DE102018113739A1 - Coaxial optical system of a friction-free scanning system for light detection and distance measurement, LIDAR, measurements - Google Patents

Abstract

A scanning system (100) includes a deflecting mirror (150) having a reflective surface (151) and an elastic suspension (902) of the deflecting mirror (150). An actuator (901) is arranged to actuate by elastic deformation of the elastic suspension (902) resonant motion of a mass filter system formed by the deflection mirror (150) and the elastic suspension (902). A laser (101) is arranged to emit primary light (111) along a transmission beam (121). A detector (102) is arranged to detect secondary light (112) along a receive beam (122), the transmit beam (131) and receive beam (122) being along an overlap portion (125) of the transmit beam (121) and the receive beam (122 ), wherein the overlap portion (125) comprises the reflective surface (151) of the deflecting mirror (150). A coaxial optical system can thereby be implemented. LIDAR applications are possible.

Description

TECHNICAL AREA

Various examples of the invention generally relate to light detection and distance measurement, LIDAR. In particular, various examples of the invention relate to a corresponding scanning system which uses frictionless movement of a deflection mirror and has a coaxial optical system.

BACKGROUND

Light detection and distance measurement (LIDAR, sometimes referred to as laser distance measurement or LADAR) makes it possible to provide 3D point clouds of a scene. Objects can be detected accurately. Distance measurement is possible. Pulsed or continuous wave laser light is transmitted along a transmit beam and detected after reflection on an object along a receive beam. This makes it possible to determine the distance of the object (Z-position).

LIDAR can be used in busy areas. Eye safety concerns must be met here. Therefore, the laser power must be limited to avoid damage to the human eye. Examples include the use of LIDAR for automotive application scenarios.

In order to determine the XY position (lateral position) of the object, the laser light can be deflected. There are several ways to distract laser light. Examples include non-mechanical beam deflection using an optical phase coherent array (see for example US20160161600A1 ) or Flash LIDAR (see for example US20170343653A1 ). Such techniques are often subject to certain limitations related to range; Typical ranges can range from 30 m to 100 m for laser performance that meets eye safety requirements.

A second option available to deflect laser light involves mechanically deflecting the beam. Here, a scanner includes a deflector, such as a mirror, which is used to deflect the laser light. Macroscopic approaches are known in which a bearing - for example a ball bearing - is used to move the mirror, see for example US20110216304A1 or EP2541273B1 , Such approaches to implementing bearings are often subject to resistance-related limitations. When the mirror is moved, friction on the bearing results in wear; this in turn limits the time between error events. Also, stock-based scanners are often bulky. In automotive application scenarios, such scanning units are sometimes mounted on the roof of the vehicle because it is difficult to integrate into the vehicle chassis. On the other hand, macroscopic approaches typically allow large mirrors to be used, which helps to increase the range. Typical ranges can be up to 250 m for laser performance that is eye safety compliant.

Another subset of mechanical beam deflections employs frictionless scanning using micromirrors and elastic suspensions that can elastically deform to move the mirror. See for example US20100296146A1 or US20150062677A1 , Sometimes, frictionless scanning is also called solid-state scanning.

SUMMARY

Therefore, there is a need for improved techniques of frictionless mechanical deflection of laser light for LIDAR. A need exists for techniques that overcome or mitigate at least some of the above limitations or disadvantages.

This object is achieved by the features of the independent claims. The features of the dependent claims define embodiments.

A scanning system includes a deflecting mirror with a reflective surface. The scanning system further comprises an elastic suspension of the deflection mirror. The scanning system further includes an actuator configured to actuate, by means of elastic deformation of the elastic suspension, resonant motion of a mass-spring system formed by the deflection mirror and the elastic suspension. The scanning system further includes a laser configured to emit primary light along a transmit beam. The scanning system further includes a detector configured to detect secondary light along a receive beam, wherein the transmit beam and the receive beam are aligned along an overlap portion. The overlapping portion includes the reflective surface of the deflecting mirror. A size of the reflecting surface of the deflecting mirror is in the range of 120 mm ² to 230 mm ² , optionally in the range of 180 mm ² to 220 mm ² . A divergence from at least one axis of the primary light along the overlap portion is in the range of 0.09 ° to 0.15 ° at the deflecting mirror.

A scanning system comprises a deflecting mirror with a reflecting surface and an elastic suspension of the deflecting mirror. The scanning system further includes an actuator configured to provide resonant motion of a mass-spring system by means of elastic deformation of the elastic suspension. The mass-spring system is formed by the deflection mirror and the elastic suspension. The scanning system further includes a laser configured to emit primary light along a transmit beam. The scanning system further includes a detector configured to detect secondary light along a receive beam, wherein the transmit beam and the receive beam are aligned along an overlap portion, the overlap portion comprising the reflective surface of the deflecting mirror. The primary light has a fast axis and a slow axis, with the fast axis having a greater divergence than the slow axis. A field width of the slow axis of the primary light along the slow axis is not less than 90% of a corresponding width of the deflection mirror perpendicular to an optical axis of the transmission beam.

A scanning system comprises a deflecting mirror with a reflecting surface and an elastic suspension of the deflecting mirror. The scanning system further includes an actuator configured to actuate, by means of elastic deformation of the elastic suspension, resonant motion of a mass-spring system formed by the deflection mirror and the elastic suspension. The scanning system further includes a laser configured to emit primary light along a transmit beam. The scanning system further includes a detector configured to detect secondary light along a receive beam: the transmit beam and the receive beam are aligned along an overlap portion, the overlap portion comprising the reflective surface of the deflecting mirror. The scanning system further includes a collimator lens configured to collimate at least one axis of the primary light. The collimator lens is disposed in the overlap portion.

A scanning system includes a deflecting mirror with a reflective surface. The scanning system further comprises an elastic suspension of the deflection mirror. The scanning system further includes an actuator configured to actuate, by means of elastic deformation of the elastic suspension, resonant motion of a mass-spring system formed by the deflection mirror and the elastic suspension. The scanning system further includes a laser configured to emit primary light along a transmit beam. The scanning system further comprises a detector lens and a detector disposed in a focal plane of the detector lens and configured to detect secondary light along a receive beam, wherein the transmit beam and the receive beam are aligned along an overlap portion, the overlap portion being the reflective one Surface of the deflection mirror comprises: The scanning system further comprises a beam splitter comprising a coupling mirror with a reflectivity of at least 86%, and which is arranged to split the transmission beam and the receiving beam at one end of the overlapping portion, wherein the coupling mirror between the detector lens and the Detector is arranged.

The various examples can be combined to form further examples. For example, it would be possible to arrange the beam splitter between the detector lens and the detector even if the slow axis and fast axis collimation is performed between the laser and the beam splitter. Further, the relative dimensioning of the transmissivity and divergence as described above may also be used for scenarios where, for example, the beam splitter is located between the detector lens and the detector and / or where the collimator lens is located in the overlap portion of the transmit beam and the receive beam.

list of figures

• 1 schematically illustrates a scanning system that includes a coaxial optical system and a frictionless deflection mirror according to various examples.
• 2 schematically illustrates an example implementation of the coaxial optical system according to various examples.
• 3 schematically illustrates a field width of the primary light transmitted along a transmission beam path of the coaxial optical system according to various examples.
• 4 schematically illustrates a field width of the primary light transmitted along a transmission beam of the coaxial optical system with respect to a size of the deflection mirror according to various examples.
• 5 schematically illustrates a field width of the primary light transmitted along a transmission beam of the coaxial optical system with respect to a size of a deflection mirror according to various examples.
• 6 schematically illustrates a dependence of a transmission of the transmit beam with respect to the receive beam of the coaxial optical system of a divergence of a slow axis of the primary light according to various examples.
• 7 schematically illustrates an example implementation of the coaxial optical system according to various examples.
• 8th schematically illustrates a multi-focus lens body according to various examples.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, the embodiments of the invention will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the embodiments is not to be construed in a narrow sense. The scope of the invention should not be limited by the embodiments described below or by the drawings, which are given by way of illustration only.

The drawings are to be regarded as schematic representations and elements shown in the drawings are not necessarily drawn to scale. Rather, the various elements are presented in such a way that their function and their general purpose will become apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components or other physical or functional units described in the drawings or herein may also be implemented by indirect connection or coupling. A coupling between the components can also be made via a wireless connection. Functional blocks may be implemented in hardware, firmware, software or a combination thereof.

Hereinafter, techniques of using a deflection mirror to deflect light will be described. The deflection mirror has a reflective surface. For example, a reflectivity of the reflective surface of the deflecting mirror may be greater than 86%, optionally greater than 90%. A light beam of the light can be deflected by reflection at the reflecting surface. For example, the reflective surface may be coated with gold or silver or other reflective metal coating or other coating. The deflection mirror can be deflected by reversible deformation of at least one spring of an elastic suspension of the deflection mirror. Adapted deflection of the deflection mirror allows the deflection of the light. The at least one spring can be reversibly deformed, that is structural damage to the material - for example, silicon, such as crystalline silicon. As a general rule, in the various examples described herein, one or more springs may be used to implement the elastic suspension.

In other words, techniques are described that use a solid-state, frictionless scanner to deflect light.

