat frequencies; • the evaluation device (160) being designed to subsequently, on the basis of the stored measurement times, make a clear assignment between the distance values resulting from the respectively measured beat frequencies and the locations on the object belonging to these distance values ( 140), characterized in that the evaluation device is also set up to • subdivide the measurement into several distance intervals to which different locations on the object (140) are assigned, and to assign a beat frequency measured in a sampling interval to a location that corresponds to an n- Sampling intervals is assigned to older sampling intervals, where n = 0,1,2, .. and increases proportionally with increasing beat frequency.

Description

BACKGROUND OF THE INVENTION

Field of invention

The invention relates to a device and a method for scanning the distance determination of an object. The method or the device can be used to determine distances both from moving and still objects and in particular to determine the topography or shape of a spatially extended three-dimensional object.

State of the art

For optical distance measurement of objects, a measuring principle, also known as LIDAR, is known, in which an optical signal, in which the frequency is continuously - in a preferred form linearly - changed as a function of time, is emitted to the object in question and after the object has been reflected back is evaluated. The distance between the object and the measuring device is determined on the basis of the frequency difference between the measuring signal reflected on the object and a reference signal not reflected on the object, detected at a specific point in time.

In practice, there is a need to realize the most accurate and reliable distance measurement possible, even for objects that are located at greater distances (possibly also moving), which may be vehicles in road traffic, for example.

A problem that arises here is that the maximum scan speed that can be achieved when carrying out the scan process is limited by the light or signal transit time (tof = "time of flight"), this transit time being one microsecond (µs) at an exemplary distance of 150m. With a typical time period of approximately 2 μs required for signal evaluation per image point or pixel, a maximum data rate of 500 kHz or 500 kpixel / s results. The 20kpixel images that can be generated in this way at a frame rate of 25Hz are too coarse for typical applications such as road traffic.

A parallel use of several LIDAR systems (each with a smaller field), which is generally considered, leads to an undesirable increase in complexity and costs and, if necessary, to an increased space requirement.

For the state of the art, reference is made to US 2016/0299 228 A1 by way of example only.

US 2018/024246 A1 discloses a LIDAR measuring system with grating couplers which emit the measuring light in different directions as a function of the wavelength.

The US 10 340 651 B1 discloses a lidar measurement system in which optical trigger pulses are used to determine a point in time at which a range pulse is transmitted.

US 2018/0 275 249 A1 describes different scan patterns that are generated by a LIDAR measurement system.

SUMMARY OF THE INVENTION

Against the above background, it is an object of the present invention to provide a device and a method for the scanning distance determination of an object, which enables the most accurate and reliable distance measurement possible even for an object located at a comparatively great distance (e.g. several 100m).

This object is achieved by the device according to the features of independent patent claim 1 or the method according to the features of the independent patent claim 7.

• - Aussenden, unter Verwendung wenigstens einer Lichtquelle, eines optischen Signals mit zeitlich variierender Frequenz;
• - Erzeugen einer Winkelverteilung eines aus dem optischen Signal hervorgegangenen Messsignals durch ein dispersives Element, wobei Teilsignale des Messsignals unter voneinander verschiedenen Abstrahlwinkeln zu dem Objekt gelenkt werden; und
• - Ermitteln von Werten des Abstandes des Objekts auf Basis von jeweils einer Überlagerung der an dem Objekt reflektierten Teilsignale mit einem nicht an dem Objekt reflektierten Referenzsignal resultierenden Schwebungsfrequenzen;
• - wobei die Messzeitpunkte unterschiedlicher Schwebungsfrequenzen gespeichert werden; und
• - wobei auf Basis der gespeicherten Messzeitpunkte eine nachträgliche eindeutige Zuordnung zwischen aus den jeweils gemessenen Schwebungsfrequenzen resultierenden Abstandswerten und den zu diesen Abstandswerten gehörenden Orten auf dem Objekt vorgenommen wird
• - die Messung in mehrere Abstandsintervalle unterteilt wird, denen unterschiedliche Orte auf dem Objekt zugeordnet sind, und
• - wobei eine in einem Abtastintervall gemessene Schwebungsfrequenz einem Ort zugewiesen wird, der einem n Abtastintervalle älteren Abtastintervall zugeordnet ist, wobei n = 0, 1, 2, ..., ist und proportional mit zunehmender Schwebungsfrequenz ansteigt.

