EP3724674A1

EP3724674A1 - 3d sensor system having a freeform optic

Info

Publication number: EP3724674A1
Application number: EP18826219.0A
Authority: EP
Inventors: Urs Hunziker; Johannes Eckstein; Beat Wyss; Christian Seiler
Original assignee: Bircher Reglomat AG
Current assignee: Bircher Reglomat AG
Priority date: 2017-12-12
Filing date: 2018-12-11
Publication date: 2020-10-21
Also published as: DE102017129641A1; WO2019115558A1

Abstract

The invention relates to a sensor system (100) as well as a method for three-dimensionally detecting a scene (190). The sensor system comprises: (a) an illumination device (130) for illuminating the scene with an illumination light (131) along an illumination beam path; (b) a measuring device (115) for receiving measuring light (196) along a measuring light beam path, wherein the measuring light is at least partially illumination light scattered back by at least one object (195), and for measuring distances between the sensor system and the object based on a light propagation time of the illumination light and the measuring light; (c) a data processing device (150), arranged downstream of the measuring device, for determining the three-dimensional characteristics of the scene based on the measured distances; and (d) a freeform optic (140, 142) which is arranged in the illumination beam path and/or in the measuring light beam path, wherein the freeform optic is configured in such a way that, (i) when arranged in the illumination beam path, an illumination intensity of the illumination light depends on the solid angle of the illumination beam path, and (ii) when arranged in the measuring light beam path, a measuring light intensity of the measuring light depends on the solid angle of the measuring light beam path, such that a distance-based intensity loss of the illumination light and the measuring light is at least partially compensated. The invention also relates to uses of the sensor system.

Description

3D sensor system with a free-form optics

Technical area

The present invention relates to a sensor system and a method for three-dimensional acquisition of a scene based on transit time measurements. Furthermore, the present invention relates to several uses of such

Sensor system.

Background of the invention

For opening and / or closing of openings are often by means of

Actuators operated closure body used, which facilitate the handling of the respective closure body for operators or automatically operated without any action, for example, when an object to be passed to the opening passes into the region of the opening. Such an opening may, for example, be a passageway in a building. A closure body may be, for example, a door or a gate.

To automatically open and close a high level of operational safety

To achieve closing closure bodies, it is known to detect the area in front of or within an opening which can be covered by a closing body by means of an optical sensor system. This can on the one hand be ensured that when shooting the opening accidentally an object, such as a person, is clamped by the closing body. In addition, in some applications such a sensor system may cause automatic opening of the closure body or opening. In this context, it is also known that such a sensor system or a data processing device connected downstream of such a sensor system uses known methods of image processing

Performs object detection and releases the opening only if an authorized to pass the openings object in the range of (still

closed opening). Such object recognition can

for example, a face recognition.

From EP 2 453 252 B1, a 3D sensor system is known for the field of application of the monitoring of automatically opening doors and / or gates, which is based on the principle of transit time measurement of light beams emitted by illumination sources and after an at least partial reflection or 180 ° Backscatter be detected by a light receiver. Such sensor systems are commonly referred to as "time-of-flight" (TOF) sensor systems. However, TOF sensor systems have the disadvantage that with

increasing distance d of the object to be detected, the intensity of the (backscattered) measuring light to be detected by a light receiver of the TOF sensor is weakened in two respects. In the case of a punctiform illumination light source without a special focus, it scales

Attenuation of the illumination light emitted by the illumination sources with l / d ^/ 2, where d is the distance to the illumination light source. The same applies to the measurement light, if one a point of the object, at which the

Illumination light is scattered isotropically, perceived as a point light source. As a result, this leads to a l / d 'scaling of the intensity of the received measurement light. In the case of beamforming realized in any manner, for example focusing, of the illumination light, of the measuring light and / or in the case of non-isotropic scattering of the illumination light with a preferred beam

Transmission of the measuring light in the direction of the light receiver, is the

Intensity attenuation correspondingly lower, but still contributes to one significant loss of light output at. This in turn leads to a correspondingly poor energy efficiency of a TOF sensor system.

It is an object of the present invention to provide an energetically efficient and nevertheless reliable three-dimensional detection of a scene which also includes relatively distant objects.

Summary of the invention

This task is solved by the objects of the independent ones

Claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, a sensor system for

Three-dimensional capture a scene described. The described

Sensor system comprises (a) a lighting device for illuminating the scene with an illumination light along an illumination beam path; (B) a measuring device (BL) for receiving measuring light along a

Measuring light beam path, wherein the measuring light is at least partially backscattered by at least one object in the scene illumination light and (b2) for measuring distances between the sensor system and the at least one object based on a light transit time of the illumination light and

Measuring light; (c) one of the measuring device downstream

Data processing device for determining the three-dimensional

Characteristic of the scene based on the measured distances; and (d) free-form optics which are arranged in the illumination beam path and / or in the illumination beam path

Measuring light beam path is arranged. The free-form optical system is configured in such a way that (dl), when arranged in the illumination beam path, has a

Illumination light intensity of the illumination light depends on the solid angle of the illumination beam path, and (d2) in an arrangement in the Measuring light beam path, a measuring light intensity of the measuring light depends on the solid angle of the measuring light beam path, so that a distance-based loss of intensity of the illumination light and the measuring light is at least partially compensated.

The described sensor system, which is a so-called Time Of Flight (TOF) sensor system, is based on the knowledge that at least partially compensated by a suitably designed freeform optics of the scene geometry and the spatial angle dependent influences on the intensity distribution of the received measurement light. Illustratively, the free-form optics ensure that in an image of the scene generated by the received measurement light, there are neither (excessively) underexposed nor (excessively) overexposed portions. If the free-form optical system is in the beam path of the illumination light, then already by a suitable space angle-dependent intensity distribution of

Lighting light ensured that the measuring light from each part of the scene with a homogeneous distribution of intensity on a

Light receiver of the measuring device hits. Alternatively or in combination, when the free-form optical system is located in the beam path of the measuring light, then a suitable collection of measuring light beams ensures or contributes to ensuring that the measuring light is as homogeneous as possible

Intensity distribution hits the light receiver.

In other words, the free-form optical system in the illumination beam path ensures that the scene is illuminated or exposed with a lighting angle-dependent illumination intensity. In the measuring light beam path provides the

Freeform optics for the fact that the measuring light depending on the space angle collected differently, in particular with a space angle-dependent focusing. Both effects contribute to that of all parts of the scene

received measuring light is at least approximately equal in terms of its intensity. This can avoid being in an image of the captured scene from the measuring light underexposed and / or overexposed portions are.

With the described freeform optics can a space angle dependent

Intensity distribution of the illumination light or a spatial characteristic of the illumination light and / or a spatial angle-dependent collection of measurement light intensity or spatial measurement light collection characteristic are set so that the intensity of the illumination light in particular is just as high as it is associated with a reliable detection of the respective solid angle range Subsection of the scene is required.

As a result, only as much energy is required for the illumination as is necessary, so that the described sensor system is characterized by a good energy efficiency as a result.

It should be noted that with the described free-form optics, if required, it is also possible to compensate for (undesired) aberrations in the illumination beam path and / or the measurement light beam path. Such aberrations may be caused by other optical components of the

Sensorsystems come.

The term "scene" may in particular be understood to mean that spatial area which is optically detected by the sensor system. Objects in the scene are recognized by a suitable image analysis. For this purpose, the data processing device can make use of known methods for image evaluation and / or image analysis. The

Data processing device can therefore be a special

Be image processing processor and having one that is configured, known methods for image analysis and / or image processing

to apply or to carry out.

The term "object" can be understood to mean any spatially physical structure which has a surface texture which results in an at least Partial reflection or scattering of illumination light leads and thus by the resulting measuring light for the measuring device is visible. The object may be an object such as a motor vehicle or a living being such as a human. The object may be in relation to that

Sensor system be static or dormant object. Furthermore, the object may also move within, leave or enter the scene.

Through a repeated scene capture, the movement of the object can be determined (by comparing the different location positions determined with different scene acquisitions) (according to the formula speed = distance / time). Here, depending on the application, the absolute value of the speed and / or the motion vector, i. additionally the

Movement direction to be determined.