For example, the techniques described herein may facilitate 1D or 2D deflection of light. In particular, the light can be scanned. Scanning light may correspond to repeatedly redirecting light using different transmission angles. A scan rate or repetition rate of the scan may be defined by scan cycles. For the deflecting mirror can be deflected accordingly. Larger scan areas correspond to larger changes in the transmission angles during scanning; larger changes in the transmission angle can be achieved by greater deflection of the deflection mirror. This can increase the field of vision of the scan. It is possible to implement the transmission angles by deflecting the deflection angle in accordance with one or more degrees of freedom of movement of a mass-spring system formed by the elastic suspension and the deflection mirror. For example, the deflection mirror can be rotated, tilted, shifted, etc. Examples of the degrees of freedom of movement that can be used to deflect light include bending and torsion of at least one spring of the mass-spring system.

According to various examples, resonant motion of the mass-spring system is possible. In particular, the corresponding degree of freedom of movement may have a corresponding resonance characteristic - sometimes referred to as frequency response, that is, displacement as a function of frequency. The resonance characteristic may have a maximum of certain width in the frequency space. It is possible to select a driving force to have a frequency within this resonance maximum. For this purpose, an actuator can be controlled accordingly. By means of resonant motion, large changes in the transmission angles can be achieved. Large scan areas can be implemented.

Exemplary actuators that may be controlled to resonantly drive the elastic scan unit include piezoelectric comb drives, magnetic drives, piezoelectric actuators, etc.

As a general rule, the techniques described herein may find application in different application scenarios. Exemplary application scenarios include but are not limited to: LIDAR with lateral resolution, spectrometers, projectors, endoscopes, etc. In the following, for reasons of scarcity, reference is primarily made to LIDAR application scenarios; Appropriate techniques can also be used for other application scenarios.

The deflecting mirror and the elastic suspension may be part of a scanning unit. A scanning system (or simply a scanner) may include the scanning unit, a light source configured to emit light to be scanned, and / or a detector configured to receive secondary light. The scanning system may also include one or more actuators to activate the resilient suspension so as to deflect the deflecting mirror.

According to various examples, it would be possible to deflect laser light. For example, coherent or incoherent laser light can be used. Polarized or non-polarized laser light can be used. Pulsed laser or continuous wave laser light can be used. For example, short laser pulses having a width in the range of picoseconds or nanoseconds can be used. For example, a pulse duration in the range of 0.5 to 3 nanoseconds may be used. The laser light may have a wavelength in the range of 700 to 1800 nanometers, in particular 1550 nanometers or 950 nanometers. A laser light beam can be formed by different spatial modes (multimodal laser light).

As a general rule, a light source can be implemented using a laser diode. For example, a large-area laser diode can be used. The laser diode can be multimodal in space by providing multimode laser light. For example, an edge emitting large area laser diode may be used.

As a general rule, an emitting surface (sometimes referred to as an active surface) of the laser diode may not be shaped as a circle or square, but rather asymmetrically. The active area may have a short side that has a so-called fast axis ( FA ) and may have a long side which has a so-called short axis ( SA ) Are defined. The FA and the SA may be defined perpendicular to the direction of propagation of the laser light and perpendicular to the optical axis (OA). In particular, a divergence of the laser light can be large along the FA and can be small along the SA his. The divergence defines an opening angle of the laser light along the FA or the SA , In other words, the width of the laser light can expand rapidly along the FA and slowly widen along the SA ,

$$w_{FA}\times {\mathrm{\Omega }}_{FA}:=c_{FA}$$

As a general rule, the beam profile of the laser light is in the FA and the SA is defined by the respective side lengths W _SA , w _{FA of} the active surface and an emission profile which defines the divergence Ω _SA , Ω _FA : $$w_{SA}\times {\mathrm{\Omega }}_{SA}:=c_{SA}$$

$$w_{FA}\times {\mathrm{\Omega }}_{FA}:=c_{FA}$$

Equations one and two result in that the divergence of the laser light is also asymmetric.

$$w_{FA}=1\mathrm{\mu }m-15\mathrm{\mu }m,$$

$${\mathrm{\Omega }}_{SA}=10deg-30deg,$$

$${\mathrm{\Omega }}_{FA}=25deg-45deg,$$

As a general rule, laser diodes can be used which have the following properties: $$w_{SA}=50\mathrm{\mu }m-250\mathrm{\mu }m.$$

$$w_{FA}=1\mathrm{\mu }m-15\mathrm{\mu }m.$$

$${\mathrm{\Omega }}_{SA}=10deG-30deG.$$

$${\mathrm{\Omega }}_{FA}=25deG-45deG.$$

Detected light can be scattered on an object of the environment and therefore can not be coherent.

According to various examples, it is possible that the laser light being scanned satisfies eye safety regulations. Such eye safety regulations may specify an average laser power, a maximum laser power, for example, as a function of a pulse length, etc. An example of eye safety regulations that can be used is described in BS EN 60825-1: 2014, Safety of laser products. Equipment classification and requirements, published on August 31, 2014.

Various techniques are based on the finding that for such elastic scanning units used in an eye safety regime of the laser light, it may be difficult to achieve ranges in excess of 100 m, for example, for an object reflectivity of 50%. Various techniques help to increase the range above 100 m, for example to reach ranges of 100 m to 200 m.

To increase the range, spatial filtering can be used. Space filtering refers to a scenario in which primary laser light is transmitted along a transmit beam and via a deflection mirror toward the object; and secondary laser light reflected by the object is collected along a receiving beam and through the same deflecting mirror. In other words, the transmit beam overlaps at least partially with the receive beam. In particular, the transmit beam and the receive beam may overlap in an overlap section that includes the reflective surface of the scan mirror.

Sometimes such a technique of spatial filtering is referred to as a coaxial optical system because the OA of the transmit beam and the OA of the receive beam are aligned. As a general rule, there may be an offset between the transmit beam and the receive beam for a coaxial optical system, as long as there is an overlap between the beam profiles of the transmit beam and the receive beam. In a coaxial optical system, the transmit beam and the receive beam may share at least one common aperture defined by, for example, the deflection mirror.

Coaxial optical systems generally allow to limit the solid angle from which light is collected and focused on the detector. Thereby, background noise can be reduced by reducing the number of background photons, for example due to solar rays. This makes it possible to increase the signal-to-noise ratio; this increases the range.

As a general rule, when the coaxial optical system is implemented, a beam splitter is used to split the transmit beam and the receive beam at one end of the overlap section. There are several ways available to implement the beam splitter. In one example, two prisms may be used that are glued together and have a distance that allows for total reflection at this refractive index transition. Another approach relies on a partially reflective mirror, for example, using a silver coating that has a reflectivity of less than, for example, 80% along a beam profile width. A third possibility uses a fully reflective mirror (coupling mirror) with a reflectivity of, for example, more than 90%, optionally more than 86%, further optionally more than 90%. The lateral dimensions of this coupling mirror - perpendicular to the OA - are smaller than the width of the receiving beam; therefore, a part of the secondary light can pass the coupling mirror without being deflected by it, and therefore can reach the detector.

das heißt als Verhältnis zwischen (i) Leistung des primären Laserlichts im Sendestrahl gerade stromaufwärts eines Überlappabschnitts zwischen dem Sendestrahl und dem Empfangsstrahl und (ii) Leistung des sekundären Laserlichts im Empfangsstrahl gerade stromabwärts des Überlappabschnitts.The beam splitter, the deflecting mirror, etc. define a coaxial optical system. The optical system is generally associated with a transmissivity. The transmissivity can be defined as $$T=\frac{P_{TX}}{P_{RX}}.$$

that is, the ratio between (i) power of the primary laser light in the transmit beam just upstream of an overlap portion between the transmit beam and the receive beam and (ii) power of the secondary laser light in the receive beam just downstream of the overlap portion.

In equation (3), losses in the environment are not taken into account, that is, it is assumed (artificially) that all the light leaving the scanning system along the transmission beam also re-enters the scanning system along the reception beam.

• Ein erster Faktor ist der Ablenkspiegel: zum Beispiel können Ablenkspiegel in dem optischen System verwendet werden, die eine Größe aufweisen, die kleiner als die Feldbreite des primären Lichts ist; dann geht primäres Licht verloren und die Transmittivität wird reduziert (T_mirror).

The transmissivity of the transmit beam with respect to the receive beam can be reduced below the value of 1 due to various factors:

• A first factor is the deflection mirror: for example, deflection mirrors may be used in the optical system having a size smaller than the field width of the primary light; then primary light is lost and the transmissivity is reduced (T _mirror ).

A second factor is optical losses due to the use of imperfect optical elements, for example lenses, below 100% reflectivity of the mirror surfaces, etc. (T _losses ). Typically T _losses = 0.7 to 0.9. For example, if gold is used to use the reflective surface of the coupling mirror and / or a reflective surface of the deflection mirror, T _material = 0.86-0.96 of the corresponding optical element.

A third factor is the use of a beam splitter, which can result in reduced transmissivity (T _splitter ).

