OPTICAL SENSOR

Description

[0001] The invention relates to an optical sensor and a method for operating an optical sensor.

[0002] Such optical sensors can be used to detect objects in a monitored area. Examples of such optical sensors are light curtains and light barriers.

[0003] In both cases, the optical sensor has two sensor units located at opposite edges of the monitored area. The first sensor unit contains the light-emitting transmitter(s). The second sensor unit contains the light-receiving receiver(s) and an evaluation unit for processing the received signals.

[0004] These types of optical sensors operate on the principle of light barriers. In a clear monitoring area, the light beams from the transmitter(s) reach their assigned receiver unimpeded. If an object enters the monitoring area, the light beams from the transmitter(s) are interrupted, which is registered in the evaluation unit. Depending on the received signals from the receiver(s), the evaluation unit generates an object detection signal. This object detection signal is, in particular, a binary switching signal whose switching states indicate whether an object is present in the monitoring area or not.

[0005] Before the optical sensor can be used for object detection in the monitored area, the sensor units must be adjusted so that the light beams of the transmitter(s) are aligned with the assigned receiver(s).

[0006] This adjustment is made more difficult because the transmitter(s) typically emit light rays in the non-visible wavelength range, especially in the infrared range.

[0007] Therefore, the optical sensor must have suitable adjustment means. For example, at least one receiver or arrangement of alignment receivers can be assigned a display unit. The display unit then shows the amount of light from a transmitter's light beams that is registered at the receiver or alignment receivers. Based on the amount of light displayed on the display unit, a user can adjust the optical sensor.

[0008] The disadvantage here is that the sensor units must be roughly aligned beforehand so that light rays from a transmitter actually hit the receiver or alignment receivers and thus a light quantity display is performed on the display unit.

[0009] Since the light rays of the optical sensor are not visible, this rough alignment is difficult. A user has to find a rough alignment of the sensor unit through trial and error, which is cumbersome and time-consuming.

[0010] US patent 2023 / 0052882 A1 relates to a light curtain with two sensor units in separate housings, each unit comprising light-emitting transmitters and light-receiving receivers. Viewing modules can be attached to these units for aligning the sensor units. One alignment module emits visible directional beams. A second viewing module is an active indicator module that displays the location of the incident directional beams.

[0011] DE 10 2007 050 097 A1 relates to an optical sensor comprising a light source and a structured front lens which widens the focused light beam of the light source in at least one direction. In an advantageous embodiment, the structure comprises an array of several cylindrical lenses. It is preferably formed by hot stamping the surface of the front lens. The widened light beam is particularly suitable for detecting narrow objects or edges. The light source and the front lens are each aligned relative to the sensor housing.

[0012] The invention is based on the objective of enabling a simple and reliable adjustment of an optical sensor of the type mentioned above.

[0013] The features of the independent claims are provided to solve this problem. Advantageous embodiments and expedient further developments of the invention are described in the dependent claims.

[0014] The invention relates to an optical sensor with at least one light-emitting transmitter, at least one light-receiving receiver, and an evaluation unit configured for evaluating received signals from the at least one receiver. The optical sensor has two sensor units arranged at a distance from one another, in which the at least one transmitter, at least one receiver, and the evaluation unit are integrated and present, with the light beams passing between the sensor units. A mechanical alignment structure is provided on at least one side wall of at least one sensor unit, forming a target geometry that can be aimed at and extends in the direction of an optical axis of this sensor unit. The optical axis of a sensor unit (1a, 1b, 8a) extends in its direction. The target geometry (12) of a mechanical alignment structure is formed by an optical axis of a transmitter (5) or receiver (6).

[0015] The invention also relates to a corresponding method.

[0016] The mechanical alignment structure present on at least one side wall of a sensor unit enables a simple and efficient alignment of the sensor units of the optical sensor to each other, especially in the case that the transmitter(s) of the optical sensor emit light barriers in the non-visible wavelength range, especially in the infrared range.

