Optical sensor

Abstract

An optical sensor comprises at least one measuring mirror that can be pivoted over a predetermined range, a measuring light source configured to emit a measuring light beam in the direction of the measuring mirror, at least one position determination mirror that can be pivoted together with the measuring mirror, and a position determination light source configured to emit a position determination light beam in the direction of the position determination mirror.The optical sensor further comprises a receiving element configured to detect the position determination light beam reflected from the position determination mirror, and an evaluation unit configured to determine an orientation of the measuring mirror with respect to at least one reference direction based on the position of the detected position determination light beam at the receiving element and on the relative spatial arrangement of the receiving element with respect to the position determination mirror.

Description

[0001] The invention relates to an optical sensor with a movable measuring mirror that can be pivoted over a predetermined area.

[0002] Optical sensors can use movable measuring mirrors to acquire measurement data at different spatial positions. Examples of such sensors include 2D and 3D lidar systems and other optoelectronic sensors. Based on the acquired measurement data, these sensors can detect objects in space and determine their spatial orientation, i.e., their distance relative to the sensor and one or more angles relative to a reference direction in space.

[0003] However, especially when the distance between an object whose spatial location is to be determined and the sensor is large, the angle at which the sensor detects the object should be known as precisely as possible in order to resolve objects with a desired precision and to determine their spatial location or position with a specified accuracy.

[0004] Known optical sensor systems use, for example, an encoder rigidly connected to the movable measuring mirror to determine the angular deflection of the movable measuring mirror relative to a reference direction. For instance, a reflective encoder disk can be attached to a rotatable measuring mirror. Such known sensor systems with a rotatable measuring mirror and an encoder disk attached to it achieve, for example, an angular resolution of between 1° and 2°, which corresponds to the distance between lines on the encoder disk.

[0005] With such known optical sensors with a movable measuring mirror, the angle of the measuring mirror relative to a reference direction cannot be measured directly, but only the angle of the encoder disk attached to the measuring mirror relative to a reference position.

[0006] Other well-known angle measurement techniques also generally do not allow for a direct measurement of the angle by which a movable measuring mirror is currently deflected. With such indirect measurements of the angle by which the movable measuring mirror is deflected, several measured quantities must consequently be combined, which limits the accuracy of the angle measurement due to error propagation or tolerance chain. However, preventing or subsequently compensating for such a reduction in accuracy when determining the angle of a movable measuring mirror, for example by means of calibration, usually requires considerable effort if a predetermined high accuracy in the angle measurement is desired.

[0007] One object of the invention is to determine the instantaneous angle of the measuring mirror relative to a reference direction directly and with high precision in an optical sensor with a movable measuring mirror.

[0008] This problem is solved by an optical sensor having the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims, the description, and the drawings.

[0009] The optical sensor according to the invention comprises a measuring mirror which can be pivoted over a predetermined area, a measuring light source which is configured to emit a measuring light beam in the direction of the movable measuring mirror, a position determination mirror which can be pivoted together with the measuring mirror, and a position determination light source which is configured to emit a position determination light beam in the direction of the position determination mirror.The optical sensor further comprises a receiving element configured to detect the position determination light beam reflected from the position determination mirror, and an evaluation unit configured to determine the orientation of the measuring mirror with respect to at least one reference direction based on the position of the detected position determination light beam at the receiving element and the relative spatial arrangement of the receiving element with respect to the position determination mirror.

[0010] The measuring light source and the position-determining light source can each be a laser, emitting a laser beam in the direction of the movable measuring mirror and the movable position-determining mirror, respectively. The optical sensor can be a 2D or 3D lidar sensor that uses such a laser as its measuring light source.

[0011] Advantageously, the measuring light source and the position determination light source are formed by the same light source.

[0012] To allow the positioning mirror to pivot together with the measuring mirror, the movable measuring mirror and the movable positioning mirror are coupled with each other in their movement. This causes the measuring mirror and the positioning mirror to pivot synchronously. For example, they rotate synchronously around a common axis. This ensures that the orientation or rotation angle of the measuring mirror can be derived from, or corresponds to, the orientation or rotation angle of the positioning mirror. Thus, the orientation of the measuring mirror, i.e., its current rotational position, can be determined based on the current orientation or rotational position of the positioning mirror.