The total transmissivity T of the coaxial optical system - that is the transmission beam 121 just upstream of the overlap section 125 and the receiving beam 122 just downstream of the overlap section 125 - is by the various influencing factors identified above are provided: $$T=T_{lOsses}\times T_{mirrOr}\times T_{splitter},$$

A lower transmissivity T limits the range. Various techniques are based on the finding that in equation (4) in particular the beam splitter transmission T _splitter can significantly limit the total transmissivity T and thus the range. For example, in reference implementations where a prismatic beam splitter is used, T _{splitter may be} as small as, for example, 0.25.

To alleviate this disadvantage, a beam splitter incorporating a coupling mirror is used in various examples. The size of the coupling mirror is adjusted so as to provide a large beam splitter transmissivity and hence a large overall transmissivity. This makes it possible to increase the range of LIDAR measurements.

In more detail, in such a scenario, the transmissivity T _{splitter of} the beam splitter may depend on the geometric configuration of the coaxial optical system formed by the coupling mirror and deflecting mirror and optionally by lenses, etc. In particular, a lateral size of the coupling mirror-perpendicular to the OA of the transmission beam and of the reception beam-can determine the transmissivity of the beam splitter.

According to various examples described herein, the coaxial optical system is configured to provide a transmissivity of not less than 0.40, for example in the range of 0.50 to 0.85. For example, the transmissivity without losses (ie, T _losses : = 1) can range from 0.70 to 0.85. In particular, the lateral dimensions of the coupling mirror and / or the deflection mirror can be adjusted accordingly. It has been found that such a transmissivity provides for an optimized balance between (i) range of LIDAR measurements due to high transmittivity and (ii) lateral resolution of LIDAR measurements due to low divergence.

According to various examples described herein, the beam splitter may be disposed between a detector lens configured to focus secondary light on the detector and the detector. This makes it possible to provide a small outer dimension of the optical system.

1 schematically illustrates a scanning system 100 according to different examples. The scan system 100 includes a control unit 101 , a laser diode 101 , and a detector 102 , The scan system 100 defines a coaxial optical system.

The laser diode 101 is through the control unit 101 controlled to primary laser light 111 along a transmission beam 121 to emit. The transmission beam 121 passes through a beam splitter 130 through, then passes through a deflecting mirror 150 through, then passes through a housing window 151 the scanning unit and then reaches an environment 190 ,

For example, a large-area laser diode as described above can be used.

As a general rule, a reflective surface of the deflecting mirror 150 have an elliptical shape. The reflective surface may be disposed in a plane having a normal vector that is at an angle with respect to the OA of the transmit beam 121 includes, for example, a 45 ° angle. A projection of the reflective surface in a plane perpendicular to the OA may have a circular cross-section.

As a general rule, according to various examples described herein, a deflecting mirror 150 which has a reflective surface of a size that is (i) small enough to resonantly move a mass-spring system formed by an elastic suspension of the scanning mirror and the scanning mirror and (ii) large enough (iii) which is large enough to allow spatial filtering using a coaxial optical system.

As a general rule, the size of the reflecting surface of the deflecting mirror may be in the range of 120 mm ² to 230 mm ² , optionally in the range of 180 mm ² to 220 mm ² . For example, an elliptical cross-section of the reflective surface may have radial lengths along the minor semiaxis and semimajor axes of 12 mm and 16.97 mm = 203 mm ² . This represents a circular shape of a projection of the reflecting surface in a plane perpendicular to the OA of the transmitting beam 121 ready when the OA is tilted 45 ° with respect to a normal vector of the reflecting surface.

The primary laser light can be applied to an object (not in 1 illustrated) to be noncoherent secondary light 112 to create. The secondary light 112 - And backlight and / or interference light - moves along a receiving beam 122 through the window 151 , enters through the mirror 150 through and then reaches the beam splitter 130 , The beam splitter directs the secondary laser light 112 towards a detector 102 ,

The OA of the transmission beam 121 and the OA of the receive beam 122 are aligned; therefore, a coaxial optical system is implemented. Both the transmission aperture of the transmission beam 121 as well as the detector aperture of the receive beam 122 be through the deflecting mirror 150 Are defined.

As a general rule, the detector 102 by an Avalanche Photo Diode (APD) array or a single-photon APD array.

1 illustrates an overlap section 125 of the transmission beam 121 and the receiving beam 122 , The overlap section 125 has an end at the beam splitter 130 ,

The control unit 90 is set up to the deflecting mirror 150 to actuate to implement different scanning angles. This is an actuator 901 with the control unit 90 coupled. Exemplary actuators 901 include electrostatic drives, magnetic drives or piezoelectric drives. The actuator 901 is adapted to exert a force on a first end of an elastic suspension. This can cause a reversible deformation of a spring of the elastic suspension 902 causes the deflection mirror 150 , which has a second end of the elastic suspension 902 , which is opposite the first end, coupled, deflects. A spring element may extend between the first and second ends (in FIG 1 not shown).

Exemplary implementations of the elastic suspension 902 are described in US20180143322A1 : 62 and in DE 10 2016 014 001 A1 and in DE102009058762A1 and in US20100290142A1 ,

The control unit 90 can the detector 102 read. The control unit 90 may be implemented by an application specific integrated circuit (ASIC) and / or field programmable array (FPGA) and / or general processor. The control unit 90 may comprise an analog-to-digital converter and / or a time-to-digital converter.

In the example of 1 the optical system is a so-called pre-scanner optical system. This is because there are no lenses etc. with a significant optical effect on the transmit beam 121 upstream of the deflecting mirror 150 along the transmission beam 121 are arranged (as would be the case for a post-scanner optical system, which is not shown here). Therefore, the divergence of the transmission beam corresponds 121 at the deflecting mirror 150 is present, with the divergence of the transmission beam 121 that the scanning system 100 towards the environment 190 leaves. Additional beam shaping behind the deflection mirror 150 is not provided in the pre-scanner optical system.

Details regarding the optical system of the scanning system 100 of the 1 are also in 2 illustrated.

2 illustrates aspects related to the scanning system 100 , 2 is a ray-tracing schematic view of the optical system of the scanning system 100 , in particular the transmission beam 121 and the receiving beam 122 , 2 illustrates one FA 716 of the primary laser light 121 (the SA is not shown).

In 2 is a collimator lens 211 in the transmission beam 121 between the laser diode 101 and the beam splitter 130 arranged by a coupling mirror. Another collimator lens 201 is also in the transmission beam 121 arranged between the laser diode 101 and the beam splitter 130 , The collimator lens 211 is set up for the FA 716 of the primary light 111 to collapse. The collimator lens 201 is set up for the SA of the primary light 111 to collapse.

A solid mirror 202 directs the primary light 111 towards the coupling mirror 131 of the beam splitter 130 , 2 illustrates the FA -Feldbreite 321-1 . w _{TX, FA} of the primary light 111 at point A.

The coupling mirror 131 is within the receive beam 122 along which the secondary light 112 moved, arranged. The primary light 111 and the secondary light 112 move in opposite directions. An OA 199 of the transmission beam 121 and the receiving beam 122 is in the overlap area 125 in 2 illustrated.

2 illustrates the reflective surface 151 the deflection mirror 150 , The deflecting mirror 150 closes an angle of 45 ° with the OA 199 on. This allows periscope-like scanning by rotation about a rotation axis 152 be implemented. To the rotation around the rotation axis 152 , as in 2 Illustrated to provide techniques can be applied as described in DE 10 2016 014 001. As a general rule, other types of movement of the deflecting mirror 150 used, for example, a tilting etc. The exact type of elastic suspension used to move the deflecting mirror 150 is not essential for the Operation of the various techniques described herein.

As a general rule, the size of the reflective surface 151 the deflection mirror 150 in the range of 120 mm ² to 230 mm ² , optionally in the range of 180 mm ² to 220 mm ² . This allows resonant frequencies - and thus scan frequencies for the LIDAR measurements - in the range of 60 Hz to 500 Hz. Such scanning frequencies are helpful in providing acceptable repetition rates for LIDAR images. In addition, resistance to undesired movement of the mirror due to low-frequency shock can be provided.

2 also illustrates a field width 322 . w _RX of the secondary light 112 , The field width 322 is through a detector aperture of the receive beam 122 Are defined. The size of the detector aperture is defined by the size of the deflection mirror 150 ,

The field width 322 is greater than the size of the coupling mirror 130 , Therefore, the transmissivity of the beam splitter 130 T _splitter greater than 0. Part of the light reaches the detector 102 , through a detector lens 252 ,

As a general rule defines the geometric size of the coupling mirror 131 the transmissivity of the beam splitter 130 , T _splitter . For example, the transmittivity of the beam splitter decreases 130 T _splitter off when the size of the coupling mirror 131 along the FA 760 perpendicular to the OA 199 is larger (with a fixed field width 322 ), because less secondary light 112 the detector 130 reached.

The detector lens 252 has a focus length 102A such that the secondary light 112 on the detector 130 is focused. A field stop 253 is near the focal plane of the detector lens 252 provided.

