Optical sensing system

Abstract

The invention relates to an optical sensing system (1) for efficient optical sensing. The system (1) comprises at least one optical sensor (2) and an optical element (3) capable of generating an image of a scene (4) on said optical sensor (2). The system (2) further comprises at least one light source (5) and a scanning device (9) adapted to scan a light beam (33) of the light source (5) on the scene (4) along a trajectory (8). The system (1) further comprises a controller (12) adapted to vary the output light power of the light source (5) between at least a first predetermined value (11) and a second predetermined value (10) higher than the first predetermined value (11).

Description

Technical Field

[0001] The present invention relates to an optical sensing system. In particular, the present invention relates to an optical sensing system for efficient optical sensing. Background Art

[0002] Optical scanning sensing systems are used in a variety of applications. These systems rely on scanning structures or lines about a scene and based on this detect the depth of objects in the scene. An important parameter of any such system is the distance range over which such a system operates. It is desirable that such an optical sensing system be able to simultaneously obtain information about both objects that are closer to the sensor and objects that are further away. While maximizing the distance range, the power consumption of the system must be kept optimal. For example, maximizing the distance range should not result in an increase in power consumption.

[0003] Another requirement for such a system is to work in different environments with different light intensities, for example where the system is operated in a dark room or in daylight.

[0004] Therefore, there is a need for an optical scanning system that can adjust according to the distance of objects in the scene and / or the light intensity at the system while having optimal power consumption.

[0005] The present invention is intended to partially solve the above-mentioned problems. Summary of the invention

[0006] An object of an embodiment of the present invention is to provide an efficient optical sensing system. The above object is achieved by the system and method according to the present invention.

[0007] In a first aspect, the present invention relates to an optical sensing system for efficient optical sensing, comprising:

[0008] - at least one optical sensor;

[0009] - an optical element capable of producing an image of a scene on said optical sensor;

[0010] - at least one light source;

[0011] - scanning means adapted to scan the light beam from said light source over said scene along a trajectory; and

[0012] —Controller,

[0013] The invention is characterized in that the controller is adapted to change the output optical power of the light source between at least a first predetermined value and a second predetermined value higher than the first predetermined value.

[0014] An advantage of embodiments of the present invention is that a power efficient optical sensing system is obtained.

[0015] An advantage of embodiments of the present invention is that points defining objects far from the optical sensor as well as objects close to the optical sensor may be identified.

[0016] An advantage of embodiments of the present invention is that a fast sensing system is obtained since information is obtained both about objects far away from the optical sensor as well as about objects near the optical sensor.

[0017] An advantage of embodiments of the present invention is that the second predetermined value corresponds to an object that is further away from the sensor and the first predetermined value corresponds to an object that is closer to the sensor.

[0018] An advantage of embodiments of the present invention is that information about objects in the scene can be obtained from only a partial scan of the light beam from the light source over the scene.

[0019] An advantage of embodiments of the present invention is that a high dynamic range is achieved.

[0020] The advantage is that the spatial integrity of the projected structure is maintained over a wider range of distances and object albedos. In optical systems that image optical structures such as speckle, secondary signals, optical artifacts, etc., such as unwanted signals due to scattering in the optical path, glare, flare, crosstalk, etc., are typically linearly proportional to the desired signal. It is desirable to keep these secondary signals and / or artifacts below a certain detection threshold.

[0021] An advantage of embodiments of the present invention is that it maximizes the number of samples or times that the signal is within a desired range where secondary signals and / or artifacts are below a certain detection threshold.

[0022] Preferred embodiments of the first aspect of the invention include one or a suitable combination of more than one of the following features.

[0023] The optical sensor has a sampling frequency, wherein the output optical power of the light source is preferably varied or modulated between the first and second predetermined values ​​at a rate up to the sampling frequency.

[0024] An advantage of embodiments of the invention is that the power required to scan the scene is reduced. An advantage of embodiments of the invention is that a fast sensing system is obtained since information is obtained both about objects far from the optical sensor as well as objects close to the optical sensor while still maintaining a good resolution.

[0025] The optical sensing system preferably comprises a processing unit, wherein the unit is capable of estimating a power level of a reflection signal of at least one object in the scene and received by the optical sensor, wherein the unit is capable of tuning the controller to change the output optical power of the light source (e.g., between the first and second predetermined values) based on the power level of the reflection signal.

[0026] The unit is preferably capable of estimating a distance between the optical sensor and a point of the at least one object in the scene along the trajectory, wherein the unit is capable of tuning the controller to vary the output optical power of the light source based on the distance.

[0027] The unit is preferably capable of estimating a spot size of the reflected signal, wherein the unit is capable of tuning the controller to vary the output optical power of the light source based on the spot size.

[0028] An advantage of embodiments of the invention is that a power efficient system is obtained since the output light power level is optimized according to the power level of the reflected signal and / or according to the distance of the object from the optical sensor and / or according to the spot size. An advantage of embodiments of the invention is that it is simple to tune the output light power of the light source based on the power level of the reflected signal and / or the distance and / or the spot size. An advantage of embodiments of the invention is that the distance can be estimated by triangulating the points of the at least one object in the scene detected by the optical sensor using data of the emitted light of the at least one light source.

[0029] The output optical power preferably changes from said second predetermined value to said first predetermined value.

[0030] An advantage of embodiments of the invention is that the output optical power is reduced from the second predetermined value to the first predetermined value until it reaches a suitable level corresponding to an acceptable power level and / or distance and / or spot size of the reflected signal. An advantage of embodiments of the invention is that power consumption is optimized.

[0031] The system preferably comprises at least two light sources, wherein the output optical power of a first light source is the first predetermined value and the output optical power of a second light source is the second predetermined value, wherein the at least two light sources are operated at different times.

[0032] An advantage of an embodiment of the present invention is that one light source is adapted to illuminate a light beam at an object closer to the sensor, while another light source is adapted to illuminate a light beam at an object further from the sensor. An advantage of an embodiment of the present invention is that different light sources are adapted to illuminate light beams on objects at different distance ranges from the optical sensor or on objects with different reflectivity.

[0033] The optical sensor preferably comprises a plurality of pixel sensors, each pixel sensor comprising a photodetector. The photodetectors are preferably single photon detectors, preferably single photon avalanche detectors. The controller is preferably adapted to change a bias of each of the photodetectors.

[0034] An advantage of embodiments of the present invention is that the sensitivity of each photodetector to active light and noise can be adjusted, wherein a balance between the two can be achieved.

[0035] The scanning device preferably scans the light beam from the light source over the scene based on a beam steering function having a beam angular velocity, wherein the output optical power of the light source varies based on the angular velocity. When the angular velocity is less than a threshold angular velocity, the output optical power is preferably at most equal to the first predetermined value.

[0036] An advantage of embodiments of the present invention is that significant power reduction is achieved for a minimal reduction in illumination range.

[0037] The duty cycle of the light source is at most 80%, preferably at most 60%, more preferably at most 40%, and most preferably at most 20%.An advantage of the embodiments of the present invention is that power consumption is reduced.