[0013] The measuring mirror and the positioning mirror can therefore be pivoted over the same range. The measuring mirror and the positioning mirror can be mounted on a common mirror bracket and configured as separate mirror surfaces. In such a configuration, these mirror surfaces can lie in the same plane or in different planes, for example, on different facets of a rotatable polygon mirror.

[0014] The at least one reference direction can be defined by one or more predetermined spatial directions, for example, by one or more axes of a predefined coordinate system. The orientation of the movable measuring mirror relative to the at least one reference direction can therefore be defined by one or more rotation angles relative to such reference directions. Furthermore, the predetermined range for pivoting the movable mirror can be defined by a respective minimum and maximum rotation angle of the measuring mirror and the position-determining mirror relative to the common axis of rotation or reference direction. The evaluation unit can thus determine the rotation angle(s) of the movable position-determining mirror based on the spatial position of the position-determining light beam.-laser beam on the receiving element and based on the relative spatial arrangement of the receiving element in relation to the position determination mirror.

[0015] The position-determining light source or laser, the movable position-determining mirror, and the receiving element, together with the evaluation unit, form a device for determining the orientation or one or more rotation angles of the measuring mirror. For example, a 2D or 3D lidar sensor can include, in addition to the actual lidar measurement setup, such a device for determining the orientation of the measuring mirror, i.e., for example, one or more rotation angles. The optical sensor can include the device for determining the orientation of the measuring mirror in addition to elements of a measurement setup that, for example, allows the determination of distances and positions of respective objects. The measurement setup can include corresponding and known detection elements, such as those used, for example, in lidar sensors.

[0016] An advantage of the optical sensor according to the invention is that the orientation of the pivotable measuring mirror relative to the at least one reference direction can be determined directly. For this purpose, only the position of the detected position-determining light beam at the receiving element and the relative spatial arrangement of the receiving element with respect to the position-determining mirror need to be known, for example, their distance and the spatial orientation of the receiving element with respect to one or more axes of rotation of the movable position-determining mirror. The orientation or one or more rotation angles of the position-determining mirror with respect to the at least one reference direction can be determined with minimal effort and high precision or angular resolution.

[0017] This has a particularly good effect with small deflection or rotation angles of the movable measuring mirror in relation to at least one reference direction, which in known systems lie in the range of the angular resolution of, for example, an encoder disk.

[0018] Another advantage of the optical sensor is that the mass of the movable position-determining mirror is low and is not increased by additional components for angle measurement, such as an encoder disk. This is particularly true when the measuring mirror and the position-determining mirror are mounted on a common bracket or are formed by spatially separated surfaces of a single mirror. Regardless of the design of the movable mirrors, they can be moved with less force and at a higher speed than in conventional optical sensors.

[0019] Furthermore, since the orientation of the movable position-determining mirror is directly determined by means of the position-determining light source, allowing the orientation of the measuring mirror to be determined directly based on the combined pivoting or coupled movement of the measuring mirror and the position-determining mirror, the accuracy in determining this orientation is not limited by the error propagation or tolerance chain that otherwise has to be considered in known optical sensors with indirect determination of the orientation or rotation angle of the movable measuring mirror. Such an indirect determination of the orientation or...In known solutions, the angle of rotation is achieved, for example, by counting markings or teeth on an encoder disk relative to a reference marking during a joint rotation of the measuring mirror and the encoder disk, and subsequently converting the counted markings into the angle to be determined.

[0020] According to one embodiment, the measuring mirror and the positioning mirror are mounted on a common bracket and arranged in the same plane. Such an arrangement can be compact and requires little installation space.

