WO2023111667A1

WO2023111667A1 - Scanning system for range detection sensor

Info

Publication number: WO2023111667A1
Application number: PCT/IB2021/062057
Authority: WO
Inventors: André ANTUNES DE CARVALHO ALBUQUERQUE; Alexandre Manuel RIBEIRO CORREIA; Jorge Miguel NUNES DOS SANTOS CABRAL; Alexander SIMON EELES; João António GONÇALVES DE SOUSA MARQUES DE CARVALHO; João Carlos AZEVEDO GASPAR; Diogo Elói TRINDADE DE AGUIAM; Inês Sofia MOREIRA GARCIA
Original assignee: Bosch Car Multimedia Portugal, S.A.; Universidade Do Minho
Priority date: 2021-12-17
Filing date: 2021-12-21
Publication date: 2023-06-22

Abstract

The present invention describes a system and method to scan the Field of View (FoV) of interest of a LiDAR system. The invention discloses an innovative method to scan a wide angle FoV by combining diffractive optical elements with a beam steering mechanism designed for small to moderate scanning angles and an array of photodetectors. The developed system (100) comprises a laser source (1) adapted to emit a light beam; a set of optical elements (2) adapted to collect and modify the emitted light beam by the laser source (1); and a reflective apparatus (3), adapted to reflect and increase the FoV range of the modified light beam from the set of optical elements (2) towards the surrounding environment of the sensor until it reaches a fixed or moving target.

Description

DESCRIPTION

"SCANNING SYSTEM FOR RANGE DETECTION SENSOR"

Technical Field

The present application describes a system and method to scan the Field of View ( FoV) of interest of a LiDAR system .

Background art

Light Detecting and Ranging ( LiDAR) systems are used in a wide range of practical applications requiring remote measurements . In general , LiDAR comprises a set of techniques that use laser light to measure the distance to a speci fic target within a speci fic Field of View ( FoV) . In the case of a scanning LiDAR sensor, the emitted laser beam scans the FoV of interest and obtains the distance usually by measuring the time-of- f light ( ToF) a laser pulse takes to travel to a speci fic target and to return to the sensor, or by using techniques based on frequency, amplitude or polari zation modulation .

There are many di fferent techniques that can be used to scan the laser beam over the target FoV . Some examples include the mechanical rotation of the full sending and receiving parts of the sensor, galvanometer scanning mirrors , electrooptic scanners based on crystal liquids , integrated optical phased-array antennas or scanners based on 1-D or 2-D micro- electro-mechanical systems (MEMS ) mirrors .

Recently, MEMS-based scanning mirrors have been receiving high interest from the automotive industry as a particularly relevant platform to build a compact , low-power consumption and lightweight LiDAR sensor . These devices can steer an incoming laser beam to di f ferent angles of the FoV driven by an applied external signal , either through electromagnetic, electrostatic or piezoelectric actuation, or even a combination of multiple actuation mechanisms .

Despite the signi ficant breakthroughs achieved in MEMS-based LiDAR sensors , it is still very challenging to achieve large scanning angles ( >45 ° ) , in particular for 2-D scanning . This situation is caused mostly due to the strong electrostatic/magnetic fields required to tilt the MEMS mirrors and physical limitations ( inertia, torsion and bending limits , etc . ) .

Summary

The present invention describes a system comprising a laser source adapted to emit a light beam; a set of optical elements adapted to collect and modi fy the emitted light beam by the laser source ; and a reflective apparatus , adapted to reflect and increase the FoV range of the modi fied light beam from the set of optical elements towards the surrounding environment of the sensor until it reaches a fixed or moving target .

In a proposed embodiment of present invention, the system comprises a set of receiving optics and a photodetector .

Yet in another proposed embodiment of present invention, the system comprises a set of reshaping optical elements adapted to reshape the reflected light beam from the reflective apparatus . Yet in another proposed embodiment of present invention, the modi fied reflected light beam with increased FoV comprises at least one of a laser "line beam" shape , a laser "multispot" shape or a Nh x Nv laser "multispot" shape .