[0017] A key advantage is that no optoelectronic or electronic components are required to form an alignment unit. Instead, only a purely mechanical alignment structure is needed, which is located on, and in particular attached to, a side wall of a sensor unit. The resulting mechanical alignment structure is simple, robust, and cost-effective.

[0018] The operating principle of the mechanical alignment structure according to the invention is such that it forms a target geometry that extends in the direction of an optical axis of the sensor unit, advantageously parallel to this axis. The target geometry provides a direct measure for the orientation of the optical axis. The function is such that a user aims at the target geometry, i.e., holds their eye in front of it. Using the target geometry, the user can then aim at the opposite sensor units, i.e., preferably align the target geometry with a fixed point on the opposite sensor unit, thereby easily aligning the sensor units relative to each other.

[0019] According to a particularly advantageous embodiment, at least one mechanical alignment structure is provided on each sensor unit.

[0020] One advantage of this embodiment is that each sensor unit can be aligned with the other sensor unit by using its mechanical alignment structure.

[0021] A further advantage of this embodiment is that each sensor unit can be aligned to the target geometry of the other sensor unit using this target geometry; that is, the target geometry of the other sensor unit forms a target that can be aimed at by the target geometry of the mechanical alignment structure of the first sensor unit. This provides a defined reference point for alignment.

[0022] According to an advantageous embodiment, each sensor unit has a front face over which the light beams are guided. The mechanical alignment structure(s) is located on a side wall of the sensor unit adjacent to the front face.

[0023] A mechanical alignment structure can be particularly advantageously attached to the top of the sensor unit. Alternatively or additionally, a mechanical alignment structure can be arranged on the side of the sensor unit. Depending on the placement of the mechanical alignment structure, a target on the opposite sensor unit can be aimed at in different directions. By combining several mechanical alignment structures on one sensor unit, alignment in different directions can be achieved.

[0024] The terms top and bottom are defined in relation to the sensor components arranged in the sensor unit and may also refer to fastening means with which the sensor unit can be mounted on a surface, wall or the like.

[0025] Advantageously, the side wall or each side wall of a sensor unit on which the mechanical alignment structure is present forms a flat surface.

[0026] The target geometry can be easily positioned and aimed at on a flat surface.

[0027] According to a first variant, the optical sensor comprises a first sensor unit in which at least one light-emitting transmitter is present, and a second sensor unit in which a light-receiving receiver is present.

[0028] Each sensor unit expediently has a housing, wherein at least one side wall of at least one housing has a mechanical alignment structure.

[0029] This optical sensor can be used to detect objects within a monitored area, operating on the principle of a light barrier. The sensor units are located at opposite edges of the monitored area. The evaluation unit then advantageously generates a binary switching signal as the object detection signal; the switching states of this signal indicate whether an object is present within the monitored area or not.

[0030] This optical sensor can be designed as a light barrier, in which case it only has a transmitter and a receiver. Alternatively, this optical sensor can also be designed as a light curtain. In this case, the first sensor unit contains a series of transmitters emitting light beams. The second sensor unit contains a corresponding series of receivers and the evaluation unit.

[0031] In general, this type of sensor detects objects by interrupting the path of light rays.

[0032] Alternatively, the optical sensor can also function as a data light barrier. In this case, the transmitter of the data light barrier sends light beams, in which data is encoded, to the assigned receiver. The evaluation unit then decodes the data by analyzing the received signals.

[0033] According to a second variant, the optical sensor has a first sensor unit in which at least one light-emitting transmitter and at least one light-receiving receiver are present. A second sensor unit is formed by a reflector.

[0034] Advantageously, the first sensor unit has a housing, wherein at least one side wall of the housing has a mechanical alignment structure. Alternatively or additionally, a mechanical alignment structure is provided on a frame of the reflector.