[0021] The measuring mirror and the position-determining mirror can be formed, for example, by separate mirror surfaces or by respective areas of a single, continuous mirror surface. In such an embodiment, the position-determining light source emits the position-determining light beam to determine the orientation of the measuring mirror towards a predetermined edge region of the continuous mirror surface. Preferably, the position-determining light source emits the position-determining light beam exclusively into such an edge region of the continuous mirror surface in order to determine the orientation of the measuring mirror.

[0022] A primary surface or area within the single, contiguous mirror surface can then be used for the actual measurement for which the optical sensor is intended, for example, for detecting and determining the spatial position of objects within the optical sensor's field of view. In a lidar sensor, for instance, a laser beam can strike the primary surface as the measurement beam during the measurement, so that the primary surface forms the measurement mirror, while the same or a different laser beam is directed as a position determination beam to determine the orientation of the measurement mirror onto the aforementioned peripheral area, which differs from the primary surface or area.

[0023] When using the same laser beam as both the measuring beam and the position determination beam, the light beam or laser beam can be deflected in a predetermined temporal sequence such that it strikes the main surface and at least one edge region sequentially. The actual measurement, for which the optical sensor is intended, is thus not hindered by the additional determination of the orientation or rotation angle of the measuring mirror, since the main surface can be reserved for the actual measurement by the optical sensor, while the edge region can be reserved for determining the orientation or angle of the measuring mirror.

[0024] The optical sensor can have a single positioning mirror, for example, in the form of a single edge region of a single, continuous mirror surface, which can additionally include the measuring mirror as a main region. This can reduce the effort required to manufacture the two mirrors, i.e., the measuring mirror and the positioning mirror, and to assemble the arrangement for determining the orientation of the measuring mirror.

[0025] Alternatively, the optical sensor can also have at least two position-determining mirrors that are spatially separated from each other. In an embodiment with a single, continuous mirror surface, for example, two edge regions can each form a position-determining mirror, while a main region arranged between these edge regions can form the measuring mirror. In these embodiments, a single light beam, for example a laser beam, can scan the two edge regions and the main surface sequentially, or at least two light sources or lasers and a corresponding number of receiving elements can be provided, with the light beams or laser beams of the respective light sources or lasers each being directed onto one of the edge regions.

[0026] The use of at least two spaced-apart positioning mirrors or edge regions also allows for the determination of a mirror's torsion, where the measuring mirror and the two positioning mirrors are, for example, formed as different areas of a continuous mirror surface. The torsion of such a mirror can be determined, for instance, by the deviation of the respective rotation angles determined by the two edge regions. Any potential torsion of the mirror can then be taken into account when evaluating the "actual" measurement data from the optical sensor, for example, when determining distances, positions, or angles of objects using a lidar sensor.

[0027] According to a further embodiment, the optical sensor comprises a polygon mirror with at least three facets, and a measuring mirror and a position-determining mirror are formed on each of the at least three facets. In such a polygon mirror, a respective edge region can be provided as a position-determining mirror on each facet, in the direction of which the position-determining light beam is emitted. However, in this embodiment, the position-determining light beam only strikes an edge region of one of the facets of the polygon mirror at any given time.

[0028] The measuring light beam can be emitted simultaneously towards a main area of ​​the same facet or a different facet, with this main area forming the measuring mirror. Using the same or different facets offers flexibility for installing the measuring setup and the setup for determining the orientation of the measuring mirror or for position determination.

[0029] In particular, a rotatable polygon mirror can have four facets with respective edge regions. In such an embodiment, the dimensions of the receiving element can be adapted to the dimensions of each facet.

[0030] The receiving element preferably comprises at least one sensor array. Such a sensor array can be configured as a linear, i.e., one-dimensional, series of sensor elements or as a one-dimensional position-sensitive detector (PSD). The required length of the sensor array can be adapted to or defined by a predetermined angular range over which the movable mirror can be pivoted.

[0031] The instantaneous deflection angle of the position-determining mirror can then be determined from the instantaneous position of the detected position-determining light beam on the sensor array, provided the distance between the sensor array and the position-determining mirror is known. Therefore, using a sensor array as a receiving element can enable a direct determination of the orientation of the position-determining mirror, and thus of the measuring mirror, with minimal effort.