The term "illumination light" in this document means those electromagnetic waves which are emitted by a light source or a lighting unit of the illumination device and strike the relevant object of the scene. The "measuring light" are the electromagnetic waves scattered by or on the object (back), which are received by the measuring device or a light receiver of the measuring device and used for the three-dimensional evaluation of the scene, together with the

corresponding TOF distance information.

The term "characteristic of a scene" can be understood as the entirety of all spatial structures and in particular all objects which are detected by the sensor system. The characteristic of the scene changes when (i) new objects enter the scene when (ii) objects already in the scene change their position and / or their visual appearance, in particular their optical scattering behavior, and / or if (iii) Object left the scene. In this case, some structures can be recognized as being relevant and other structures as being less or even irrelevant by the data processing device by means of image processing and / or image recognition. In this document, the term "free-form optics" can be understood as any optical structure that modifies the beam path of light beams, which provides for a spatial angle-dependent modification of the intensity of the illumination light and / or for a space angle-dependent collection (the intensity of the measurement light). The freeform optics can be a static optic. This means that the scene regardless of their current characteristics in different scene captures (and scene detections or

Scene evaluations by the data processing device) is always illuminated with the same spatial angle-dependent modification of the illumination light and / or detected with the same spatial angle-dependent modification of the measurement light. In other embodiments, the operating state

For example, be modified by a change in the geometry and / or the internal structure of the freeform optics.

A free-form optics can consist of an optical element. Alternatively, a freeform optics can also consist of a plurality of optical elements connected in series and realized, for example, by means of a lens system.

The term "distance-based loss of intensity" can mean the one

Reducing the intensity of illumination light and / or measuring light are understood, which by a widening of the cross section of the

Illumination light beams or the measuring light beams (after a scattering or reflection on an object) is caused. In the case of a point light source without a special focus, this loss of illumination light scales with l / d ^, where d is the distance to the point light source. The same applies to the measuring light when a point of the object at which the illumination light is scattered isotropically, as a point light source. As a result, this leads to a l / d 'scaling of the resulting measurement signal, which is due to the

Intensity of the received measuring light is given. In one way or another and beamforming, for example focusing, of the illumination light, of the measuring light and / or in the case of a non-isotropic scattering of the illumination light with a preferred emission of the measuring light in the direction of the measuring device, the "distance-based intensity loss" is correspondingly lower, but in practice nevertheless a significant loss, which reduces the energy efficiency of a TOF sensor.

According to the invention, these losses are at least partially reduced or compensated by the free-form optics.

The terms "optical" and / or "light" may refer to electromagnetic waves having a particular wavelength or frequency or a particular spectrum of wavelengths or frequencies. In particular, the electromagnetic waves used can be assigned to the spectral range visible to the human eye. Alternatively or in combination, electromagnetic waves associated with the ultraviolet (UV) or infrared (IR) spectral regions may also be used. The IR spectral range can extend into the long-wave IR range with wavelengths between 3.5 pm to 15 pm, which are determined by means of the

Light receiver of the sensor can be detected.

It should be noted that the inventive compensation of the distance-based intensity loss by means of the space angle-dependent

Intensity modification of illumination light and / or measuring light is not only possible for TOF sensor systems, which illuminate the whole or at least larger portions of the scene simultaneously. The inventive

Freeform optics can also be optically used profitably in TOF sensor systems which sequentially illuminate the scene

Scanning light beam, such as a laser beam.

According to one embodiment of the invention, the sensor system further comprises a further free-form optics, wherein the free-form optics in the Illumination beam path is arranged and the further free-form optics is arranged in the measuring light beam path. By providing two separate and thus individually dimensionable free-form optics

Illumination light and measuring light can be optimally modified independently of each other. With variable free-form optics, both "lights" can be adaptive independently of each other in terms of their spatial angle-dependent

Intensity distribution are modified.

It should be noted that all described in this document

Features or variants of the freeform optics also apply to the further free-form optics.

According to a further exemplary embodiment of the invention, the free-form optical system has at least one reflective optical element, at least one refractive optical element and / or at least one diffractive optical element.

The term "reflective" or "reflection" in this document means (at least partial) repulsion of electromagnetic waves at an interface, with respect to a normal of this interface the angle of incidence of the incident electromagnetic wave equal to

Angle of reflection of the reflected electromagnetic wave. Preferably, the reflective interface of the freeform optics has the highest possible

Reflection coefficients on. This means that the proportion of the

Electromagnetic wave, which is not reflected with "angle of incidence = angle of reflection" is as large as possible and the proportion of the electromagnetic wave that absorbs or is scattered in other directions, is as small as possible. A reflective element may in particular be a mirror. The freeform optics can thus at least one mirror (with a suitably curved

Surface).

The term "refractive" or "refraction" (or refraction) is the Change of propagation direction of an electromagnetic wave due to a spatial change of its propagation velocity, which is specifically described for light waves by the refractive index n of a medium. A refractive element of the described free-form optics may be a suitable shaped lens. Other optically refractive elements such as, for example, a (modified prism) can also be used in order to realize a suitable beam angle-dependent beam shaping of the illumination light and / or the measurement light.

The term "diffractive" or "diffraction" (or diffraction) in this context refers generally to the spatial deflection of an electromagnetic wave at structural obstacles. Such obstacles may be an edge, a hole or a one-dimensional, a two-dimensional or even a three-dimensional grid. The diffractive optical element can be, for example and preferably, a diffractive optical element (DOE), which advantageously permits a dynamic adaptation or adaptation of the space angle-dependent characteristic of the illumination light and / or the space angle-dependent characteristic of the measurement light.

According to a further exemplary embodiment of the invention, the free-form optical system has at least one spatially and / or structurally changeable optical element, a change of the optical element resulting in a change of the solid angle dependency of the illumination light intensity and / or

Measuring light intensity leads.

Due to the described variability of the freeform optics, the solid angle dependence of the

Intensity distribution of illumination light and / or measurement light to be adapted to a change in the characteristic of the scene to be detected that all (relevant) objects in the scene with high accuracy can be detected. The described change of the free-form optics can thus be caused by the data processing device during the operation of the sensor system depending on the scene. Furthermore, the free-form optics can also be tested according to the principle of "try-and-error" or by other statistical,

incremental or history based optimization procedures. This can be done dynamically during a real operation of the sensor system or as part of a calibration by means of a detection of suitable reference objects.

A spatial change of the optical element can, for example, be a simple displacement and / or rotation of this optical element in a coordinate system of the sensor system and / or relative to other optical elements of the freeform optical system. This can be done preferably by means of an actuator in an automatic manner, wherein a control of the actuator from the data processing device or from any other with respect to the sensor device internal or external freeform control device can take place.

The variable optical element may also be an elastic element, for example a deformable mirror. Further, the elastic member may be a pressure-deformable member of an elastic optical material which changes its optical properties (reflection, diffraction and / or refraction behavior) under pressure.

For example, a structural change in a DOE can lead to a desired modification of the solid angle dependence of the illumination light and / or the measurement light. In addition, it is also possible to use micromirror arrays resulting from so-called digital light processing (DLP).

Projection technology are known. Furthermore, so-called. Micro electro

Mechanical systems (microelectromechanical systems, MEMS) devices for a targeted movement of a plurality of optical elements, In particular, micromirrors, are used, so that there is a desired spatial angle-dependent intensity distribution of the illumination light and / or the measuring light.

According to a further exemplary embodiment of the invention, the free-form optical system and / or the illumination device is or are configured, which

Provide illumination light and / or the measurement light with a space angle-dependent intensity distribution which at least approximately compensates for an edge light drop, in particular a natural edge light drop according to the one brightness in an image when a uniformly bright subject is imaged by a lens by the factor cos'M compared to the brightness in the image Center of the picture decreases.