[0038] In a second aspect, the invention relates to a method for optical sensing comprising the following steps:

[0039] — illuminating the scene with a beam of light from a light source;

[0040] - scanning the light beam along a trajectory over the scene;

[0041] - receiving, by a receiver, a reflected light signal from the scene;

[0042] - sampling the reflected light signal,

[0043] Characterized in that the method further comprises the following steps:

[0044] - varying the output optical power of the light source between at least a first predetermined value and a second predetermined value higher than the first predetermined value.

[0045] Preferred embodiments of the second aspect of the present invention include one or a suitable combination of more than one of the following features:

[0046] - the reflected signal is sampled at a predetermined sampling frequency, wherein the step of varying the output optical power between the first and second predetermined values ​​is performed at a rate up to the sampling frequency,

[0047] the method comprising the steps of estimating a power level of a reflected signal and tuning the output optical power of the light source based thereon, and / or estimating a distance between a receiver and the scene and tuning the output optical power of the light source based thereon, and / or estimating a spot size of the reflected signal and tuning the output optical power of the light source based thereon,

[0048] - the method comprises the steps of scanning the light beam over the scene based on a beam steering function having an angular velocity, wherein the output optical power of the light source varies based on the angular velocity, and,

[0049] - when the angular velocity is less than a threshold angular velocity, the output optical power is adapted to be at most equal to the first predetermined value.

[0050] The above and other characteristics, features and advantages of the present invention will become clear from the following detailed description given in conjunction with the accompanying drawings, which illustrate the principles of the present invention by way of example.This description is given for example only and does not limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present disclosure will be further illustrated by the following description and accompanying drawings.

[0052] Figure 1 and Figure 2 An optical sensing system (1) comprising an optical sensor (2) according to an embodiment of the present invention is shown, wherein the output optical power of the light source (5) changes between a first predetermined value (11) and a second predetermined value (10) at two different rates of change.

[0053] Figure 3 An optical sensing system (1) according to an embodiment of the present invention is shown, wherein the output optical power of the light source (5) changes between the first predetermined value (11) and the second predetermined value (10) based on the received signal of the optical sensor (2).

[0054] Figure 4 An optical sensor (2) according to an embodiment of the present invention is shown for a simplified field of view of near objects (a, c) and far objects (b, d) of the optical sensor (2), wherein the light source (5) has a higher output light power in (a, b) and a lower output light power in (c, d).

[0055] Figure 5 An example of an expected average photon count received by a pixel sensor during each sampling period of the pixel sensor as a function of distance to the pixel sensor according to an embodiment of the present invention is shown, wherein the output optical power of the light source (5) is 0.2W, 1W, 0.01W and 0.05W for (a, b, c, d), respectively.

[0056] Figure 6 Graph showing the field of view of the optical sensor (2) according to an embodiment of the present invention, wherein the field of view is reduced by 10%.

[0057] Figure 7 The deflection angle of a scanning device (9) for scanning the light source (5) is shown modulated by a sinusoidal function (25) according to an embodiment of the present invention, wherein the output light power changes according to the angular velocity of the function (25).

[0058] Figure 8 Schematic representation of the field of view of a plurality of pixel sensors according to an embodiment of the present invention, wherein detection with different spot sizes is represented.

[0059] Fig. 9 An implementation of an optical sensing system (1) according to an embodiment of the present invention is represented, wherein the output optical power of the light source (5) is varied in a stepwise manner when the light beam is scanned in the scene (4).

[0060] Fig.10 Shown is a light beam (7) scanned in a step-wise manner over a scene (4) according to an embodiment of the present invention.

[0061] Any reference signs in the claims should not be construed as limiting the scope.The same reference signs in different drawings refer to the same or similar elements. DETAILED DESCRIPTION

[0062] The present invention relates to an optical sensing system for efficient optical sensing.

[0063] The present invention is described with respect to specific embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims. The drawings described are only schematic and non-limiting. In the drawings, the dimensions of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and relative dimensions do not correspond to actual reductions to the practice of the invention.

[0064] The terms first, second, etc. in the specification and claims are used to distinguish between similar elements and not necessarily to describe a sequence, whether in time, space, order, or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0065] In addition, the terms above and below, etc. in the specification and claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

[0066] In the description provided herein, many specific details are set forth. However, it is to be understood that embodiments of the present invention may be implemented without these specific details. In other cases, well-known methods, structures, and techniques are not shown in detail in order not to obscure the understanding of this description.

[0067] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "in one embodiment" or "in an embodiment" in different places throughout this specification do not necessarily all refer to the same embodiment, but may be. In addition, it will be readily apparent to one of ordinary skill in the art from this disclosure that particular features, structures, or characteristics may be combined in any appropriate manner in one or more embodiments.

[0068] Similarly, it should be understood that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of simplifying the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in the various claims. On the contrary, as reflected in the following claims, inventive aspects lie in less than all the features of the individual disclosed embodiments described above. Therefore, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of the invention.

[0069] In addition, although some embodiments described herein include some features included in other embodiments but not others, as understood by those skilled in the art, the combination of features of different embodiments is intended to be within the scope of the present invention and form different embodiments. For example, in the claims below, any of the claimed embodiments may be used in any combination.

[0070] Unless otherwise defined, all terms, including technical and scientific terms, used in disclosing the present invention have the meanings commonly understood by ordinary technicians in the field to which the present invention belongs. By further guidance, term definitions are included to better understand the teachings of the present invention.

[0071] As used herein, the following terms have the following meanings:

[0072] Unless the context clearly dictates otherwise, "a", "an", and "the" refer to both the singular and the plural. As an example, "a pollutant" refers to one or more than one pollutant.

[0073] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the range, as well as the recited endpoints.

[0074] In a first aspect, the present invention relates to an optical sensing system for optical sensing, preferably for efficient optical sensing. The system comprises at least one optical sensor. The system further comprises an optical element capable of producing an image of a scene on the optical sensor.

[0075] The system further comprises at least one light source. For example, the light source is adapted to be at a wavelength detectable by the optical sensor. For example, between 100 nanometers and 10 micrometers, preferably between 100 nanometers and 1 micrometer. For example, the optical sensor is a photodetector or a matrix of photodetectors capable of detecting photons that strike each detector within a wavelength detection window falling within the range of 100 nanometers to 10 micrometers, preferably between 100 nanometers and 1 micrometer.

[0076] The system further comprises a scanning device adapted to scan a light beam from the light source over the scene, preferably at least partially, along a trajectory. The scanning is preferably continuous, so that objects in the scene are continuously scanned and identified. For example, the light source generates a light beam, which generates a spot on an object, wherein the light beam is continuously scanned over the scene along the trajectory, wherein, for example, after each period of time, the light beam scans all or almost all of the scene. The scanning may be, for example, in a Lissajous figure or a raster scan, etc. The scanning device may be, for example, a MEMS scanner.

[0077] The system further comprises a controller. For example, the controller is connected to the light source and preferably also to the scanner. The system is characterized in that the controller is adapted to change the output optical power of the light source between at least a first predetermined value and a second predetermined value higher than the first predetermined value. For example, the output optical power is changed continuously. For example, the output optical power is the first predetermined value for a predetermined time period, and then the output optical power is the second predetermined value for a predetermined time period. The first predetermined value may, for example, correspond to an object closer to the sensor, and the second predetermined value corresponds to an object farther away from the sensor. For example, depending on the scene and the objects in the scene and their proximity to the system, the output optical power may also be changed between more than two predetermined values. In other words, the controller is adapted to continuously change the optical output power of the light source in an alternating manner.