[0032] The measuring mirror and the position-determining mirror can also be pivoted together in two mutually perpendicular directions, and the receiving element can accordingly comprise at least two sensor rows. Such an embodiment can allow the determination of two instantaneous deflection or rotation angles of the measuring mirror relative to two reference directions or axes of rotation. As an alternative to the two sensor rows, the receiving element can also be designed as a two-dimensional sensor element, for example, as an array of sensor elements.

[0033] At least one of the sensor arrays can be curved. The sensor array can therefore have a bend, similar to a curved computer monitor. This can reduce the required length of the sensor array compared to a linear or flat design. This is particularly important if the measuring mirror and the positioning mirror can be swiveled over a relatively large angular range.

[0034] Alternatively or additionally, a cylindrical lens can be positioned between the positioning mirror and the receiving element. Such a cylindrical lens allows the light or laser beams reflected from the positioning mirror to be aligned parallel to, for example, a sensor array, thereby reducing the required length of the sensor array. Furthermore, such a cylindrical lens can be used to scale the angular range over which the positioning mirror can be pivoted, relative to the size or length of a sensor array. By selecting an appropriate scaling, the angular resolution for determining the orientation can be increased.

[0035] The measuring light source and the position determination light source can advantageously be identical. The light beam of such a common light source can then be used simultaneously for the "actual" measurement(s) for which the optical sensor is intended, for example, for determining distances and positions of objects using a lidar sensor, and for determining the orientation of the measuring mirror using the position determination mirror and the receiving element described above, which can be configured as one or more sensor arrays.

[0036] The simultaneous use of the light beam from the common light source for these two tasks can be achieved, for example, by briefly directing the light beam or laser beam first onto a main surface or area within a single, continuous mirror surface and then onto one or more edge regions of this mirror surface. The main area here forms the measuring mirror, while the edge region(s) form one or more position-determining mirrors.

[0037] Using a single light beam both to determine the alignment of the measuring mirror and for the actual measurement of the optical sensor reduces the effort and space required for the optical sensor, as only a single light source is needed.

[0038] The invention is described below by way of example with reference to advantageous embodiments and the accompanying figures. These show, schematically: Fig. 1. A perspective view of a mirror polygon with encoder for an optical sensor according to the state of the art. Fig. 2 an embodiment of a device according to the invention for determining the orientation of a measuring mirror in an optical sensor, Fig. 3 a further embodiment of the device according to the invention and Fig. 4 another embodiment of the device according to the invention.

[0039] Fig. Figure 1 schematically shows a perspective view of a portion of a prior art optical sensor 100, configured as a lidar sensor. This portion comprises a movable or rotatable measuring mirror 110, which is designed as a mirror polygon. During measurements using the optical sensor 100, a laser beam from a light source (not shown) or from a laser is directed onto one of the surfaces of the mirror polygon 110 and reflected from this surface into a desired spatial region.

[0040] By rotating the measuring mirror or mirror polygon 110, the laser beam is deflected into a predetermined or desired spatial region, so that this spatial region is scanned by the laser beam. If the laser beam is reflected or remitted by an object located within the predetermined spatial region, the detection of the reflected or remitted light by the lidar sensor 100 allows the determination of the object's spatial position in a known manner, i.e., for example, the angle at which the object is detected relative to one or more predetermined reference directions, a distance between the object and the sensor 100 in this angular direction (if, for example, a known time-of-flight (TOF) measurement is implemented), or even the radial velocity of the object.

[0041] The greater the distance between such an object and the optical sensor 100, the more precisely the angle at which the optical sensor 100 detects the object by means of a receiving unit (not shown) must be known in order to resolve the object with the desired accuracy and determine its spatial position. To determine the angle at which the laser beam of the optical sensor 100 is reflected by the mirror polygon 110, the known optical sensor 100 includes a reflective encoder disk 120.