The natural Randlichtabfall, which by the so-called. cos'M (cosine high 4) law depends in a known manner on the focal length of a lens used. In the case of the described TOF sensor system, such an objective can be used to image the illumination light onto the scene and / or to image the scene onto a light receiver

Measuring device can be used. In the case of the use of lenses and preferably a common objective for both (emitted from a flat light source) illumination light and for (scattered by the area scene) measuring light without the described compensation of the natural marginal light waste would occur twice and the negative influence of cos 'M law would be correspondingly strong. Therefore, in TOF sensor systems in which both the illumination light and the measurement light pass through an objective, the compensation of the natural peripheral light drop by the free-form optical system described herein and / or illumination by the illumination device uneven across the scene contribute particularly to an improvement of the light intensity ratios ,

The compensation of the natural Randlichtabfalls by a suitable Room angle-dependent intensity modification of illumination light and / or measurement light can be at least 30%, preferably 50%, more preferably 80% and even more preferably 90% or even 95%. These percentages refer (with a fixed focal length of the objective used) to the ratio between the intensities at the edge of the image of the scene (for the measuring light) imaged on the measuring device which (a) coincides with the

described compensation and (b) occur without the described compensation of the natural edge drop. Accordingly, a 100%

Compensation a complete elimination of the natural Randlichtabfalls mean. In the case of a (fictive) scene, which diffuses the illuminating light equally strongly in all partial areas, the brightness in one picture would be in all cases

Be equal parts, wherein the image is the (complete) image of the scene on a light receiver of the measuring device.

It should be noted that in relation to the brightness distribution of the illumination light in the scene in preferred embodiments a

Overcompensation of natural Randlichtabfalls takes place. These

Overcompensation should just be so strong that the natural marginal light drop of the measuring light is just compensated so that it in the on the

Measuring device pictured scene to the best possible

Compensation of natural edge light waste comes.

According to a further embodiment of the invention, the

Sensor system further coupled to the illumination device

Illumination light controller, which is configured, the

To control lighting device such that a characteristic of the

Illumination light, which describes the dependence of the illumination intensity of the illumination light on the solid angle, is dynamically changeable during an operation of the sensor system.

Through a dynamic variability of the characteristics of the Illumination light, one and the same scene can be recorded multiple times under different lighting conditions (successively). As a result, different data sets of one and the same scene are available to the data processing device, so that by means of a suitable method of image analysis (by the data processing device) that data record can be used for determining the three-dimensional characteristic of the scene which most accurately reproduces the scene. If necessary, an "a priori knowledge" of the optical and / or

geometric properties of objects in the scene

be taken into account.

Furthermore, an optimal lighting characteristic can also be determined according to the "try-and-error" principle or by other statistical optimization procedures. This can be done dynamically during a real operation of the sensor system or as part of a calibration by means of a recognition of suitable reference objects (as in the above-described spatial and / or structural change of an optical element of the freeform optics).

In some embodiments, those at different

Lighting characteristics recorded 3D images of the scene are processed together so that a comprehensive data set is available for a final determination of the 3D characteristic of the scene. In such a common processing, different partial areas of the scene can be characterized in that for a first partial area a first partial data record recorded in a first illumination characteristic and for a second partial area of the second partial data set recorded for a second illumination characteristic for the determination of the

Overall characteristic of the scene can be used. Of course, more than three can be used to capture the overall characteristics of the scene

Records are used, each of a different Lighting light characteristic are assigned.

According to a further embodiment of the invention is the

Data processing device coupled to the illumination light controller and configured to evaluate the determined three-dimensional characteristic of the scene and based on a result of this evaluation to change the characteristic of the illumination light.

Vividly, the way the scene depends on one

Scene detection is dependent on the angle of illumination illuminated by the illumination device, of measurement and evaluation results, which have been determined from a previous scene detection. The characteristic of the lighting becomes so dynamically on the basis of results of a

adapted to previous scene capture. This means that, correctly speaking, not only a control of the lighting device but rather a regulation thereof takes place. This advantageously allows a particularly accurate adaptation of the scene lighting with regard to an optimum

Scene analysis.

Appropriate control of the lighting device may depend on current environmental conditions resulting in the result of

Reflect scene evaluation. Such environmental conditions may be weather conditions such as the presence of rain, snow, hail, fog, smoke, suspended particles, etc. in the scene.

According to a further exemplary embodiment of the invention, the result of the evaluation depends on the optical scattering behavior of at least one object contained in the scene. This has the advantage that in addition to the distance-based

Compensation also a possibly existing different scattering behavior and / or reflection behavior of different objects in the Scene can be considered, so that the measuring light with an at least approximately spatially uniform intensity distribution to a

Light receiver of the measuring device impinges. A brightness which is as uniform as possible over the light-sensitive surface of the light receiver favors precise distance measurement by the described TOF sensor system.

It should be noted that in many objects, the litter or. Reflection behavior depends on the wavelength or the frequency of the illumination light. Consideration of such a frequency dependence can advantageously contribute to a further improvement of the scene lighting and the subsequent scene evaluation.

According to a further embodiment of the invention, the

Lighting device on at least one of the group consisting of

(a) a laser light source for spatially scanning the scene with an emitted laser beam illuminating light;

(B) an at least approximately punctiform illumination light source;

(c) a plurality of individual illumination light sources which are in particular individually controllable and each associated with a specific solid angle range of the scene; and

(D) a flat illumination light source, in particular with a non-homogeneous emitted over the surface luminous intensity.

A scanning the scene laser beam can be directed in a known manner via two rotatable mirrors with mutually non-parallel and preferably perpendicular to each other oriented axes of rotation to each illuminated point of the scene. For such a (dynamically adaptive) deflection can also non-mechanical optical elements such as diffractive

Optical elements (DOEs) are used. The deflection can be controlled in particular by the illumination light control device described above. Also a dynamic adaptation of the freeform lens by means of The above-described spatial and / or structural change of an optical element of the freeform lens can provide for a suitable beam deflection of the laser beam.

The at least approximately punctiform illumination light source may be a (sufficiently strong) semiconductor diode, for example a laser or light emitting diode. In order to illuminate the scene areally, suitable

Beam shaping systems and in particular the described freeform optics are used. In order to realize a non-uniform illumination of the scene depending on the spatial angle, suitable optical elements can also be used

Beam deflection, beam splitting and / or beam merge can be used.

The plurality of illumination light sources, which are also in particular laser or light-emitting diodes, can be controlled (in particular individually) by the illumination light control device described above. This advantageously allows an adaptively controlled or even regulated adjustment of the characteristic of the illumination light.

A flat light source can also be the source for a spatially-dependent, non-homogeneous intensity distribution. If it is a spatially homogeneously illuminated surface, suitable optical elements for

Beam deflection, beam splitting, beam merging and / or

Beam shaping, in particular (also) the described freeform optics are used to realize a spatial angle dependent uneven illumination of the scene.

To provide illumination light with a beam cross-section deviating from a circular shape. As a result, scenes that are "not round" can have one inadequate illumination of corner areas of the scene can be avoided. Although inadequate illumination of the corner areas could possibly be prevented by an overall increased intensity of the illumination light, in this case, however, the middle areas of the scene would be overexposed, which would be very disadvantageous, at least from an energetic point of view.

In many embodiments or applications of the sensor system, it is advantageous if the illumination light has a rectangular beam cross section. Preferably, the beam cross-section is adapted to achieve as homogeneous as possible illumination to the shape of the scene to be detected. A suitable shaping of the beam cross section can be realized not only by a corresponding shaping of the luminous area of the illumination device and / or configuration of the freeform optics, but also by optical components such as mirrors and refractive optical elements (e.g.

Lens system) can be adapted in a suitable manner. Also diffractive optical elements (DOE) can be used, which optionally even one

enable dynamic and / or scene-dependent shaping of the beam cross section. In addition, micromirror arrays known from the so-called Digital Light Processing (DLP) projection technology can also be used. Even with so-called microelectromechanical systems (MEMS) devices, a large number of optical elements can be moved in such a way that they produce a desired spatial angle-dependent

Illumination intensity comes.

According to a further embodiment of the invention, the

Measuring device on a light receiver having a plurality of pixels for receiving the measuring light, wherein first pixels in a first portion of the light receiver have a first Lichtsensitivität and second pixels in a second portion of the light receiver having a second Lichtsensitivität. The second light sensitivity is different from the first one

Light sensitivity. The unequal pixel sensitivity described may also help to ensure that in an image of the scene the difference between a brighter region and a darker region is not so great as to jeopardize reliable scene capture and / or scene evaluation by the computing device.

In some embodiments, light receivers are used in which the spatial distribution between first pixels and second pixels can be varied dynamically or adaptively. Such a variation may also be controlled by the data processing device and may depend on a result of a previous scene evaluation.