Yet in another proposed embodiment of present invention, the reflective apparatus comprises a MEMS mirror and a DOE .

Yet in another proposed embodiment of present invention, the MEMS mirror comprises one of single scanning axis or double scanning axis .

Yet in another proposed embodiment of present invention, the DOE comprises one of a " line beam" shape , a "multispot" shape or a Nh x Nv "multispot" shape .

Yet in another proposed embodiment of present invention, the MEMS mirror and a DOE are arranged separately or embedded together in a single element inside the reflective apparatus .

Yet in another proposed embodiment of present invention, the photodetector comprises a matrix with a set of pixels , said matrix being characteri zed by an angular resolution determined by the size of the pixels and by the focal length of the receiving optics .

Yet in another proposed embodiment of present invention, the resulting modi fied light beam from the set of optical elements reaches the DOE in an angle of incidence determined by the scanning angle of the MEMS mirror .

Yet in another proposed embodiment of present invention, the scanning angle of the MEMS mirror and angle of incidence at the DOE, being arranged separately or embedded together a single element, are variably adjusted to allow the increase of the FoV.

General Description

The present application describes a system and method to scan the Field of View (FoV) of interest of a LiDAR system.

Present invention combines micro-electro-mechanical systems (MEMS) mirror with diffractive optical elements (DOEs) as a solution to increase the FoV or alleviate the design requirements of a MEMS-based LiDAR. Here, the DOE creates a specific pattern (multispot or line beam) that is then swept over a target FoV by the MEMS mirror. It is also disclosed how to combine the DOE with the MEMS mirrors in a single device, embedding the DOEs that produce a multispot pattern or line beam (instead of a simple grating) , allowing to greatly simplify the alignment and complexity of the system leading to a more robust solution.

Therefore, the present invention aims to solve several existing problems present in state-of-the-art technologies, particularly :

- Produce a laser sensor capable of detecting objects within a large FoV range area;

- Develop a scanning subsystem for a LiDAR sensor that is able to steer a laser beam over a large FoV area in both vertical and horizontal directions;

- Develop a compact, lightweight and cost-effective steering method;

- Alleviate the requirements of MEMS mirrors to achieve large FoV angles; Increase the FoV angles and/or alleviate the MEMS mirror requirements of the scanning subsystem without signi ficantly increasing the complexity of the subsystem .

Therefore , the technological advances disclosed by present invention introduce several advantages , particularly :

Increase the FoV angles when compared to unique and single 1-D or 2-D MEMS mirrors ;

- Extend the maximum FoV angles of a MEMS-based LiDAR sensor beyond the maximum limit of the MEMS mirror ;

- Mitigate the need of additional MEMS mirror requirement to perform the large 2 -D FoV scanning;

- Obtain a compact and lightweight solution;

- The MEMS + DOE approach can achieve a similar FoV scanning range as with a single MEMS mirror, but with smaller rotation angles of the MEMS mirror ;

- Obtain multiple combinations of 1-D or 2-D MEMS mirrors and DOEs ;

- Embed the DOE on the surface of the MEMS mirror to obtain a compact and simple solution .

Brief description of the drawings

For better understanding of the present application, figures representing preferred embodiments are herein attached which, however, are not intended to limit the technique disclosed herein .

Fig . 1 - illustrates the block diagram of the LiDAR system, wherein the reference numbers refer to :

100 - LiDAR system / sensor ;

1 - laser source ; 2 - sending optical elements;

3 - reflective apparatus / MEMS mirror + DOE subsystem;

4 - reshaping optical elements;

5 - target;

6 - receiving optics;

7 - receiving photodetector.

Fig. 2 - illustrates a schematic representation of MEMS mirror + DOE subsystem based on a laser "line beam" DOE with separate MEMS mirror and separate DOE, wherein the reference numbers refer to:

1 - laser source;

2 - sending optical elements;

3 - reflective apparatus / MEMS mirror + DOE subsystem;

31 - MEMS mirror with single scanning axis (1-D) ;

32 - DOE set with "line beam" shape;

80 - laser line beam.

