FUNCTIONALITY TESTING OF A LASER SCANNER

Description

[0001] The present invention relates to a method for functional testing of a laser scanner comprising a housing with a translucent window, a transmitting unit arranged within the housing for emitting laser signals, a movable deflection unit for deflecting the laser signals, and a detector unit arranged within the housing. At least one test signal is transmitted by means of the transmitting unit during a test phase, and the deflection unit is aligned with respect to the transmitting unit during the test phase such that the at least one test signal is not directed onto the window. The invention also relates to a corresponding laser scanner device comprising a computing unit and a laser scanner, a motor vehicle comprising a laser scanner device, and a computer program product.

[0002] Lidar systems can be mounted on motor vehicles to implement a variety of functions in electronic vehicle guidance systems or driver assistance systems. These functions include distance measurement, adaptive cruise control algorithms, lane departure warning, object tracking, and so on.

[0003] A common type of lidar system is a laser scanner, in which a laser beam is deflected by a deflection unit, allowing the laser scanner to be positioned at various angles. The emitted laser beams can be partially reflected or scattered in the environment, and scattered or reflected portions can in turn impinge on the laser scanner, particularly on a detector unit of the laser scanner, which can generate corresponding detector signals based on the detected portions. The transmitter unit of a laser scanner contains one or more laser light sources, and the detector unit contains one or more optical detectors, such as photodiodes.

[0004] The maximum range of the laser scanner is, in general and especially in the automotive context, of great importance. The functionality and in particular the maximum range of a laser scanner can be affected, for example, by contamination of the light sources or the optical detectors. The contamination can be caused, for example, by dust particles that occur during the manufacturing process. Such dust particles can partially obscure the light source or the optical detector and thus reduce the range of the laser scanner. In principle, contamination can be identified, for example, through tests at the end of the manufacturing process. However, it is possible that the contamination only arises after the test, or that contamination already present before the test only obscures the light source or the optical detector after the test.

[0005] Document DE 10 2018 110 566 A1 describes a method for testing the functionality of a laser scanner. A light signal is transmitted via a transmitter of the laser scanner, while a rotatable or pivotable deflection mirror unit is aligned so that light signals from the transmitter cannot be directed onto a window in the laser scanner housing. The light signal scattered inside the housing is received by the receiver and compared with a reference intensity distribution. Depending on the result of the comparison, an indication of the functionality of the laser scanner may be generated.

[0006] Document DE 10 2013 205312 A1 describes a method for testing the functionality of an ultrasonic sensor, comprising the steps of acquiring first measurement signals in a first time window, determining a threshold value based on the acquired first measurement signals, acquiring second measurement signals in a second time window, and generating a characteristic value based on the acquired second measurement signals and the threshold value. A signal representing the functionality of the ultrasonic sensor is generated based on the characteristic value.

[0007] A disadvantage of this method is that the reference intensity distribution is generally temperature dependent, so that different reference intensity distributions must be maintained for different temperatures.

[0008] Against this background, it is an object of the present invention to provide an improved concept for functional testing of a laser scanner that is more robust against temperature fluctuations.

[0009] This object is achieved by the respective subject matter of the independent claims. Advantageous further developments and preferred embodiments are the subject matter of the dependent claims.

[0010] The improved concept is based on the idea of ​​determining a pulse width for each corresponding detector signal in a laser scanner whose detector unit contains at least two optical detectors and determining the sum of the pulse widths in order to check the functionality.