[0042] Observing the reflection of another light or laser beam at the encoder disk 120 allows, in a known manner, the determination of the rotational position or angle of rotation of the mirror polygon 110 relative to a reference position. During the rotation of the encoder disk 120, the lines traversed on the encoder disk 120, or corresponding step pulses, are counted. Based on this count, and given the known incremental angle between the lines or per step pulse, the angle by which the mirror polygon 110 is rotated overall can be determined.

[0043] In similar optical sensors to the optical sensor 100, an encoder disk with a predetermined number of lines can also be mounted below a rotatable mirror carrier. Furthermore, such rotatable mirror carriers can also be equipped with magnetic or capacitive encoders.

[0044] However, in the optical sensors 100 according to the state of the art, a deflection angle or rotation angle of a movable mirror is always determined via an encoder, which, for example, is the encoder disk 120. Fig. 1, which is rigidly connected to the mirror polygon 110. However, the deflection angle of the mirror 110 is not measured directly using such encoders, but only the relative rotation angle about the axis of rotation around which the movable mirror, such as the mirror polygon 110, rotates, is determined based on the counted step pulses.

[0045] To determine the actual deflection angle of the movable mirror 110, several quantities determined in different ways must be linked together, creating a tolerance chain between a surface of the mirror polygon 110, onto which the laser beam strikes, and the encoder, which leads to error propagation. This limits the accuracy with which known systems or optical sensors 100 can determine the deflection angle of the rotatable mirror, such as the mirror polygon 110. In the case of the Fig. The optical sensor 100 shown enables the encoder disk 120 to achieve a resolution of 1.33° from line to line of the encoder disk 120. To prevent the reduction in accuracy when determining the deflection angle of the rotatable mirror 110, or to compensate for this subsequently, for example by means of calibration, a high level of effort is usually required if high accuracy in determining the deflection angle of the mirror polygon 110 is to be achieved.

[0046] To solve this problem, the following is needed: Fig. Figure 2 shows a device or arrangement for the direct and precise determination of a deflection angle α of a movable mirror within an optical sensor 200 according to the invention. The optical sensor 200 shown, like the sensor 100 described above, is a lidar sensor and comprises a position-determining light source 210, which is designed as a laser and emits a laser beam 212 as a position-determining light beam in the direction of a movable mirror 220.

[0047] The movable mirror 220 has a rotation axis 222 about which the movable mirror 220 can be pivoted over a predetermined angular range, as indicated by the rotation arrow 223. The movable mirror 220 further comprises a mirror holder 224, a main surface or main area 226 for performing the measuring function for which the optical sensor 200 is provided, and an edge area 228, which is provided for determining the instantaneous deflection angle or rotation angle α of the movable mirror 220.

[0048] The main surface 226 thus forms a measuring mirror, since the measuring function of the optical sensor or lidar sensor 200 is carried out in a manner known per se via this mirror. The edge region 228, on the other hand, forms a position determination mirror, since the instantaneous rotational position or orientation of the measuring mirror 226 can be determined via this mirror surface 228, as explained below.

[0049] In the present embodiment, the rotatable mirror 220 has a single, continuous reflective surface located in a plane 225. However, a respective part or area of ​​this continuous reflective surface forms the measuring mirror 226 and the position-determining mirror 228, which are thus formed by the main area and the edge area of ​​the mirror 220, respectively. The reflective surfaces of the measuring mirror 226 and the position-determining mirror 228 are therefore arranged in the same plane 225 on the front face of the mirror 220.

[0050] Alternatively, the measuring mirror 226 and the position-determining mirror 228 can also be designed as separate mirror surfaces, for example with a non-reflective bridge between them. These separate mirror surfaces can also be located in different planes. In such embodiments, however, the measuring mirror 226 and the position-determining mirror 228 must be mechanically coupled in such a way that they can only be pivoted together, for example by being attached to the same mirror mount and by rotating them about a common axis of rotation.