The transmissivity T of the transmission beam 121 in relation to the receiving beam 122 in the coaxial optical system used in 1 is shown as the ratio between the power of the primary light 111 at a point A of the transmission beam 121 and the power of the secondary light 112 at a point B of the receiving beam 122 defines, assuming that the environment of the scanning system 100 the light is completely reflected and no light is added in the environment. That means the entire primary light 111 , which runs through the environment, as a secondary light 112 re-enters.

Hereinafter, it is assumed that the transmissivity is set by the geometrical configuration of the coaxial optical system. Therefore, the transmissivity is set by the geometric configuration of the coupling mirror 131 and the deflecting mirror 150 (T _mirror ) and the geometric configuration of the beam splitter 130 (T _splitter ), see equation (4). Other losses are neglected, for example losses due to sub-100% reflectivity of the material of the reflective surfaces of the mirrors 131 . 150 , This means that equation (4) assumes T _losses : = 1.

Next, details regarding the design of the coaxial optical system will be described with respect to the transmissivity T associated with 3 - 6 adapt.

3 schematically illustrates a beam profile 701 of the primary light 111 , 3 illustrates the rectangular beam profile 701 along the SA 715 - with a low divergence - and along the FA 716 - with a big divergence.

The field width 321-1 along the FA 716 (With w _{TX, FA} designated) and the field width 321-2 along the SA 715 (With w _{TX, SA} are shown) are shown. The field widths 321-1 . 321-2 are through one or more collimator lenses - for example, the collimator lens 201 of the 1 - under the boundary conditions caused by the laser diode 101 are imprinted by equations (1) and (2). If, for example, the field width 321-1 or 321-2 through the collimator lens 201 is reduced, then the divergence increases according to equation (1).

4 schematically illustrates the beam profile 701 of the primary light 111 in terms of projection 151a the reflective surface 151 in the plane perpendicular to the OA 199 , 4 also illustrates the beam profile 701 of the primary light 111 in terms of the coupling mirror 131 of the beam splitter 130 ,

As a general rule, it is as in 4 shown, possible that the size of the coupling mirror 131 is not larger than the size of the beam profile 701 of the primary light 111 , In particular, the size of the coupling mirror 131 to the size of the beam profile 701 of the primary light 111 be adjusted. For example, the field size 321-1 in the range of 80% to 120% of the corresponding size 131-1 of the coupling mirror 130 lie. For example, the field width 321-2 in the range of 80% to 120% of the corresponding size 131-2 of the coupling mirror 130 lie. This reduces the transmittivity of the coupling mirror 131 of the beam splitter 130 for the primary light 111 avoided.

Furthermore limited as in 4 represented, the size of the reflective surface 151 the deflection mirror 150 the aperture of the transmission beam 121 . for the SA 715 , In particular, the appropriate size 151a-1 the projection 151a the reflective surface 151 smaller than the field width 321 - 2 of the primary light 111 along the SA 715 , Not all primary light 111 is through the deflecting mirror 150 reflected - which reduces the mirror transmissivity T _mirror <1 (unreflected light is indicated by the arrows in FIG 4 highlighted). On the other hand, the divergence is comparatively small because the field width 321-2 along the SA 715 is large, see equation (1). Local modes of the primary light 111 which have a comparatively small divergence, are due to the orientation of the center of the projection 151a the reflective surface 151 the deflection mirror 150 with the OA 199 selected; Local modes of the primary light 111 , which have a comparatively large divergence, are cut off at the arrows.

As a general rule, it may not be easy to experience a loss of primary light 111 at the mirrors 131 . 150 to compensate. This is because the maximum transmission power of the laser diode 101 may be limited.

As a general rule, it would be possible for the laser diode 101 at transmission powers of at least primary light 111 operating within 20% of the thermal breakpoint. The thermal breakpoint may be associated with transmit power resulting in irreversible damage to the integrity of the laser diode 101 result.

In 4 is the size of the coupling mirror 131 to the size of the beam profile 701 of the primary light 111 customized. Therefore, the transmissivity is not due to losses of the primary light 111 at the coupling mirror 111 reduced.

In 4 defines the size of the projection 151a , A _smirror the detector _{aperture of} the receive _beam 122 , Therefore defines the size of the projection 151a the field width 322 of the secondary light 112 ,

As in 4 is shown is the size 158 the projection 151a along the SA 751 smaller than the size 131-2 of the coupling mirror 131 along the SA 751 , That is why the primary light goes 111 at the deflecting mirror 150 lost. A * is the area of the beam profile 701 that are within the projection 151a comes to rest, that is, through the deflecting mirror 150 is reflected (dashed lines in 4 . 701 * ).

wobei A_cmirror die Fläche des Kopplungsspiegels 131 ist, das heißt A_cmirror= w_TX,SA × w_TX,FA.That is why the transmittance of the primary light 112 along the transmission beam 121 in such scenarios given by: $$T_{TX}=T_{mirrOr}=\frac{A*}{A_{cmirrOr}}\alpha \frac{w_{TX.SA}}{A_{cmirrOr}}.$$

where A _{cmirror is} the area of the coupling _mirror 131 is, that is A _cmirror = w _{TX, SA} × w _{TX, FA} .

Secondary light 122 is over the entire area of the projection 151a collected. So defines the size of the projection 151a , A _smirror in terms of the size of the coupling _mirror A _cmirror the beam splitter _{transmissivity} T _splitter , and the _{transmissivity of} the secondary light 112 along the receiving beam 122 is given by: $$T_{RX}=T_{splitter}=1-\frac{A*}{A_{smirrOr}},$$

Finally, the total transmissivity is given by: $$T=T_{TX}\times T_{RX}=T_{splitter}\times T_{mirrOr}=\frac{A*}{A_{cmirrOr}}\left(1-\frac{A*}{A_{smirrOr}}\right),$$

As already emphasized, equation (7) is based on the assumption that the size of the reflecting surface 131 of the coupling mirror 130 adapted to the size of the beam profile 701 ,

5 schematically illustrates the beam profile 701 of the primary light 111 in terms of projection 151a the reflective surface 151 in the plane perpendicular to the OA 199 , 5 also illustrates the beam profile 701 of the primary light 111 in terms of the coupling mirror 131 of the beam splitter 130 ,

The scenario of 5 generally corresponds to the scenario of 4 , However, in the scenario the 5 the collimator lens 201 set up to the field width 321-2 of the primary light 111 along the SA 715 to reduce. Then the field width 321-2 smaller than the corresponding size 151a - 1 the projection 151a the reflective surface 151 the deflection mirror 150 , Therefore, the mirror transmissivity T _mirror = 1. Primary laser light 111 do not go at the mirror 150 lost. On the other hand, the divergence of the primary light 111 along the SA 715 big, because the field width 321-2 is small, see equation (1).

In 4 and 5 is a suspension of the coupling mirror 131 not shown for the sake of simplicity.

Furthermore follows from a comparison of 4 and 5 that the coupling mirror 131 in the scenario of 5 be sized smaller can, as in the scenario of 4 , due to the reduced field width 321-2 , In particular, the length can be 131-2 the corresponding side of the coupling mirror 131 be reduced. That is why in the scenario the 5 the transmissivity T _{splitter of} the beam splitter 130 larger than for the scenario of 4 , see equation (4).

As with the above discussion of 4 and 5 can be understood, there is a correlation between (i) transmissivity of the transmit beam 121 in relation to the receiving beam 122 and (ii) divergence of the primary light 111 There is a general tendency for greater transmittivity in a greater divergence of primary light 111 results. This is in 6 shown.

6 illustrates a dependence of the transmittivity 601 - 604 T of the optical system as a function of divergence 610 , In 6 this dependence is for different sizes of reflective surface 151 the deflection mirror 150 shown. The dependence on 6 is obtained from equation (7). 6 Assuming T _losses : = 1, that is, no losses due to imperfections of optical elements as such.

Illustrated as reference 6 the transmissivity T 609 for a conventional prism-based beam splitter. A prism-based beam splitter typically has T _{splitter, ref} = 0.25. Therefore, the horizontal dashed line represents the transmittivity 609 a reference of at best for such a scenario using a prism-based beam splitter. The reference transmissivity does not depend on the divergence of the primary light 111 from.

Other than that, when a commercial optical system according to various examples is used, larger sizes of the reflective surface result 151 A _smirror in larger _{transmissions} 601 - 604 because the transmissivity of the beam splitter increases, compare equation (7). This dependence is indicated by the vertical dotted arrow in 6 highlighted.

1. (A) Die laterale Auflösung des LIDAR-Bilds kann besser für kleinere Divergenzen sein. Dies liegt daran, dass der Spot des primären Laserlichts eine kleinere Zielfläche des Objekts für kleinere Divergenzen beleuchtet. Deshalb nimmt die Mittelung im Ortsraum für zunehmende Divergenzen zu. Deshalb ist es allgemein erstrebenswert, dass koaxiale optische System auszubilden, so dass dieses links im Plot der 6 liegt.
2. (B) Eine kleinere Transmittivität resultiert in einem kleineren Signal am Detektor 102. Ein kleineres Signal limitiert die Reichweite, weil immer weniger Photonen des sekundären Laserlichts 112 den Detektor 102 erreichen. Damit wird eine bessere Reichweite der LIDAR-Messungen für größere Transmittivitäten erzielt. Deshalb ist es allgemein erstrebenswert, dass koaxiale optische System auszubilden, so dass dieses oben im Plot der 6 liegt.