[0011] According to the improved concept, a method for functional testing of a laser scanner is specified. The laser scanner has a housing with a translucent window and a sensor arranged within the housing for emitting laser signals. The laser scanner also has a movable deflection unit for deflecting the laser signals and a detector unit arranged within the housing with at least two optical detectors. According to the method, at least one test signal is transmitted by means of the transmitting unit during a test phase. During the test phase, the deflection unit is aligned with respect to the transmitting unit, in particular by means of a control unit of the laser scanner, in such a way that the at least one test signal is not directed onto the window, in particular by the deflection unit.Portions of the at least one test signal, in particular reflected and / or scattered portions, are detected by the at least two optical detectors, and based on the detected portions, at least two detector signals are generated by the at least two optical detectors. By means of a computing unit, in particular by means of a computing unit of the laser scanner or by means of a computing unit coupled to the laser scanner, a pulse width is determined for each of the at least two detector signals, and a sum of the determined pulse widths, in particular of all determined pulse widths, is calculated. The functionality of the transmitting unit and / or the detector unit is checked, in particular by means of the computing unit, based on the sum.

[0012] Here and below, the term "light" can be understood to include electromagnetic waves in the visible, infrared, and / or ultraviolet ranges. Accordingly, the term "optical" can also be understood to refer to light in this sense. Preferably, the laser signals and the test signal correspond to light in the infrared range.

[0013] The translucent window of the housing is particularly translucent for light that can be emitted by the transmitting unit, particularly in the form of laser signals or the test signal. Apart from the window, the housing can be opaque, for example.

[0014] The laser signals and the at least one test signal each correspond to laser signals that can be emitted by one or more light sources of the transmitting unit, in particular laser light sources, for example, laser diodes. In particular, the at least one test signal can be considered a special case of laser signals, namely a laser signal that is emitted during the test phase. Nevertheless, the test signals can also be generated and emitted with a specifically adapted spectral or other composition or structure that can differ from other laser signals generated and emitted outside the test phase. However, this is not mandatory.

[0015] The detector unit, in particular the at least two optical detectors, is or are configured to detect reflected or scattered portions of the laser signals and of the at least one test signal. If the laser signals are emitted through the translucent window into the surroundings of the housing, then, for example, portions of the laser signal reflected or scattered outside the laser scanner or the housing can re-enter the housing and be detected. In the case of the at least one test signal, portions of the at least one test signal that may have been reflected and / or scattered multiple times, in particular within the housing, are detected by the at least two optical detectors. In particular, the at least one test signal essentially does not leave the housing of the laser scanner because it is not directed onto the window.

[0016] The fact that the at least one test signal is not directed onto the window can be understood in particular based on a ray-optical understanding or an understanding according to geometric optics.

[0017] Each optical detector of the at least two optical detectors generates, in particular, an associated detector signal of the at least two detector signals based on the components detected by the respective optical detector. Depending on the specific embodiment of the laser scanner, the at least two optical detectors can be configured differently. Preferably, the at least two optical detectors each contain a photodiode, for example, an avalanche photodiode (APD). The temporal profile of one of the detector signals therefore reflects the temporal profile of the number of photons striking a corresponding optically active surface of the respective optical detector.

[0018] The detector signals, in particular, comprise signal pulses, which can also be referred to as echoes. The pulse width of a detector signal therefore corresponds, in particular, to the pulse width of a corresponding signal pulse. The pulse width is defined as the period of time during which the amplitude of the corresponding detector signal assumes a value above a predefined limit. This pulse width is also referred to as the echo pulse width (EPW).

[0019] Checking the functionality of the transmitting unit and / or the detector unit can be understood in particular as meaning that, based on the sum of the pulse widths, a check is carried out to determine whether there is a restriction compared to normal operation or unrestricted operation or unrestricted function of the transmitting unit and / or the detector unit.

[0020] In particular, the number of photons striking the active surface of an optical detector affects the pulse shape of the corresponding signal pulse and thus the pulse width. Therefore, if the pulse width under reproducible conditions, such as those prevailing during the test phase, differs from that expected for regular or unrestricted operation, this may indicate limited functionality of the transmitting unit and / or the detector unit. This can be caused, in particular, by the partial or complete obscuration of a light source of the transmitting unit or one of the optical detectors, i.e., in particular, of an active surface of one of the optical detectors.