[0051] The laser beam, or position-determining beam, 212 strikes the edge region, or position-determining mirror, 228 to determine the orientation or deflection angle α of the movable mirror 220 and is reflected by it towards a receiving element 230, which is configured as a sensor array. The laser beam 212 strikes the edge region, or position-determining mirror, 228 at a momentary or current position P. a on sensor line 230. The position P a lies between a position P0 =0 at one end of the sensor row 230, which corresponds to a minimum deflection angle of the movable mirror 220, and a position P max = L at the opposite end of sensor row 230, which has a maximum deflection angle α max of the movable mirror 220 corresponds.

[0052] The sensor array 230 has a predetermined length L, which is linked to a maximum deflection angle α maxof the movable mirror 220. In other words, the length L of the sensor array 230 is chosen such that the laser beam 212 falls on the sensor array 230 at all desired deflection angles α of the movable mirror 220.

[0053] In the present embodiment, a distance d between the sensor array 230 and the axis of rotation 222 of the movable mirror 220 is defined at the center of the sensor array 230, i.e., perpendicular to the sensor array 230 at a position P = L / 2. When the distance d and the maximum deflection angle α max Since the dimensions of the movable mirror 220 are known, the required length L of the sensor row 230 is given as follows: L=2d*tanαmax2

[0054] The angle α max This refers to a reference direction 232, which runs perpendicular to the axis of rotation 222 and through the position at P0 = 0 at the lower end of the sensor row 230.

[0055] In order to determine the instantaneous deflection angle α of the laser beam 212, which corresponds to the instantaneous rotation angle of the movable mirror 220 with respect to the reference direction 232, the instantaneous position P is a by means of an evaluation and control unit 240 of the optical sensor 200, which determines the orientation or deflection angle α of the movable mirror 220 with respect to the reference direction 232 based on the current position P a of the laser beam 212 at the sensor line 230 and based on the relative spatial arrangement of the sensor line 230 in relation to the movable mirror 220.

[0056] The evaluation and control unit 240 is also connected to the light source or laser 210 and to a drive (not shown) for rotating the mirror 220 in order to control the orientation of the light beam or laser beam 212 and the rotational position of the mirror 220. The connection of the evaluation and control unit 240 with the light source 210 and the mirror 220 is shown in Fig. 2 schematically represented by dashed lines.

[0057] The sensor array 230 is spatially arranged such that its length L determines the maximum deflection angle α max covers and the distance d between the sensor row 230 and the rotation axis 222 in the middle of the sensor row 230 at P = L / 2 or in the middle of the opening angle or maximum deflection angle at α max / 2 is defined. How to in Fig. As can be seen in Figure 2, the instantaneous deflection angle α is determined by the instantaneous position P. awith known distance d, known length L of sensor row 230 and known maximum deflection angle α max given based on the following relationships: tanβ=Pa−L2d α=αmax2+β

[0058] The angle β is defined in the right-angled triangle formed by the laser beam 212 between the mirror 220 and the sensor array 230, a line along the distance d, and the segment of the sensor array 230 between them. Furthermore, the angle β with respect to the line along the distance d represents the complementary angle to the deflection angle α, which is defined with respect to the reference direction 232, i.e., the complementary angle with respect to α. max / 2.

[0059] If the position P a Since, with respect to P0 = 0, tanβ is negative, resulting in a negative angle β and the deflection angle α is correctly smaller than α max / 2 is. This is in the representation of Fig. 2 to 4 are illustrated by the opposing arrows of the angles α and β.

[0060] The in Fig. The arrangement shown in Figure 2 enables a direct and precise determination of the instantaneous deflection angle α of the movable mirror 220. In contrast to the arrangement of Fig. 1 is in the arrangement according to the invention of Fig. 2. No encoder, and therefore no encoder disk 120, or similar element is required, so that, moreover, the mass of the movable mirror 220 is lower compared to the mirror arrangement of Fig. 1 is reduced. This allows the movable mirror 220 to be moved faster and with less force. The in Fig. The direct determination of the deflection angle α of the movable mirror 220 shown in Figure 2 is therefore more accurate than the indirect determination using encoder disk 120 (see Figure 2). Fig. 1) because the tolerance chain of the indirect determination does not need to be taken into account.