[0035] This optical sensor can also be used to detect objects within a monitored area, operating in this case according to the principle of a reflective light barrier. Again, the sensor units are located at opposite edges of the monitored area.

[0036] In the evaluation unit, an object detection signal in the form of a binary switching signal is generated again; its switching states indicate whether an object is in the monitoring area or not.

[0037] The optical sensor can be designed as a reflective light barrier, in which case it has only one transmitter and one receiver. Alternatively, the optical sensor can be designed as a reflective light curtain with multiple transmitter-receiver pairs.

[0038] Alternatively, this type of sensor can also be configured as a distance sensor, in which case distance measurements are taken against the reflector. These distance measurements can be performed, for example, using a pulse-time-of-flight method or a phase measurement method.

[0039] The optical axis of a sensor unit, in the direction of which the target geometry of a mechanical alignment structure runs, is formed by an optical axis of a transmitter or receiver.

[0040] In an optical sensor comprising a reflector, the optical axis of a sensor unit, in the direction of which the target geometry of a mechanical alignment structure runs, is formed by the optical axis of the reflector. The reflector has a planar reflector surface, with the normal vector of the reflector surface forming the optical axis of the reflector.

[0041] According to an advantageous embodiment, the target geometry is formed by a notch and / or edge structure.

[0042] The notch and edge structure runs along a line that aligns with an optical axis, specifically parallel to that optical axis. This structure geometrically defines a unique target geometry that can be easily recognized and aimed at by a user.

[0043] According to one variant, the target geometry is formed by a continuous notch or edge structure extending in the direction of the optical axis.

[0044] The target geometry then forms a continuous line structure.

[0045] According to a second variant, the target geometry has several discrete target geometry elements arranged one behind the other in the direction of the optical axis, which have a notch or edge structure.

[0046] The target geometry elements then form a broken line structure. Aiming at such a target geometry is done according to the sight-sight principle.

[0047] In both cases, the target geometry of a mechanical alignment structure extends over most of the extent of the side wall of the sensor unit running in the direction of the optical axis.

[0048] A large proportion means that the target geometry extends over at least 30% of the sensor unit's dimensions in the direction of the optical axis.

[0049] Advantageously, a rough alignment of the sensor unit of the optical sensor is achieved using the mechanical alignment structure or any other mechanical alignment structure.

[0050] Afterwards, the sensor unit can be fine-tuned using suitable adjustment mechanisms. For example, a display unit can be integrated into the sensor unit, which contains the receiver(s). The evaluation unit registers and analyzes the amount of light from the transmitter's light beams that reaches the receiver(s). Based on the registered light levels, the alignment accuracy of the sensor unit is determined over time and visualized on the display unit, allowing the user to monitor the adjustment progress.

[0051] It is also possible to provide alignment receivers directly adjacent to the receiver(s), whereby the alignment quality is determined based on the amount of light from the transmitter(s) or other auxiliary transmitter(s) striking the alignment receiver(s).

[0052] The invention will be explained below with reference to the drawings. The drawings show: Figure 1a-b: First embodiment of the optical sensor according to the invention during two alignment processes. Figure 2a-b: Second embodiment of the optical sensor according to the invention during two alignment processes. Figure 3: First embodiment of a mechanical alignment structure with a target geometry. Figure 4a-c: Cross-sectional views of different mechanical alignment structures according to Figure 3Figure 5: Second embodiment of a mechanical alignment structure with a target geometry. Figures 6a-d: Cross-sectional views of target geometry channels of the mechanical alignment structures according to Figure 4 .

[0053] The Figures 1a, 1b Figure 1 shows a first embodiment of the optical sensor according to the invention in the form of a light curtain 1. The light curtain 1 serves to detect objects in a monitoring area. The light curtain 1 has two sensor units 1a, 1b, which are arranged at opposite edges of the monitoring area. Each of the sensor units 1a, 1b has a housing 2a, 2b in which sensor components are located. An exit window 3a, 3b is located in the front side of each housing 2a, 2b facing the monitoring area.

