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) which is 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; wherein the beam manipulation device (3) is fixedly connected to the adjustable object or is part of the adjustable object and comprises: a reflecting section (3a) configured to reflect a first part of the light beams emitted by the light source (2) towards the light receiver (4), an eliminating 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 reflecting 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). A further aspect of the present invention relates to a tilting mirror comprising the measuring device (1) and an object (O) which is adjustable about at least one axis of rotation, preferably in the form of a mirror support.

Description

[0001] Measuring device and tilting mirror with such a measuring device

[0002] The present invention relates to a measuring device for determining an angular position of an object adjustable about at least one rotation axis and to a tilting mirror comprising such a measuring device.

[0003] Such measuring devices are known. For example, tilting mirrors, which are used for the dynamic guidance (deflection) of electromechanical radiation, such as light, and are also known as fast steering mirrors (FSMs), require a corresponding measuring device capable of determining the angular position of the mirror. By determining the angular position of the mirror, the angular position can be controlled in a closed control loop. DE 10 2021 202 120 A1 discloses such a controlled tilting mirror.

[0004] Measuring devices used in this context can be based on different technologies. For example, measuring devices that use linear encoders or strain gauges (SGs) are widely used. However, neither linear encoders nor strain gauges can directly measure the angular position of the mirror. Furthermore, linear encoders for large tilt ranges require a lot of space and are comparatively expensive. Strain gauges are complex to apply and, due to the adhesive layers, provide only a limited observation bandwidth.

[0005] Therefore, it is the object of the present invention to provide a measuring device for determining an angular position of an object adjustable about at least one rotation axis and a tilting mirror comprising such a measuring device, which avoid the above-mentioned disadvantages and in particular have inexpensive and robust components that are easy to install.

[0006] The object is achieved by a measuring device according to claim 1 and a tilting mirror according to claim 11.

[0007] 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 adjustable object or is part of the adjustable 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 based on the received light beams, and the evaluation unit is configured toto determine the angular position of the adjustable object based on the signal output by the light receiver.

[0008] With the measuring device according to the invention, the angular position of the adjustable object can be determined optically. The measuring principle implemented by the measuring device according to the invention is based on the fact that only a first portion of the diverging light beams emitted by the light source is reflected by the beam manipulation device toward the light receiver and is used to determine the angular position of the adjustable object, while a second portion of the diverging light beams emitted by the light source are 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 as a divergent light source, which requires little installation space and is of low complexity, while the incidence of disturbing light rays resulting from the divergent light source on the light receiver is avoided.

[0009] Preferred embodiments are the subject matter of the subclaims. Further embodiments result from combinations of the subclaims.

[0010] It may be advantageous if the reflection section is designed as a collimator, which is configured to reflect the first portion of the light beams as parallel light beams, in particular as a parallel light bundle. Beam shaping (parallel bundling) therefore 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 that does not require dedicated optics for beam shaping.

[0011] It can be useful if the reflection section is designed as a concave mirror. With a concave mirror, incoming light rays can be easily reflected into a parallel beam.

[0012] It may also be useful for the reflection section to be designed as an optical grating. This allows the measuring device to cover a larger angular range. It may be advantageous if the elimination section has a conical shape, at least in sections. Light rays, especially the second part of the light rays emitted by the light source, that strike the conical surface can thus be reflected away from the light receiver and, in particular, diffusely reflected in other directions.

[0013] It may be practical if the elimination section comprises a radiation-absorbing coating for absorbing the second part of the light rays emitted by the light source.

[0014] It may be useful for the light source to be an LED or laser diode, especially an edge or surface emitter. Such diodes are simple and inexpensive components.

[0015] 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).

[0016] It may be useful if the light receiver comprises photodiodes, in particular several individual photodiodes or a multi-quadrant diode.

[0017] However, it can also be useful if the light receiver includes a CMOS sensor or CCD sensor.

[0018] 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 adjustable about at least one axis of rotation, preferably in the form of a mirror carrier.

[0019] It may be advantageous if a mirror is arranged on a front side of the mirror support and the beam manipulation device is arranged on a rear side of the mirror support opposite the front side.

[0020] Terms and definitions

[0021] The feature "reflection section configured to reflect a first portion of the light rays emitted by the light source toward the light receiver" broadly describes the arrangement and alignment of the reflection section and the light receiver within the intended adjustment range of the adjustable object or the measuring range of the measuring device. In other words, the reflection section and the light receiver are arranged and aligned relative to one another such that, upon an adjustment movement of the adjustable object within the intended or measuring range, the first portion of the light rays emitted by the light source is reflected by the reflection section toward the light receiver and, in particular, is incident within its detection range.

[0022] The feature "elimination section configured to reflect a second portion of the light rays emitted by the light source away from the light receiver" broadly describes the arrangement and alignment of the elimination section and the light receiver within the intended adjustment range of the adjustable object or the measuring range of the measuring device. In other words, the elimination section and the light receiver are arranged and aligned relative to one another such that, during an adjustment movement of the adjustable object within the intended adjustment range, the second portion of the light rays emitted by the light source is reflected away from the light receiver by the elimination section, so that, in particular, this second portion does not fall within the detection range of the light receiver.

[0023] Short description of the figure

[0024] Fig. 1 shows a schematic view of the measuring device according to the invention.

[0025] Detailed description of the preferred embodiments

[0026] The present invention will be described below with reference to Fig. 1.

[0027] The measuring device 1 comprises a light source 2, a beam manipulation device 3, a light receiver 4 and an evaluation unit.

[0028] The light source 2 is configured to emit diverging light beams. The light source may be, in particular, an LED or laser diode, in particular a surface emitter (VCSEL) or an edge emitter.