[0061] During measurements using the optical sensor 200, the laser beam 212 is additionally deflected laterally such that it sweeps across the rotatable mirror 220 in such a way that it first strikes the edge region 228 and then the main region 226. When the laser beam 212 is reflected in the main region 226, it passes through a sensor window (not shown) into a predetermined spatial region outside the optical sensor 220, where it can be reflected or remitted by an object located there (not shown).

[0062] The laser beam reflected or remitted by such an object is subsequently detected by means of a detection device (not shown) of the optical sensor or lidar sensor 200 in order to determine the spatial position of the object in the manner known for lidar sensors, i.e., for example, the angle at which the object is detected with respect to one or more predefined reference directions 232, a distance between the object and the sensor 200 in this angular direction (if, for example, a time-of-flight measurement (TOF) known per se is implemented), or also a radial velocity of the object with respect to the lidar sensor 200.

[0063] Fig. Figure 3 shows a further embodiment of the device or arrangement according to the invention for determining the orientation or deflection angle α of the rotatable mirror 220 with respect to the reference direction 232. The arrangement of Fig. 3 differs from the arrangement of Fig. 2 merely by the fact that the movable mirror 220 has a first edge region 228 on the left side of the main surface or main region 226 and a second edge region 229 on the right side of the main region 226. Otherwise, all depicted elements 200 to 240 correspond to Fig. 3 the elements described above of Fig. 2, so that the description of Fig. 2 also for the arrangement of Fig. 3 is valid. The mirror surfaces of the measuring mirror 226 and the two edge areas or position determination mirrors 228, 229 are again arranged in the same plane 225 on the front of the mirror 220.

[0064] During measurements using the optical sensor 200, the laser beam 212 is further deflected laterally so that it sweeps across the rotatable mirror 220 in such a way that it successively strikes first the first edge region 228, then the main region 226, and finally the second edge region 229. The sensor array 230 can be arranged such that the laser beam 212 is reflected back onto the sensor array 230 both when it strikes the first edge region 228 and when it strikes the second edge region 229. Alternatively, a second sensor array 230 can be used.

[0065] The use of two edge regions 228, 229 to determine the deflection angle α of the movable mirror 220 and its spatial orientation relative to the reference direction 232 additionally enables the determination and measurement of any torsion of the movable mirror 220. This torsion is detectable if the respective deflection angles α differ from one another, as determined by the first edge region 228 and the second edge region 229, respectively. The torsion of the mirror 220 can then be taken into account when evaluating the measured values ​​of the optical sensor 200, which are acquired via the main region 226 of the movable mirror 220.

[0066] Fig. Figure 4 shows a further embodiment of the device or arrangement according to the invention for determining the orientation or deflection angle α of the rotatable mirror 220 in the optical sensor 200. In the embodiment of Fig. 4 the rotatable mirror 220 is designed as a polygon mirror wheel 250 which has a polygon rotation axis 252 and is rotatable about this.

[0067] The Polygon Mirror Wheel 250 from Fig. 4 has four facets, two of which are facets 260, 270 in the representation of Fig. 4 are visible. Each of the facets 260, 270 has a respective main area or measuring mirror 226 for the actual measuring function of the optical sensor 200 and a respective lower edge area or position determination mirror 228 for determining the instantaneous orientation or the instantaneous deflection angle α of the polygon mirror wheel 250. Thus, each facet 260, 270 of the polygon mirror wheel 250 corresponds to the front face of the movable mirror 220 of Fig. 2 and therefore has the same functionality as the arrangement of Fig. 2, which is described above. Therefore, the description of Fig. 2. This also applies analogously to the arrangement of Fig. 4 valid. The mirror surfaces of the measuring mirror 226 and the position determination mirror 228 are furthermore arranged on the front of each of the facets 260, 270 in the same plane 225.

[0068] The laser beam 212 emitted by the light source or laser 210 strikes the arrangement of Fig. 4 onto the respective position determination mirror 228 at one of the facets 260, 270 and is in turn reflected by these in the direction of the sensor row 230 with length L. The opening angle α max The area swept out by the reflected laser beam 212 during a rotation of the polygon mirror wheel 250 therefore corresponds to the length L of the sensor array 230. Conversely, the length L of the sensor array 230 with the opening angle α max agreed.