[0078] Since objects at different distances to the system reflect light differently, for example due to their distance from the system, or for example due to different reflectivities of the objects, the output optical power of the light source must be tuned so that the reflected signal detected by the optical sensor is within a range suitable for this, for example within a power limit adapted to the optical sensor. For example, so that the optical sensor is not overstimulated or understimulated. Since the output optical power is tuned based on, for example, the proximity and / or reflectivity of the object, etc., this is advantageous for obtaining a power efficient system. This is also advantageous since objects of different proximity and reflectivity can be identified by using as few as one light source, for example, by tuning the light source to different output optical power levels depending on it. This also allows fast sensing since a single, fast and partial scan can produce information about different objects. This also allows a high dynamic range since objects of different proximity can be identified in one scan almost simultaneously.

[0079] As described below, the output optical power can also be tuned based on other factors other than proximity and / or reflectivity. This also allows the detected optical signal to have good spatial integrity.

[0080] Artifacts in the optical and / or imaging system, such as scattering, glare, flare, ghosting, color speckle, etc., result in secondary signals (tertiary signals, etc.) that are often undesirable. The stronger the reflected optical signal from the scene, the stronger the undesired secondary signal. The reflected signal may become too high, so that the secondary undesired signal jeopardizes adequate imaging of the desired optical signal, meaning that the spatial integrity of the optical signal is reduced. By providing a measurement scene with lower, different or adaptive optical power, we can guarantee good spatial integrity in at least one scene.

[0081] Alternatively, as an alternating alternative, the controller may start with an initial output optical power and then adjust its value based on, for example, the distance of the object, the albedo of the object, or the spot size of the reflected signal. The value is then updated, for example, periodically, for example, after a predetermined period of time. For example, as described below, the output optical power is changed from the second predetermined value to the first predetermined value.

[0082] Preferably, the optical sensor has a sampling frequency, wherein the output optical power of the light source is varied or modulated between the first and second predetermined values ​​at a rate up to the sampling frequency. Preferably, the variation rate or modulation rate is such that different parts of the scene are scanned by the light beam from the light source having an output optical power of either the first or the second predetermined value. For example, certain parts of the scene are scanned by the light beam from the light source having an output optical power of the first predetermined value, while other parts of the scene are scanned by the light beam from the light source having an output optical power of the second predetermined value. For example, the modulation rate may be at most 2 times, preferably at most 5 times, preferably at most 10 times smaller than the sampling rate. Alternatively, the modulation rate may be such that the output optical power of the light source is varied between the first and second predetermined values ​​each time the scanning device scans at least 1% of the scene, or for example at least 5% of the scene.

[0083] The change or modulation is advantageous because information about different objects in the scene can be obtained while still maintaining good resolution. For example, the modulation is fast enough to maintain good resolution of objects in the scene while identifying the proximity and / or reflectivity of objects in the scene, for example based on the reflected signal detected by the sensor.

[0084] The output optical power may depend on the proximity and / or reflectivity of the object. However, it may also be possible to start by scanning the light beam while the light source is modulated in a random manner between the first and second predetermined values, on the basis of which it is determined whether certain areas in the scene then need to be scanned by the light beam from the light source having an output optical power of the first predetermined value or the second predetermined value. For example, based on a reflection signal detected by the sensor (e.g., the power of the reflection signal). This is advantageous for reducing the power required to scan the scene.

[0085] Preferably, the sampling rate of the optical sensor is at least 1 MHz, preferably at least 10 MHz, more preferably at least 100 MHz. This is suitable since in real life objects do not move very fast compared to such a sampling rate of the detector. For example, the optical sensor has a time resolution of at least 1 microsecond, preferably at least 100 nanoseconds, more preferably at least 40 nanoseconds. This is advantageous for scanning the scene before knowing, for example, which parts of the scene contain which objects, have which reflectivity and / or are at which proximity to the optical sensor.

[0086] Preferably, the system comprises a processing unit. For example, the processing unit is connected to the optical sensor.

[0087] The unit is preferably capable of estimating a power level of a reflected signal of at least one object in the scene and received by the optical sensor.The unit is then capable of tuning the controller to vary the output optical power of the light source based on the power level of the reflected signal.

[0088] The unit is preferably capable of estimating the distance between the optical sensor and a point of at least one object in the scene along the trajectory.The unit is then capable of tuning the controller to vary the output optical power of the light source based on the distance.

[0089] The unit is preferably capable of estimating a spot size of the reflected signal.The unit is then capable of tuning the controller to vary the output optical power of the light source based on the spot size.

[0090] Since the light source emits light with the required amount of output light power, the processing unit is advantageous in optimizing the power consumption of the system in a simple manner.

[0091] Preferably, the distance can be estimated by triangulating the points of the at least one object in the scene detected by the optical sensor using the data of the emitted light of the at least one light source. Since the data of the emitted light of the light source is known, i.e., it is known at which part of the scene the light will be irradiated at a specific time, this is similar to the triangulation output of two optical sensors.

[0092] Preferably, for example, in order to estimate the distance and / or the reflectivity of the object, the unit is capable of estimating the ratio between the output optical power emitted by the light source and the optical power received by the sensor. For example, if the ratio is too high, this means that the object is too close and / or the reflection is too strong. Alternatively, if the ratio is too low, this means that the object is too far or there is no reflection. Preferably, the ratio is kept between a lower limit value and an upper limit value. For example, if the ratio is too high, the output optical power of the light source is reduced so that the ratio remains between the lower limit and the upper limit value.

[0093] Preferably, the unit is capable of classifying the areas in the scene into at least two areas. For example, the first area contains objects that are far away from the optical sensor and / or have a low reflectivity, and the second area contains objects that are closer to the optical sensor and / or have a high reflectivity, for example, so that the reflected signal is suitable for being received by the optical sensor, for example, to avoid the reflected signal being too strong and thus generating artifacts such as glare, lens flare, scattering, etc., or too weak and therefore not being detected. In addition, the system may be able to track the movement of objects in any area (for example, within the same distance range) to adjust the light source to illuminate the light with an output optical power suitable for the object, for example during and after the movement of the object. The system is also capable of tracking the movement of objects that are closer to or farther away from the optical sensor and adjusting the output optical power of the light source accordingly. For example, if an object close to the sensor moves away from the sensor, for example exceeding a threshold distance from the sensor, or for example moving so that the reflected signal is lower than the sensor is suitable for receiving, the output optical power of the light source is increased, for example, from the first predetermined value to the second predetermined value. For example, there is a control loop or feedback loop that allows the output optical power to be adjusted based on different scenarios.

[0094] Preferably, after an object (e.g., an object of interest) is identified, the system is adjusted to allocate a higher scan density on the object relative to the background. For example, the object is tracked because it is more important to track the movement of the object and its distance in the scene than the background. For example, if the background is a wall, the distance of the wall will remain the same in most cases compared to the moving objects in the scene.