It should be noted that the term light sensitivity relates to the ability of the pixel in question to accumulate incident photons within a short exposure time. A different pixel sensitivity may e.g. by reducing the noise of individual pixels or zones of pixels. Since the noise is often correlated with the heat of the sensor, e.g. a higher sensitivity can be achieved by means of a heat pump (e.g., a Peltier element) for a portion of the light receiver. The more punctually this temperature change can be generated on the light receiver, the higher the energy efficiency of the sensor system can be. Thus, for example, in a particular embodiment

Imprint the temperature gradient across the light receiver so that the measuring light coming from a more distant subarea of the scene reaches a cooler zone of the light receiver.

According to a further embodiment of the invention, the

Measuring device further coupled to a coupled to the light receiver

A light receiver control device, wherein the light receiver control device and the light receiver are configured such that in a modified Operation of the sensor system at least two pixels of the plurality of pixels are combined to form a parent pixel.

Such aggregation of pixels, also referred to as "binning", has the effect of increasing the number of photons of the measurement light collected during a scene acquisition of one pixel, in proportion to the number of pixels, at the expense of spatial resolution pixels summed up to a parent pixel. Due to the resulting increased photon accumulation per (superordinate) pixel, the light sensitivity per pixel is significantly increased. This reduces

especially with a weak measuring light the so-called statistical

Photon noise, which improves the scene evaluation accuracy. A "binning" is therefore particularly advantageous for a weak measuring light when a high spatial resolution is not required.

Typically, at least some of the plurality of pixels are grouped together so that a certain number of pixels are combined into a higher-level pixel. The certain number may be, for example, (preferably) two, three, (preferably) four, six, (preferably) eight, or (preferably) nine. Of course, an even stronger summary of pixels is possible.

It should be noted that binning can also be carried out locally in only at least a partial area of the active areas of the light receiver via the surface of the light receiver. Although this leads to an inhomogeneous spatial resolution, which is not necessarily desired. However, the disadvantage of such an inhomogeneous spatial resolution is in many cases due to the increased photon accumulation (per pixel).

overcompensated. A local "binning" can be done at least in some known light receivers without special electronic or apparative elements simply by a corresponding control of the light receiver, which Control determines the "binning" and thus the operating mode of the sensor system.

In preferred embodiments, a local "binning" is performed in that, measured by the measuring device and / or by the

Data processing device learns exactly those areas of the

Light receiver, which have received in at least one previous scene detection too little light energy, by a suitable control of the light receiver by the light receiver control device in subsequent scene captures in a suitable manner to higher-level pixels

be summarized. Such dynamically controlled or controlled "binning" can during a normal operation of the sensor system (learned) and / or during the configuration of the sensor system, for example in

Framework of a (first) installation, a maintenance, a cyclic or

automatic re-configuration etc. are performed.

At this point, it should be noted that with a non-square number of individual pixels combined into a superordinate pixel, the spatial resolution of the light receiver along different directions is different in each case if the individual pixels have a square shape. This can be exploited in some cases in an advantageous manner. Such an application is present, for example, when movement of an object of the scene along a previously known spatial direction is to be detected with increased accuracy. In such a case, the number of pixels arranged along a line perpendicular to this known spatial direction (as depicted on the light receiver) may be larger than the number of pixels arranged along a line perpendicular thereto. Then the spatial resolution along the

Movement direction greater than the spatial resolution perpendicular to the

Movement direction and the motion profile of such a linearly moving object can also with a comparatively weak measuring light with a particularly high accuracy can be determined.

According to a further embodiment of the invention, the

Measuring means on (a) one or the light receiver for receiving the measuring light and (b) a measuring unit connected downstream of the light receiver, which is configured to measure the light running time based on (i) a measurement of the time span between a transmission of a pulse of the

Illumination light and the reception of the measurement light associated with the pulse and / or (ii) a measurement of a phase shift between a temporal modulation of the illumination light and an associated temporal modulation of the received measurement light. This has the advantage that the described sensor system can be realized in a suitable manner, depending on the particular application, by utilizing a respectively suitable TOF measuring principle. In some embodiments, the sensor system is configured in such a way that it is possible to switch between the two different measurement principles "pulse mode" and "phase measurement" flexibly or, if necessary, between the two different measurement principles.

Regardless of the measuring principle used, the light receiver has a light-sensitive surface which, as described above, is subdivided into a multiplicity of pixels. With or on each pixel those photons of the measuring light are accumulated, which from a certain

Solid angle range or the associated sub-area of the scene come. The measuring unit is used to determine the runtime of the associated light beams of the illumination light and the measuring light for each pixel.

According to a further embodiment of the invention, the

Sensor system further comprises a holder, which at least with the

The measuring device is mechanically coupled, wherein the holder is designed such that the sensor system can be attached to a stationary in relation to the scene to be detected holding structure. To put it clearly, the holder ensures that the described sensor system can be a stationary system which has a certain spatially fixed detection range and therefore always monitors the same scene, which of course can have a different scene characteristic at different times. By comparing different temporally spaced detections of the dependent of the orientation of the sensor system scene spatially stationary objects that are present in the scene can be detected in an image analysis and hidden in a further image analysis with respect to movement profiles. As a result, computing power can be saved and the energy efficiency of the described sensor system can be improved.

The stationary support structure may be directly or indirectly mechanically coupled to a device for controlling a coverage characteristic of an opening to be passed through the object by at least one closure body.

Preferably, this device in addition to a suitable guide or

Storage of the closing body an actuator for moving the

Closing on, in particular for moving the closing body between a closed position and an open position (and vice versa).

In the area of building security, the opening can be an entrance,

for example, for a person or a vehicle. The closure body may be a door, for example a front door or a garage door. The stationary one

Holding structure may be, for example, the stationary frame structure of an entrance, such as the frame of a door.

According to a further embodiment of the invention is the

Data processing device further configured such that a

Covering characteristic of an opening to be passed by an object by at least one closing body is controllable. This allows the opening, which is, for example, an entrance (or an exit) of a building, are automatically monitored in an energetically favorable manner, and by a suitable actuation of an actuator, the closing body can be automatically moved between an open position and a closed position. For this purpose, the data processing device of the described

Sensor system coupled with the control of a known control system for a closure body.

According to a further aspect of the invention, a method for the

Three-dimensional capture a scene described. The described

A method comprises (a) illuminating the scene with an illuminating light emitted by a lighting device along a

Illuminating beam path is emitted; (b) receiving, by means of a measuring device, measuring light along a measuring light beam path, wherein the measuring light is at least partially backscattered by at least one object in the scene illumination light; (c) measuring by means of

Measuring device of distances between the sensor system and the at least one object based on a light transit time of the illumination light and the measuring light; and (d) determining the three-dimensional characteristic of the scene based on the measured distances by means of a data processing device downstream of the measuring device. According to the invention, a free-form optical system in the illumination beam path and / or in the

Measuring light beam path arranged, wherein the free-form optical system is configured such that (i) in an arrangement in the illumination beam path, a

Illumination light intensity of the illumination light depends on the solid angle of the illumination beam path and (ii) in an arrangement in the

Measuring light beam path a measuring light intensity of the measuring light of the

Solid angle of the measuring light beam path depends, so that a distance-based loss of intensity of the illumination light and the measuring light is at least partially compensated. The described method is also based on the knowledge that a suitably designed or configured free-form optical system of the

Scene geometry and spatial angle dependent influences on the

Intensity distribution of the received measuring light at least partially

can be compensated.

In the beam path of the illumination light, the free-form optics can provide a suitable space-angle-dependent intensity distribution of the illumination light so that the measurement light from each subarea of the scene strikes a light receiver of the measuring device with as homogeneous a distribution of intensity as possible. In the beam path of the measuring light, the

Free-form optics for a suitable spatial angle-dependent collection of

Measuring light intensity ensure, so that (also) the measuring light with a homogeneous distribution of intensity as possible hits the light receiver.

According to an embodiment of the invention, the method further comprises (a) detecting an object in the scene; (b) comparing the detected object with at least one stored in a database

Comparison object; and, (c) if the object agrees with a comparison object within predetermined permissible deviations, identifying the object as an object authorized for a particular action.

The approved action may, for example, be an authorized passage through an opening in a building, which opening is closed by a closure body prior to identification as an approved object and is opened only after successful identification by a corresponding movement of the closure body. The objects to be identified may preferably be persons and / or vehicles. Successful identification may be to control or activate a closure mechanism for a closure body prior to opening a building. According to a further aspect of the invention, a use of a sensor system described above for controlling a

Covering characteristic of an opening to be passed by an object by at least one closing body.