[0021] The improved concept exploits the finding that the sum of the pulse widths, especially for a predefined detector sensitivity of the entire detector unit, is at least approximately invariant to temperature fluctuations, even if the individual optical detectors have differing temperature characteristics. For example, if the relationship between temperature and voltage, especially the reverse voltage, with which the optical detector must be operated to achieve a certain sensitivity, is not exactly the same for all optical detectors. Such different temperature characteristics can be attributed, for example, to slightly different sizes of the respective active areas of the optical detectors.The individual pulse widths may vary with temperature changes, but the sum of all pulse widths remains at least approximately constant, since a possibly smaller pulse width of one of the detectors is compensated by correspondingly larger pulse widths of the other detectors. It has been shown that this is still the case even if one of the at least two optical detectors differs significantly in its temperature characteristics from the other optical detectors.

[0022] If the calculated sum of the pulse widths deviates from an expected value, which can be determined, for example, during calibration, this indicates a limited function of one of the optical detectors or a light source of the transmitting unit, for example due to contamination. Furthermore, the magnitude of the deviation of the sum value from the expected value with unrestricted function can provide information about the severity of the functional limitation or contamination. The greater the occlusion, the fewer photons are detected by the corresponding optical detector and the smaller the pulse width becomes, which consequently results in a correspondingly greater deviation of the sum.

[0023] By using the test signals in the manner described, any possible influence of ambient light is also reduced or almost eliminated.

[0024] According to at least one embodiment of the method according to the improved concept, the sum is compared with a predetermined reference value by means of the computing unit and the functionality of the transmitting unit and / or the detector unit is checked based on a result of the comparison.

[0025] The reference value can, in particular, be the sum of the pulse widths at an earlier point in time, for example, during calibration. Deviations of the sum from the reference value, in particular those that exceed a predefined tolerance value, indicate limited functionality of the at least two optical detectors or a light source.

[0026] In various embodiments, the reference value can also be updated or periodically updated, for example, when activating or deactivating the laser scanner. If, in particular, no significant impairment of the functionality of the transmitter unit and / or the detector unit is detected, the calculated sum of the pulse widths can be set and stored as the new reference value. This allows for the effects of normal aging of the components, especially the optical detectors, to be compensated.

[0027] According to at least one embodiment, the at least two optical detectors each include a photodiode, for example an avalanche photodiode (APD), which is operated in the reverse direction, in particular by means of a control unit of the laser scanner. A reverse voltage for operating the photodiodes is regulated during the test phase, in particular by means of the control unit, in order to set a predefined detector sensitivity of the detector unit and, in particular, to maintain it constant.

[0028] The detector sensitivity is, in particular, the combined sensitivity of all optical detectors of the at least two optical detectors. This can be determined, for example, by a total dark current of the at least two optical detectors and / or, particularly in the case of APDs, a total multiplication factor of the at least two optical detectors. The multiplication factor indicates, in particular, how many charge carriers are generated per detected photon by the at least two optical detectors, for example, on average.

[0029] In particular, the at least two optical detectors are all operated with the same blocking voltage.

[0030] According to at least one embodiment, a target value for the control of the blocking voltage is determined, in particular by means of the control unit, based on predetermined calibration data as a function of the detector sensitivity.

[0031] The calibration data can, for example, describe a relationship between a temperature, for example, an ambient temperature of the at least two optical detectors or a heat sink temperature of the at least two optical detectors, or the like, and the blocking voltage required to achieve the detector sensitivity. This relationship can, in particular, be at least approximately linear. The relationship can be stored, for example, in the form of a conversion table or look-up table, in a memory element of the computing unit or the control unit.

[0032] For calibration, for example, the detector sensitivity or a corresponding dark current or multiplication factor can be specified. The corresponding blocking voltage required to achieve the detector sensitivity or dark current or multiplication factor can then be determined for two or more temperatures. Blocking voltages for other temperatures can then be determined by linear interpolation and / or extrapolation.

