Measuring device and tilting mirror with such a measuring device

Abstract

The present invention relates to a measuring device (1) for determining an angular position of an object (O) that can be adjusted about at least one axis of rotation, comprising a light source (2), a beam manipulation device (3), a light receiver (4) and an evaluation unit, wherein the light source (2) is designed to emit divergent light beams, the beam manipulation device (3) is firmly connected to the adjustable object or is part of the adjustable object and comprises: a reflection section (3a) that is designed to reflect a first part of the light beams emitted by the light source (2) towards the light receiver (4), an elimination section (3b) that is designed to reflect or absorb a second part of the light beams emitted by the light source (2) away from the light receiver (4);wherein the light receiver (4) is configured to receive the first portion of the light beams reflected by the reflection section (3a) and to output a corresponding signal based on the received light beams; and the evaluation unit is configured to determine the angular position of the adjustable object (O) based on the signal output by the light receiver (4). A further aspect of the present invention relates to a tilting mirror comprising the measuring device (1) and an object (O) adjustable about at least one rotational axis, preferably in the form of a mirror carrier.

Description

The present invention relates to a measuring device for determining an angular position of an object adjustable about at least one axis of rotation, and to a tilting mirror comprising such a measuring device.Such measuring devices are known. For example, tilting mirrors which serve for the dynamic guidance (deflection) of electromechanical radiation, such as light, and are also referred to as fast steering mirrors (FSM), require a corresponding measuring device which is capable of determining the angular position of the mirror. By determining the angular position of the mirror, the angular position can be controlled in the closed control loop. DE 10 2021 202 120 A1 discloses such a controlled tilting mirror.Measuring devices used in this context can be based on different technologies. For example, measuring devices using linear encoders or strain gauges (DMS) are widely used. However, both with linear encoders and with strain gauges, it is not possible to measure the angular position of the mirror directly. Furthermore, linear encoders require a large amount of installation space for large tilting regions and are comparatively expensive. Strain gauges are complicated to apply and provide only a limited observation bandwidth due to the adhesive layers.It is therefore the object of the present invention to provide a measuring device for determining an angular position of an object adjustable about at least one axis of rotation and a tilting mirror comprising such a measuring device, which avoid the above-mentioned disadvantages and in particular have favorable and robust components which are easy to install.The object is achieved by a measuring device according to claim 1 and a tilting mirror according to claim 11.According to the invention, the measuring device comprises a light source, a beam manipulation device, a light receiver and an evaluation unit, wherein the light source is configured to emit divergent light beams, the beam manipulation device is fixedly connected to the displaceable object or is part of the displaceable object and comprises a reflection section configured to reflect a first part of the light beams emitted by the light source towards the light receiver, and an elimination section configured to reflect or absorb a second part of the light beams emitted by the light source away from the light receiver, wherein the light receiver is configured to receive the first part of the light beams reflected by the reflection section and to output a corresponding signal on the basis of the received light beams, and the evaluation unit is configured to determine the angular position of the displaceable object on the basis of the signal output by the light receiver.With the measuring device according to the invention, the angular position of the adjustable object can be determined optically. The measuring principle realized by the measuring device according to the invention is based analogously on the fact that only a first part of the diverging light beams emitted by the light source is reflected by the beam manipulation device toward the light receiver and is used for determining the angular position of the adjustable object, while a second part of the diverging light beams emitted by the light source is reflected or absorbed by the beam manipulation device away from the light receiver. As a result, a simple light source, such as an LED or a laser diode, can be used in particular as divergent light source, which requires little installation space and has a low complexity, while the incidence of disturbing light beams resulting from the divergent light source on the light receiver is avoided.Preferred embodiments are the subject matter of the dependent claims. Further embodiments result from combinations of the dependent claims.It can be advantageous if the reflection section is designed as a collimator which is configured to reflect the first part of the light beams as parallel light beams, in particular as a parallel light beam. The beam forming (parallel bundling) consequently takes place directly at the reflection section and not at the light source or in the beam path between the light source and the beam manipulation device. As already mentioned above, the light source can therefore be a simple divergent light source which does not require dedicated optics for beam forming.It can be useful if the reflection section is designed as a concave mirror. With a concave shaped concave mirror, incident light beams can be easily reflected in a parallel light beam.It can also be expedient if the reflection section is designed as an optical grating. As a result, a larger angular range can be detected with the measuring device.It can be advantageous if the elimination section has a conical shape at least in sections. Light beams, in particular the second part of the light beams emitted by the light source, which strike the conical surface, can thereby be reflected away from the light receiver and in particular diffusely in other directions.It may be practical if the eliminating section comprises a radiation-absorbing coating for absorbing the second part of the light beams emitted by the light source.It can be expedient if the light source is designed as an LED or laser diode, in particular as an edge emitter or surface emitter. Such diodes are simple and cost-effective components.It can be useful if the light receiver is designed as an optical position sensor. Such a sensor comprises a detector surface capable of detecting the position of an incident light beam (light spot).It can be useful if the light receiver comprises photodiodes, in particular a plurality of individual photodiodes or a multi-quadrant diode.However, it can also be expedient if the light receiver comprises a CMOS sensor or CCD sensor.A further aspect of the present invention relates to a tilting mirror, comprising: the measuring device according to one of the preceding embodiments, and an object which can be adjusted about at least one axis of rotation, preferably in the form of a mirror carrier.It can be advantageous if a mirror is arranged on a front side of the mirror carrier and the beam manipulation device is arranged on a rear side of the mirror carrier opposite the front side.Terms and definitionsThe feature "reflection section, which is configured to reflect a first part of the light beams emitted by the light source toward the light receiver" describes in the broader sense the arrangement and orientation of the reflection section and the light receiver within the intended adjustment range of the adjustable object or measurement