Fig. 3 - illustrates a schematic representation of MEMS mirror + DOE subsystem based on a laser "line beam" DOE with MEMS mirror and DOE combined in a single element, wherein the reference numbers refer to:

1 - laser source;

2 - sending optical elements;

3 - reflective apparatus / MEMS mirror + DOE subsystem;

33 - MEMS mirror with single scanning axis and embedded "line beam" DOE single element;

80 laser line beam.

Fig. 4 - Illustration of the resulting laser "line beam" of the MEMS mirror + DOE subsystem imaged at the photodetector matrix, wherein the reference numbers refer to:

80 - laser line beam; 81 - photodetector matrix;

82 - photodetector pixel.

Fig. 5 - illustrates a schematic representation of MEMS mirror + DOE subsystem based on a "multispot" DOE generating four separate laser spots with separate MEMS mirror and separate DOE, wherein the reference numbers refer to:

1 - laser source;

2 - sending optical elements;

3 - reflective apparatus / MEMS mirror + DOE subsystem;

31 - MEMS mirror with dual scanning axis (2-D) ;

32 - DOE set with "multispot" shape;

83 - multiple laser spots.

Fig. 6 - illustrates a schematic representation of MEMS mirror + DOE subsystem based on a "multispot" DOE generating four separate laser spots with MEMS mirror and DOE combined in a single element, wherein the reference numbers refer to:

1 - laser source;

2 - sending optical elements;

3 - reflective apparatus / MEMS mirror + DOE subsystem;

33 - MEMS mirror with dual scanning axis and embedded "multispot" DOE single element;

83 - multiple laser spots.

Fig. 7 - Illustration of the resulting four laser spots of the MEMS mirror + DOE subsystem imaged at the photodetector matrix, wherein the reference numbers refer to:

81 - photodetector matrix;

82 - photodetector pixel;

83 - multiple laser spots;

90 - 0MEMs,h + 0DOE,h angle, -

91 - 0MEMS,V + 0DOE,V angle; 92 — 0MEMS , V angle ;

93 - 0DOE,h angle ;

94 - 0DOE, V angle ;

95 - 0MEMs,h angle .

The inner rectangle delimited by a dashed line indicates the maximum FoV of the MEMS mirror for a single beam, without the DOE . The dashed arrows represent the directions and amplitude of the MEMS mirror scanning .

Fig . 8 - illustrates a schematic representation of MEMS mirror + DOE subsystem based on a Nh x Nv "multispot" DOE generating Nh x Nv multiple separate laser spots with separate MEMS mirror and separate DOE , wherein the reference numbers refer to :

1 - laser source ;

2 - sending optical elements ;

3 - reflective apparatus / MEMS mirror + DOE subsystem;

31 - MEMS mirror with dual scanning axis ;

32 - DOE set with Nh x Nv "multispot" shape ;

84 - Nh x Nv multiple laser spots .

Fig . 9 - illustrates a schematic representation of MEMS mirror + DOE subsystem based on a Nh x Nv "multispot" DOE generating Nh x Nv multiple separate laser spots with MEMS mirror and DOE combined in a single element , wherein the reference numbers refer to :

1 - laser source ;

2 - sending optical elements ;

3 - reflective apparatus / MEMS mirror + DOE subsystem;

33 - MEMS mirror with dual scanning axis and embedded Nh x Nv "multispot" DOE single element ;

84 - Nh x Nv multiple laser spots . Fig. 10 - Illustration of the resulting multiple pixels per spot of the Nh x Nv laser spots imaged at the photodetector matrix with of the separated MEMS mirror + DOE subsystem, wherein the reference numbers refer to:

81 - photodetector matrix;

82 - photodetector pixel;

84 - Nh x Nv multiple laser spots;

92 — 0MEMS,V angle;

93 - 0DOE,h angle;

94 - 0DOE,V angle;

95 - 0MEMs,h angle;

96 - Nh x 0DOE,h angle;

97 - Nv x 0DOE,V angle;

The inner rectangle delimited by a dashed line indicates the maximum FoV of the MEMS mirror for a single beam, without the DOE. The dashed arrows represent the directions and amplitude of the MEMS mirror scanning.

