Optical Sensing System

Abstract

The present invention relates to an optical sensing system (1) for optical sensing. The optical sensing system (1) includes a plurality of sensing units (2'), preferably arranged in a matrix, each of the sensing units (2'), preferably a pixel sensor (2'), with each sensing unit including a photodetector, and each photodetector having at least one optical sensor (30) adapted to output a signal in response to detecting a photon. The optical sensing system (1) further includes an optical system (3) capable of generating an image of a scene (4) on the optical sensor (30). The optical sensing system (2) includes a plurality of processing means (5') connected to each of the at least one sensing units (2'). Each of the processing means (5') is adapted to receive at least one input corresponding to at least one output (7') of the corresponding sensing unit (2'). The processing means (5') is adapted to integrate the output (7', 7'', 7''') of the corresponding sensing unit (2', 2'', 2''') to obtain a first integrated output (10). The processing means is adapted to generate a first output signal (8) when the first integral output (10) reaches at least the first predetermined value (9) within a first predetermined time period (Δt).

Description

[Technical Field]

[0001] The present invention relates to an optical sensing system, and more particularly to an optical sensing system for compact optical sensing. [Background technology]

[0002] Optical sensing systems are used in a variety of applications. Many of these systems are synchronous. Such systems can only detect optical signals at specific time instances, meaning that signals arriving outside of these time instances will not be detected. The solution to this problem is to check the optical signal very frequently, which is energy consuming. Furthermore, many of these systems are bulky and complex.

[0003] Therefore, there is a need for an optical sensing system that can detect optical signals as they arrive without consuming a lot of energy, e.g., asynchronous detection, while at the same time being compact and simple.

[0004] The present invention aims to partially solve the above problems. Summary of the Invention

[0005] SUMMARY OF THE INVENTION It is an object of embodiments of the present invention to provide a compact and reliable optical sensing system. This object is achieved by a system and method according to the present invention.

[0006] In a first aspect, the present invention relates to an optical sensing system for optical sensing, said optical sensing system comprising: - at least one optical sensor comprising a plurality of sensing units, preferably in a matrix configuration, each of said sensing units being preferably a pixel sensor, each sensing unit comprising a photodetector, each photodetector adapted to output a signal in response to detecting a photon; an optical system capable of generating an image of a scene on said optical sensor; - a plurality of processing means, each connected to a corresponding at least one sensing unit; It has. each of said processing means adapted to receive at least one input corresponding to at least one output of a corresponding sensing unit; each of the processing means is adapted to integrate the output of a corresponding sensing unit to obtain a first integrated output; The processing means is adapted to generate a first output signal when the first integral output reaches at least the first predetermined value within a first predetermined time period.

[0007] For example, the processing means is adapted to generate the output signal when a total number of photons detected by the sensing unit reaches at least a predetermined number within the first predetermined time period.

[0008] It is an advantage of embodiments of the present invention that false detections are filtered out. It is an advantage of embodiments of the present invention that noise such as ambient light is reduced or removed. It is an advantage of embodiments of the present invention that reliable detection is obtained.

[0009] An advantage of embodiments of the present invention is that asynchronous detection is provided.

[0010] An advantage of embodiments of the present invention is that they provide a simple system with low power consumption.

[0011] An advantage of embodiments of the present invention is that the processing of the sensed information is performed by a processing structure with massively parallel input connections to each of the pixel sensors, implemented for example using a neural network, rather than by a conventional processor with serialized data and instructions.

[0012] Preferred embodiments of the first aspect of the present invention include suitable combinations of one or more of the following features:

[0013] Preferably, the optical sensing system comprises at least one adjacent sensing unit adjacent to the sensing unit and at least one adjacent processing means adjacent to the processing means, and each sensing unit is connected to the at least one adjacent processing means corresponding to the at least one adjacent sensing unit. Preferably, each of the processing means is adapted to integrate the output of the corresponding sensing unit and at least one adjacent sensing unit to obtain the first integrated output. An advantage of embodiments of the present invention is that processing is performed in a parallel manner, thus resulting in fast and efficient processing. It is an advantage of embodiments of the present invention that parallel connections result in a compact system.

[0014] An advantage of embodiments of the present invention is that pulses corresponding to different adjacent optical sensors are taken into account, resulting in a more reliable detection due to detection confirmation by said adjacent optical sensors, thus filtering out false detections and ambient light.