A method according to the invention for the scanning distance determination of an object has the following steps:

• - Emitting, using at least one light source, an optical signal with a frequency that varies over time;
• - Generating an angular distribution of a measurement signal resulting from the optical signal by a dispersive element, partial signals of the measurement signal being directed to the object at radiation angles that differ from one another; and
• Determining values of the distance of the object on the basis of a respective superposition of the partial signals reflected on the object with a reference signal not reflected on the object resulting in beat frequencies;
• - The measurement times of different beat frequencies are stored; and
• - a subsequent unambiguous association between the distance values resulting from the respectively measured beat frequencies and the locations on the object belonging to these distance values being made on the basis of the stored measurement times
• the measurement is subdivided into several distance intervals to which different locations on the object are assigned, and
• a beat frequency measured in a sampling interval is assigned to a location which is assigned to an older sampling interval n sampling intervals, where n = 0, 1, 2, ..., and increases proportionally with increasing beat frequency.

According to one embodiment, for a measured beat frequency, the associated radiation angle of the partial signal causing this beat frequency is calculated back, taking into account the measurement time of the relevant beat frequency and the distance of the object resulting from the relevant beat frequency.

According to one embodiment, the length of a temporal sampling interval over which the respective beat frequencies are determined is in the range from 0.1 μs to 1 μs.

The invention is initially based on the concept of realizing a scanning of the object in a device for determining the distance of an object by creating an angular distribution of the different frequencies present in the optical signal emitted by a light source in the signal path in front of the object via a dispersive element is effected when these frequencies or the partial beams having the respective frequencies are directed onto the object at different tilts or at different angles, so that scanning of the object is achieved without the need for moving components such as scanning or deflecting mirrors .

The use of a dispersive scanner according to the invention has the advantage, compared to the use of movable components such as scanning or deflecting mirrors, that the respective signals due to the fact that the direction of emission and reception are each wavelength-dependent and there is no change in wavelength for one and the same object location (whereby the frequency shift caused by the Doppler effect can generally be neglected), regardless of the speed of the scanning process, always run back into the transmitter / receiver channel, i.e. light returning from the object always reaches the receiver or detector.

On the basis of this principle, the invention now includes in particular the concept of detecting the respective point in time at which the respective beat frequency is measured for beat frequencies obtained from the partial signals generated as described above and their respective superimposition with the reference signal, in order to be based on the respective To calculate back the measurement time of the relevant beat frequency and the distance of the object resulting from the relevant beat frequency, which radiation angle - and thus which location on the object - is to be assigned to the beat frequency or the resulting, determined distance of the object.

As a result, in the method according to the invention, each beat frequency (or each frequency peak in the Fourier spectrum of the superimposed signal obtained) can be uniquely assigned both an object distance and a radiation angle or object location.

The method according to the invention has the advantage, on the one hand, that a significantly faster scanning process can be implemented compared to a run-time or tof-limited method, since the inventive "subsequent" assignment of beat frequencies or object distances to Emission angles or object locations, the dwell time of a respective measurement spot on the object to be scanned can be selected regardless of the transit time of the signal and, in particular, shorter than this transit time.

Another advantage resulting from the method according to the invention is that even when two or more beat frequencies or frequency peaks are detected in the Fourier spectrum of the superimposed signal, based on the above-described recalculation according to the invention, it can be determined which frequency peak or which beat frequency belongs to which radiation angle or object location .