The described use is based on the finding that a detection and evaluation of an optical scene made in an energy-efficient manner can be used advantageously in passages which can be closed by a closing body. This is especially true for passages which a closure or a

Covering characteristic, which is controlled by the described sensor system or at least co-controlled. Because such sensor systems

Usually powered by the closure systems for the closure body, it is particularly important to operate with a comparatively small amount of energy and still to reliable TOF

Scene evaluations to come.

By the inventive use of the above-described

Sensor system can be monitored in an energetically efficient manner and larger distances, which naturally leads to an earlier detection of a

Opening request of the closure body leads. This can be of great advantage, especially in the case of fast moving objects. Furthermore, the scene can be detected in an energy-efficient manner with a wider detection angle, which can lead, for example, to an early detection of transverse traffic moving transversely to the opening and thus to a more reliable detection of objects in the security area of the closure system. This can be suppressed in cross traffic unnecessary opening request.

According to one embodiment of the invention, the opening is an entrance or an exit, in particular an emergency exit in a building. By recognizing an existing, but possibly not moving object in a passage area can monitor an input or output, in particular a blocked emergency exit detected, and the corresponding information to an affiliated system, for example to a

Monitoring system to be transmitted.

According to a further embodiment of the invention, the object is a person or a vehicle. In this case, the building may in particular be a house or a garage.

According to a further aspect of the invention, there is described a use of a sensor system described above for detecting and / or controlling traffic flows of objects moving through a scene of the sensor system, the scene being represented by a spatial

Detection range of the sensor system is determined.

This use is also based on the finding that an energy-efficient sensor system is important in traffic detection and / or traffic flow control, since this sensor system is typically constantly in operation and, moreover, a very high number of such sensor systems are typically used, in particular for larger traffic flows.

The relevant objects for the traffic stream in question can

For example, people, vehicles, products such. B. packages, suitcases, etc. be. Since a plurality or even a multiplicity of 3D sensors are usually used for such applications, energy savings have a particularly positive effect here.

It should be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments of the invention with device claims and other embodiments of the invention with method claims or with Usage claims described. However, it will be readily apparent to those skilled in the art upon reading this application that, unless explicitly stated otherwise, in addition to a combination of features belonging to a type of subject matter, any combination of features that may result in different types of features is also possible

Subject matters belong.

Before describing exemplary embodiments of the invention with reference to the drawings, some technical considerations related to the invention will be described here.

TOF-based sensor systems can generally be used both in terms of the

Lighting light as well as in relation to the measuring light in two fundamentally different classes are divided, which can be combined with each other.

Bl: The first alternative (Bl) for the lighting is characterized by the fact that the scene by means of a single illumination light beam high

Focusing and low divergence (ie high collimation) is scanned sequentially. For each position of the illumination light beam in the scene, a measurement of the duration of the illumination light and the measurement light

performed. The scanning can be realized using movable optical components, in particular mirrors. Alternatively or in

Combination can be used for sequential scanning of the scene with the

Illuminating light beam can be used a solid body, which manages without mechanically moving parts and has integrated photonic structures or circuits. With a suitable control of these structures, the illumination light beam is then directed to the desired location of the scene. Such a solid is known for example from US 2015/293224 Al. B2: The second alternative (B2) for lighting is characterized by the fact that the entire scene is illuminated (all at once and flatly). If necessary, the intensity of the illumination light in selected subregions of the scene can be (selectively) increased in order to enable improved 3D object detection at these locations. Such spatially uneven distribution of the intensity of the illumination light can be done without moving optical

Components for example by means of a so-called. Diffractive optical element (DOE) take place.

M l: A first alternative (M l) for the measurement is based on pulsed

Illumination light beams. The "travel time" of a light pulse on the receiver side for each pixel within a time window is determined and derived from the distance.

M2: The second alternative (M2) for the measurement is based on a temporal, preferably sinusoidal, modulation of the illumination light with a

predetermined frequency, with appropriate values for this frequency depending on the expected transit time or the maximum detection distance. On the side of the light receiver, the phase difference is measured for each pixel and derived therefrom the distance information.

Both measuring principles Ml and M2 are based on an integration of the number of photons or the photoelectrons generated in the light receiver, which arrive on each pixel to be measured. In this context, it is obvious that an ever-present light or photon noise depends on the number of photons accumulated in a pixel. Therefore, the higher the number of accumulated photons, the more accurate the distance information obtained from the TOF measurement becomes. Further advantages and features of the present invention will become apparent from the following exemplary description of presently preferred embodiments.

Short description of the drawing

Figure 1 shows the use of a sensor system for controlling a

Covering characteristic of an opening by means of closing bodies designed as sliding doors.

FIGS. 2a and 2b illustrate a deformation of a free-form optical system designed as an elastic optical element.

FIG. 3 shows the use of a sensor system for detecting a

Traffic flow of transported on a conveyor belt objects.

Figures 4a and 4b illustrate a collection of single pixels of a light receiver.

FIGS. 5a to 5c show different beam cross sections of a

Lighting light to adjust the lighting to the shape of the

capturing scene.

Detailed description

It should be noted that the following

Embodiments only a limited selection of possible

Represent variants of the invention. In particular, it is possible to suitably combine the features of individual embodiments with one another, so that those skilled in the art are explicitly shown here Embodiments a variety of different embodiments are to be regarded as obviously disclosed.

Before the figures are described in detail in this section, some aspects of a number of embodiments are explained below.

(1) Considering the importance of energy efficient operation in many applications of 3D sensor systems, it can be applied to the

Light receiver to optimize the incident optical energy of the measuring light by illuminating the scene differently (intensively) depending on the characteristics of the scene.

(2) However, for most applications of TOF sensor systems, the scene to be captured is cuboidal or cubic in nature. However, known TOF sensors typically have a detection range that has at least approximately the same range for all detected solid angles. The

(Outside) boundary of the detection area is therefore part of a spherical shell (where all points have the same distance to the TOF sensor system). The TOF sensor system described in this document is now able to at least partially abandon or compensate for this "spherical shell boundary" by selectively increasing or reducing the illumination intensity in selected subregions of the scene. By reducing the illumination intensity in the center of the scene realized by a free-form lens and increasing the illumination intensity towards the edge of the scene and in particular to the corners, this can be reduced with the cos' law described above and the negative effect on the

Lighting used energy can be optimally utilized.

(3) In addition, certain subregions of the scene which are dependent on the spatial-geometric arrangement of the sensor system and the scene to be detected can be "exposed" in a generalized manner with an optimum intensity of illuminating light. For example, a TOF sensor system is typically mounted above the average height of the objects to be observed (people, products, vehicles, etc.) to make it undesirable for a plurality of objects

Object shading is less problematic. However, this means that in most cases the upper part of the scene contains larger measurement distances than the lower part. This knowledge about the mounting location of the sensor system with respect to the sensing scene can be taken into account for further optimizing the operation of the described sensor system, in particular with regard to the energy efficiency, by correspondingly less illuminating the upper area of the scene through the use of the free-form optics described. is "exposed".

(4) In a light source which consists of several individual illumination intensity supplying elements, which represent the entire illumination device (for example an array of laser or light-emitting diodes), a

spatial angle-dependent intensity distribution of illumination light by a variation of the brightness of individual elements over other elements are supported. This variation can be constructive in design (eg, laser or light emitting diodes with different intensity) as well as the type of control (via variable current per laser or light emitting diode by a suitable electronics, for example by a measuring at the (first) Installation set). Furthermore, a dynamic adjustment of the individual laser or LEDs during operation is possible. In this case, simply those laser or light emitting diodes, which are assigned to areas of the scene that provide little measuring light, are correspondingly more energized. This is particularly suitable for the o.g. Lighting principle B2 in combination with the o. Measuring principle M l or M2.

(5) For lighting devices which sequentially scan (scan) the entire scene with an illuminating light beam, the respective instantaneous solid angle of the illuminating light beam is known at all times. By Varying the intensity of this illumination light beam as a function of the respective solid angle can thus the illumination intensity depending on the

Scene geometry (and with optional dynamic "result control" also depending on the amount of reflection or scattered light) for each solid angle which are already controlled by the illumination device light intensity controlled. Thus, a static scene can be measured, with the appropriate intensity for each solid angle is taught to illuminating light.