[0015] The first integrated output preferably has a decay rate, which is preferably adjustable. It is an advantage of embodiments of the present invention that the decay rate determines the first predetermined time duration over which a total number of pulses must be received to generate the output signal. It is an advantage of embodiments of the present invention that by adjusting the decay rate, power consumption in the system can be controlled and reduced.

[0016] Each processing means preferably comprises (or consists of) a first processing means connected in series with a second processing means, the decay rate of the first processing means being faster than the decay rate of the second processing means.

[0017] Preferably, the second processing means is adapted to integrate the first output signal of the first processing means to obtain a second integrated output, and the second processing means is adapted to generate a second output signal when the second integrated output is at least a second predetermined value.

[0018] An advantage of embodiments of the present invention is that the first processing means and the second processing means are two different filtering layers with two different filtering requirements.

[0019] Each processing means is preferably adapted to at least partially reset after generating said output signal. An advantage of embodiments of the present invention is that said processing means can be used to receive and process long pulse trains. An advantage of embodiments of the present invention is that said processing means is reset after generating said output signal and is ready to receive a new set of pulses, thereby providing asynchronous detection.

[0020] The optical sensing system preferably comprises a switching element for each processing means, the switching elements being adapted to be able to bypass the processing means. An advantage of embodiments of the present invention is that it is possible to select whether to use the first processing means or the second processing means depending on detection conditions such as ambient light conditions.

[0021] Each processing means is preferably a neuron, preferably a leaky integrate-and-fire (LIF) neuron. An advantage of embodiments of the present invention is that a compact system is obtained. An advantage of embodiments of the present invention is that a simple and uncomplicated system is obtained. An advantage of embodiments of the present invention is that the decay rate of the neurons can be adjusted.

[0022] The optical sensing system preferably further comprises at least one light source and scanning means adapted to scan a light beam from the light source along a trajectory over the scene, preferably continuously. An advantage of embodiments of the present invention is that the light source enables triangulation and determination of a depth profile of field between the optical sensor and objects in the scene, wherein the light source and the optical sensor are asynchronous, i.e. light generation and detection are not synchronized.

[0023] The optical sensing system preferably comprises at least two optical sensors.An advantage of embodiments of the present invention is that triangulation is possible.

[0024] In a second aspect, the present invention relates to an optical sensing method, said optical sensing method comprising: a- receiving a plurality of optical signals; b- an integrating step, in parallel for each optical signal, integrating said optical signal to obtain a first integrated output; c- generating a first output signal when the first integrated output reaches at least a first predetermined value within a first time duration; It has.

[0025] Preferred embodiments of the second aspect of the present invention include suitable combinations of one or more of the following features: The method preferably further comprises a damping step of damping the integrated output over time, the rate of damping preferably being adjustable. - said method comprising: d- for each first output signal, in parallel, integrating said first output signal to obtain a second integrated output; e- generating a second output signal when said second integral output is at least a second predetermined value; and The rate of decay in steps a to c is faster than that in steps d to e. resetting the first integral output after generating the first output signal and resetting the second integral output after generating the second output signal.

[0026] These and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention, the description being given for purposes of example only, without limiting the scope of the invention. [Brief explanation of the drawings]