As a result, for example, scenarios can also be metrologically recorded in which, during a comparatively fast scanning process, an object located at a relatively short distance (e.g. a few meters) such as the edge of a house immediately follows an object comparatively far (e.g. several hundred meters) away, since in in this case, both frequency peaks obtained can be clearly assigned to the respective emission angle.

In other words, the invention includes the concept of simultaneously determining distances to the object and the respective associated radiation angles of the dispersive scanner in a device equipped with a dispersive scanner for distance determination, with the result that distances to several objects at different distances are also within a - and the same time window can be clearly determined.

The feature of “using at least one light source” is intended to express in particular that a plurality of light sources operated in parallel (and a plurality of detectors) can also be used to achieve higher data rates.

• - wenigstens einer Lichtquelle zum Aussenden eines optischen Signals mit zeitlich variierender Frequenz;
• - einem dispersiven Element, welches eine Winkelverteilung eines aus dem optischen Signal hervorgegangenen Messsignals bewirkt, wobei Teilsignale des Messsignals unter voneinander verschiedenen Abstrahlwinkeln zu dem Objekt gelenkt werden;
• - einer Auswerteeinrichtung zur Ermittlung von Werten des Abstandes des Objekts auf Basis von jeweils aus einer Überlagerung der an dem Objekt reflektierten Teilsignale mit einem nicht an dem Objekt reflektierten Referenzsignal resultierenden Schwebungsfrequenzen; und
• - einer Speichereinheit zur Speicherung der Messzeitpunkte unterschiedlicher Schwebungsfrequenzen;
• - wobei die Auswerteeinrichtung dazu ausgelegt ist, auf Basis der gespeicherten Messzeitpunkte nachträglich eine eindeutige Zuordnung zwischen aus den jeweils gemessenen Schwebungsfrequenzen resultierenden Abstandswerten und den zu diesen Abstandswerten gehörenden Orten auf dem Objekt vorzunehmen

wobei die Auswerteeinrichtung ferner dazu eingerichtet ist,

• - die Messung in mehrere Abstandsintervalle zu unterteilen, denen unterschiedliche Orte auf dem Objekt (140) zugeordnet sind, und
• - eine in einem Abtastintervall gemessene Schwebungsfrequenz einem Ort zuzuweisen, der einem n Abtastintervalle älteren Abtastintervall zugeordnet ist, wobei n = 0, 1, 2, ..., ist und proportional mit zunehmender Schwebungsfrequenz ansteigt.

The invention further relates to a device for determining the distance of an object by scanning

• - At least one light source for emitting an optical signal with a frequency that varies over time;
• a dispersive element which causes an angular distribution of a measurement signal resulting from the optical signal, partial signals of the measurement signal being directed to the object at different radiation angles;
• an evaluation device for determining values of the distance of the object on the basis of beat frequencies resulting from a superposition of the partial signals reflected on the object with a reference signal not reflected on the object; and
• - A memory unit for storing the measurement times of different beat frequencies;
• - The evaluation device being designed to subsequently make a clear association between the distance values resulting from the respectively measured beat frequencies and the locations on the object belonging to these distance values on the basis of the stored measurement times

wherein the evaluation device is also set up to

• - to divide the measurement into several distance intervals to which different locations on the object ( 140 ) are assigned, and
• assign a beat frequency measured in a sampling interval to a location which is assigned to an older sampling interval n sampling intervals, where n = 0, 1, 2,..., and increases proportionally with increasing beat frequency.

According to one embodiment, with the device according to the invention, when detecting object distances of up to 100m, in particular up to 200m, further in particular up to 300m, with the device a scan rate of at least 0.6MHz, in particular of at least 0.8MHz, further in particular of at least 1MHz, achievable. The scan rate is the number of pixels, the distance of which can be measured, per second.