Fig. 11 - Illustration of the resulting single photodetector pixels per spot of the Nh x Nv laser spots imaged at the photodetector matrix with of the combined MEMS mirror + DOE subsystem, wherein the reference numbers refer to:

81 - photodetector matrix;

82 - photodetector pixel;

84 - Nh x Nv multiple laser spots;

92 — 0MEMS,V angle;

95 - 0MEMs,h angle;

96 - Nh x 0DOE,h angle;

97 - Nv x 0DOE,V angle;

The inner rectangle delimited by a dashed line indicates the maximum FoV of the MEMS mirror for a single beam, without the DOE. The dashed arrows represent the directions and amplitude of the MEMS mirror scanning. Description of Embodiments

With reference to the figures, some embodiments are now described in more detail, which are however not intended to limit the scope of the present application.

The invention herein reported describes a method and apparatus for a scanning subsystem in a LiDAR sensor. The invention relies on combining DDEs with MEMS mirrors to scan a specific FoV area.

A simplified block diagram of the LiDAR system (100) is represented in Figure 1. As shown in the figure, the LiDAR system (100) comprises a laser source (1) responsible for emitting the laser pulse light beams. Such laser source (1) can be built using different types of lasers, e.g., edgeemitting (Fabry-Perot) lasers, vertical-cavity surfaceemitting lasers (VCSELs) , fiber lasers, etc. The laser light emitted by the laser source (1) then goes through a set of optical elements (2) , collimating or focusing lens, that are responsible for collimating or focusing the laser beam onto the MEMS mirror + DOE subsystem (3) . After the MEMS mirror + DOE subsystem (3) , an additional set of optical elements (4) can be optionally used to collimate or reshape the beam or even to adapt the FoV. The resulting laser beam then propagates through the environment until it reaches a target within a certain FoV. A portion of the reflected light beam then returns to the LiDAR system (100) and is focused onto the photodetector (7) through the receiving optics (6) . In a possible embodiment of the invention, illustrated in Figure 2, the reflective apparatus (3) comprises a MEMS mirror (31) with single scanning axis for laser beam steering (1-D MEMS mirror) and a transmissive DOE (32) that is especially designed to produce a laser "line beam" DOE (80) . In this embodiment, the laser source (1) generates a laser light beam that passes through the set of optical elements (2) (collimating optical lens) , before reaching the single scanning axis MEMS mirror (31) . It is assumed here that the laser beam is first collimated before the MEMS mirror (31) , but other configurations are possible, e.g., using a lens (2) to focus the laser beam on the MEMS mirror (31) .

The MEMS mirror (31) then reflects the laser beam towards the DOE set (32) . The angle of incidence at which the laser beam reaches the DOE (32) is determined by the scanning angle of the MEMS mirror (31) . The DOE (32) is responsible for spreading the laser light beam (80) perpendicularly to the scanning axis. Along with this direction, the laser line beam (80) illuminates the entire FoV (e.g., along either in the horizontal or vertical direction) , as in a flash LiDAR, and a matrix (81) in the receiving photodetector (7) must be used to resolve the different angular positions of the received reflection light. A schematic representation of the resulting reflected MEMS mirror + DOE subsystem received laser light beam (80) in the matrix (81) of the photodetector (7) is imaged in Figure 4. The entire FoV can thus be scanned by sweeping the line beam perpendicularly to the line, which can be achieved through the rotation of the MEMS mirror (31) . The proposed invention can be considered as a hybrid approach that combines a flash illumination strategy (along the direction of the line) and scanning (perpendicularly to the line) . As previously mentioned, the invention requires a two- dimensional photodetector (7) with a matrix (81) adapted to resolve the different angular positions of the reflected light. Alternatively, it is also possible to consider a single scanning axis photodetector array that discriminates the different angles along the direction of the array via focal plane imaging combined with an additional single scanning axis scanning mirror at the receiver that sweeps in a direction perpendicular to the line and the single scanning axis photodetector array. The additional mirror must be therefore synchronized with the MEMS mirror at the emitting part of the system.