[0033] According to the improved concept, a laser scanner device comprising a computing unit and a laser scanner is also specified. The laser scanner has a housing with a translucent window and a transmitting unit arranged within the housing for emitting laser signals. The laser scanner has a control unit and a movable deflection unit for deflecting the laser signals, and a detector unit arranged within the housing with two or more optical detectors. The control unit is configured to control the transmitting unit to transmit at least one test signal during a test phase. The control unit is also configured to control the deflection unit such that the deflection unit is aligned with respect to the transmitting unit during the test phase such that the at least one test signal is not directed onto the window.The at least two optical detectors are configured to detect reflected and / or scattered components of the at least one test signal and to generate at least two detector signals based on the detected components. The computing unit is configured to determine a pulse width for each of the at least two detector signals and to calculate a sum of the pulse widths. The computing unit is configured to check the functionality of the transmitting unit and / or the detector unit based on the sum.

[0034] The computing unit can be part of the laser scanner or be provided separately from it. If the laser scanner device is intended for use in or on a motor vehicle, the computing unit can be implemented, for example, as an electronic control unit of the motor vehicle. The control unit can also be part of the computing unit if necessary. In particular, described functions or tasks of the computing unit can be performed by the control unit in various embodiments, or vice versa.

[0035] According to at least one embodiment of the laser scanner device, the deflection unit includes a rotatable or pivotable mirror or a microelectromechanical mirror system, i.e. a mirror designed as a microelectromechanical system, MEMS.

[0036] In particular, the control unit can control the deflection unit during the test phase in such a way that test signals transmitted by the transmitting unit do not hit a reflective surface of the deflection unit, in particular the mirror, or are deflected by the reflective surface into an area within the housing that does not correspond to the window.

[0037] In various embodiments, the pivotable or rotatable mirror comprises a mirror body, which in particular can be substantially cuboid-shaped, with a reflective surface located on one side surface of the cuboid. In various embodiments, a further reflective surface can be arranged on a side of the cuboid opposite the reflective surface. The mirror body is mounted so as to be rotatable or pivotable about an axis of rotation, which in particular passes through two further opposite side surfaces of the cuboid. The remaining two side surfaces of the cuboid, which therefore correspond neither to a reflective surface nor to a side surface through which the axis of rotation passes, can be referred to, for example, as end faces.

[0038] In various embodiments, the control unit is configured to control the deflection unit during the test phase in such a way that the emitted test signals hit one of the end faces.

[0039] According to at least one embodiment, the at least two optical detectors each include a photodiode, in particular an APD. The control unit is configured to operate the photodiodes in the reverse direction and to regulate a reverse voltage for operating the photodiodes during the test phase in order to set a predefined detector sensitivity of the detector unit.

[0040] According to at least one embodiment, the control unit is configured to operate all photodiodes of the at least two optical detectors with the same regulated blocking voltage during the test phase.

[0041] According to at least one embodiment, the control unit is configured to determine a target value for the regulation of the blocking voltage based on predetermined calibration data depending on the detector sensitivity.

[0042] Further embodiments of the laser scanner device follow directly from the various embodiments of the method according to the improved concept, and vice versa. In particular, a laser scanner device according to the improved concept can be configured or programmed to perform a method according to the improved concept, or the laser scanner device performs such a method.

[0043] According to the improved concept, a motor vehicle is also provided which includes an embodiment of a laser scanner device according to the improved concept.

[0044] According to the improved concept, a computer program with instructions is also provided. When the instructions or the computer program are executed by a laser scanner device according to the improved concept, the instructions cause the laser scanner device to perform a method according to the improved concept.

[0045] According to the improved concept, a computer-readable storage medium is also specified which stores a computer program according to the improved concept.

[0046] Computer programs as well as computer-readable storage media according to the improved concept can be referred to as respective computer program products with the instructions.