According to one embodiment, a scan rate that can be achieved with the device is increased by a factor of at least two, in particular by a factor of at least three, further in particular by a factor of at least four, compared to a second scan rate when detecting object distances of up to 100 m, this second scan rate can be achieved with an alternative device for the scanning distance determination of an object, with this alternative device no subsequent assignment takes place between distance values resulting from respectively measured beat frequencies and the locations on the object belonging to these distance values on the basis of stored measurement times.

According to one embodiment, the dispersive element has an AWG.

Further refinements of the invention can be found in the description and in the subclaims.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the accompanying figures.

Figure list

• 1 eine schematische Darstellung zur Erläuterung von Aufbau und Wirkungsweise einer Vorrichtung zur Abstandsermittlung, mit welcher das erfindungsgemäße Verfahren realisierbar ist;
• 2 eine schematische Darstellung zur Erläuterung einer Ausführungsform des erfindungsgemäßen Verfahrens; und
• 3a-3b weitere Diagramme zur Erläuterung des erfindungsgemäßen Verfahrens.

Show it:

• 1 a schematic representation to explain the structure and mode of operation of a device for determining distance with which the method according to the invention can be implemented;
• 2 a schematic representation to explain an embodiment of the method according to the invention; and
• 3a-3b further diagrams to explain the method according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The method according to the invention is described below in an exemplary embodiment with reference to the schematic representations in FIG 1 and 2 described.

1 shows first of all a basic structure of a device for determining distance with which the method according to the invention can be carried out.

A source of light 110 is used to send out an optical signal 111 with a frequency that varies over time. The light source 110 can only have a (central) wavelength of 1550nm ± 100nm by way of example. Other wavelengths or bandwidths (eg 910nm ± 50nm) are also possible. In the exemplary embodiment, the signal has a frequency profile with a linear time dependency. That from the light source 110 The transmitted signal with a frequency that has changed over time (also known as “chirp”) is transmitted via a beam splitter 115 (eg a partially transparent mirror or a fiber optic splitter) split into two partial signals.

The two partial signals are transmitted via a signal coupler 145 coupled and attached to a detector 150 superimposed on each other, with the first partial signal as a reference signal without reflection at the object labeled “140” to the signal coupler 145 and the detector 150 got. The second on the signal coupler 145 or at the detector 150 In contrast, incoming partial signals initially run as a measurement signal via an optical circulator 120 and a collimator and scanner unit 130 to the object 140 , is reflected back by this and reaches the signal coupler with a time delay and a correspondingly changed frequency compared to the reference signal 145 and to the detector 150 .

The beam corresponding to the measurement signal has different frequencies at different times and hits the collimator and scanner unit 130 existing dispersive element 131 , from which different frequencies (ie partial beams having the respective frequencies 102 , 102 , ...) in different directions to the object 140 be distracted. Although this basically means that the object is scanned 140 is made possible without the need for moving components such as scanning or deflecting mirrors, can also be used to carry out a two-dimensional scanning process - in combination with the dispersive element 131 - one (or more) mechanical components such as a scanning or deflecting mirror are used.

In the signal coupler 145 the partial signals generated from the measurement signal as described above are combined with the reference signal. Via an evaluation device 160 is that from the detector 150 delivered detector signal relative to the measuring device or the light source 110 evaluated, the difference frequency detected at a certain point in time between the measurement signal and the reference signal characteristic of the distance to the object 140 from the measuring device or the light source 110 is. in the 1 with "D" the beam diameter and with "d" the distance of the object 140 designated by the measuring device.

According to the invention, in addition to the beat frequencies obtained for the superposition of the respective partial signals with the reference signal, the respective measurement time at which the relevant beat frequency is measured is now recorded in order, based on the measurement time of the relevant beat frequency and the distance of the resulting from the frequency value of the relevant beat frequency Object 140 to calculate back which beam angle - and thus which location on the object 140 - the beat frequency or the resulting, determined distance of the object 140 is to be assigned. In particular, the mean value between the initial value in time and the final value in time of a sampling interval in which the respective measurement takes place can be used as the “measurement time” of a beat frequency.