However, the proposed embodiment as some limitations related to the geometric arrangement of the MEMS mirror (31) and the DOE (32) . Whenever the MEMS mirror (31) redirects the beam to a different angle, the laser beam does not hit the DOE

(32) at the same position. In fact, if the two elements are relatively far apart from each other inside the reflective apparatus (3) and/or the DOE (32) is small, the reflected beam by the MEMS (31) may not even hit the DOE (32) . To overcome this building limitation and increase the overall performance of the sensor (100) , an alternative embodiment of the invention is presented in Figure 3. In the proposed embodiment, the DOE and MEMS mirror are combined in a single element (33) , embedded together inside the reflective apparatus, producing the diffraction pattern of the laser line beam DOE (80) on the surface of the embedded MEMS mirror

(33) . Hence, the MEMS mirror with the embedded diffraction pattern single element (33) can simultaneously produce the laser line beam (80) and scan it over the perpendicular direction. With the proposed approach, not only the main limitation of the previous embodiment of Figure 2 is overcome, but the overall complexity of the system also simplifies .

As aforementioned, the receiving photodetector (7) , in one of the proposed embodiments of the invention, resorts to the use of a photodetector matrix (81) , which can include, but not limited to, photodiodes, phototransistors, avalanche photodiodes (APDs) , or single-photon avalanche photodiodes (SPADs) .

Along the direction of the laser line beam (80) , the angular resolution is determined by the number and size of the pixels (82) in the photodetector matrix (81) and by the focal length of the objective lens / receiving optics (6) at the receiving part of the sensor (100) . In this case, each pixel (82) of the matrix (81) , corresponds to a specific angular position, similarly to what happens in a standard camera (focal plane imaging technique) . In the perpendicular direction, the same technique can be used or alternatively, the sensor (100) can read the tilt angle of the MEMS mirror (31) and translate it into an angular position in the FoV.

These above-described embodiments focus on generating a laser line beam (80) , and scanning it along a single direction, perpendicular to generated laser line. In different and alternative approaches of the invention, the MEMS + DOE subsystem (3) comprises a MEMS mirror (31) adapted to steer the emitted light beam in two different directions (2-D MEMS mirror) and a shaped DOE (32) that splits the emitted light beam by the laser source into multiple beams (multispot DOE) , each beam pointing to a different angular position. In one not limiting possible configuration, shown in Figure 5, the DOE (32) splits the beam into four spots (83) arranged in a rectangular configuration. By changing the angle of the dual scanning axis MEMS mirror (31) , the angle of incidence at the DOE (32) and, consequently, the output angle of the multiple emitted laser light beams (83) can be adjusted. Thus, the multiple laser beams (83) can scan the entire FoV. The main advantage of the proposed arrangement, when compared to using a single scanning axis MEMS mirror, is the possibility to increase the FoV from the 0MEMS,V angle (92) to 0MEMS,V (92) + 0DOE,V (94) angle in the vertical direction, and from 0MEMS,H angle (95) to 0MEMS,H (95) + 0DOE,h (93) angle, where 0MEMS,V (92) and 0MEMS,H (95) are the vertical and horizontal FoV angles achieved using only the MEMS mirror (31) , and 0DOE,V (94) and 0DOE,H (93) are the vertical and horizontal angular separations between the beam spots (83) of the DOE (32) . The light beams reflected by the target and imaged by the receiving optics (6) on the matrix (81) of the receiving photodetector (7) for the proposed embodiment are schematically represented in Figure 7. If no DOE (32) is used in combination with the MEMS mirror (31) in the MEMS + DOE subsystem (3) , only a single laser spot will be imaged at the matrix (81) of the receiver photodetector (7) . Such imaged laser beam is formed in a certain position inside the dashed rectangle in Figure 7, which depends on the deflection angle of the MEMS mirror (31) . When the DOE (32) is added, such beam is splitted into four new laser beams (83) at angles corresponding to combinations of ±0DOE,V/2 vertically, and ±0DOE,H/2 horizontally. Consequently, it leads to an increase of the horizontal FoV by 0DOE,H (93) and of the vertical FoV by 0DOE,V (94) . It should be noted however, that in order to avoid either scanning gaps or overlaps, 0MEMS,H (95) and 0MEMS,V (92) angles must be respectively equal to, or approximately equal to 0DOE,h (92) and 0DOE,V (94) angles.