[0047] Further features of the invention emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be encompassed by the improved concept not only in the respective combination specified, but also in other combinations. Thus, embodiments of the improved concept are also encompassed and disclosed that are not explicitly shown and / or explained in the figures, but which emerge and can be generated from the explained embodiments through separate combinations of features.

[0048] The figures show: Fig. 1 shows a schematic representation of a motor vehicle with an exemplary embodiment of a laser scanner device according to the improved concept; Fig. 2 shows a schematic representation of a further exemplary embodiment of a laser scanner device according to the improved concept; Fig. 3 shows schematic representations of a transmitting unit of a further exemplary embodiment of a laser scanner device according to the improved concept; Fig. 4 shows schematically a part of a further exemplary embodiment of a laser scanner device according to the improved concept in a scanning phase; and Fig. 5 shows a schematic representation of a further exemplary embodiment of a laser scanner device according to the improved concept in a testing phase.

[0049] In Fig. 1 An exemplary embodiment of a motor vehicle 1 according to the improved concept is schematically shown. The motor vehicle 1 includes a laser scanner device 2 according to an exemplary embodiment of the improved concept. The laser scanner device 2 can emit laser signals 9 into an environment of the motor vehicle 1 and detect portions 9' of the laser signals reflected by an object 3 in the environment. Based on the detected reflected portions 9', the laser scanner device 2 can determine a position and / or distance of the object 3 from the laser scanner device 2. This can be carried out, for example, based on the concept of time-of-flight (ToF) measurement.

[0050] Fig. 2 shows schematically a block diagram of an exemplary embodiment of a laser scanner device 2, for example the laser scanner device 2 of the motor vehicle 1 from Fig. 1 The laser scanner device 2 has a laser scanner 2b and a computing unit 2a connected to the laser scanner 2b, which can be designed, for example, as an electronic control unit of the motor vehicle 1. The laser scanner 2b has a housing 4 with a translucent window 5 and a transmitting unit 6 arranged within the housing 4 for transmitting the laser signals 9 through the translucent window 5. The laser scanner 2b contains a control unit 8, which is connected to the computing unit 2a and to the transmitting unit 6 in order to control the latter to transmit the laser signals 9. The laser scanner 2b also contains a detector unit 7 with at least two optical detectors, which are designed in particular as photodiodes, for example as APDs. The transmitting unit 6 contains at least one light source, in particular a laser source, for example at least one infrared laser diode.

[0051] The detector unit 7 can detect the reflected portions 9' of the laser signals 9, and based thereon, each of the at least two optical detectors can generate a corresponding detector signal and transmit it to the control unit 8 and / or the computing unit 2a.

[0052] The laser scanner 2b also includes a deflection unit, which can, for example, have a mirror 10 mounted rotatably about a rotation axis 11. The rotation axis 11 is in Fig. 2 perpendicular to the plane of the drawing. The deflection unit is also connected to the control unit 8, and the control unit 8 can control the deflection unit accordingly, so that the mirror 10 is rotated about the rotation axis 11. The rotation of the mirror 10 can thus vary the emission angle of the laser signals 9. A reception path for the reflected portions 9' of the laser signals 9, which were reflected, for example, by the object 3, leads via the mirror 10 to the detector unit 7, in particular to an active surface of one of the optical detectors. The reflected portions 9' are then detected by the corresponding optical detector, so that by rotating the mirror 10 about the rotation axis 11, each of the optical detectors can detect reflected portions 9' of the laser signals 9 incident from different directions.The instantaneous position of the mirror 10 can be determined, for example, via a rotary encoder (not shown) coupled to the rotation axis 11 or a corresponding shaft.

[0053] By knowing the instantaneous position of mirror 10 at any given time, for example, a set of sample points, also referred to as a point cloud, can be generated from the temporal sequence of the detected reflected portions 9'. A subset of the sample points, or point cloud, is generated using each optical detector. A subset of sample points generated by one of the optical detectors can also be referred to as the position of sample points.