[0095] Preferably, in the case where the system is used for object tracking, it may be desirable to illuminate only the object of interest, without illuminating the background. This is beneficial to further reduce power consumption.

[0096] Preferably, the output optical power is modulated until the signal is correctly seen by the optical sensor. For example, if the object is far away, the output optical power is increased to the extent that the received signal is correctly seen by the optical sensor.

[0097] Preferably, the system further comprises at least one memory element, wherein the element is capable of storing the positions of objects in the scene at different times. For example, so that the light beam is irradiated on the objects in the scene with an appropriate output light power, for example based on a previous scanning cycle. This also helps the system to remember the positions of objects in the scene and thus irradiate them with a light beam with an appropriate output light power.

[0098] Preferably, the output optical power is defined so that it is proportional to the square of the distance of the object from the sensor. Therefore, the farther the object is from the sensor, the greater the output optical power of the light source should be, so that the power level of the reflected signal received by the sensor remains within the range suitable for the sensor to receive. Vice versa, the closer the object is to the sensor and / or the light source, the lower the output optical power of the light source should be, so that the intensity of the optical signal sensed or measured by the image sensor remains within the preferred range.

[0099] Preferably, the spot size is below a threshold spot size. The spot size may or may refer to the size of a spot generated by illuminating a light beam on an object in a scene, and / or the size of a spot generated by reflected light from the object and detected by the optical sensor. For high intensity signals, the measured spot size may become larger due to effects such as glare, light scattering, haloing in the sensor pixel array, optical and / or electrical crosstalk in the sensor pixel array. Therefore, the measurement of the spot size can be used to quantify spatial integrity and determine whether the change in output optical power at the spot position is expected. The threshold spot size may refer to the maximum spot size allowed, such as the spot size at which the sensor is suitable for operation. For example, in the case where the optical sensor includes a plurality of pixel sensors (e.g., wherein each pixel sensor includes a photodetector), the spot size is preferably less than 3 pixel sensors, more preferably less than 4 pixel sensors, and even more preferably less than 5 pixel sensors. For example, the spot size may provide an indication of the distance of an object from the optical sensor, and for certain illumination types, such as a collimated beam with an optical aperture, a large spot size means that the object is closer to the sensor, while a small spot size means that the object is farther away from the sensor. Alternatively, spot size may refer to the size of a spot resulting from light impinging on an object. For example, if an object is not smooth or flat, the impingement of light on the object may result in the light being reflected multiple times on the object before finally reaching the optical sensor. This may increase the spot size on the object. Another example is if light is absorbed by the object, wherein the spot size may be different than expected. The threshold spot size determines whether the output optical power should be increased or decreased. For example, if the spot is larger than the threshold spot size, the output optical power is decreased.

[0100] Preferably, the power level received by the optical sensor is within a window in which the sensor is suitable for operation, for example, between an upper power value and a lower power value, or for example corresponding to a predetermined upper photon count and a lower photon count per sampling period, for example, 5 to 500 expected photon strikes per pixel region per sampling period.

[0101] Preferably, the present invention is implemented based on estimating at least one of the above mentioned elements, i.e., the distance (e.g., obtained using triangulation), the power level and spot size of the reflected signal, and the reflectivity. Thus, one or more of these elements may be estimated as long as the main objective is achieved: estimating the appropriate output optical power of the light source to achieve an appropriate power level of the reflected signal for the sensor to operate properly.

[0102] Preferably, the output optical power is changed from the second predetermined value to the first predetermined value. For example, based on the power level of the reflected signal and / or the distance and / or the spot size. For example, the initial output optical power of the light source is the second predetermined value. However, after obtaining information about the power level of the reflected signal and / or the distance and / or the spot size, the output optical power is either kept equal to the second predetermined value, for example in areas of the scene where the object is further away from the optical sensor, or reduced to the first predetermined value, for example in areas of the scene where the object is closer to the optical sensor, so as to always keep the power level of the reflected signal within the range suitable for the sensor to operate. This is done continuously, so that, for example, in the case where an object that initially received light at the first predetermined value is away from the sensor, the output optical power is readjusted to the second predetermined value. This is advantageous for optimizing power consumption.

[0103] The system preferably comprises at least one optical sensor, wherein the distance is estimated by a displacement on the sensor of an optical signal corresponding to a point of the at least one object in the scene detected by the optical sensor, the displacement being an expected position based on a priori knowledge of the light source and / or the displacement being a displacement of an optical signal corresponding to a point of the at least one object in the scene detected by at least one other optical sensor. This is advantageous in that the distance between each object and the sensor is easily obtained and then the output optical power of the light source is adjusted according to the distance.

[0104] Scanning a light beam from the light source advantageously allows triangulation. For example, using a system comprising a light source that illuminates a light beam on a scene (e.g., an environment) and two sensors in the optical sensor, for example, oriented differently from each other, wherein the two sensors have a shared field of view of the scene, it is possible to convert xy-time data of the two sensors into xyz-time data by triangulation. For example, by adapting the light source to illuminate a light beam on the scene in an illumination trajectory, wherein the light source comprises means adapted to scan (preferably continuously) the light beam on the scene, wherein the optical sensor monitors a light spot produced by the light beam and outputs the position of a point of at least one object in the scene (e.g., a point of the surface of the object) along the trajectory in a plurality of instances, wherein the xy-time data of the two optical sensors can be converted into xyz-time data using triangulation. The light source can act as, for example, a reference point so that the positions of the points of the object of the first optical sensor can be synchronized with those of the second optical sensor to create a depth or z dimension. The light source can illuminate and scan the light beam on the scene to be imaged in a Lissajous manner or in a pattern or raster scan, etc. This illumination trajectory facilitates efficient and fast image detection since after a few illumination cycles a significant portion of the image has been illuminated.Other illumination patterns are contemplated.

[0105] Preferably, the system comprises two light sources. For example, wherein the output optical power of the first light source is the first predetermined value, and the output optical power of the second light source is the second predetermined value, wherein the first light source and the second light source operate at different times, i.e. they do not operate simultaneously. For example, the first light source operates at T=10-20 nanoseconds, 30-40 nanoseconds, 50-60 nanoseconds, and the second light source operates at T=20-30 nanoseconds, 40-50 nanoseconds, 60-70 nanoseconds, etc. For example, wherein one light source, for example a light source having an output optical power equal to the second predetermined value, is suitable for irradiating a light beam on an object further away from the sensor, while the other light source, for example a light source having an output optical power equal to the first predetermined value, is suitable for irradiating a light beam on an object closer to the sensor. Distance is not the only criterion, the reflectivity of the object also determines whether the object is irradiated by light having an output optical power of the first or second predetermined value. For example, an object that reflects too much light so that the reflected signal received by the optical sensor is too strong is irradiated by a light beam of a light source having an output optical power of the first predetermined value.

[0106] Preferably, the optical sensor comprises a plurality of pixel sensors, each pixel sensor comprising a photodetector. Preferably, the photodetector is a single photon detector, preferably a single photon avalanche detector. Alternatively, the photodetector is an avalanche photodetector.