[0054] The first sensor unit 1a contains a series of light beam 4 emitting transmitters 5, which are controlled by a transmitter control unit (not shown). The transmitters 5 emit light beams 4 in the non-visible wavelength range, particularly in the infrared range. The second sensor unit 1b contains a series of light beam 4 receiving receivers 6. The second sensor unit 1b also contains an evaluation unit (not shown) that controls the operation of the receivers 6 and evaluates the received signals generated in the receivers 6.

[0055] In this case, four transmitters 5 and four receivers 6 are provided, with each transmitter 5 and its associated receiver 6 forming a transmitter-receiver pair. Of course, a different number of transmitter-receiver pairs can also be provided. In particular, only one transmitter-receiver pair can be provided. The optical transmitter 5 then forms a light barrier. In principle, such a light barrier can also be designed as a data light barrier.

[0056] Advantageously, optical synchronization is achieved via the light beams 4 of a transmitter-receiver pair, whereby the transmitter-receiver pairs are cyclically activated individually one after the other.

[0057] As the Figures 1a, 1b As shown, the light rays 4, and thus the optical axes of the transmitters 5, run parallel at a distance from each other. The optical axes of the receivers 6 also run parallel at a distance from each other.

[0058] In a clear monitoring area, the light beams 4 of all transmitters 5, guided through the exit windows 3a, 3b, 10a of the sensor units 1a, 1b, reach the assigned receiver 6 unimpeded. If an object enters the monitoring area, the light beams 4 of at least one transmitter 5 are interrupted. In the evaluation unit, an object detection signal in the form of a binary switching signal is generated based on the received signals from the receivers 6. The switching states of the switching signals indicate whether an object is located in the monitoring area or not.

[0059] In the event that the optical sensor forms a safety sensor suitable for use in the field of safety technology, its evaluation unit has a fail-safe design, for example in the form of two mutually monitoring computer units.

[0060] According to the invention, mechanical alignment structures 7a, 7b are provided on the sensor units 1a, 1b, by means of which alignment of the sensor units 1a, 1b is enabled. As the Figures 1a, 1b As shown, each sensor unit 1a, 1b has a mechanical alignment structure 7a, 7b. In principle, a mechanical alignment structure 7a, 7b can also be present on only one sensor unit 1a, 1b. In the present case, each mechanical alignment structure 7a, 7b is arranged on the top surface of a sensor unit 1a, 1b. Alternatively or additionally, a mechanical alignment structure 7a, 7b can also be provided on a side wall of a sensor unit 1a, 1b.

[0061] The Figures 2a, 2bFigure 1 shows an embodiment of an optical sensor in the form of a reflective light barrier 8, which serves to detect objects in a monitoring area. The reflective light barrier 8 has two sensor units 8a, 8b arranged at opposite edges of the monitoring area. The reflective light barrier 8 has a first sensor unit 8a, the sensor components of which are integrated in a housing 9a with an exit window 10a.

[0062] The housing 9a contains a light beam 4 emitting transmitter 5, a light beam 4 receiving receiver 6, and an evaluation unit (not shown) that controls the transmitter 5 and receiver 6 and evaluates the received signals to generate an object detection signal, which is again a binary switching signal. The transmitters 5 emit light beams 4 in the non-visible wavelength range. The optical axes of the transmitter 5 and receiver 6 are parallel to each other.

[0063] The second sensor unit 8b is formed by a reflector. The reflector is mounted in a frame and has a planar reflector surface 11, whose normal vector forms the optical axis of the reflector.

[0064] With the monitoring area clear, the light beams 4 from the transmitter 5 are guided through the exit window 10a into the monitoring area, strike the reflector, and are reflected back from there in such a way that they are guided through the exit window 10a to the receiver 6. If an object is disturbed within the monitoring area, the path of the light beams 4 is interrupted.