[0069] The laser beam 212 can be used in the embodiment of Fig. 4 Similar to the embodiments described above, both the positioning light beam 212 and the measuring light beam are formed by deflecting the laser beam 212 vertically, i.e., in a direction parallel to the polygon rotation axis 252. As a result, the laser beam 212 again strikes the edge region 228 for position determination and the main region 226 for measurement, successively.

[0070] Alternatively, the measuring beam can also be emitted from another measuring light source (not shown) that is different from the position determination light source 210, which emits the position determination light beam 212. In such an embodiment, the measuring beam and the position determination light beam 212 can also be emitted onto different facets 260, 270 of the polygon mirror wheel. Thus, the measuring light beam can be emitted in the illustration of Fig.4 are emitted in the direction of the main area 226 of the facet 260, while the position determination light beam 212 is emitted in the direction of the edge area 228 of the adjacent facet 270. Reference symbol list 100 optical sensors according to the state of the art 110 mirror polygon 120 encoder disc 200 optical sensor according to the invention 210 Light source or laser 212 Light beam or laser beam 220 movable mirror 222 axis of rotation 223 rotation angle 224 Mirror bracket 225 Plane on the front of the movable mirror 226 Main area or measuring mirror 228 first marginal area or first position determination mirror 229 second marginal area or second positioning mirror 230 Receiving element or sensor row 232 Reference direction 250 polygon mirror wheel 252 Polygon rotation axis 260, 270 facet of the polygon mirror wheel

Claims

Optical sensor (200) comprising: at least one measuring mirror (226) which is pivotable over a predetermined range, a measuring light source which is configured to emit a measuring light beam in the direction of the measuring mirror (226), at least one position determination mirror (228, 229) which is pivotable together with the measuring mirror (226), a position determination light source (210) which is configured to emit a position determination light beam (212) in the direction of the position determination mirror (228, 229), a receiving element (230) which is configured to detect the position determination light beam (212) reflected at the position determination mirror (228, 229), and an evaluation unit (240) which is configuredto determine an orientation (α) of the measuring mirror (226) with respect to at least one reference direction (232) based on a position (Pa) of the detected position determination light beam (212) at the receiving element (230) and based on the relative spatial arrangement of the receiving element (230) with respect to the position determination mirror (228, 229). Optical sensor (200) according to claim 1, wherein the at least one measuring mirror (226) and the at least position determining mirror (228, 229) are mounted on a common support (224) and arranged in the same plane (225). Optical sensor (200) according to claim 1 or 2, wherein the at least one measuring mirror (226) and the at least one position determining mirror (228, 229) are formed as respective areas of a single, contiguous mirror surface. Optical sensor (200) according to one of the preceding claims, wherein a single position determination mirror (228) is provided. Optical sensor (200) according to one of claims 1 to 3, wherein at least two position determination mirrors (228, 229) are provided which are spatially separated from each other. Optical sensor (200) according to one of the preceding claims, comprising a polygon mirror (250) with at least three facets (260, 270), wherein a respective measuring mirror (226) and a respective position determining mirror (228) are formed on each of the three facets (260, 270) of the polygon mirror (250). Optical sensor (200) according to one of the preceding claims, wherein the receiving element (230) comprises at least one sensor row. Optical sensor (200) according to one of the preceding claims, wherein the measuring mirror (226) and the position determining mirror (228) are jointly pivotable in two mutually perpendicular directions and the receiving element (230) comprises at least two sensor rows. Optical sensor (200) according to claim 7 or 8, wherein at least one of the sensor rows (230) is curved. Optical sensor (200) according to one of the preceding claims, wherein a cylindrical lens is arranged between the position determining mirror (228) and the receiving element (230). Optical sensor (200) according to one of the preceding claims, wherein the measuring light source and the position determination light source (210) are identical.

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