(6) The above and optional dynamic adjustment of the

Intensity of illumination light by the illumination device can be adaptive both in real time and from "frame to frame". In this case, for the parts of the scene from which too little measuring light is received, immediately the intensity of the corresponding part (illumination light) is increased. This means that, depending on the result values of a last scene capture for the next scene capture, those areas with "overexposure"

illuminated and those with "underexposure" brightened. This approach is particularly well suited for the lighting principle Bl in combination with the measuring principle M l or M2.

(7) An embodiment of the invention achieves energy saving by means of dynamic lighting energy optimization, wherein

Illumination energies of different wavelengths or frequencies are used. Depending on the color of the object, for example, the wavelengths that contribute to the most intense reflections or

Light scattering lead to be emitted with a lower intensity. In contrast, other wavelengths or other wavelength regions with less reflection or scattering may be present in the wavelength spectrum with a higher intensity. Thus, for example, a red object can be illuminated primarily with a red light component and the green and blue light components are reduced (for the relevant solid angle), preferably to at least approximately an intensity of zero. The same principle can also be applied in the relationship between visible light and infrared (IR) light.

The information obtained in the context of a variable frequency or wavelength variable illumination with respect to reflection and scattering properties with associated distance and solid angle can be used in a subsequent

Scene analysis of moving objects can be of great advantage, because it allows easier objects to be detected and tracked, since the

Functional cohesion of spatial points on the reflection or scattering properties can be interpreted in addition grouping.

(8) The sensor system described in this document may be used, for example, in passageways, especially in passageways having a shutter characteristic that is automatically controlled (e.g., by means of doors, gates, barriers, traffic lights, etc.). Since the sensors for a

Passage control is usually powered by the existing closure systems with energy, it is with a given amount of energy as much sensory effect to achieve. The sensor system described in this document allows (i) a comparison with known sensor systems

Data acquisition for larger distances (earlier detection of a

Opening request, especially for faster moving objects), (ii) wider detection angles (e.g., early detection and tracking of

Cross-traffic) and / or (iii) a more reliable detection of objects in a security area of the closure system.

(9) In another embodiment, which is especially for the

Lighting principle B2 is suitable, an (additional) spatial variation of the illumination light is achieved by DOE's, which also as part of the

described freeform optics can be viewed. At DOE's in the

Related to laser systems can be the maximum illumination energy be exploited because those portions of the illumination light beams, which are to hit the scene with less intensity, are not simply hidden by a mask but their intensity is redistributed by the DOE to other areas of the scene. Thus, the energy of the illumination light can be almost completely utilized. The same effect of the concentration of illumination light in a part of the scene (albeit with a lower one)

Efficiency) can also be achieved through mechanisms such as those for

Pattern projections are required, which are required for 3D sensors, which are based on the known principle of structured illumination or the so-called. Strip projection.

(10) In a further embodiment, the scene to be detected is first illuminated conventionally, in particular according to the illumination principle B2.

After determining the distance information of the whole scene in the following scene captures the "overexposed regions" with a

illuminated lower illumination intensity. Particularly in sensor systems which are intended to detect temporal changes of objects in the scene, the sensor system can be operated at the lower limit of the measurability as long as the scene is (still) static. However, if a change in the scene is (grossly) detected or at least suspected, then an increase in the illumination intensity can be reacted immediately, so that the scene or the scene changes can then be detected and evaluated with high accuracy. This mechanism can be used both for IR sensor systems and for sensor systems with

work visible light.

In the following detailed description referring to the figures, features of different embodiments, which are the same or at least functionally identical to the corresponding features or components of another embodiment, are provided with the same reference numerals or with reference numerals, which in the last two digits are identical. In order to avoid unnecessary repetitions, features or components already explained on the basis of a previously described embodiment will not be explained in detail later.

1 shows the use of a sensor system 100 to control a coverage characteristic of an opening 184 depending on the characteristics of a scene 190 monitored by the sensor system 100. According to the embodiment shown here, the opening 184 is an entrance for persons into a building or garage entrance for motor vehicles. The corresponding input structure is provided with the reference numeral 180. An object 195 located in the scene 190 is intended to be such a person or a person

Symbolize motor vehicle.

The input structure 180 comprises a stationary support structure 182, which constitutes a frame and a guide for two closing bodies 186 designed as sliding doors. The sliding doors 186 can each be represented by means of a motor 187 along the two thick double arrows

Move instructions are moved. The actuation of the motors 187 takes place, as explained below, by means of the sensor system 100 described in this document.

The sensor system 100 comprises (a) a TOF detection system 110, (b) a data processing device 150 and (c) a database 160. The TOF detection system 110 in turn has (a) a lighting device 130 for emitting illumination light 131 and (a2 ) a measuring device 115, which is responsible for the detection and measurement of measuring light 196. In accordance with the principle of a 3D TOF detection, the measurement light 196 is at least partially backscattered by the object 195 illumination light 131. In the architecture of the TOF detection system 110 shown in Figure 1, the measuring device 115 (a2-i) a light receiver 120 and (a2 -ii) a measuring unit 125, which is connected downstream of the light receiver 120 and which is adapted to measure a light transit time between the

Lighting device 130 emitted illumination light 131 and received by the light receiver 120 measuring light 196. Further, the measuring device 115 is associated with a light receiver controller 122, which controls the operation of the light receiver 120 with respect to different operating modes.

According to the exemplary embodiment illustrated here, the TOF detection system 110 has (a3) an illumination light control device 135 for controlling the operation of the illumination device 130 and (a4) a free-form optical control device 145 for actuating actuators 131 , 143, by means of which the optical imaging properties of free-form optics 140 and 142 can be selectively adjusted.

As can be seen from FIG. 1, according to the exemplary embodiment illustrated here, the sensor system 100 has two free-form optics 140 which are each assigned to one of two light sources or illumination units of the illumination device 130 and are located in the corresponding beam path of the respective illumination light 131. According to the exemplary embodiment shown here, the two free-form optics 140 are not static but can be deformed by means of a respective schematically illustrated actuator 141. This changes the imaging properties of the

Free-form optics 140 and there is a relation to the space angle-dependent intensity distribution of the illumination light, as it of the respective

Lighting unit of the lighting device 130 is emitted,

modified intensity distribution of illumination light 131 as it hits the scene 190 and illuminates or illuminates. Through a targeted

Deformation of the elastic free-form optics 140, which is caused by the free-form optical control device 145 and performed by the respective actuators 141, the spatial characteristics of the illumination light 131, as it encounters the scene 190, may be adjusted in view of a desired space angle-dependent distribution of the intensity of the illumination light 131 in the scene 190. The desired spatial angle-dependent distribution of the illumination light intensity is typically the one

Intensity distribution, in which the detection of the scene by the light receiver 120 and the signal processing by the downstream measuring unit 125 and the data processing device 150 can be as reliable and / or accurate as possible.

With respect to the further free-form optics 142, which is arranged in the beam path of the measuring light 196, the same principles of operation apply as in the two free-form optics 140. The optical properties with respect to a modification of the intensity distribution of the measuring light 196 are provided by an actuator 143 of the Free-form optical control device 145 controlled.

By selectively deforming the further free-form optics 142, the collection of the intensity of the measurement light 196 depending on the spatial angle is modified. This preferably takes place in such a way that the measurement light 196, which is inhomogeneously distributed with respect to its intensity, is "homogenized" (as shown in FIG. 1 from below) on the freeform optical system 140, so that the measurement light has a distribution of intensity which is as homogeneous as possible Light receiver 120 hits.

It should be noted that the solid angle dependence of the illumination light and the measurement light described here can also be realized by only one type of free-form optics. For example, the whole

"Raumwinkelmodifikation" done only with the freeform optics 140 or only with the freeform optics 142. It is further noted that the free-form optics 140 and 142 can be realized instead of elastic refractive optical elements with other optical elements, for example by means of diffractive and / or reflective optical elements. It is further pointed out that the illumination light and the measuring light can be guided at least partially through the same free-form optics.