[0107] Preferably, each photodetector is adapted to generate a stream of pulses, for example, whereby each pulse is the result of a detection of an impinging photon. On average, the time interval between pulses is related to the intensity of the optical signal being detected. The higher the intensity in a given time window, the shorter the average time between pulses. Of course, as known to those skilled in the art, the actual time between pulses follows a Poisson distribution.

[0108] Preferably, each detector may be arranged in a reverse bias configuration. The detector is capable of detecting a single photon impinging thereon. The detector may be adapted to output a logic signal, e.g., an electrical detection signal, upon detection of a photon. For example, a detection signal may be represented by a signal comprising a logic "1" (e.g., detection), while a non-detection signal may be represented by a signal comprising a logic "0" (e.g., non-detection). Alternatively, a detection signal may be represented by or result in a pulse signal, e.g., transitioning from a logic "0" to a logic "1" and then from a logic "1" to a logic "0", while a non-detection may be represented by the absence of such a pulse signal (or result in it).

[0109] Preferably, the optical sensor comprises more than 100 pixel sensors, preferably more than 1000 pixel sensors, more preferably more than 10000 pixel sensors, even more preferably more than 100000 pixel sensors, and most preferably more than 1000000 pixel sensors. For example, the optical sensor may be arranged in a matrix, wherein the optical sensor comprises 1000 pixel sensor rows and 1000 pixel sensor columns.

[0110] Preferably, the controller is adapted to change the bias of each of the photodetectors arbitrarily together, in groups or individually. For example, the bias voltage of the photodetector can change the sensitivity of the photodetector. Changing the bias allows the sensitivity and noise of the detector to be controlled by switching the detector from a state in which it has a high quantum efficiency to a state in which it has a low quantum efficiency. For example, by operating in a state with a low quantum efficiency, the noise can be reduced, but at the same time the sensitivity to active light is reduced. On the other hand, by operating in a state with a high quantum efficiency, the sensitivity to active light is increased, but the noise is also increased. Therefore, it is desirable to achieve a balance between the two (i.e. sensitivity and noise).

[0111] Preferably, the scanning device scans the light beam from the light source over the scene based on a beam steering function having a beam angular velocity. The function is preferably a sinusoidal function. For example, the deflection angle of the light beam is modulated based on the beam steering function. The output optical power of the light source varies based on the beam angular velocity. For example, the beam angular velocity has a maximum value, wherein the light source illuminates the light beam on the scene for an angular velocity that is 1%, preferably 2%, more preferably 5%, even more preferably 10%, and most preferably 20% higher than the maximum value. In other words, for low angular velocities (e.g., less than a threshold angular velocity), the light source is turned off or illuminates the scene with a minimum output optical power. In other words, this means that the ends of the scene, e.g., the areas corresponding to the highest deflection angle of the beam steering function or e.g., the very edges of the scene, are either not illuminated by the light beam or are minimally illuminated by the light beam. Preferably, when the angular velocity is less than a threshold angular velocity, the output optical power is at most equal to the first predetermined value, more preferably, when the angular velocity is less than a threshold angular velocity, the output optical power is at most equal to a minimum value or zero.

[0112] It is worth noting that the scanner moves along the same trajectory even in areas where the scene is illuminated with minimal or zero output optical power. Although the illumination field (i.e., the area where the scene is illuminated) is slightly reduced, the power reduction is significant in the case of non-uniform beam steering angular velocity. For example, in the case of sinusoidal beam steering, a 10% reduction in illumination field results in a 50% power reduction. As follows Figure 6 As shown, a 10% reduction in the irradiated field is very tolerable.

[0113] Preferably, the system comprises image rendering means, for example a screen or other image rendering device, to reproduce the positions of points of said objects in said scene.

[0114] Preferably, the optical system is used for 3D vision applications. For example, the system can be used to visualize objects in three dimensions. Alternatively, the sensor can allow a scene to be analyzed, for example by extracting features of objects in the scene, without having to generate an image of the scene.

[0115] Preferably, the system also includes multiple optical sensors and / or multiple light sources. This is advantageous in creating 3D vision. For example, the orientation of each optical sensor may be different so that a 3D perception of the scene to be imaged is captured, for example by triangulating the output of two such optical sensors.

[0116] Preferably, the duty cycle of the light source is a maximum of 80%, preferably a maximum of 60%, more preferably a maximum of 40%, most preferably a maximum of 20%. For example, the controller controls the duty cycle of the light source. This reduces the power consumption of the system. The duty cycle can be changed dynamically, for example, 100% at a certain point in time and 40% at another point in time. This can be based on, for example, whether the scene the user is viewing is changing and how fast the change is. For example, in the case where the user is viewing the same scene, for example without changing their head posture, the duty cycle is reduced.

[0117] In a second aspect, the present invention relates to a method for optical sensing. The method comprises the step of illuminating a scene by a light beam from a light source. The method further comprises the step of scanning the light beam over the scene along a trajectory, for example by using a scanner, for example a MEMS scanner. The method further comprises the step of receiving, by a receiver, a reflected light signal from the scene, for example receiving a reflected light signal from an object in the scene. For example, the receiver is an optical sensor, for example comprising a plurality of pixel sensors, each pixel sensor comprising a photodetector, preferably a single photon detector. For example, the light beam is irradiated at a wavelength detectable by the detector of the optical sensor.

[0118] The method further comprises the step of sampling the reflected signal. For example, the sampling is performed at a predetermined sampling frequency. The method is characterized in that the method further comprises the step of changing the output optical power of the light source between at least a first predetermined value and a second predetermined value higher than the first predetermined value. For example, by a controller that controls the output optical power of the light source.

[0119] Preferably, the reflected signal is sampled at a predetermined sampling frequency, wherein the step of varying the output optical power between the first predetermined value and the second predetermined value is performed at a rate up to the sampling frequency. For example, the rate of variation or modulation of the output optical power may be at most 2 times, preferably at most 5 times, preferably at most 10 times or 20 times less than the sampling rate. The step of varying may also be performed each time the scanning device scans at least 1% of the scene, or for example at least 5% of the scene.

[0120] Preferably, the method comprises the step of estimating the power level of the reflected optical signal and tuning the output optical power of said light source based thereon.

[0121] Preferably, the method comprises the step of estimating the distance between a receiver and said scene and tuning the output optical power of said light source based thereon.

[0122] Preferably, the method comprises the step of estimating the spot size of the reflected optical signal and tuning the output optical power of the light source based thereon.

[0123] Preferably, the method comprises the step of triangulating the points of the object in the scene detected by the receiver using the points of the object in the scene detected by the second receiver. Alternatively, the method comprises the step of triangulating the points of the object in the scene detected by the receiver using data of the light beam emitted by the light source.

[0124] Preferably, the method comprises the step of classifying the areas in the scene into at least two areas, preferably at least three areas. For example, based on the proximity and / or reflectivity of objects in the scene to the receiver. For example, areas illuminated by the light beam from the light source having the output light power of the first predetermined value, and areas illuminated by the light beam from the light source having the output light power of the second predetermined value.