As discussed for the embodiment depicted in Figure 3, it is also possible to combine the DOE (32) and the MEMS mirror (31) in a single element (33) , as suggested in Figure 6, to simultaneously simplify the system and to ensure that the emitted light beam hits the DOE even when the tilt angle of the MEMS mirror is large.

In both illustrative embodiments shown in Figure 5 and Figure 6, since the DOE only splits the laser beam into four laser spots (83) , one still requires both a large tilt angle of the combined MEMS mirror (31) and a large angular separation between the multiple laser spots (83) in order to obtain a large FoV and large scanning angles.

In a generalization of the previous embodiment, illustrated in Figure 8, the DOE (32) is designed to split the emitted light beam into a rectangular Nh x Nv array of multiple laser narrow spots (84) , with Nh and Nv being the number of spots in the horizontal and vertical directions, respectively. In addition, the angular separation between adjacent spots is purposely designed to be large in order to achieve a large FoV. Each generated Nh x Nv array of multiple laser spots (84) has a low divergence angle, which must be equal to the minimum angular resolution required for the whole LiDAR system (100) . If the MEMS mirror (31) is not moving and stays, for instance, at a 0° tilt angle position, the LiDAR system (100) can only map a discrete set of angles in the FoV with coarse spacing, which corresponds to the FoV regions illuminated by each of the multispot laser beams (84) generated by the DOE (32) . At the receiver side, the receiving optics (6) collect and focus the reflected light from the illuminated targets onto the matrix (81) of the receiving photodetector (7) , which images the incoming reflected light as a set of discrete spots (84) , as shown in Figure 10. Each of such spots (84) corresponds to a specific laser beam generated by the DOE (32) and, consequently, to a different angle of the FoV.

Even without changing the angle of the MEMS mirror (31) , the multispot beam generated by the DOE (32) is able to illuminate multiple targets simultaneously within almost the entire FoV, but with a coarse angular resolution. A finer resolution can be obtained by tilting the MEMS mirror (31) axis with a relatively small angular step. As discussed before, this changes the angle of incidence of the emitted laser beam on the DOE (32) and, consequently, the angles of the multiple emitted light beams after the DOE (32) . Thus, the proposed approach can be seen as an hybrid flash/ scanning system where the multispot DOE (32) is responsible to flash a discrete and coarse set of angles over the entire FoV, whereas the MEMS mirror (31) is responsible for scanning the multiple beams with a much finer angular resolution. As a consequence, the maximum angular scanning range required for the MEMS mirror (31) to cover is much smaller than for the embodiment shown in Figure 5 and Figure 6, and equal to the angular spacing between adjacent beams generated by the "multispot" DOE, i.e., 0MEMS,H (95) = 0DOE,H (93) angle and 0MEMS,V (92) = 0DOE,V (94) angle, with 0DOE,H (93) and 0DOE,V (94) now being the horizontal and vertical angular separation between adjacent spots (84) . However, such advantage comes at the cost of a more challenging design of the DOE (32) and lower power per spot, for the same power emitted by the laser source (1) . The maximum horizontal and vertical FoV angles for this embodiment are thus given by Nh x 0DOE,h and Nv x

0DOE,V, respectively.

In a preferred variant of this embodiment, shown in Figure 9, the "multispot" DOE (32) and MEMS mirror (31) are combined in a single element (33) , wherein the diffraction pattern of the DOE (32) is embedded at the surface of the MEMS mirror (31) .