2 Fig. 13 is a diagram illustrating the above concept. According to 2 are temporal sampling intervals, which are significantly shorter than an expected light or signal transit time (tof = "time of flight"), denoted by "1", "2", "3", .... Typical orders of magnitude of the temporal sampling intervals for a distance of 150m can be 0.5µs. In the sampling interval “3”, two peaks “A” and “B” are observed in the Fourier spectrum of the signal. Peak “A” has a beat frequency which corresponds to a time delay between the transmitted measurement signal and the received measurement signal of one sampling interval. The associated angle of radiation therefore corresponds to the angle of radiation in sampling interval “2”, in which, however, the returning signal was not yet observable because the light or signal propagation time was greater than a sampling interval. Peak "B" has a beat frequency which corresponds to a delay of two sampling intervals. The associated radiation angle therefore belongs to the sampling interval "1". Since a mean angle is assigned to each sampling interval and the assignment “angle to time” is also known, the associated radiation angle can be calculated if the beat frequency is known by taking the time offset (which is proportional to the beat frequency) into account.

The concept according to the invention is explained below using a specific exemplary embodiment.

zugrundegelegt, wobei κ die Chirprate bezeichnet. Wenn die Frequenz einen Maximalwert f+Δf erreicht hat, springt der Frequenzwert zurück auf den Ausgangswert, woraufhin sich die Frequenz-Durchstimmung wiederholt. Bei einer Durchlaufzeit τ für eine vollständige Frequenz-Durchstimmung bis zum maximalen Frequenzwert f+Δf ergibt sich eine Chirprate κ=Δf/τ.A linear time dependency of the frequency of the light source is only exemplified 110 emitted signal according to $$\text{f}\left(\text{t}\right)={\text{f}}_0+\text{k}\ast \text{t}$$

based, where κ denotes the chirp rate. When the frequency has reached a maximum value f + Δf, the frequency value jumps back to the initial value, whereupon the frequency tuning is repeated. With a throughput time τ for a complete frequency tuning up to the maximum frequency value f + Δf, a chirp rate κ = Δf / τ results.

As a result of the dispersive collimator and scanner unit used according to the invention 130 the radiation angle Φ (t) is directly coupled to the wavelength and thus also to the frequency. Without loss of generality, it is now assumed that the radiation angle changes by an amount ΔΦ in the case of a complete frequency tuning. Thus, emitted light for which there is no significant change in wavelength (caused by the Doppler effect) or change in location within the light transit time tof (which can have typical values of less than 1µs) is reflected on the object 140 always in the detector 150 fed back, even if the angle of radiation has already changed significantly during the time of flight.

wobei c die Lichtgeschwindigkeit bezeichnet. Tritt nun gleichzeitige Interferenz mehrerer Signale aus unterschiedlichen Entfernungen am Detektor 150 auf, so entstehen mehrere Schwebungsfrequenzen, welche durch eine Fouriertransformation des Schwebungssignals eindeutig bestimmt werden können. Bei Aufteilung der Durchlaufzeit τ in n Messintervalle werden gleichzeitig n verschiedene Winkelpositionen innerhalb des Bereichs [φ, φ+Δφ] definiert. Im Folgenden wird nun das Messsignal in einem Messzeitfenster [t, t+τ/n] betrachtet, wobei der Wert von τ/n wesentlich kleiner als die Lichtlaufzeit 2*d/c angenommen wird. Dabei kann der Abstand d typischerweise 150m betragen.Will that from the light source 110 outgoing light is split into a reference beam and a measuring beam, which are then sent to the detector 150 interfere, a distance-dependent beat signal is generated, the frequency of which can be determined from the chirp rate κ. At a distance d, the following applies to the beat frequency: $${\text{f}}_{\text{Beat}}\left(\text{d}\right)=2\ast \text{k}\ast \text{d / c}$$

where c denotes the speed of light. If there is now simultaneous interference of several signals from different distances at the detector 150 on, then several beat frequencies arise, which can be clearly determined by a Fourier transformation of the beat signal. When dividing the throughput time τ into n measurement intervals, n different angular positions are simultaneously defined within the range [φ, φ + Δφ]. In the following, the measurement signal is considered in a measurement time window [t, t + τ / n], where the value of τ / n is assumed to be significantly smaller than the time of flight 2 * d / c. The distance d can typically be 150 m.