range of the measuring device. In other words, the reflection section and the light receiver are arranged and aligned with respect to one another in such a way that, during an adjustment movement of the adjustable object within the intended or measurement range, the first part of the light beams emitted by the light source is reflected from the reflection section toward the light receiver and in particular enters within the detection range thereof.The feature "elimination section, which is configured to reflect a second part of the light beams emitted by the light source away from the light receiver" describes in the broader sense the arrangement and orientation of the elimination section and the light receiver within the intended adjustment range of the adjustable object or measurement range of the measurement device. In other words, the elimination section and the light receiver are arranged and aligned with respect to one another in such a way that, during an adjustment movement of the adjustable object within the intended adjustment range or the second part of the light beams emitted by the light source is reflected away from the light receiver by the elimination section, so that in particular this second part does not enter within the detection range of the light receiver.Brief Description of the FigureFIG. 1 shows a schematic view of the measuring device according to the invention.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSThe present invention will be described below with reference to FIG. 1.The measuring device 1 comprises a light source 2, a beam manipulation device 3, a light receiver 4 and an evaluation unit.The light source 2 is configured to emit diverging light beams. The light source can be, in particular, an LED or laser diode, in particular a surface emitter (VCSEL) or an edge emitter.The beam manipulation device 3 is firmly connected to an adjustable object O or an integral part of the adjustable object O. The adjustable object O is an object which is adjustable about at least one axis of rotation, preferably continuously, in order to be able to assume different angular positions. In a preferred embodiment, the adjustable object O is a mirror carrier, on the front side of which a mirror is arranged and on the rear side of which the beam manipulation device 3 is arranged.The beam manipulation device 3 includes a reflection section 3 aand an elimination section 3 b. The reflection section 3 ais configured to reflect a first part of the light beams emitted by the light source 2 towards the light receiver 4, while the elimination section 3 bis configured to reflect or absorb a second part of the light beams emitted by the light source 2 away from the light receiver 4.In an embodiment in which the elimination section 3 bis designed to be reflective, the beam manipulation device 3 preferably has approximately the shape of a truncated cone, wherein the reflection section 3 aconstitutes the top surface of the truncated cone and the elimination section 3 babove the lateral surface of the truncated cone. Due to the conical shape of the lateral surface, light rays incident in this region can be diffusely reflected in different directions. Such a beam manipulation device 3 can be made of, for example, aluminum, and the reflection portion 3 aand the elimination portion 3 bare formed by processing the respective portions to reflect the incident light beams using appropriate surface processing.In another embodiment in which the eliminating portion 3 bis formed to be absorbent, the reflecting portion 3 aand the eliminating portion 3 bare preferably formed concentrically, and the eliminating portion 3 bsurrounds the reflecting portion 3 a. For absorbing the incident light rays, the eliminator portion 3b is coated suitably. Such a beam manipulation device 3 can likewise be produced from aluminum, wherein the reflection section 3 aand the elimination section 3 bare produced by initially anodizing the entire beam manipulation device 3 in black, and the reflection section 3 ais worked out in a subsequent step, for example by means of diamond milling or turning. All the sections, in particular the elimination section 3 b, which are not post-processed are then accordingly absorbent.As shown in FIG. 1, it is additionally conceivable for the beam manipulation device 3 to have the shape of a truncated cone, in which the reflection section 3 aconstitutes the top surface of the truncated cone and the elimination section 3 bform the lateral surface of the truncated cone, wherein the elimination section 3 bacts to absorb the light beams emitted by the light source 2 and is coated accordingly. This results in a particularly effective avoidance of undesired reflections of light beams toward the light receiver 4.In all embodiments, it is preferred that the reflection section 3 ais designed as a collimator, in particular as a concave concave concave mirror or as a grating, in order to reflect the first part of the diverging light beams emitted by the light source 2 as a parallel light bundle.The light receiver 4 is configured to receive the light beams reflected by the reflection portion 3 a. The light receiver 4 can be an analog or digital optical position sensor which is capable of detecting the position of the incident light beam with the aid of a detector surface. In an analog embodiment, the position sensor may be embodied as:• 2 individual photodiodes for measuring an angle• 3 individual photodiodes (120° rotated relative to each other, 3 pie pieces) for measuring two angles• 4 individual photodiodes for measuring two angles• 2-quadrant diode for measuring an angle• 3-quadrant diode (120° rotated against each other, 3 pie pieces) for measuring two angles• 4 quadrant diode for measuring two angles• PSD (Position Sensitive Device)In the case of the aforementioned analog sensors, the signals must subsequently be further amplified and processed.In a digital embodiment, the position sensor can be embodied as:• CMOS chip• CCD chipThe light receiver 4 is consequently configured to output a corresponding signal on the basis of the detected position of the incident light beam. The evaluation unit is finally configured to determine the angular position of the adjustable object O on the basis of the signal output by the light receiver 4. The evaluation unit can be integrated into the light receiver 4 or can be a separate unit. For example, the evaluation unit can also be part of a central control unit.The mode of operation of the measuring device 1 described above is explained below.The light source 2 emits diverging light beams towards the beam manipulation device 3. A first part of the light beams emitted by the light source 2 is reflected by the reflection section 3a as a parallel light beam towards the light receiver 4. The light receiver 4 receives this light beam on its detector surface and outputs a signal based on the detected position of the light beam on the detector surface. The evaluation unit determines the angular position of the adjustable object on the basis of the output signal. An adjustment of the adjustable object O directly leads to an adjustment of the beam manipulation device 3. By adjusting the beam manipulation device 3, the position of the light beam on the detector surface of the light receiver 4 changes, whereby a correspondingly changed signal is output, on the basis of which the new angular position of the adjustable object O is determined by the evaluation unit. During the entire process, a second part of the diverging light beams emitted by the light source 2 is reflected or absorbed by the eliminating section 3b away from the light receiver 4, so that no disturbing light beams can be incident on the detector surface of the light receiver 4, which would lead to a doubtful, inaccurate or unusable signal.List of reference characters1 Measuring device 2 Light source 3 Beam manipulation device 3 a Reflexions section 3 b Section 4 Light receiverReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 202 120 A1