As general rules:

1. (A) The lateral resolution of the LIDAR image may be better for smaller divergences. This is because the spot of the primary laser light illuminates a smaller target area of the object for smaller divergences. Therefore, the averaging in the space increases for increasing divergences. Therefore, it is generally desirable to form coaxial optical systems so that this is left in the plot of the 6 lies.
2. (B) A smaller transmissivity results in a smaller signal at the detector 102 , A smaller signal limits the range, because fewer and fewer photons of the secondary laser light 112 the detector 102 to reach. This achieves a better range of LIDAR measurements for larger transmissions. Therefore, it is generally desirable to form coaxial optical system so that this is the top of the plot 6 lies.

Out 6 It can be seen that there is a trade-off situation between (A) lateral resolution / low divergence and (B) range / high transmittivity.

The regime 671 in 6 corresponds to the scenario of 4 : if the field width 321-2 . w _{TX, SA} increases, more and more primary light goes 121 at the deflecting mirror 150 (Arrows in 4 ) - therefore the transmittivity decreases 601 - 604 compare equation (5) and equation (1). On the other hand, if the field width 321-2 . w _{TX, SA} increases, the divergence decreases 610 from.

The regime 673 in 7 corresponds to the scenario of 5 : if the field width 321-2 increases, the divergence decreases 610 from; on the other hand, if the field width 321 - 2 increases, the coupling mirror becomes 131 larger and larger and again T _splitter decreases - see equation (7) - and together with T _splitter decreases the transmissivity.

The transitional regime 672 between the regimes 671 and 672 corresponds to a scenario in which the field width 321-2 of the primary light 111 along the SA 715 about the size of the corresponding width 131-2 Has. In the model of 6 is the regime 671 by a linear change in the transmissivity 601 - 604 with the divergence 610 characterized. The regime 673 is due to a sub-linear change in the transmissivity 601 - 604 with the divergence 610 characterized.

The transitional regime 672 is a sweet spot of the weighing situation between (A) lateral resolution / low divergence and (B) range / high transmittivity. This is because a further increase in (B) range / large transmissivity is associated with increased costs associated with excessively increased divergence, that is, excessively reduced lateral resolution. At the same time, a further (A) reduction of the divergence, that is to say a further increase in the spatial resolution, greatly reduces the (B) transmittivity and thus the range.

Therefore, as a general rule, the collimation of the primary light 111 and the size of the deflection mirror 150 in the transitional regime 672 between a linear and a sub-linear dependence of the transmittivity 601 - 604 from the divergence 610 ,

As another general rule, the SA -Feldbreite 321-2 . w _{TX, SA} of the primary light 111 just before / upstream of the mirror 150 not smaller than 90% of the corresponding width 158 the reflective surface 151 perpendicular to the OA 199 that is the projection 151a his. In addition, the SA -Feldbreite 321-2 of the primary light 111 just before / upstream of the mirror 150 not greater than 120% of the corresponding width 158 the reflective surface 151 perpendicular to the OA 199 to be excessive loss of primary light 111 (reduced transmissivity according to equation (5)), which is not simply due to the limited in the transmission power laser diode 101 can be compensated to avoid.

About such general rules for the relative sizing of the different parts of the optical system of the scanning system 100 Going out, it is also possible to make quantitative lessons 6 derive. In particular, as already mentioned above, it is for resonantly driven deflection mirrors 150 Often helpful, the mass of the deflecting mirror 150 to limit. In detail, when the mass of the deflecting mirror 150 increases, a resonant frequency of the corresponding movement decreases. On the other hand, it has been observed that resonant frequencies below, for example, 60 Hz or 80 Hz can not meet the requirements for certain application scenarios, including automotive application scenarios. This is due to a reduced repetition rate of LIDAR images, as well as increased susceptibility to shock.

A typical implementation of the deflection mirror 150 based on microelectromechanical (MEMS) manufacturing techniques. For example, a material of the deflecting mirror 150 Be silicon, for example, single-crystal silicon. For example, lithography and wet etching and / or dry etching, for example, reactive ion beam etching for fabricating the deflection mirror 150 be used. On a mirror backside, fins and cavities can sometimes be provided to provide a reduced mass with great structural rigidity; this is sometimes referred to as backside reinforcement. Then, within such an approach, the MEMS fabrication of the deflection mirror became 150 observed that reflective surfaces 151 the deflection mirror 150 greater than, for example, 220 mm ² , result in a resonant frequency falling below, for example, 60 Hz to 80 Hz. On the other hand follows 6 in that surfaces of the reflective surface 151 the deflection mirror 150 which are significantly smaller than 180 mm ² , the divergence necessarily results above 0.15 °. At specified ranges of LIDAR measurements from 150 m to 250 m, divergences above 0.15 ° are typically unacceptable with respect to the reduced lateral resolution at these ranges. Therefore follows out 6 in that, in a coaxial optical system using a frictionless, resonantly driven deflection mirror, it is desirable to have a reflective surface 151 to implement, which has a size in the range of 180 mm ² to 220 mm ² (it is noted that the projection 151a the reflective surface 151 may be smaller in the plane perpendicular to the OA of the optical system). In addition, the divergence may be in the range of 0.09 ° to 0.15 °. Smaller divergences can not be desirable because of the reduced transmissivity. Also, minor divergences may not be needed due to the inherently limited range design of the LIDAR measurements at approximately 150 m to 250 m, which corresponds to a spot width of approximately 43 cm at 250 m for a divergence of 0.10 ° along the SA 715 equivalent. The transmissivity can range from 0.7 to 0.85 at T _losses : = 1, as in 6 shown. Assuming that the losses due to imperfections are T _losses ≈ 0.57, then it can be assumed that the transmissivity is not less than T = 0.4. This is still significantly greater than the reference transmittance 609 T _{splitter, ref} = 0.25.

As will be appreciated, with reference to FIG 4 - 6 primarily limitations of the coaxial optical system with respect to SA 715 discussed. For example, the field width 321-1 of the primary light 111 along the FA 716 be much smaller than the field width 321-2 of the primary light 112 along the SA 716 , at the coupling mirror 131 and at the deflecting mirror 150 , In particular, as in 4 and 5 Illustrates the field width 321-1 of the primary light 111 along the FA 716 less than 50% of the corresponding width 159 the projection 151a the reflective surface 151 the deflection mirror 150 in the plane perpendicular to the OA 199 his. Typically, the quality of the laser light is that through the laser diode 101 along the FA 716 is emitted much better than the quality of the laser light that passes through the laser diode 101 along the SA 715 is emitted. c _FA << c _SA , see equations (1) and (2). That is why it is possible to change the field width 321-1 of the primary light 111 along the FA 716 limit, while the low divergence of the primary light 111 along the FA 716 is maintained. A collimator lens for collimating the FA 716 can be inside the housing of the laser diode 111 be integrated.

The coaxial optical system of the scanning system 100 according to the example of 2 is just an example implementation. Other configurations of the coaxial optical system are conceivable. Another exemplary implementation of the optical system of the scanning system 100 is related to 7 illustrated. Also for that optical system, which in 7 is illustrated, or other implementation of the coaxial optical system, the techniques that are generally related to 3 - 6 described are applied immediately.

7 illustrates aspects related to the scanning system 100 , 7 is a ray tracing schematic of the optical system of the scanning system 100 , in particular the transmission beam 121 and the receiving beam 122 , 7 illustrates one FA 716 of the primary laser light 121 (the SA is not shown).

The scenario of 7 generally corresponds to the scenario of 2 , For example, the scenario illustrates the 7 a coaxial optical system.

In the example of 7 is the beam splitter 130 between the detector lens 252 and the detector 102 arranged (while in the example of the 2 the detector lens 252 between the beam splitter 130 and the detector 102 is arranged).

Such an arrangement of the beam splitter 130 as they are in 7 has different effects. For example, it may be possible to use the laser diode 101 and the detector 102 to integrate into a common housing. As a result, the robustness against environmental influences such as moisture etc. can be increased. In addition, packaging with a reduced dimension can be achieved.

In the scenario of 7 is a lens 702 illustrated. The Lens 702 acts on the SA 715 of the primary light 111 and does not work or does not significantly affect the FA 716 of the primary light 111 , The Lens 702 does not collapse the SA 715 of the primary light 111 , Rather, the lens 702 in a first implementation, set a beam width of the primary light 111 along the SA 715 towards the beam splitter 130 to reduce; while in a second implementation the lens 702 is set to a beam width of the primary light 111 along the SA 715 expand to the beam splitter.

The primary light 111 which is in the lens 702 must not be collimated, it may be divergent, for example at least along the SA 715 ,

Considering a scenario in which the field width 321 - 2 of the primary light 111 towards the coupling mirror 131 of the beam splitter 130 decreases. For example, it would be possible for the coupling mirror 131 in an image plane of the lens 702 is arranged - while the laser diode 101 in an object plane of the lens 702 is arranged. Then the appropriate width 131-2 of the coupling mirror along the SA 715 be reduced, along with a reduced field width 321 - 2 of the primary light 111 , This in turn increases the transmissivity of the optical system T of the scanning unit 100 because the beam splitter transmissivity T _{splitter is} increased, see equation (6). In particular, the transmissivity 601 - 604 about the dependencies, as in 6 are increased beyond.