In the TOF detection system 110, in particular all optical

Components of the sensor system 100 included. This also applies to the

Free-form optics 140 and 142 and the actuators 141 and 143, which are mounted on a housing of the TOF detection system 110 via support structures, not shown in Figure 1 for reasons of clarity. By means of a holder 111, at least the TOF detection system 110 is attached to the stationary support structure 182 in a mechanically stable and spatially fixed manner. Preferably, the entire sensor system 100 (in contrast to the representation of FIG. 1) is constructed as a module which, in addition to the TOF detection system 110, also has the data processing device 150 and the database 160 within a compact design.

According to the embodiment illustrated here, the light receiver controller 122 may cause the light receiver 120 to operate in a particular one of at least two different modes of operation. In the various operating modes, for example, caused by a prior scene evaluation by means of the data processing device 150, individual pixels of the light receiver 120 may have a different sensitivity or a different efficiency with respect to an accumulation of photons. Also below with reference to Figures 4a and 4b

described scene-dependent summarization of pixels of the

Light receiver 120 may be initiated by the light receiver controller 122.

An external control signal 152a transferred to the data processing device 150 via an interface 152 can be used to make the operation of the data processing device 150 at least partially dependent on external information. In particular, via the control signal 152a an "a priori knowledge" about an object 195 for an improved evaluation of the detected scene 190 and in particular for an improved object recognition are transmitted.

According to the embodiment shown here, the illuminated

Lighting device 130, which may be, for example, an array of individually controllable laser or light-emitting diodes, the scene 190 and thus also located in the scene 190 object 195 with a pulsed and thus temporally modulated illumination light 131. The illumination light control device 135 is configured, the Lighting device 130 to control such that a characteristic of the illumination light 131, which describes the dependence of the illumination intensity of the illumination light 131 of the solid angle (in which the illumination light 131 strikes the free-form optical system 140), during an operation of the sensor system 100 dynamically

is changeable.

The space angle-dependent intensity distribution of the illumination light 131 is not shown in FIG. 1 for reasons of clarity. In order to achieve a uniform distribution of the intensity of the backscattered measuring light 196 (as it encounters the light receiver), those

Solid angle of the scene 190, which are associated with a larger measuring distance, illuminated more than other solid angles, which are associated with a smaller measuring distance.

The illumination light controller 135 may be the characteristic of the

Illumination light 131 may also modify other (non-spatial) properties of illumination light 131, such as its (a) wavelength, (b) spectral intensity distribution, (c) polarization direction, and (d)

Intensity distribution for different polarization directions. These further properties can be selected such that they contribute to the most reliable and accurate object recognition possible. Again, a "a Priori knowledge "about optical properties of the object 195 are considered.

It should be noted that the illumination device 130 in addition to the illumination units shown in Figure 1 can also have other lighting units that illuminate the scene 190 from a different angle. Likewise, the two lighting units can also be arranged even outside the housing of the TOF detection system 110 and thus be further spaced from the light receiver 120. This does not change the principles of the TOF measurement.

According to the exemplary embodiment illustrated here, based on this 3D data, the acquired optical scene 190 is processed with the data processing device 150 using suitable methods of image evaluation

evaluated. For this purpose, a plurality of images, which of the scene 190 under different lighting conditions or different

Lighting characteristics were recorded, used together.

According to the exemplary embodiment illustrated here, the sensor system 100 is able to perform an object recognition. This is what the

Data processing device 150 to a stored in the database 160 record of reference objects corresponding to selected objects that are authorized to pass through the opening 184. This means that with a suitable approach of the object 195 to the input 184, the sliding doors 186 are opened only when the detected object 195 at least approximately coincides with one of the stored reference objects. This clearly indicates that in the use described here of the

Sensor system 100, the coverage characteristic of the object 184 also depends on the result of an object-based access control. FIGS. 2 a and 2 b illustrate a deformation of a free-form optical system designed as an elastic, optically refractive element. FIG. 2a shows the optical element 240a in a first operating state, which is characterized by a first spatial structure. As shown here

Embodiment, the first operating state characterized by the fact that apart from any existing internal voltage from the outside (by an actuator) no force or no pressure on the freeform optics 240a is exercised. The corresponding (not warped) coordinate system is shown in Figure 2a in the optical element 240a.

FIG. 2b shows the optical element, which is now designated by the reference numeral 240b, in a second (strained) operating state, which is characterized by a second spatial structure that is different from the first spatial structure. It is obvious that this also changes the light shaping properties, in particular with regard to a modification of the intensity distribution of illuminating light or measuring light passing through.

The second operating state is set by exerting a force or a pressure on the optical element 240b from the outside (from an actuator, not shown). The corresponding (warped) coordinate system of the optical element is illustrated in FIG. 2b. The dimensions or lengths of the freeform optical system 240b that are changed in relation to the first state along the coordinate axes are illustrated by coordinate axes of different lengths. FIG. 3 shows a further use or a further use of the invention

Sensor system 100. For reasons of clarity, only the TOF detection system 110 of the sensor system 100 is shown in FIG.

According to the embodiment illustrated here, the TOF detection system 110 detects a traffic flow of (various) objects 395a, 395b, 395c, 395d, and 395e that are on a conveyor belt 398 and move through a scene 390 along the direction of movement represented by an arrow. Reliable knowledge of the number and / or type of objects 395a to 395e may be used in the field of logistics for traffic flow control. Only an example of such

Controlling a traffic flow is the control of luggage transport in an airport. In this case, labels on the respective objects 395a - 395e can also determine the type of the respective object. It should be noted, however, that use in an airport is merely one example of a variety of other uses in the field

Traffic control is.

FIGS. 4a and 4b illustrate a collection of single pixels of a light receiver 420a or 420b formed as a semiconductor or CCD chip. The light receiver 420a has a plurality of light-sensitive or

Photon-collecting pixels 422a. As shown here

Embodiment, the pixels 422 a of the full spatial resolution of the light receiver 420 a are assigned, which resolution is predetermined by the semiconductor architecture of the chip 420 a.

In the light receiver 420b, four of the light-sensitive pixels (for a full resolution) are respectively added to a higher-level pixel 422b (for an increased resolution)

Photon accumulation per pixel at the expense of a reduced spatial

Resolution). Illustratively, a pixel 422b collects 4 times the amount of light compared to a single pixel 422a.

Such "binning" of pixels reduces the required (minimum) intensity of the detected measurement light needed to evaluate the corresponding image area of the scene. Since the intensity of the measurement light depends directly on the intensity of the illumination light, binning reduces the intensity of the illumination light and thus reduces the energy consumption of the sensor system.

The described "binning" can also be realized dynamically by a corresponding activation of one and the same light receiver 420a or 420b. In this case, the light receiver is operated either in a first operating mode (with full resolution) or in a second operating mode (with photon-collecting combined pixels). Switching between different modes of operation may be controlled by external control signals. Alternatively or in combination, such switching may also depend on the result of a scene evaluation, so that "binning"

Operating mode is regulated for a next scene capture.

It should be noted that more than two different

Operating modes, each with a different strong summary of pixels can be used. Furthermore, it is possible to combine a different number of individual pixels into a higher-order pixel in different partial areas of the light receiver. Then, individual portions of the scene with a higher spatial resolution (and less photon accumulation) and other portions of the scene with a lower spatial resolution (and higher

Photon accumulation). The described local and

Different levels of pixel aggregation can be carried out dynamically or adaptively in exactly those subregions in which a particular object is currently located. FIGS. 5a to 5c show different beam cross sections of an illumination light for adapting the illumination to the shape of the illumination

capturing scene. A first illumination light 531a illustrated in FIG. 5a has a substantially circular beam cross section and is preferably suitable for "round scenes". However, for most applications which do not detect (and evaluate) a "round scene", a beam cross section deviating from a circular shape is suitable. FIG. 5b shows an illumination light 531b with an elliptical beam cross section. FIG. 5c shows

Illumination light 531c with a rectangular beam cross section. As

already mentioned above, the beam cross section through a

corresponding shape of the free-form optics and optionally additionally adapted by a suitable operation of the lighting device. Diffractive optical elements (DOEs) can also be used, which optionally even allow a dynamic and / or scene-dependent shaping of the beam cross-section.