[0065] The optical sensor according to the Figures 2a, 2b It can also form a distance sensor. Then, using the light beams 4 of the transmitter 5, a distance measurement is taken against a reflector or against an object with diffuse reflection properties, whereby the distance measurement can be carried out according to a pulse-time method or a phase measurement method.

[0066] The optical sensor according to the Figures 2a, 2b It can also be further developed as a reflective light curtain in which several transmitter-receiver pairs are arranged in the first sensor unit 1a.

[0067] In accordance with the embodiment as per the Figures 1a, 1b are also in the embodiment of the Figures 2a, 2b Mechanical alignment structures 7a, 7b are present on the sensor units 8a, 8b.

[0068] Each mechanical alignment structure 7a, 7b has a target geometry 12. The target geometry 12 runs along a line that is oriented in the direction of the optical axis of the sensor units 1a, 1b, 8a, 8b, and in particular runs parallel to it.

[0069] Figure 3 Figure 1 shows a top view of the mechanical alignment structure 7a, wherein the mechanical alignment structure 7b is preferably designed accordingly. The target geometry 12 according to Figure 3is linear in form and extends over the entire extent of the sensor units 1a, 1b, 8a, 8b in the direction of their optical axis. The side surfaces of the sensor units 1a, 1b, 8a, 8b, on which a mechanical alignment structure 7a, 7b is attached, advantageously form a flat surface, so that the linear target geometry 12 runs along a straight line.

[0070] In general, it is advantageous if the target geometry 12 of a mechanical alignment structure extends over most of the extent of the side wall of the sensor unit 1a, 1b, 8a, 8b in the direction of the optical axis.

[0071] In this context, "large part" advantageously means an extension of the target geometry 12 over at least 30% of the extension of the sensor units 1a, 1b, 8a, 8b.

[0072] The cross-section of the target geometry 12 is advantageously constant over its length. Advantageously, the target geometry 12 forms a notch or edge structure.

[0073] The Figures 4a bis 4c Three embodiments of cross-sections of the target geometry 12 are shown. The cross-section according to Figur 4a forms an edge 13. The cross-section according to Figur 4b exhibits a projection 14 forming an edge structure. The cross-section according to Figur 4c forms a V-shaped notch 15.

[0074] Figure 5Figure 1 shows a top view of a mechanical alignment structure 7a, with a further embodiment of a target geometry 12 consisting of target geometry elements 16a and 16b. The interrupted target geometry 12 facilitates alignment because the target geometry elements 16a, 16b, and the optical target must be aligned, thus enabling faster detection and correction of misalignment. This target geometry 12 can also be present in the mechanical alignment structure 7b. Such a target geometry can also be used when, for example, existing elements are employed. These could be, for instance, screw heads or other existing fasteners or structures.

[0075] The target geometry 12 according to Figure 5 runs along a line that runs parallel to the optical axis of the associated sensor units 1a, 1b, 8a, 8b.

[0076] In the present case, however, the target geometry 12 does not form a continuous line structure. The target geometry 12 consists of two discrete target geometry elements 16a, 16b, arranged along a straight line parallel to the optical axis. In this case, it is also advantageous if the target geometry elements 16a, 16b extend over the majority of the extent of the side wall of the sensor unit 1a, 1b, 8a, 8b in the direction of the optical axis. "Much" advantageously means an extent of the target geometry over at least 30% of the extent of the sensor units 1a, 1b, 8a, 8b.

[0077] The cross-sections of the target geometry elements 16a, 16b in the longitudinal direction of the target geometry 12 are again constant. Figures 6a, 6b Figure 1 shows two embodiments of cross-sections of target geometry elements 16a, each forming an edge 13, 13'. Figures 6c, 6dFigure 1 shows two embodiments of cross-sections of target geometry elements 16b which form a notch 15 or a projection 14.