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Claims

Measuring device (1) for determining an angular position of an object (O) adjustable about at least one axis of rotation, comprising a light source (2), a beam manipulation device (3), a light receiver (4) and an evaluation unit, wherein the light source (2) is configured to emit divergent light beams, the beam manipulation device (3) is fixedly connected to the adjustable object or is part of the adjustable object and comprises: a reflection section (3a) configured to reflect a first part of the light beams emitted by the light source (2) towards the light receiver (4), an elimination section (3b) configured to reflect or absorb a second part of the light beams emitted by the light source (2) away from the light receiver (4); wherein the light receiver (4) is configured to receive the first part of the light beams reflected by the reflection section (3a) and to output a corresponding signal on the basis of the received light beams; and the evaluation unit is configured to determine the angular position of the adjustable object (O) on the basis of the signal output by the light receiver (4).Measuring device (1) according to claim 1, characterised in that the reflection section (3a) is designed as a collimator, which is configured to reflect the first part of the light beams as parallel light beams, in particular as a parallel light beam.Measuring device (1) according to claim 1 or 2, characterised in that the reflecting section (3a) is designed as a concave mirror.Measuring device (1) according to claim 1 or 2, characterised in that the reflection section (3a) is designed as an optical grating.Measuring device (1) according to one of the preceding claims, characterized in that the elimination section (3b) has a conical shape at least in sections.Measuring device (1) according to one of the preceding claims, characterized in that the elimination section (3b) comprises a radiation-absorbing coating for absorbing the second part of the light beams emitted by the light source (2).Measuring device (1) according to one of the preceding claims, characterized in that the light source (2) is designed as an LED or laser diode, in particular as an edge emitter or surface emitter.Measuring device (1) according to one of the preceding claims, characterized in that the light receiver (4) is designed as an optical position sensor.Measuring device (1) according to the preceding claim, characterized in that the light receiver (4) comprises photodiodes, in particular a plurality of individual photodiodes or a multi-quadrant diode.Measuring device (1) according to claim 9, characterised in that the light receiver (4) comprises a CMOS sensor or CCD sensor.Tilting mirror, comprising: the measuring device (1) according to one of the preceding claims, and an object (O) adjustable about at least one axis of rotation, preferably in the form of a mirror carrier.Tilting mirror according to the preceding claim, characterized in that a mirror is arranged on a front side of the mirror carrier and the beam manipulation device (3) is arranged on a rear side of the mirror carrier opposite the front side.

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