[0125] Preferably, the method comprises the step of scanning the light beam on the scene based on a beam steering function having an angular velocity of the beam, wherein the output optical power of the light source varies based on the angular velocity. For example, the method may comprise the step of irradiating the light beam from the light source onto the scene for an angular velocity higher than 1% of a maximum value (preferably higher than 2% of the maximum value, more preferably higher than 5% of the maximum value, even preferably higher than 10% of the maximum value, most preferably higher than 20% of the maximum value). For example, the method may comprise the step of irradiating the light beam of the light source onto the scene with the light source having an output optical power of the second predetermined value for an angular velocity higher than a threshold angular velocity, and irradiating the light beam of the light source onto the scene with the light source having an output optical power of the first predetermined value or zero for an angular velocity lower than the threshold angular velocity. Preferably, the output optical power is adapted to be at most equal to the first predetermined value when the angular velocity is lower than the threshold angular velocity.

[0126] Any features of the second aspect (method) may be described accordingly as in the first aspect (system).

[0127] In a third aspect, the present invention relates to the use of the system according to the first aspect and / or the method according to the second aspect for optical sensing, preferably for efficient optical sensing.

[0128] Other features and advantages of embodiments of the invention are described with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments shown in these drawings or described in the examples, but only by the claims.

[0129] Figure 1An optical sensing system (1) is shown comprising an optical sensor (2) and an optical element (3) capable of generating an image of a scene (4) on the optical sensor (2). The system (1) also comprises a light source (5) for irradiating a light beam (33) generating a light spot (7) on the scene (4). However, the present invention is not limited to generating a point-shaped light spot (7) but can be any other suitable irradiation pattern. The system (1) also comprises a scanning device (9) suitable for scanning the light beam (33) on the scene (4). For example, the scanning device (9) can be a reflector or a MEMS reflector or the like capable of scanning the light beam (33) on the scene (4), for example on different parts of the scene (4). The light beam (33) is scanned along the irradiation trajectory (8), for example in a Lissajous manner.

[0130] The system (1) further comprises a controller (12) connected to the light source (5) and the scanning device (9). The controller (12) is adapted to continuously vary the output optical power of the light source (5). For example, by varying the input to the light source (5). For example, the output optical power of the light source (5) is varied between a first predetermined value (11), for example a lower output optical power level represented by a thinner line, and a second predetermined value (10), for example a higher output optical power level represented by a thicker line, which occurs repeatedly. For example, the output optical power varies at a rate up to a sampling rate of the optical sensor (2), for example 100 MHz. A high modulation rate in combination with Lissajous scanning is particularly advantageous in, for example, scanning different objects in a scene (4) almost simultaneously, both in cases where the objects are far from or close to the optical sensor (2). However, variations or modulation rates that are, for example, 10 or 20 times smaller than the sampling rate are still effective. This means that the sensor is capable of sampling, for at least one sampling period, a return optical signal associated with a first predetermined value (11) of the light source (5) alternating with at least one sample associated with a second predetermined value (10).

[0131] Figure 2 and Figure 1 The system (1) is represented similarly, but the output optical power of the light source (5) is expressed as Figure 1 The controller (12) may be configured to change the output light power of the light source (5) at a slower rate. For example, 10 times or 100 times slower. Alternatively, for example, each time the scanning device (9) scans a predetermined portion of the scene (4), for example at least 1%, 2% or 5% of the scene (4), the output light power of the light source (5) is changed. For example, the controller (12) may repeatedly change the output light power between a first predetermined value (11) for the predetermined portion or interval of the scene (4) and a second predetermined value (10) for the predetermined portion or interval of the scene (4). This is more Figure 1 The implementation shown is more time consuming, but it allows obtaining better resolution for the objects in scene (4).

[0132] Figure 3 The system (1) further comprises a processing unit (not shown), for example connected to the optical sensor (2). The unit is capable of estimating the power level of a reflected light signal from an object and received by the optical sensor (2), and / or estimating the distance between the sensor (2) and at least one point of an object in the scene (4) along the trajectory (8) and / or the spot size of the signal. For example, for a first set of points (13) of objects at a closer distance (e.g., closer than a predetermined distance) from the optical sensor (2), and a second set of points (14) of objects at a farther distance (e.g., farther than the predetermined distance) from the optical sensor (2). For example, the unit is capable of classifying areas of the scene (4) into areas with objects at a closer distance (e.g., closer than the predetermined distance) from the optical sensor (2), such as a first area (27), and areas with objects at a farther distance (e.g., farther than the predetermined distance) from the optical sensor (2), such as a second area (28). For example, if the object is farther from the optical sensor (2) than a predetermined distance, it belongs to the second area (28). Figure 3 The predetermined distance shown is 1.5 meters. However, as discussed in the specification, distance is not the only factor that determines which objects belong to which region. For example, a highly reflective object that is farther than the predetermined distance may belong to the first region (27), and similarly, a weakly reflective object that is closer than the predetermined distance may belong to the second region (28). This also means that the predetermined distance is not always 1.5 meters.

[0133] After classifying the scene (4) into the first and second areas (27, 28), the unit tunes the controller (12) to change the output optical power of the light source (5). For example, for an object farther than 1.5 meters from the optical sensor (2), the output optical power of the light source (5) needs to be higher, such as the second predetermined value (10), and for an object closer than 1.5 meters from the optical sensor (2), the output optical power of the light source (5) needs to be lower, such as the first predetermined value (11). This is because the farther the object is, the weaker the reflected signal from the object.

[0134] In another implementation, the scene is not classified, and the output optical power of the light source (5) is continuously adjusted based on the evaluation of previous samples. In fact, by sampling at a frequency much higher than the scanning speed of the illuminator, the controller has enough time to "dynamically" adjust the output optical power of the light source (5). For example, if no light spot or reflection signal is detected in the previous sampling window, the controller can increase the output optical power; similarly, if the sensor senses that the incident signal is too high, the controller can reduce the output optical power.

[0135] The distance between the optical sensor (2) and an object in the scene (4) can be estimated based on the output light power of the light source (5) and the light detected by the optical sensor (2), or for example the ratio between the two. For example, if the output light power is high, for example 0.2 W, an object farther than 1.5 meters from the optical sensor (2) will be accurately detected by the optical sensor (2), while an object closer than 1.5 meters from the optical sensor (2) will not be accurately detected. This is because, due to the closer distance of the object, many photons are reflected by the object and received by the optical sensor (2), which is more than the optical sensor (2) can accommodate, for example, through the pixel sensor of the optical sensor (2), which leads to inaccurate detection due to glare effects (6). On the other hand, if the output light power is low, for example 0.01 W, due to the small number of photons reflected by the object and received by the optical sensor (2), an object farther than 1.5 meters from the optical sensor (2) will not be detected, while an object closer than 1.5 meters from the optical sensor (2) will be accurately detected. Figure 4 This is shown in , as explained below. There may be a second optical sensor, wherein, as described in the above description, the distance may be found by triangulating the data of the two optical sensors.

[0136] Objects in all areas are continuously monitored, for example their distance from the optical sensor (2). For example, if an object in the first area (27) moves away from the optical sensor (2), for example farther than the 1.5 meters, the controller (12) tunes the light source (5) to illuminate the light beam (33) with a higher output light power, for example the output light power of the light source (5) is a second predetermined value (10). The same applies when an object far from the optical sensor (2) (for example greater than 1.5 meters) moves closer to the optical sensor (2).