If a signal with the frequency 2 * κ * d / c is observed in the above-mentioned measurement window, this signal was transmitted in the time window [t-2 * d / c, t + τ / n-2 * d / c]. Since the associated angle can be clearly determined from the angle / time dependency, the location of the scattering or reflecting object can be clearly identified 140 to be determined.

As a limitation, it is assumed that at typical speeds with values of, for example, 100km / h, typical measurement intervals with values in the range of 0.1µs and typical light transit times (tof) with values in the range of 1µs, only minor changes in the location occur. For example, at a speed of 100 km / h, the distance would only change by 28 µm during the light travel time, which is negligible compared to measurement errors. The maximum detector frequency also determines the maximum detectable distance. Light that is scattered back from a greater distance can no longer be detected. In a specific exemplary embodiment, according to Table 1, for an exemplary value of the chirp rate κ of the light source 110 of κ = 5 * 10 ¹⁵ Hz / s and different distances of the object 140 up to 150m based on a measurement time of 0.08µs per pixel (to achieve a pixel rate of 25fps with 0.5MPixels) the respective values of the beat frequency as well as the delay time and the pixel offset for the respective measurement of these beat frequencies are listed.

Table 1: Distance [m] Beat frequency [Hz] Delay time [s] Pixel offset 10 3.67 * 10 ⁸ 6.67 * 10 ^-8 0 20th 7.35 * 10 ⁸ 1.33 * 10 ^-7 1 30th 1.10 * 10 ⁹ 2.00 * 10 ^-7 2 40 1.47 * 10 ⁹ 2.67 * 10 ^-7 3rd 50 1.84 * 10 ⁹ 3. 33 * 10- ⁷ 4th 60 2.20 * 10 ⁹ 4.00 * 10 ^-7 4th 70 2.57 * 10 ⁹ 4.67 * 10 ^-7 5 80 2.94 * 10 ⁹ 5. 33 * 10- ⁷ 6th 90 3.31 * 10 ⁹ 6:00 * 10- ⁷ 7th 100 3.67 * 10 ⁹ 6.67 * 10 ^-7 8th 110 4.04 * 10 ⁹ 7. 33 * 10- ⁷ 9 120 4.41 * 10 ⁹ 8.00 * 10 ^-7 9 130 4.77 * 10 ⁹ 8.67 * 10 ^-7 10 140 5.14 * 10 ⁹ 9. 33 * 10- ⁷ 11 150 5.51 * 10 ⁹ 1.00 * 10 ^-6 12th

At a distance of 150m, the delay time corresponds to a pixel offset of 12 pixels. If one now observes the signal in a time interval [t, t + 0.08 ps], one would in a Fourier transform of the signal according to 3a several frequency peaks according to 3b , which in the exemplary embodiment correspond to the object distances 10m, 50m, 100m and 150m.

When using a conventional scanning mirror, only the “10m peak” would be observed, since the light would no longer reach the detector from greater distances within the pixel time.

In the exemplary embodiment, the 150 m peak has a pixel offset of 12 pixels. The corresponding distance calculation therefore does not have to use the radiation angle in the time interval [t, t + 0.08 ps], but the radiation angle in the interval [t-0.96 µs, t + 0.84 µs] or [t-12 * 0.08 µs, t + 0.08 µs- 12 * 0.08 µs] can be assigned. The corresponding radiation angles are calculated analogously for the other peaks. As a result, a distance and a radiation angle can be clearly assigned to each frequency peak.