To highly divergent primary light 111 along the SA 715 which the scan unit 100 towards the environment 190 at the deflecting mirror 150 leaves to avoid is the collimator lens 201 for the SA 715 in the transmission beam 121 behind the beam splitter 130 arranged, that is, the collimator lens 201 is in the overlap section 125 arranged.

Generally it would be possible to use the collimator lens 201 and the detector lens 252 to implement separately. However, in the example of 7 the collimator lens 201 and the detector lens 252 into a common multifocal lens body 800 (see 9 ) integrated in a first region 801 a focal length for focusing the secondary light 112 on the detector 102 and in a second region 802 Collimation of the primary light 111 (see 8th ). The multifocus lens body 800 can in regions 801 and 802 be segmented. The region 801 surrounds the region 802 , As will be appreciated, secondary light becomes 112 that is on the region 802 is lost, in any case lost due to reflection at the coupling mirror 131 , Therefore, providing the collimator lens affects 201 in the overlap section 125 taken individually, the transmissivity of the transmission beam 121 in relation to the receiving beam 122 not significant. By the lenses 201 . 252 in the common lens body 800 can be integrated, a particularly compact design of the optical system can be achieved.

Furthermore, by providing the lens 702 , the divergence of the primary light 111 along the SA 715 increase. Therefore, the distance between the laser diode 101 and the collimator lens 201 be reduced. A reduced distance between the laser diode 101 and the collimator lens 201 in turn allows a shorter focal length of the detector lens 252 , This in turn allows for small dimensions of the coaxial optical system. For example, the coaxial optical system can be integrated into a smaller housing.

A comparable effect can also be achieved when the lens 702 the primary light 111 directly widened, that is when the SA field width 321-2 of the primary light is widened directly. This can correspond to a virtual image plane. Here is the distance between the lens 702 and the virtual image plane at least 20% of the distance between the lens 702 and the collimator lens 201 amount to a sufficiently large expansion of the SA field width 321-2 to reach.

Furthermore, as a general rule above scenarios have been described in which the lens 702 selective to the primary light 111 along the SA 715 acts. However, in other examples it would also be possible to use the lens 702 on the FA 716 acts, in addition or alternatively to the SA 715 ,

In summary, techniques have been described above that enable the implementation of an eye safety compliant LIDAR sensor unit that incorporates a scanning system that implements a coaxial optical system. A resonantly driven deflection mirror is used.

• Beispiel 1. Scansystem (100), welches umfasst:
  • - einen Ablenkspiegel (150) mit einer reflektierenden Oberfläche (151),
  • - eine elastische Aufhängung (902) des Ablenkspiegels (150),
  • - einen Aktuator (901), der eingerichtet ist, um mittels elastischer Verformung der elastischen Aufhängung (902) resonante Bewegung eines Masse-Federsystems, welches durch den Ablenkspiegel (150) und die elastische Aufhängung (902) ausgebildet ist, zu aktuieren,
  • - einen Laser (101), der eingerichtet ist, um primäres Licht (111) entlang eines Sendestrahls (121) zu emittieren, und
  • - einen Detektor (102), der eingerichtet ist, um sekundäres Licht (112) entlang eines Empfangsstrahls (122) zu detektieren, wobei der Sendestrahl (121) und der Empfangsstrahl (122) entlang eines Überlappabschnitts (125) ausgerichtet sind, wobei der Überlappabschnitt (125) die reflektierende Oberfläche (151) des Ablenkspiegels (150) umfasst,
  wobei eine Größe (158, 159) der reflektierenden Oberfläche (151) des Ablenkspiegels (150) im Bereich von 120 mm² bis 230 mm² ist, optional im Bereich von 180 mm² bis 220 mm² ist, und wobei eine Divergenz (610) von mindestens einer Achse des primären Lichts (111) entlang des Überlappabschnitts (125) im Bereich von 0,09° bis 0,15° beim Ablenkspiegel (150) ist.
• Beispiel 2. Das Scansystem (100) nach Beispiel 1, welches weiterhin umfasst:
  • wobei eine Transmittivität (601-604) des primären Lichts (111) beim Sendestrahl (121) stromaufwärts des Überlappabschnitts (125) in Bezug auf das sekundäre Licht (112) beim entsprechenden Strahl (122) stromabwärts des Überlappabschnitts (125) nicht geringer als 0,40 ist.
• Beispiel 3. Scansystem (100), welches umfasst
  • - einen Ablenkspiegel (150) mit einer reflektierenden Oberfläche (151),
  • - eine elastische Aufhängung (902) des Ablenkspiegels (150),
  • - einen Aktuator (901), der eingerichtet ist, um mittels elastischer Verformung der elastischen Aufhängung (902) resonante Bewegung eines Masse-Federsystems, welches durch den Ablenkspiegel (150) und die elastische Aufhängung (902) ausgebildet ist, zu aktuieren,
  • - einen Laser (101), der eingerichtet ist, um primäres Licht (111) entlang eines Sendestrahls (121) zu emittieren, und
  • - einen Detektor (102), der eingerichtet ist, um sekundäres Licht (112) entlang eines Empfangsstrahls (122) zu detektieren, wobei der Sendestrahl (121) und der Empfangsstrahl (122) entlang eines Überlappabschnitts (125) ausgerichtet sind, wobei der Überlappabschnitt (125) die reflektierende Oberfläche (151) des Ablenkspiegels (150) umfasst,
  wobei das primäre Licht (111) eine schnelle Achse (716) und eine langsame Achse (715) hat, wobei die schnelle Achse (716) eine größere Divergenz (610) als die langsame Achse (715) hat, wobei eine Feldbreite (321-2) der langsamen Achse des primären Lichts (111) entlang der langsamen Achse (715) nicht kleiner als 90% einer entsprechenden Breite (151a, 158) des Ablenkspiegels (150) senkrecht zu einer optischen Achse (199) des Sendestrahls (121) ist.
• Beispiel 4. Scansystem (100) nach Beispiel 3, wobei die Feldbreite (321-2) der langsamen Achse des primären Lichts (111) nicht größer als 120% der entsprechenden Breite (151a, 158) des Ablenkspiegel (150) senkrecht zur optischen Achse (199) des Sendestrahls (121) ist.
• Beispiel 5. Scansystem (100) nach Beispiel 3 oder 4, wobei eine Feldbreite (321-1) der schnellen Achse des primären Lichts (111) entlang der schnellen Achse (716) nicht größer als 50% einer entsprechenden Breite (151a, 159) des Ablenkspiegels (150) senkrecht zu einer optischen Achse (199) des Sendestrahls (121) ist.
• Beispiel 6. Scansystem (100), welches umfasst:
  • - einen Ablenkspiegel (150) mit einer reflektierenden Oberfläche (151),
  • - eine elastische Aufhängung (902) des Ablenkspiegels (150),
  • - einen Aktuator (901), der eingerichtet ist, um mittels elastischer Verformung der elastischen Aufhängung (902) resonante Bewegung eines Masse-Federsystems, welches durch den Ablenkspiegel (150) und die elastische Aufhängung (902) ausgebildet ist, zu aktuieren,
  • - einen Laser (101), der eingerichtet ist, um primäres Licht (111) entlang eines Sendestrahls (121) zu emittieren,
  • - einen Detektor (102), der eingerichtet ist, um sekundäres Licht (112) entlang eines Empfangsstrahls (122) zu detektieren, wobei der Sendestrahl (121) und der Empfangsstrahl (122) entlang eines Überlappabschnitts (125) ausgerichtet sind, wobei der Überlappabschnitt (125) die reflektierende Oberfläche (151) des Ablenkspiegels (150) umfasst, und
  • - eine Kollimatorlinse (201) die eingerichtet ist, um mindestens eine Achse (715, 716) des primären Lichts (111) zu kollimieren,
  wobei die Kollimatorlinse (201) in dem Überlappabschnitt (125) angeordnet ist.
• Beispiel 7. Scansystem (100) nach Beispiel 6, welches weiterhin umfasst:
  • - einen Strahlteiler (130), der einen Kopplungsspiegel (131) mit einer Reflektivität von mindestens 86% umfasst, und der eingerichtet ist, um den Sendestrahl (121) und den Empfangsstrahl (122) an einem Ende des Überlappabschnitts (125) aufzuspalten, und
  • - eine Linse (702), die im Sendestrahl (121) zwischen dem Laser (101) und dem Strahlteiler (130) angeordnet ist,
  wobei die Linse (702) eingerichtet ist, um eine Feldbreite (321-2) des primären Lichts (111) entlang mindestens einer Achse (715, 716) des primären Lichts (111) hin zum Strahlteiler (130) zu verengen oder aufzuweiten.
• Beispiel 8. Scansystem (100) nach Beispiel 6 oder 7, welches weiterhin umfasst:
  • - eine Detektorlinse (252), die eingerichtet ist, um das sekundäre Licht (112) auf den Detektor (102) zu fokussieren,
  wobei die Kollimatorlinse und die Detektorlinse (252) in einen Multifokussegmentierten (801, 802) Linsenkörper (800) integriert sind.
• Beispiel 9. Scansystem (100) nach Beispielen 7 und 8, wobei der Kopplungsspiegel (131) zwischen der Detektorlinse (252) und den Detektor (102) angeordnet ist.
• Beispiel 10. Scansystem (100), welches umfasst:
  • - einen Ablenkspiegel (150) mit einer reflektierenden Oberfläche (151),
  • - eine elastische Aufhängung (902) des Ablenkspiegels (150),
  • - einen Aktuator (901), der eingerichtet ist, um mittels elastischer Verformung der elastischen Aufhängung (902) resonante Bewegung eines Masse-Federsystems, welches durch den Ablenkspiegel (150) und die elastische Aufhängung (902) ausgebildet ist, zu aktuieren,
  • - einen Laser (101), der eingerichtet ist, um primäres Licht (111) entlang eines Sendestrahls (121) zu emittieren,
  • - eine Detektorlinse (252),
  • - einen Detektor (102), der in einer Fokusebene der Detektorlinse (252) angeordnet ist, und der eingerichtet ist, um sekundäres Licht (112) entlang eines Empfangsstrahls (122) zu detektieren, wobei der Sendestrahl (121) und der Empfangsstrahl (122) entlang eines Überlappabschnitts (125) ausgerichtet sind, wobei der Überlappabschnitt (125) die reflektierende Oberfläche (151) des Ablenkspiegels (150) umfasst, und
  • - einen Strahlteiler (130) der einen Kopplungsspiegel (131) mit einer Reflektivität von mindestens 86% umfasst, und der eingerichtet ist, um den Sendestrahl (121) und den Empfangsstrahl (122) an einem Ende des Überlappabschnitts (125) aufzuspalten,
  wobei der Kopplungsspiegel (131) zwischen der Detektorlinse (252) und dem Detektor (102) angeordnet ist.
• Beispiel 11. Scansystem (100) nach einem der voranstehenden Beispiele, wobei der Laser (101) durch eine großflächige Laserdiode mit einer asymmetrischen aktiven Fläche, die eine schnelle Achse (716) des primären Lichts (111) und eine langsame Achse (715) des primären Lichts. (111) definiert, implementiert ist.
• Beispiel 12. Scansystem (100) nach Beispiel 12, wobei die großflächige Laserdiode bei einer Sendeleistung innerhalb von 20% des thermischen Abbruchpunkts betrieben wird, wenn das primäre Licht (111) emittiert wird.
• Beispiel 13. Scansystem (100) gemäß einem der voranstehenden Beispiele, wobei der Sendestrahl (121) und Empfangsstrahl (122) ein Pre-Scanner-koaxiales optisches System mit koaxialen optischen Achsen (199) des Sendestrahls (121) und des Empfangsstrahls (122) implementieren.
• Beispiel 14. Scansystem (100) gemäß einem der voranstehenden Beispiele, wobei der Aktuator (901) eingerichtet ist, um die resonante Bewegung bei Frequenzen im Bereich von 60 Hz bis 500 Hz zu aktuieren.
• Beispiel 15. Scansystem (100) gemäß einem der voranstehenden Beispiele, wobei eine Detektorapertur des Empfangsstrahls und eine Sendeapertur des Sendestrahls beide durch den Ablenkspiegel (150) implementiert werden.
• Beispiel 16. Scansystem (100) gemäß einem der voranstehenden Beispiele, wobei der Laser (101) und der Detektor (102) in einem gemeinsamen Gehäuse integriert sind.