It is noted that the term "comprising" does not exclude other elements and that the "on" does not exclude a plurality. Also, elements described in connection with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

Reference sign:

100 sensor system

110 TOF detection system

111 bracket

115 measuring device

120 light receiver

122 light receiver control device

125 measuring unit

130 lighting device

131 Illumination light / illumination beam path

135 illumination light controller

140 freeform optics

141 actuator

142 further freeform optics

143 more actuator

145 freeform optics controller

150 data processing device

152 interface

152a external control signal

160 database

180 entrance structure

182 stationary holding structure

184 opening / entrance

186 closing body / sliding door

187 engine

190 scene

195 object

196 measuring light / measuring light beam path 240a freeform optic / optically refractive element in 1st state

240b freeform optics / optically refractive element in the 2nd state

390 scene

395a-e objects

398 conveyor belt

420a / b light receiver / sensor chip

422a pixels

422b parent pixel / pooled pixel

531a Illuminating light with round cross section

531b Illumination light with elliptical cross section

531c Illuminating light with rectangular cross section

Claims

Patent claims

A sensor system (100) for three-dimensionally capturing a scene (190) comprising the sensor system (100)

an illumination device (130) for illuminating the scene (190) with an illumination light (131) along an illumination beam path (131); a measuring device (115)

for receiving measurement light (196) along a measurement light beam path (196), wherein the measurement light (196) is at least partially backscattered by at least one object (195) in the scene (190) illumination light (131) and for measuring distances between the sensor system ( 100) and the at least one object (195) based on a light transit time of the

Illumination light (131) and the measurement light (196);

a data processing device (150) connected downstream of the measuring device (115) for determining the three-dimensional characteristic of the scene (190) based on the measured distances; and

a free-form optical system (140, 142) which is arranged in the illumination beam path (131) and / or in the measurement light beam path (196), wherein the free-form optical system (140, 142) is configured such that

(i) in an arrangement in the illumination beam path (131) a

Illuminance light intensity of the illumination light (130) depends on the solid angle of the illumination beam path (131) and

(ii) when mounted in the measuring light path (196)

Measuring light intensity of the measuring light (196) from the solid angle of the

Measuring light beam path (196) depends,

so that a distance-based intensity loss of the illumination light (131) and the measurement light (196) is at least partially compensated.

2. Sensor system (100) according to the preceding claim, further comprising a further freeform optics (142), wherein the free-form optical system (140) is arranged in the illumination beam path (131) and

the further free-form optical system (142) is arranged in the measuring light beam path (196).

3. sensor system (100) according to one of the preceding claims, wherein the freeform optics (140, 142) comprises at least one reflective optical element, at least one refractive optical element and / or at least one diffractive optical element.

4. Sensor system (100) according to one of the preceding claims, wherein the freeform optics (140, 142) at least one spatially and / or structurally variable optical element (240a, 240b), wherein a change of the optical element (240a, 240b) to a Change in the

Solid angle dependence of the illumination light intensity and / or the

Measuring light intensity leads.

5. sensor system (100) according to one of the preceding claims, wherein the freeform optics (140, 142) and / or the illumination device (130) is configured to provide the illumination light (131) and / or the measurement light (196) with a space angle-dependent intensity distribution, which at least approximately compensates for an edge light drop, in particular one

natural edge light fall according to the one brightness in an image

Imaging an evenly bright subject through a lens by a factor of cos' relative to the brightness in the center of the image decreases.

6. The sensor system (100) according to one of the preceding claims, further comprising

an illumination light control device (135) coupled to the illumination device (130) and configured to control the illumination device (130) in such a way that a characteristic of the illumination light (131), which describes the dependence of the illumination intensity of the illumination light (131) on the solid angle, is dynamically changeable during an operation of the sensor system (100).

7. Sensor system (100) according to the preceding claim, wherein

the data processing device (150) is coupled to the illumination light control device (135) and is configured to evaluate the determined three-dimensional characteristic of the scene (190) and to change the characteristic of the illumination light (131) based on a result of this evaluation.

8. Sensor system (100) according to the preceding claim, wherein

the result of the evaluation depends on the optical scattering behavior of at least one object (195) contained in the scene (190).

9. sensor system (100) according to one of the preceding claims, wherein the illumination device (130) comprises at least one of the group consisting of

(A) designed as a laser illumination light source for spatial

Scanning the scene with a transmitted laser beam illumination light;

(B) an at least approximately punctiform illumination light source;

(D) a flat illumination light source, in particular with a light intensity not homogeneous over the surface.

10. sensor system (100) according to one of the preceding claims, wherein the freeform optics (140, 142) and / or the illumination device (130)

is or are configured to provide the illumination light (131) with a beam cross-section (531b, 531c) deviating from a circular shape.

11. Sensor system (100) according to one of the preceding claims, wherein the measuring device (115)

a light receiver (120, 420a) having a plurality of pixels (422a) for receiving the measurement light (196), wherein first pixels in a first

Part of the light receiver have a first Lichtsensitivität and second pixels in a second portion of the light receiver, a second

Have light sensitivity, wherein the second Lichtsensitivität is different from the first Lichtsensitivität.

12. Sensor system (100) according to the preceding claim, wherein

the measuring device (115) further comprises

a light receiver controller (122) coupled to the light receiver (120), wherein the light receiver controller (122) and the light receiver (120) are configured such that in a modified operation of the sensor system (100), at least two pixels of the plurality of pixels (422a) are merged into a parent pixel (422b).

13. Sensor system (100) according to one of the preceding claims, wherein the measuring device (115)

or, if referred to in any one of the preceding claims, the light receiver (120) for receiving the measurement light (196) and a measurement unit (125) connected downstream of the light receiver (120) configured to measure the light transit time based on

(a) measuring the time between sending out a pulse of the illumination light (131) and receiving the pulse associated with it

Measuring light (196) and / or (B) a measurement of a phase shift between a temporal modulation of the illumination light (131) and an associated temporal modulation of the received measurement light (196).

14. A sensor system (100) according to one of the preceding claims, further comprising

a holder (111) which is mechanically coupled at least to the measuring device (115), wherein the holder (111) is designed such that the sensor system (100) is fixed to a holding structure (182) stationary relative to the scene (190) to be detected ) is attachable.

15. The sensor system according to claim 1, wherein the data processing device is further configured in such a way that a coverage characteristic of an opening to be passed by an object can be controlled by at least one closure body.

16. A method of three-dimensionally capturing a scene (190), comprising the method

Illuminating the scene (190) with an illumination light (131), which is illuminated by a lighting device (130) along a

Illumination beam path (131) is emitted;

Receiving, by means of a measuring device (115), measuring light (131) along a measuring light beam path (131), wherein the measuring light (131) is at least partially backscattered by at least one object (195) in the scene (190) illumination light (131);

Measuring, by means of the measuring device (115), distances between the sensor system (100) and the at least one object (195) based on a light transit time of the illumination light (131) and the measurement light (196); and

Determining the three-dimensional characteristic of the scene (190) based on the measured distances by means of a data processing device (150) connected downstream of the measuring device (115); wherein a freeform optics (140, 142) in the illumination beam path (131) and / or in the measuring light beam path (196) is arranged, wherein the

Freeform optics (140, 142) is configured such that

(i) in an arrangement in the illumination beam path (131) a

Illuminance light intensity of the illumination light (131) depends on the solid angle of the illumination beam path and

(ii) when mounted in the measuring light path (196)

Measuring light beam path (196) depends, so that a distance-based

Intensity loss of the illumination light (131) and the measuring light (196) is at least partially compensated.

17. A method according to the preceding claim, further comprising

Detecting an object (195) in the scene (190);

Comparing the detected object (195) with at least one comparison object stored in a database (160); and,

if the object (195) agrees with a comparison object within predetermined permissible deviations, identifying the object (195) as an object (195) permitted for a particular action.

18. Use of a sensor system (100) according to one of the preceding claims 1 to 15 for controlling a coverage characteristic of an object (195) to be passed through opening (184) by at least one closure body (186).

19. Use according to the preceding claim, wherein

the opening (184) is an input or an output, in particular a

Emergency exit in a building.

Use according to one of the two preceding claims, wherein the object (195) is a person or a vehicle.

The use of a sensor system (100) according to one of the preceding claims 1 to 15 for detecting and / or controlling traffic flows of objects (395a - 395e) moving through a scene (190) of the sensor system (100), the Scene (190) by a spatial

Detection range of the sensor system (100) is determined.