In further embodiments, one (or more) mechanical component (s) such as a scanning or deflecting mirror can also be used - in combination with the dispersive element - to carry out a two-dimensional scanning process. In this way, comparatively fast dispersive scanning along one axis or in one spatial direction can be combined with comparatively slow mechanical scanning in the other (typically vertical) spatial direction. If, as above, a 0.5MPixel image is used as a basis, this corresponds to 707 pixels * 707 pixels, assuming a square image field as an example. While the angle is changed every 0.08µs for the fast dispersive scanning process (corresponding to the measuring time in the above example), with the comparatively slow mechanical scanning a change of direction only takes place every 56µs (which is not critical compared to the running time).

In 3a-3b are to explain the effect achieved by the method according to the invention, the peaks obtained for different distance values in the signal spectrum obtained on the basis of a Fourier transformation of the beat signal both for a scenario without application of the method according to the invention or with a non-dispersive scanning device such as a galvo scanner ( 3a) as well as for a scenario using the method according to the invention ( 3b) shown.

According to 3b Using the method according to the invention, several frequency peaks (corresponding to distance values of 10 m, 50 m, 100 m or 150 m) can be determined in the signal spectrum obtained using a Fourier transformation of the beat signal. At the same time, on the basis of the back calculation according to the invention, it can be determined which of these frequency peaks or which beat frequency belongs to which emission angle or object location. As a result, scenarios can also be metrologically recorded in which, in the course of a comparatively fast scanning process, an object located at a relatively short distance (e.g. a few meters) such as the edge of a house immediately follows an object comparatively far (e.g. several hundred meters) away, since then both frequency peaks obtained can be clearly assigned to the respective radiation angle.

• Wenn man etwa in einem einfachen Berechnungsbeispiel von einer Signalauswertungszeit von 1µs ausgeht, ergibt sich für ein herkömmliches Verfahren eine Daten- bzw. Pixelrate vom IMPixel/s. Infolge der Laufzeitbegrenzung würde sich jedoch bei einem Objektabstand von 150m die gesamte, pro Messpunkt erforderliche Messzeit (für Signalauswertung sowie Hin- und Zurücklaufen des Signals zum bzw. vom Objekt) auf t_ges. = 1µs (Signalauswertungszeit) + 1µs (Laufzeit) = 2µs erhöhen, da für jeden Messpunkt das Zurücklaufen des am Objekt reflektierten Signals abgewartet werden muss. Bei einem Objektabstand von 300m würde sich die gesamte erforderliche Messzeit pro Messpunkt auf tges. = 1µs (Signalauswertungszeit) +2µs (Laufzeit) =3µs erhöhen, etc.

From the above it follows that when the method according to the invention is used, the decrease in the data or pixel rate that can be achieved with the scanning distance determination, which is conventionally given with increasing object distance, is omitted:

• If, for example, a signal evaluation time of 1µs is assumed in a simple calculation example, a data or pixel rate of IMPixel / s results for a conventional method. As a result of the transit time limitation, however, at an object distance of 150 m, the total measuring time required per measuring point (for signal evaluation and for the signal to and from the object) would be t _total. = 1µs (signal evaluation time) + 1µs (running time) = 2µs increase, since for each measuring point you have to wait for the signal reflected on the object to return. With an object distance of 300m, the total required measuring time per measuring point would amount to ttotal. = 1µs (signal evaluation time) + 2µs (runtime) = 3µs increase, etc.

Since in the method according to the invention the return of the signal reflected on the object does not have to be waited for for the individual measuring points (i.e. the time limit is not applicable), the signal evaluation time of 1µs is only required for each measuring point regardless of the object distance, with the result that the one achievable in the calculation example The data or pixel rate of the IMPixel / s is maintained even at distances of, for example, more than 100m, in particular more than 200m.