[0054] In Fig. 3 are schematically the transmitting unit 6 of the laser scanner 2b from Fig. 2 as well as the laser signals 9 and the object 3. The upper figure in Fig. 3 corresponds, for example, to a side view, i.e. a view perpendicular to the rotation axis of the mirror 10. The lower figure in Fig. 3 corresponds, for example, to a top view of the transmitting unit 6, i.e. a view with a viewing direction parallel to the rotation axis of the mirror 10. As can be seen from the figures of the Fig. 3 As can be seen, the respective beam expansion of the laser signals 9 can be different in different planes.

[0055] In Fig. 4 the detector unit 7 and the mirror 10 of the laser scanner 2b of the Fig. 2 schematically shown again, with the reception path of the reflected portions 9' indicated. Optionally, the laser scanner 2b can have a lens arrangement 14 for beam guidance, which is arranged in the reception path for the reflected portions 9'.

[0056] In the example of Fig. 4 Four optical detectors 7a, 7b, 7c, 7d of the detector unit 7 are shown, which are arranged, for example, linearly next to one another. For example, the transmitting unit 6 can have two or more light sources, with each light source being assigned two or more of the optical detectors 7a, 7b, 7c, 7d.

[0057] In Fig. 4 The mirror 10 has an approximately or substantially cuboid-shaped mirror body. However, the side surfaces of the mirror body do not necessarily have to be flat, but can also be curved, for example. The mirror 10 has, for example, two opposite reflecting sides 12a, 12b arranged parallel to the rotation axis 11. Two non-reflecting end faces 13a, 13b of the mirror body are arranged perpendicular to the reflecting sides 12a, 12b and also parallel to the rotation axis 11.

[0058] In Fig. 4 The laser scanner 2b is shown, for example, during a scanning phase. The transmitting unit 6 emits the laser signals 9, which strike one of the reflecting surfaces 12a, 12b and, as in Fig. 2 schematically shown, are directed by the deflection unit onto the window 5 so that they can leave the housing 4. The reflected portions 9' also strike the reflective surface 12a, 12b and are accordingly deflected onto the detector unit 7.

[0059] In Fig. 5The laser scanner 2b is shown during a test phase. During the test phase, the mirror 10 is aligned with respect to the transmitting unit 6 such that the test signals 15 emitted during the test phase strike one of the end faces 13a, 13b and are therefore not directed toward the window 5, but are instead reflected or scattered multiple times within the housing 4. The correspondingly multiple-reflected and scattered portions 15' of the test signal 15 in turn strike the active surfaces of the optical detectors 7a, 7b, 7c, 7d, which generate corresponding detector signals based thereon and transmit them to the computing unit. The computing unit 2a then determines a corresponding pulse width for each of the detector signals, which can also be referred to as the echo pulse width (EPW).

[0060] The computing unit 2a also calculates a sum of all determined pulse widths and compares the sum with a predefined reference value, for example, determined during calibration of the laser scanner 2b. If the sum deviates from the reference value by more than a predefined tolerance value, it can be concluded that the functionality of one of the optical detectors 7a, 7b, 7c, 7d or one of the light sources is limited, for example, due to corresponding particle contamination. In this case, the computing unit 2a can, for example, output a warning or error message.

[0061] As described in particular with reference to the figures, the improved concept enables the determination of functional limitations of a laser scanner, particularly due to contamination of light sources or optical detectors of the laser scanner, with greater reliability and robustness against temperature fluctuations. For this purpose, the invariance of the characteristic sum of pulse widths is exploited.