As concerns the receiver side apparatus and the embodiments illustrated in both Figure 8 and Figure 9, two possible alternatives exist for the photodetector matrix (81) . In a first alternative, depicted in Figure 10, the maximum angular resolution is defined by the size of the pixel (82) and the focal length of the receiving optics (6) . In this case, however, even if the angle position of the MEMS mirror of the single element (33) could be controlled with much finer angular precision, the resolution would be defined by the pixel size (82) and focal length of the receiving optics (6) . Moreover, the invention is also compatible with super resolution techniques, for instance, by measuring the intensity of the received light beam in neighbouring pixels (82) and computing the so-called centroid position.

A different alternative is presented in Figure 11, in which there is a one-to-one mapping between each spot (84) of the reflected multispot beam and each pixel (82) of the photodetector matrix (81) . At the image plane, each laser spot (84) may be focused at a slightly different location within a macropixel, depending on the tilt angle of the combined MEMS mirror of the single element (33) , but it always stays focused on the same pixel (82) . By relying only on the photodetector matrix (81) , this approach provides an angular discrimination with coarse resolution, equal to the angular spacing between the adj acent spots ( 84 ) . However, a finer resolution can be achieved by using narrow LiDAR spots which illuminate di f ferent targets within the FoV region defined by the macropixel reception cone and reading the angular position of the combined MEMS single element ( 33 ) . Hence , each pixel ( 82 ) of the photodetector array ( 7 ) is responsible for defining an angular region in space from which the reflected rays may be coming from and the tilt angle position of the MEMS mirror defines the angle within this region with higher precision . This alternative has the advantage of not requiring a pixel density at the photodetector matrix as high as for the alternative in Figure 10 , but at the expense of requiring to read the tilt angle position of the MEMS mirror with high precision and accuracy . Moreover, it is also impaired by "blind zones" between adj acent pixels , in which the detector is not sensitive .

Claims

1. System (100) comprising a laser source (1) adapted to emit a light beam; a set of optical elements (2) adapted to collect and modify the emitted light beam by the laser source (1) ; and a reflective apparatus (3) adapted to reflect and increase the FoV range of the modified light beam from the set of optical elements (2) towards the surrounding environment of the sensor until it reaches a fixed or moving target.

2. System (100) according to previous claim, comprising a set of receiving optics (6) and a photodetector (7) .

3. System (100) according to previous claims, comprising a set of reshaping optical elements (4) adapted to reshape the reflected light beam from the reflective apparatus (3) .

4. System (100) according to previous claims, wherein the modified reflected light beam with increased FoV comprises at least one of a laser "line beam" shape (80) , a laser "multispot" shape (83) or a Nh x Nv laser "multispot" shape (84) .

5. System (100) according to previous claims, wherein the reflective apparatus (3) comprises a MEMS mirror (31) and a DOE (32) .

6. System (100) according to previous claims, wherein the MEMS mirror (31) comprises one of single scanning axis or double scanning axis.

7. System (100) according to previous claims, wherein the DOE (32) comprises one of a "line beam" shape, a "multispot" shape or a Nh x Nv "multispot" shape.

8. System (100) according to previous claims, wherein the MEMS mirror (31) and a DOE (32) are arranged separately or embedded together in a single element (33) inside the reflective apparatus (3) .

9. System (100) according to previous claims, wherein the photodetector (7) comprises a matrix (81) with a set of pixels (82) , said matrix (81) being characterized by an angular resolution determined by the size of the pixels (82) and by the focal length of the receiving optics (6) .

10. System (100) according to previous claims, wherein the resulting modified light beam from the set of optical elements (2) reaches the DOE (32) in an angle of incidence determined by the scanning angle of the MEMS mirror (31) .

11. System (100) according to previous claims, wherein the scanning angle of the MEMS mirror (31) and angle of incidence at the DOE (32) , being arranged separately (31, 32) or embedded together in a single element (33) , are variably adjusted to allow the increase of the FoV.