Although the invention has also been described on the basis of specific embodiments, numerous variations and alternative embodiments will be apparent to those skilled in the art, for example by combining and / or exchanging features of individual embodiments. Accordingly, it is understood by a person skilled in the art that such variations and alternative embodiments are also included in the present invention and that the scope of the invention is limited only within the meaning of the attached patent claims and their equivalents.

Claims (9)

Device for scanning the distance of an object, with • at least one light source (110) for emitting an optical signal with a frequency that varies over time; • a dispersive element (131) which effects an angular distribution of a measurement signal resulting from the optical signal, partial signals of the measurement signal being directed to the object (140) at radiation angles different from one another; • an evaluation device (160) for determining values of the distance of the object (140) on the basis of beat frequencies resulting from a superposition of the partial signals reflected on the object (140) with a reference signal not reflected on the object (140); and • a memory unit for storing the measurement times of different beat frequencies; The evaluation device (160) is designed to subsequently make an unambiguous assignment between the distance values resulting from the respective measured beat frequencies and the locations on the object (140) belonging to these distance values on the basis of the stored measurement times, characterized in that the evaluation device also is set up to • divide the measurement into several distance intervals to which different locations on the object (140) are assigned, and to assign a beat frequency measured in a sampling interval to a location that is assigned to an older sampling interval n sampling intervals, where n = 0 , 1,2, .. and increases proportionally with increasing beat frequency. Device according to Claim 1 , characterized in that it is designed to detect object distances of more than 100m, further in particular of more than 200m. Device according to Claim 1 or 2 , characterized in that when detecting object distances of up to 100m, in particular up to 200m, further in particular up to 300m, a scan rate of at least 0.6MHz, in particular of at least 0.8MHz, further in particular of at least 1MHz, can be achieved with the device. Device according to one of the Claims 1 to 3rd , characterized in that a scan rate achievable with the device is increased by a factor of at least two, in particular by a factor of at least three, further in particular by a factor of at least four, compared to a second scan rate when detecting object distances of up to 100m This second scan rate can be achieved with an alternative device for the scanning distance determination of an object, with this alternative device no subsequent assignment between distance values resulting from each measured beat frequencies and the locations on the object belonging to these distance values on the basis of stored measurement times. Device according to one of the Claims 1 to 4th , characterized in that the dispersive element (131) has an AWG. Device according to one of the Claims 1 to 5 , characterized in that the length of a temporal sampling interval over which the respective beat frequencies are determined is in the range from 0.1µs to 1µs. Method for scanning the distance determination of an object, the method comprising the following steps: emitting, using at least one light source (110), an optical signal with a frequency that varies over time; • Generating an angular distribution of a measurement signal originating from the optical signal by a dispersive element (131), partial signals of the measurement signal being directed to the object (140) at radiation angles different from one another; and • determining values of the distance of the object (140) on the basis of beat frequencies resulting from a superposition of the partial signals reflected on the object (140) with a reference signal not reflected on the object (140); • The measurement times of different beat frequencies are stored; and • where, on the basis of the stored measurement times, an unambiguous assignment is subsequently made between the distance values resulting from the respectively measured beat frequencies and the locations on the object belonging to these distance values, characterized in that • the measurement is divided into several distance intervals to which different locations are located are assigned to the object, and to assign a beat frequency measured in a sampling interval to a location which is assigned to an older sampling interval n sampling intervals, where n = 0,1,2, .. and increases proportionally with increasing beat frequency. Procedure according to Claim 7 , characterized in that for a measured beat frequency on the associated radiation angle of the respective causal component signal for this beat frequency Taking into account the measurement time of the relevant beat frequency and the distance of the object resulting from the relevant beat frequency is calculated back. Procedure according to Claim 7 or 8th , characterized in that the length of a temporal sampling interval over which the respective beat frequencies are determined is in the range from 0.1µs to 1µs.

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