Claims

1. Method for checking the function of a laser scanner (2b), which a housing (4) with a light-transmissive window (5), a transmitter unit (6) for emitting laser signals (9) which is arranged within the housing (4), a movable deflection unit (10) for deflecting the laser signals (9), and a detector unit (7) arranged within the housing (4), wherein according to the method - at least one test signal (15) is transmitted by means of the transmitter unit (6) during a test phase; - the deflection unit (10) is aligned vis-à-vis the transmitter unit (6) during the test phase so that the at least one test signal (15) is not directed at the window (5); characterized in that - components (15') of the at least one test signal (15) are recorded by means of at least two optical detectors (7a, 7b, 7c, 7d) of the detector unit (7) and at least two detector signals are generated on the basis of the detected components (15'); - a pulse width is determined by means of a computing unit (2a) for each of the at least two detector signals and a sum of the determined pulse widths is calculated; and - a functionality of the transmitter unit (6) and / or detector unit (7) is checked on the basis of the sum.

2. Method according to Claim 1, characterized in that - the sum is compared with a given reference value by means of the computing unit (2a); and - the functionality of the transmitter unit (6) and / or detector unit (7) is checked on the basis of a result of the comparison.

3. Method according to either of the preceding claims, characterized in that - the at least two optical detectors (7a, 7b, 7c, 7d) each contain a photodiode operated in the reverse direction; - a reverse voltage for operating the photodiodes is controlled during the test phase in order to set a predefined detector sensitivity of the detector unit (7) .

4. Method according to Claim 3, characterized in that all photodiodes of the at least two optical detectors (7a, 7b, 7c, 7d) are respectively operated with the same controlled reverse voltage during the test phase.

5. Method according to either of Claims 3 and 4, characterized in that a setpoint value for the closed-loop control of the reverse voltage is determined dependent on the detector sensitivity on the basis of given calibration data.

6. Laser scanner device having a computing unit (2a) and a laser scanner (2b), wherein - the laser scanner (2b) has a housing (4) with a light-transmissive window (5), a transmitter unit (6) for emitting laser signals (9) which is arranged within the housing (4), a control unit (8), a movable deflection unit (10) for deflecting the laser signals (9), and a detector unit (7) arranged within the housing (4); - the control unit (8) is configured to drive the transmitter unit (6) such that the transmitter unit (6) transmits at least one test signal (15) during a test phase, and to drive the deflection unit (10) in such a way that the deflection unit (10) is aligned vis-à-vis the transmitter unit (6) during the test phase so that the at least one test signal (15) is not directed at the window (5); characterized in that - the detector unit (7) has at least two optical detectors (7a, 7b, 7c, 7d) which are configured to record components (15') of the at least one test signal (15) and to generate at least two detector signals on the basis of the detected components (15'); and - the computing unit (2a) is configured - to determine a pulse width for each of the at least two detector signals and to calculate a sum of the determined pulse widths; and - to check a functionality of the transmitter unit (6) and / or detector unit (7) on the basis of the sum.

7. Laser scanner device according to Claim 6, characterized in that the deflection unit (10) contains a rotatable or pivotable mirror or a microelectromechanical mirror system.

8. Laser scanner device according to either of Claims 6 and 7, characterized in that - the at least two optical detectors (7a, 7b, 7c, 7d) each contain a photodiode; - the control unit (8) is configured to operate the photodiodes in the reverse direction and to control a reverse voltage for operating the photodiodes during the test phase in order to set a predefined detector sensitivity of the detector unit (7).

9. Laser scanner device according to Claim 8, characterized in that the control unit (8) is configured to operate all photodiodes of the at least two optical detectors (7a, 7b, 7c, 7d) using the same controlled reverse voltage in each case during the test phase.

10. Laser scanner device according to either of Claims 8 and 9, characterized in that the control unit (8) is configured to determine a setpoint value for the closed-loop control of the reverse voltage dependent on the detector sensitivity on the basis of given calibration data.

11. Motor vehicle having a laser scanner device (2) according to any one of Claims 6 to 10.

12. Computer program product having instructions which cause a laser scanner device (2) according to any one of Claims 6 to 10 to carry out a method according to any one of Claims 1 to 5.