[0078] The functionality of the alignment of the sensor units 1b and the light curtain 1 is explained using the Figures 1a, 1b explained, with the same for the reflective light barrier 8 according to the Figures 2a, 2b applies.

[0079] As in Figur 1a As illustrated, a user uses the mechanical alignment structure 7a to align the sensor unit 1a with the opposite sensor unit 1b. The user aims at the target geometry 12 of the mechanical alignment structure (indicated by the dashed line) and thus aims at a target point of the opposite sensor unit 1b, where the target geometry 12 of the mechanical alignment structure 7b of the sensor unit 1b is advantageously used as the target point.

[0080] The user adjusts sensor unit 1a until the target geometry 12 of the mechanical alignment structure 7a precisely aligns with a target point of the opposite sensor unit 1b. Since the target geometry 12 of the mechanical alignment structure 7a runs in the direction of the optical axes of the transmitters 5, this alignment process aligns the optical axes with the target point of the opposite sensor unit 1b.

[0081] Accordingly, a user can align the sensor unit 1b with the sensor unit 1a using the target geometry 12 of the mechanical alignment structure 7a ( Figur 1b ).

[0082] In the embodiment of the Figure 3 The target geometry 12 forms a continuous line that is targeted by the user.

[0083] In the embodiment of the Figure 5 The user aims at both target geometry channels using the front and rear sight principle. Reference symbol list

[0084] (1) Light curtain (1a) Sensor unit (1b) Sensor unit (2a) Housing (2b) Housing (3a) Exit window (3b) Exit window (4) Light beam (5) Transmitter (6) Receiver (7a) Mechanical alignment structure (7b) Mechanical alignment structure (8) Reflective light barrier (8a) Sensor unit (8b) Sensor unit (9a) Housing (10a) Exit window (11) Reflector surface (12) Target geometry (13) Edge (13') Edge (14) Projection (15) Notch (16a) Target geometry element (16b) Target geometry element

Claims

1. An optical sensor comprising at least one transmitter (5) emitting light beams (4), at least one receiver (6) receiving light beams (4), and an evaluation unit configured to evaluate received signals from said at least one receiver (6), wherein two sensor units (1a, 1b, 8a, 8b) are present, in which said at least one transmitter and at least one receiver and the evaluation unit are integrated, wherein the light beams (4) run between the sensor units (1a, 1b, 8a, 8b), wherein a mechanical alignment structure (7a, 7b) is provided on at least one side wall of at least one sensor unit (1a, 1b, 8a, 8b), which forms a target geometry (12) that can be aligned in the direction of an optical axis of this sensor unit (1a, 1b, 8a, 8b), characterised in that the optical axis of a sensor unit (1a, 1b, 8a) in the direction of which the target geometry (12) of a mechanical alignment structure extends is formed by an optical axis of a transmitter (5) or receiver (6).

2. Optical sensor according to claim 1, characterised in that at least one mechanical alignment structure (7a, 7b) is provided on each of the sensor units (1a, 1b, 8a, 8b).

3. Optical sensor according to one of claims 1 or 2, characterised in that each sensor unit (1a, 1b, 8a, 8b) has a front face through which the light beams (4) are guided, and that the or each mechanical alignment structure (7a, 7b) is provided on a side wall of a sensor unit (1a, 1b, 8a, 8b) adjacent to the front face.

4. An optical sensor according to any one of claims 1 to 3, characterised in that the or each side wall of a sensor unit (1a, 1b, 8a, 8b) on which the mechanical alignment structure (7a, 7b) is provided forms a flat surface.

5. An optical sensor according to any one of claims 1 to 4, characterised in th , this sensor comprises a first sensor unit (1a), in which at least one transmitter (5) emitting a light beam (4) is provided, and a second sensor unit (1b), in which a receiver (6) receiving a light beam (4) is provided.