[0137] Figure 4 Represents a simplified field of view of an optical sensor (2), for example, wherein the optical sensor (2) includes a plurality of pixel sensors, for example, wherein a plurality of fields of view (21) correspond to the plurality of pixel sensors (for example, each pixel sensor includes a photodetector). Figure 4 Indicates four different situations. Figure 4 In (a), the output optical power of the light source (5) is high, for example 0.2 W. In this case, the object is very close to a plurality of pixel sensors, for example less than 1.5 meters from the pixel sensors. This results in many photons being reflected by the object and received by the pixel sensors, for example more than the pixel sensors are adapted to receive, which can for example result in the glare effect (6) shown. The glare effect (6) makes it difficult to distinguish between the detections of different adjacent pixel sensors. On the other hand, if Figure 4As shown in (b), for objects farther away from the pixel sensor (e.g., more than 1.5 meters away), the detection is more accurate because the number of reflected and received photons is less due to the greater distance, and there is no glare effect. In this case, the number of photons corresponds to the number that the pixel sensor is suitable for receiving. Figure 4 In the third case (c), the output optical power of the light source (5) is low, for example, 0.01 W, which is suitable for a relatively close object, for example, an object less than 1.5 meters away from the plurality of pixel sensors. Figure 4 As shown in (d), for a farther object, this is not suitable because only few photons or no photons are received by the multiple pixel sensors.

[0138] Figure 5 An example of an expected average photon count received by a pixel sensor including a photodetector in each sampling period of the pixel sensor as a function of the distance to the pixel sensor is shown, wherein the optical sensor (2) includes a plurality of pixel sensors. In (a) and (c), the output optical power of the light source (5) is 0.2 W and 0.01 W, respectively. The pixel sensor is adapted to operate in a region where the photon count has a maximum expected value (17) and a minimum expected value (16). As a function of the distance to the pixel sensor, the photon count when the target is a Lambertian reflector with a reflectivity of 100% is shown in (18). Similarly, the photon count when the target is a Lambertian reflector with a reflectivity of 10% is shown in (19). As shown in (a), for an object in the second region (28), the two curves (18, 19) are within the maximum value (17) and the minimum value (16). This indicates that a high output optical power, such as 0.2 W, is required to detect an object in the second region (28). The opposite situation is shown in (c), where a low output optical power, for example 0.01 W, is required to detect objects in the first region (27). Figure 5 In (a) and (c), the photodetector is biased so that it has high quantum efficiency.

[0139] on the other hand, Figure 5 (b) and Figure 5 (d) shows a similar diagram, but in which the photodetector is biased so that it has a low quantum efficiency. Figure 5 (a) Figure 5 Compared with the implementation in (c), this implementation has the advantage of reducing noise. However, the disadvantage is that the sensitivity to active light is reduced. Figure 5 (b) and Figure 5 The output optical powers of the light source (5) in (d) are, for example, 1 W and 0.05 W respectively.

[0140] As mentioned above, the distance between the object and the optical sensor (2) is either in the first region (28), for example greater than 1.2 meters, or in the second region (27), for example less than 0.75 meters. Figure 5 As shown, the object may also be in a third region (29), for example, 0.75 m to 1.2 m. For example, for an object at a distance of 0.75 m to 1.2 m from the pixel sensor, the photon count will not be within the maximum value (17) and the minimum value (16). In this case, a different output optical power of the light source (5) is required. Therefore, the controller (12) may also be adapted to change the output optical power of the light source (5) between a first predetermined value (11), a second predetermined value (10) higher than the first predetermined value (11), and a third predetermined value higher than the first predetermined value (11) and lower than the second predetermined value (10).

[0141] Figure 6 represents the field of view of the optical sensor (2). The scanning device (9) scans the light beam (33) of the light source (5) over the scene (4). The deflection angle of the device (9) is modulated, for example in a Lissajous manner, based on a light beam steering function. When the deflection angle reaches its extreme value, for example at the edge of the scene (4), the beam angular velocity of the function decreases. Thus, Figure 6 As shown in (b), the scene (4) can be divided into two regions: a field of view region (22) where the angular velocity of the function is at its lowest (e.g., lower than a predetermined angular velocity), and a field of view region (23) where the angular velocity of the function is at its highest (e.g., higher than a predetermined angular velocity). Figure 6 As shown in (b), by turning off the light source (5) during the period when the angular velocity is at its lowest, power consumption can be reduced without significantly affecting the field of view. Figure 6 (b) Figure 6 As shown in (c), by reducing the field of view by 10% on each axis, power consumption has been reduced by 50%. This is a particularly advantageous effect. Figure 6 (a) shows the field of view in the standard case, i.e., when the light source (5) is not turned off.

[0142] Figure 7An example of the beam steering function is shown, in which case a sinusoidal function (25) modulates the deflection angle of the scanning device (9) when scanning the light beam (33) of the light source (5). The output optical power varies based on the angular velocity of the function (25). The function (25) has two parts with respect to its angular velocity: a part (24) where the angular velocity is at its lowest and a part (26) where the angular velocity is at its highest. By operating the light source (5) only in the region (26) where the angular velocity is at its highest (e.g. above a threshold angular velocity), the field of view may be slightly reduced, e.g. by 10%, while power consumption is significantly reduced, e.g. by 50%.

[0143] Figure 8 Represents a plurality of fields of view (21) corresponding to a plurality of pixel sensors, wherein represents detection with different spot sizes, wherein a single spot size (30) covers one pixel sensor. For example, in (a), the spot size is 1 pixel sensor, while in (b), the spot size is 4 pixel sensors and for (c) 9 pixel sensors. The processing unit is capable of tuning the controller (12) to change the output optical power of the light source (5) based on the spot size. For example, if the spot size is 9 as in (c), this indicates that the object is very close to the pixel sensor and therefore the output optical power of the light source (5) should be reduced. The controller (5) of the light source (12) is then tuned to reduce the output optical power. A predetermined threshold spot size can be selected, for example, to determine whether to tune the controller (12), for example, to detect whether an object is very close or very far from the optical sensor (2).

[0144] Fig. 9 An implementation of an optical sensing system (1) is represented, wherein the output optical power of the light source (5) is varied in a step-wise manner when being scanned in a scene (4). For example, it is useful, in an initial phase, to determine the positions of objects in the scene (4) which are further away or closer to the sensing system (1). This can be repeated at each predetermined time period, for example, to update the data of objects in the scene (4), for example in the case where objects which are closer move further away, or vice versa. Based on findings, for example based on the distance of the object to the scene, or for example based on the spot size of the reflected signal of the object, or for example based on the ratio of the transmitted power from the light source (5) to the received power of the sensor (2), the output optical power can be adjusted accordingly. As described below, in Fig.10 This is also shown in (a). The positive step shown in (a) and the negative step shown in (b) can be applied sequentially at the same position of the scene (4). For example, to see which of the two is more suitable for illuminating a specific part of the scene (4). The change of the output optical power can be performed in a digital discontinuous step manner (32) or in an analog continuous function manner (31).