In summary, the following examples have been described above:

• Example 1. Scanning system ( 100 ), which comprises:
  • - a deflecting mirror ( 150 ) with a reflective surface ( 151 )
  • - an elastic suspension ( 902 ) of the deflection mirror ( 150 )
  • an actuator ( 901 ) which is adapted to be deformed by means of elastic deformation of the elastic suspension ( 902 ) resonant motion of a mass-spring system, which by the deflection mirror ( 150 ) and the elastic suspension ( 902 ) is designed to actuate
  • a laser ( 101 ), which is set up to receive primary light ( 111 ) along a transmission beam ( 121 ) to emit, and
  • a detector ( 102 ), which is adapted to secondary light ( 112 ) along a receive beam ( 122 ) to detect where the transmit beam ( 121 ) and the receiving beam ( 122 ) along an overlap section ( 125 ), wherein the overlapping section ( 125 ) the reflective surface ( 151 ) of the deflection mirror ( 150 ),
  where one size ( 158 . 159 ) of the reflective surface ( 151 ) of the deflection mirror ( 150 ) is in the range of 120 mm ² to 230 mm ² , optionally in the range of 180 mm ² to 220 mm ² , and wherein a divergence ( 610 ) of at least one axis of the primary light ( 111 ) along the overlap section ( 125 ) in the range of 0.09 ° to 0.15 ° at the deflection mirror ( 150 ).
• Example 2. The scan system ( 100 ) according to Example 1, which further comprises:
  • where a transmissivity ( 601 - 604 ) of the primary light ( 111 ) at the transmission beam ( 121 ) upstream of the overlap section ( 125 ) with respect to the secondary light ( 112 ) at the corresponding beam ( 122 ) downstream of the overlap section ( 125 ) is not less than 0.40.
• Example 3. Scanning system ( 100 ), which includes
  • a deflecting mirror ( 150 ) with a reflective surface ( 151 )
  • - an elastic suspension ( 902 ) of the deflection mirror ( 150 )
  • an actuator ( 901 ) which is adapted to be deformed by means of elastic deformation of the elastic suspension ( 902 ) resonant motion of a mass-spring system, which by the deflection mirror ( 150 ) and the elastic suspension ( 902 ) is designed to actuate
  • a laser ( 101 ), which is set up to receive primary light ( 111 ) along a transmission beam ( 121 ) to emit, and
  • a detector ( 102 ), which is adapted to secondary light ( 112 ) along a receive beam ( 122 ), the transmit beam ( 121 ) and the receiving beam ( 122 ) along an overlap section ( 125 ), wherein the overlapping section ( 125 ) the reflective surface ( 151 ) of the deflection mirror ( 150 ),
  where the primary light ( 111 ) a fast axis ( 716 ) and a slow axis ( 715 ), where the fast axis ( 716 ) a greater divergence ( 610 ) as the slow axis ( 715 ), where one field width ( 321-2 ) of the slow axis of the primary light ( 111 ) along the slow axis ( 715 ) not less than 90% of a corresponding width ( 151a . 158 ) of the deflection mirror ( 150 ) perpendicular to an optical axis ( 199 ) of the transmission beam ( 121 ).
• Example 4. Scanning system ( 100 ) according to Example 3, wherein the field width ( 321-2 ) of the slow axis of the primary light ( 111 ) not greater than 120% of the corresponding width ( 151a . 158 ) of the deflecting mirror ( 150 ) perpendicular to the optical axis ( 199 ) of the transmission beam ( 121 ).
• Example 5. Scanning system ( 100 ) according to example 3 or 4, wherein one field width ( 321-1 ) of the fast axis of the primary light ( 111 ) along the fast axis ( 716 ) not greater than 50% of a corresponding width ( 151a . 159 ) of the deflection mirror ( 150 ) perpendicular to an optical axis ( 199 ) of the transmission beam ( 121 ).
• Example 6. Scanning system ( 100 ), which comprises:
  • a deflecting mirror ( 150 ) with a reflective surface ( 151 )
  • - an elastic suspension ( 902 ) of the deflection mirror ( 150 )
  • an actuator ( 901 ) which is adapted to be deformed by means of elastic deformation of the elastic suspension ( 902 ) resonant motion of a mass-spring system, which by the deflection mirror ( 150 ) and the elastic suspension ( 902 ) is designed to actuate
  • a laser ( 101 ), which is set up to receive primary light ( 111 ) along a transmission beam ( 121 ) to emit,
  • a detector ( 102 ), which is adapted to secondary light ( 112 ) along a receive beam ( 122 ), the transmit beam ( 121 ) and the receiving beam ( 122 ) along an overlap section ( 125 ), wherein the overlapping section ( 125 ) the reflective surface ( 151 ) of the deflection mirror ( 150 ), and
  • a collimator lens ( 201 ) which is adapted to at least one axis ( 715 . 716 ) of the primary light ( 111 ) to collimate,
  the collimator lens ( 201 ) in the overlapping section ( 125 ) is arranged.
• Example 7. Scanning System ( 100 ) according to Example 6, which further comprises:
  • a beam splitter ( 130 ), which has a coupling mirror ( 131 ) with a reflectivity of at least 86%, and which is arranged to control the transmission beam ( 121 ) and the receiving beam ( 122 ) at one end of the overlap section ( 125 ), and
  • - a lens ( 702 ), which are in the transmission beam ( 121 ) between the laser ( 101 ) and the beam splitter ( 130 ) is arranged
  the lens ( 702 ) is set to a field width ( 321-2 ) of the primary light ( 111 ) along at least one axis ( 715 . 716 ) of the primary light ( 111 ) to the beam splitter ( 130 ) to narrow or widen.
• Example 8. Scanning System ( 100 ) according to Example 6 or 7, which further comprises:
  • a detector lens ( 252 ) which is adapted to the secondary light ( 112 ) on the detector ( 102 ) to focus
  the collimator lens and the detector lens ( 252 ) into a multi-focus segmented ( 801 . 802 ) Lens body ( 800 ) are integrated.
• Example 9. Scanning System ( 100 ) according to Examples 7 and 8, wherein the coupling mirror ( 131 ) between the detector lens ( 252 ) and the detector ( 102 ) is arranged.
• Example 10. Scanning System ( 100 ), which comprises:
  • a deflecting mirror ( 150 ) with a reflective surface ( 151 )
  • - an elastic suspension ( 902 ) of the deflection mirror ( 150 )
  • an actuator ( 901 ) which is adapted to be deformed by means of elastic deformation of the elastic suspension ( 902 ) resonant motion of a mass-spring system, which by the deflection mirror ( 150 ) and the elastic suspension ( 902 ) is designed to actuate
  • a laser ( 101 ), which is set up to receive primary light ( 111 ) along a transmission beam ( 121 ) to emit,
  • a detector lens ( 252 )
  • a detector ( 102 ), which in a focal plane of the detector lens ( 252 ) is arranged and which is adapted to secondary light ( 112 ) along a receive beam ( 122 ), the transmit beam ( 121 ) and the receiving beam ( 122 ) along an overlap section ( 125 ), wherein the overlapping section ( 125 ) the reflective surface ( 151 ) of the deflection mirror ( 150 ), and
  • a beam splitter ( 130 ) of a coupling mirror ( 131 ) with a reflectivity of at least 86%, and which is arranged to control the transmission beam ( 121 ) and the receiving beam ( 122 ) at one end of the overlap section ( 125 ),
  where the coupling mirror ( 131 ) between the detector lens ( 252 ) and the detector ( 102 ) is arranged.
• Example 11. Scanning System ( 100 ) according to one of the preceding examples, wherein the laser ( 101 ) by a large-area laser diode with an asymmetric active surface, which has a fast axis ( 716 ) of the primary light ( 111 ) and a slow axis ( 715 ) of the primary light. ( 111 ) is implemented.
• Example 12. Scanning System ( 100 ) according to Example 12, wherein the large-area laser diode is operated at a transmission power within 20% of the thermal termination point when the primary light ( 111 ) is emitted.
• Example 13. Scanning System ( 100 ) according to one of the preceding examples, wherein the transmission beam ( 121 ) and receiving beam ( 122 ) a pre-scanner coaxial optical system with coaxial optical axes ( 199 ) of the transmission beam ( 121 ) and the receiving beam ( 122 ) to implement.
• Example 14. Scanning System ( 100 ) according to one of the preceding examples, wherein the actuator ( 901 ) is arranged to actuate the resonant motion at frequencies in the range of 60 Hz to 500 Hz.
• Example 15. Scanning System ( 100 ) according to one of the preceding examples, wherein a detector aperture of the receive beam and a transmit aperture of the transmit beam both through the deflection mirror ( 150 ).
• Example 16. Scanning System ( 100 ) according to one of the preceding examples, wherein the laser ( 101 ) and the detector ( 102 ) are integrated in a common housing.