6. Optical sensor according to claim 5, characterised in that each sensor unit (1a, 1b, 8a, 8b) comprises a housing (2a, 2b, 9a), wherein a mechanical alignment structure (7a, 7b) is provided on at least one side wall of at least one housing (2a, 2b, 9a).

7. An optical sensor according to any one of claims 1 to 4, characterised in that it comprises a first sensor unit (8a) in which at least one transmitter (5) emitting a light beam (4) and at least one receiver (6) receiving a light beam (4) are provided, and in that a second sensor unit (8b) is formed by a reflector.

8. Optical sensor according to claim 7, characterised in that the first sensor unit (8a) comprises a housing (9a), wherein a mechanical alignment structure (7a) is provided on at least one side wall of the housing (9a), and / or that a mechanical alignment structure (7b) is provided on a frame of the reflector.

9. Optical sensor according to claim 7, characterised in that the optical axis of a sensor unit (8b), in the direction of which the target geometry (12) of a mechanical alignment structure extends, is formed by the optical axis of the reflector.

10. Optical sensor according to claim 9, characterised in that the reflector has a flat reflector surface (11), wherein the normal vector of the reflector surface (11) forms the optical axis of the reflector.

11. Optical sensor according to any one of claims 1 to 10, characterised in that the target geometry (12) is formed by a notched and / or edged structure.

12. Optical sensor according to claim 11, characterised in that the target geometry (12) is formed by a continuous notch or edge structure extending in the direction of the optical axis.

13. Optical sensor according to claim 11, characterised in that the target geometry (12) comprises a plurality of discrete target geometry elements (16a, 16b) arranged in succession in the direction of the optical axis, which have a notch or edge structure.

14. Optical sensor according to claim 13, characterised in that discrete target geometry elements (16a, 16b) are formed from housing or fastening elements.

15. An optical sensor according to any one of claims 1 to 14, characterised in that the target geometry (12) of a mechanical alignment structure extends over the majority of the side wall of the sensor unit (1a, 1b, 8a, 8b) extending in the direction of the optical axis.

16. Optical sensor according to any one of claims 1 to 15, characterised in that the transmitter(s) (5) emit light beams (4) in the non-visible wavelength range.

17. An optical sensor according to any one of claims 1 to 16, characterised in that a coarse alignment of the sensor units (1a, 1b, 8a, 8b) is carried out by means of the mechanical alignment structure (7a, 7b), and in that means for fine adjustment of the sensor units (1a, 1b, 8a, 8b) are provided.

18. An optical sensor according to any one of claims 1 to 17, characterised in that it is designed to detect objects within a monitoring area, wherein the sensor units (1a, 1b, 8a, 8b) are arranged at opposite edges of the monitoring area.

19. An optical sensor according to claim 17, characterised in that objects are detected by interruption of the path of light beams (4).

20. An optical sensor according to any one of claims 7 to 17, characterised in that it forms a distance sensor.

21. An optical sensor according to any one of claims 5 to 17, characterised in that it forms a data light barrier.

22. A method for operating an optical sensor comprising at least one transmitter (5) emitting light beams (4), at least one receiver (6) receiving light beams (4), and an evaluation unit configured to evaluate reception signals from said at least one receiver (6), wherein two sensor units (1a, 1b, 8a, 8b) are present , in which said at least one transmitter and said at least one receiver and the evaluation unit are integrated, wherein the light beams (4) travel between the sensor units (la, lb, 8a, 8b), wherein a mechanical alignment structure (7a, 7b) is provided on at least one side wall of at least one sensor unit (1a, 1b, 8a, 8b), which forms a target geometry (12) that can be aligned in the direction of an optical axis of this sensor unit (1a, 1b, 8a, 8b), characterised in that the optical axis of a sensor unit (1a, 1b, 8a), in the direction of which the target geometry (12) of a mechanical alignment structure extends, is formed by an optical axis of a transmitter (5) or receiver (6).