[0029] The beam manipulation device 3 is fixedly connected to an adjustable object O or is an integral part of the adjustable object O. The adjustable object O is an object that is adjustable about at least one rotational axis, preferably continuously, in order to be able to assume various 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 comprises a reflection section 3a and an elimination section 3b.The reflection section 3a is configured to reflect a first part of the light rays emitted by the light source 2 toward the light receiver 4, while the elimination section 3b is configured to reflect or absorb a second part of the light rays emitted by the light source 2 away from the light receiver 4.

[0030] In an embodiment in which the elimination section 3b is reflective, the beam manipulation device 3 preferably has the approximate shape of a truncated cone, with the reflection section 3a forming the top surface of the truncated cone and the elimination section 3b forming the lateral surface of the truncated cone. Due to the conical shape of the lateral surface, light rays incident into this area can be diffusely reflected in different directions. Such a beam manipulation device 3 can be manufactured from aluminum, for example, with the reflection section 3a and the elimination section 3b being produced by machining the corresponding sections using suitable surface treatment so that they reflect the incident light rays.

[0031] In another embodiment, in which the elimination section 3b is designed to be absorbent, the reflection section 3a and the elimination section 3b are preferably designed concentrically, with the elimination section 3b surrounding the reflection section 3a. To absorb the incident light rays, the elimination section 3b is suitably coated. Such a beam manipulation device 3 can also be manufactured from aluminum, with the reflection section 3a and the elimination section 3b being produced by first anodizing the entire beam manipulation device 3 black, and the reflection section 3a being machined out in a subsequent step, for example, by diamond milling or turning. All sections, in particular the elimination section 3b, that are not reworked are then correspondingly absorbent.

[0032] As shown in Fig. 1, it is also conceivable for the beam manipulation device 3 to have the shape of a truncated cone, in which the reflection section 3a forms the top surface of the truncated cone and the elimination section 3b forms the lateral surface of the truncated cone. The elimination section 3b has an absorbing effect on the light beams emitted by the light source 2 and is coated accordingly. This provides a particularly effective prevention of unwanted reflections of light beams toward the light receiver 4.

[0033] In all embodiments, it is preferred that the reflection section 3a is designed as a collimator, in particular as a concave concave mirror or as a grating, in order to reflect the first part of the diverging light rays emitted by the light source 2 as a parallel light beam.

[0034] The light receiver 4 is configured to receive the light beams reflected by the reflection section 3a. The light receiver 4 can be an analog or digital optical position sensor capable of detecting the position of the incident light beam using a detector surface. In an analog embodiment, the position sensor can be designed, for example, as:

[0035] • 2 individual photodiodes for measuring an angle

[0036] • 3 individual photodiodes (120° rotated against each other, 3 pie slices) for measuring two angles

[0037] • 4 individual photodiodes for measuring two angles

[0038] • 2-quadrant diode for measuring an angle

[0039] • 3-quadrant diode (120° rotated against each other, 3 pie slices) for measuring two angles

[0040] • 4-quadrant diode for measuring two angles

[0041] • PSD (position sensitive device)

[0042] With the analog sensors mentioned, the signals must then be further amplified and processed.

[0043] In a digital embodiment, the position sensor can be designed, for example, as:

[0044] • CMOS chip

[0045] • CCD chip

[0046] The light receiver 4 is thus configured to output a corresponding signal based on the detected position of the incident light beam. Finally, 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. 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.

[0047] The operation of the measuring device 1 described above is explained below. The light source 2 emits diverging light beams in the direction of the beam manipulation device 3. A first portion of the light beams emitted by the light source 2 is reflected by the reflection section 3a as a parallel light beam toward 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 based on the output signal. Adjusting the adjustable object O directly leads to adjusting 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, resulting in a correspondingly modified signal being 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 portion of the diverging light beams emitted by the light source 2 is reflected or absorbed away from the light receiver 4 by the elimination section 3b, so that no interfering light beams can impinge on the detector surface of the light receiver 4, which would lead to a dubious, inaccurate, or unevaluable signal.

[0048] List of reference symbols

[0049] 1 measuring device

[0050] 2 light source

[0051] 3 Beam manipulation device

[0052] 3a Reflection section

[0053] 3b Elimination section

[0054] 4 light receivers

Claims

Claims 1 . 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 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 portion of the light beams emitted by the light source (2) toward the light receiver (4), an elimination section (3b) configured to reflect or absorb a second portion 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).

2. Measuring device (1) according to claim 1, characterized in that the reflection section (3a) is designed as a collimator which is adapted to reflect the first part of the light rays as parallel light rays, in particular as a parallel light bundle.

3. Measuring device (1) according to claim 1 or 2, characterized in that the reflection section (3a) is designed as a concave mirror.

4. Measuring device (1) according to claim 1 or 2, characterized in that the reflection section (3a) is designed as an optical grating.

5. 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.

6. 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 rays emitted by the light source (2).

7. 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 or surface emitter.

8. Measuring device (1) according to one of the preceding claims, characterized in that the light receiver (4) is designed as an optical position sensor.

9. Measuring device (1) according to the preceding claim, characterized in that the light receiver (4) comprises photodiodes, in particular several individual photodiodes or a multi-quadrant diode.

10. Measuring device (1) according to claim 9, characterized in that the light receiver (4) comprises a CMOS sensor or CCD sensor.

11. 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.

12. Tilting mirror according to the preceding claim, characterized in that a mirror is arranged on a front side of the mirror support and the beam manipulation device (3) is arranged on a rear side of the mirror support opposite the front side.

Images