[0145] and Fig. 9 similar, Fig.10 The light spot (7) of the light beam (33) scanned in a step-wise manner on the scene (4) is shown. Different line widths correspond to different output optical powers of the light source (5). Fig.10 (a) and Fig.10 (b) but with opposite output optical powers when scanning the same portion of the scene (4). Fig. 9 As shown, this can be used to determine which of the two types of illumination is more suitable for a particular part of the scene (4). After this is determined, the appropriate output light power is illuminated at the corresponding part of the scene (4). For example, Fig.10 (c) represents two different output optical power levels suitable for illuminating different parts of the scene (4). For example, where a first area is illuminated by a lower output optical power and a second area is illuminated by a higher output optical power. Finally, Fig.10 (d) indicates that the duty cycle can also vary, for example, when the user is viewing a scene that does not change or changes slowly.

[0146] Other configurations for achieving the objectives of the methods and apparatus embodying the present invention will be clear to those skilled in the art. The foregoing description gives details of certain embodiments of the present invention. However, it is clear that no matter how detailed the above content is ultimately in the text, the present invention can be applied in a variety of ways. It should be noted that the use of certain terms in describing certain features or aspects of the present invention should not be interpreted as implying that the terms herein are again defined to be limited to the specific features or aspects of the invention coupled to the terms.

[0147] List of Reference Numerals

[0148] 1 Optical Sensing System

[0149] 2 Optical Sensors

[0150] 3 Optical components

[0151] 4 Scenario

[0152] 5 Light Source

[0153] 6 Glare Effect

[0154] 7 Light Spot

[0155] 8 Trajectory

[0156] 9 Scanning device

[0157] 10 Second preset value

[0158] 11 First preset value

[0159] 12 Controller

[0160] 13 The first set of points

[0161] 14 The second set of points

[0162] 16 Minimum photon count

[0163] 17 Maximum photon counts

[0164] 18 photon counts for 100% output optical power

[0165] 19 photon counts for 10% output optical power

[0166] Field of view of 21-megapixel sensor

[0167] 22 corresponds to the field of view with the minimum angular velocity

[0168] 23 corresponds to the field of view area of ​​maximum angular velocity

[0169] 24 The part of the modulation function with the lowest angular velocity

[0170] 25 modulation functions

[0171] 26 The part of the modulation function with the highest angular velocity

[0172] 27 First Area

[0173] 28 Second Area

[0174] 29 Third Area

[0175] 30 Single spot size

[0176] 31 Digital discontinuous step function

[0177] 32 Simulating a continuous step function

[0178] 33 Beam

Claims

1. An optical sensing system (1) for optical sensing, comprising: - at least one optical sensor (2), - an optical element (3) capable of producing an image of a scene (4) on the optical sensor (2), - at least one light source (5), - scanning means (9) adapted to scan the light beam (33) coming from the light source (5) over the scene (4) along a trajectory (8); and - a controller (12), The controller (12) is adapted to change the output optical power of the light source (5) between at least a first predetermined value (11) and a second predetermined value (10) higher than the first predetermined value (11), It is characterized in that The controller (12) is adapted to continuously vary the light output power of the light source (5) in an alternating manner.

2. The optical sensing system (1) according to claim 1, wherein: The optical sensor (2) has a sampling frequency, wherein the output optical power of the light source (5) varies between the first and second predetermined values ​​(11, 10) at a rate up to the sampling frequency.

3. The optical sensing system (1) according to any one of claims 1 or 2, wherein: The system (1) comprises a processing unit, wherein the unit is capable of estimating a power level of a reflected signal of at least one object in the scene (4) and received by the optical sensor (2), wherein the unit is capable of tuning the controller (12) to change the output optical power of the light source (5) based on the power level of the reflected signal.

4. The optical sensing system (1) according to any one of claims 1 or 2, wherein: The system (1) comprises a processing unit, wherein the unit is capable of estimating the distance between the optical sensor (2) and a point of at least one object in the scene (4) along the trajectory (8), wherein the unit is capable of tuning the controller (12) to vary the output optical power of the light source (5) based on the distance.

5. The optical sensing system (1) according to any one of claims 1 or 2, wherein: The system (1) comprises a processing unit, wherein the unit is capable of estimating a spot size of a reflected signal, wherein the unit is capable of tuning the controller (12) to vary the output optical power of the light source (5) based on the spot size.

6. The optical sensing system (1) according to claim 4, wherein: The system (1) comprises at least two optical sensors (2), wherein the distance is estimated by triangulating a point of the at least one object in the scene (4) detected by a first optical sensor, using a point of the at least one object in the scene (4) detected by a second optical sensor or using data of emitted light of the at least one light source (5).

7. The optical sensing system (1) according to any one of claims 3 to 6, wherein: The unit is capable of classifying areas in the scene into at least two areas, wherein each of the areas corresponds to an output optical power between the first predetermined value (11) and the second predetermined value (10).

8. The optical sensing system (1) according to any one of the preceding claims, wherein: The output optical power changes from the second predetermined value (10) to the first predetermined value (11).

9. The optical sensing system (1) according to any one of the preceding claims, wherein: The system (1) comprises at least two light sources (5), wherein the output optical power of the first light source is the first predetermined value (11), and the output optical power of the second light source is the second predetermined value (10), wherein the at least two light sources are operated at different times.

10. The optical sensing system (1) according to any one of the preceding claims, wherein: The optical sensor (2) comprises a plurality of pixel sensors, each pixel sensor comprising a photodetector, wherein the controller (12) is adapted to change a bias of each of the photodetectors.

11. The optical sensing system (1) according to any one of the preceding claims, wherein: A scanning device (9) scans the light beam (33) of the light source (5) over the scene (4) based on a beam steering function having a beam angular velocity, wherein the output optical power of the light source (5) varies based on the angular velocity.

12. The optical sensing system (1) according to claim 11, wherein: When the angular velocity is less than a threshold angular velocity, the output optical power is adjusted to be equal to the first predetermined value (11) at most.

13. The optical sensing system (1) according to any one of the preceding claims, wherein: The duty cycle of the light source (5) is at most 80%, preferably at most 60%, more preferably at most 40%, and most preferably at most 20%, wherein the duty cycle changes dynamically.

14. A method for optical sensing, comprising the steps of: - the scene (4) is illuminated by a light beam (33) from a light source (5), - scanning the light beam (33) over the scene (4) along a trajectory (8), - receiving, by means of a receiver, a reflected light signal from said scene (4), - sampling the reflected light signal, and - varying the output optical power of the light source (5) between at least a first predetermined value (11) and a second predetermined value (10) higher than the first predetermined value (11), It is characterized in that Changing the light output power of the light source (5) is performed continuously in an alternating manner.

15. The method according to claim 14, wherein: The reflected signal is sampled at a predetermined sampling frequency, wherein the step of varying the output optical power between the first and second predetermined values ​​(11, 10) is performed at a rate up to the sampling frequency.

16. The method according to any one of claims 14 or 15, wherein: The method further comprises the following steps: - estimating the power level of the reflected signal and tuning the output optical power of the light source (5) based thereon, and / or - estimating the distance between the receiver and at least one object and tuning the output optical power of the light source (5) based on this, and / or - Estimating the spot size of the reflected signal and tuning the output optical power of the light source (5) based thereon.

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