Although particular embodiments have been expressly described above, other embodiments will become apparent to those skilled in the art upon a reading and understanding of the specification. All such implementations are deemed to fall within the scope of the present invention, which is limited only by the appended claims.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 20160161600 A1 [0004]
• US 20170343653 A1 [0004]
• US 20110216304 A1 [0005]
• EP 2541273 B1 [0005]
• US 20100296146 A1 [0006]
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• US 20180143322 A1 [0058]
• DE 102016014001 A1 [0058]
• DE 102009058762 A1 [0058]
• US 20100290142 A1 [0058]

Claims (10)

A scanning system (100) comprising: - a deflecting mirror (150) having a reflective surface (151), - an elastic suspension (902) of the deflecting mirror (150), - an actuator (901) adapted to deform by means of elastic deformation the elastic suspension (902) actuate resonant motion of a mass-spring system formed by the deflection mirror (150) and the elastic suspension (902), - a laser (101) adapted to receive primary light (111) along a transmit beam (121), and - a detector (102) arranged to detect secondary light (112) along a receive beam (122), the transmit beam (121) and the receive beam (122) passing along a beam Overlap portion (125) are aligned, wherein the overlap portion (125) the reflective surface (151) of the deflection mirror (150), wherein a size (158, 159) of the reflective surface (151) of the deflection mirror (150) in Be range from 120 mm ² to 230 mm ² , optionally in the range of 180 mm ² to 220 mm ² , and wherein a divergence (610) of at least one axis of the primary light (111) along the overlap portion (125) in the range of 0.09 ° to 0.15 ° at the deflecting mirror (150). Scan system (100) Claim 1 which further comprises: a transmittivity (601-604) of the primary light (111) at the transmitting beam (121) upstream of the overlapping portion (125) with respect to the secondary light (112) at the corresponding beam (122) downstream of the overlapping portion (125 ) is not less than 0.40, Scanning system (100) comprising a deflection mirror (150) having a reflective surface (151), an elastic suspension (902) of the deflection mirror (150), an actuator (901) adapted to actuate by elastic deformation of the elastic suspension (902) resonant motion of a mass-spring system formed by the deflection mirror (150) and the elastic suspension (902), a laser (101) arranged to emit primary light (111) along a transmission beam (121), and a detector (102) arranged to detect secondary light (112) along a receive beam (122), the transmit beam (121) and the receive beam (122) being aligned along an overlap portion (125), the overlap portion (125) comprises the reflecting surface (151) of the deflecting mirror (150), wherein the primary light (111) has a fast axis (716) and a slow axis (715), the fast axis (716) having a greater divergence (610) than the slow axis (715), wherein a field width (321-2) of the slow axis of the primary light (111) along the slow axis (715) is not less than 90% of a corresponding width (151a, 158) of the deflection mirror (150) perpendicular to an optical axis (199). of the transmission beam (121). Scan system (100) Claim 3 wherein the field width (321-2) of the slow axis of the primary light (111) is not greater than 120% of the corresponding width (151a, 158) of the deflection mirror (150) perpendicular to the optical axis (199) of the transmit beam (121). Scan system (100) Claim 3 or 4 wherein a field width (321-1) of the fast axis of the primary light (111) along the fast axis (716) is not greater than 50% of a corresponding width (151a, 159) of the deflection mirror (150) perpendicular to an optical axis (199 ) of the transmission beam (121). Scanning system (100) comprising a deflection mirror (150) having a reflective surface (151), an elastic suspension (902) of the deflection mirror (150), an actuator (901) adapted to actuate by elastic deformation of the elastic suspension (902) resonant motion of a mass-spring system formed by the deflection mirror (150) and the elastic suspension (902), a laser (101) arranged to emit primary light (111) along a transmission beam (121), a detector (102) arranged to detect secondary light (112) along a receive beam (122), the transmit beam (121) and the receive beam (122) being aligned along an overlap portion (125), the overlap portion (125) comprises the reflecting surface (151) of the deflecting mirror (150), and a collimator lens (201) arranged to collimate at least one axis (715, 716) of the primary light (111), the collimator lens (201) being disposed in the overlap portion (125). Scan system (100) Claim 6 , which further comprises: - a beam splitter (130) comprising a coupling mirror (131) with a reflectivity of at least 86%, and which is arranged to transmit the transmission beam (121) and splitting the receive beam (122) at an end of the overlap portion (125); and a lens (702) disposed in the transmit beam (121) between the laser (101) and the beam splitter (130); Lens (702) is arranged to narrow or widen a field width (321-2) of the primary light (111) along at least one axis (715, 716) of the primary light (111) toward the beam splitter (130). Scan system (100) Claim 6 or 7 and further comprising: a detector lens (252) arranged to focus the secondary light (112) onto the detector (102), the collimator lens and the detector lens (252) arranged in a multi-focus segmented (801, 802) lens body (800) are integrated. Scan system (100) Claim 7 and 8th wherein the coupling mirror (131) is disposed between the detector lens (252) and the detector (102). Scanning system (100) comprising: a deflection mirror (150) having a reflective surface (151), an elastic suspension (902) of the deflection mirror (150), an actuator (901) adapted to actuate by elastic deformation of the elastic suspension (902) resonant motion of a mass-spring system formed by the deflection mirror (150) and the elastic suspension (902), a laser (101) arranged to emit primary light (111) along a transmission beam (121), a detector lens (252), a detector (102) disposed in a focal plane of the detector lens (252) and arranged to detect secondary light (112) along a receive beam (122), the transmit beam (121) and the receive beam (122 ) are aligned along an overlap portion (125), the overlap portion (125) comprising the reflective surface (151) of the deflecting mirror (150), and - A beam splitter (130) comprising a coupling mirror (131) having a reflectivity of at least 86%, and which is arranged to split the transmission beam (121) and the receiving beam (122) at one end of the overlapping portion (125) Coupling mirror (131) between the detector lens (252) and the detector (102) is arranged.

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