[0027] The present disclosure is further explained by the following description and accompanying drawings. [Figure 1] FIG. 1 illustrates an optical sensing system (1) according to an embodiment of the present invention, comprising a plurality of sensing units (2', 2'', 2''') and a plurality of processing means (5', 5'', 5''', 5''''), where each sensing unit (2', 2'', 2''') is connected to a corresponding processing means (5', 5''), and a first processing means (5', 5'') and a second processing means (5''', 5'''') are connected in series. [Figure 2] FIG. 2 illustrates an embodiment of the present invention, in which an optical sensing system (1) includes a plurality of sensing units (2′, 2″, 2′″) and a plurality of processing means (5′, 5″), each of the sensing units (2′, 2″, 2′″) being connected to a corresponding processing means (5′, 5″), and the processing means (5′, 5″) includes a first neuron (12) and a second neuron (13) connected in series. [Figure 3] FIG. 3 shows a processing means (5) adapted, according to an embodiment of the present invention, to generate a pulse (21) when the total number of input pulses (7) to the processing means (5) is at least a predetermined number (11) within a predetermined time span (Δt). [Figure 4]FIG. 4 shows a processing means (5) including a first neuron (12) and a second neuron (13). (a) shows an example output (7'') of the sensing unit (2''). (b) shows the corresponding integrated output (10) by the first neuron (12). (c) shows the corresponding output (17) of the first neuron (12). (d) shows the corresponding integrated output (23) of the first neuron (12) by the second neuron (13). (e) shows the corresponding output (18) of the second neuron (13). [Figure 5] Figure 5 shows a similar situation to Figure 4 in a vertical view. (a) shows an example output (7'') of sensing unit (2''). (b) shows the corresponding integrated output (10) by the first neuron (12). (c) shows the corresponding output (17) of the first neuron (12). (d) shows the corresponding integrated output (23) of the first neuron (12) by the second neuron (13). (e) shows the corresponding output (18) of the second neuron (13). [Figure 6] FIG. 6 relates to an embodiment of the present invention and shows a processing means (5) in which in (a) a first neuron (12) and a second neuron (13) are connected in series, and in (b) a first switching means (22′) and a second switching means (22″) precede each of the first neuron (12) and the second neuron (13). [Figure 7] Figure 7 shows an example of synchronous detection, relating to the prior art, where (a) the pulse train input (24) is shown, (b) the observation window (25) is shown, and (c) the output (26). [Figure 8] FIG. 8 shows detection under strong ambient light conditions (a) and weak ambient light conditions (b) for an embodiment of the present invention. [Figure 9] 9 shows an example of asynchronous detection according to an embodiment of the present invention. Reference signs in the claims should not be construed as limiting the scope. In different drawings, the same reference signs refer to the same or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention relates to an optical sensing system for optical sensing.

[0029] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are schematic and non-limiting. In the drawings, the size 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 practice of the invention.

[0030] Terms such as first, second, etc. in this specification and claims are used to distinguish between similar elements and are not necessarily used to describe an order in time, space, sequence, or otherwise. The terms so used are interchangeable under appropriate circumstances, and it is understood that the embodiments of the invention described herein are capable of operating in sequences other than those described or illustrated herein.

[0031] Furthermore, terms such as top, under, and the like are used in this specification and claims for descriptive purposes and not necessarily to describe 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 orientations other than those described or illustrated herein.

[0032] Numerous specific details are set forth herein. However, it will be understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this specification.

[0033] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, although they may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0034] Similarly, in describing exemplary embodiments of the invention, it should be understood that various features of the invention may be grouped together in a single embodiment, figure, or description for the purpose of streamlining the disclosure and facilitating an understanding of one or more various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single prior-disclosed embodiment. Accordingly, the claims following the detailed description are expressly incorporated into this specification, with each claim standing on its own as a separate embodiment of this invention.

[0035] Furthermore, although some embodiments described herein include some features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the present invention and form different embodiments, as would be understood by one skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0036] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs. As a further guide, term definitions are included to better understand the teachings of the present invention.

[0037] As used herein, the following terms have the following meanings: "A," "an," and "the" as used herein refer to both the singular and the plural unless the context clearly dictates otherwise. By way of example, "a contaminant" refers to one or more contaminants.

[0038] The recitation of numerical ranges by endpoints includes not only the recited endpoints but also all numbers and fractions subsumed within that range.

[0039] In a first aspect, the present invention relates to an optical sensing system for optical sensing, preferably for compact optical sensing. The system includes a plurality of sensing units, each having at least one optical sensor. Each of the sensing units is preferably a pixel sensor. Each sensing unit includes a photodetector. Preferably, the photodetector is a single-photon detector, preferably a single-photon avalanche detector. Alternatively, the photodetector is an avalanche photodetector. Each of the photodetectors is adapted to output a signal in response to detecting a photon. For example, in response to detecting one photon or a predetermined number of photons, the photodetector outputs a signal (e.g., a pulse). The system further includes an optical system capable of generating an image of a scene on the optical sensor. The system further includes a plurality of processing means. Each of the processing means is connected to at least one sensing unit corresponding to the processing means. For example, each sensing unit has a processing means corresponding to the sensing unit. The sensing units are connected in parallel to the processing means corresponding to the sensing unit. Such a parallel connection is advantageous, for example, because it enables a fast, efficient, and compact system.

[0040] Each of the processing means is adapted to receive at least one input corresponding to at least one output of a corresponding sensing unit, e.g., the processing means is connected to the sensing unit and receives input from the sensing unit, the output of the sensing unit being, for example, a pulse or pulse train corresponding to whether or not a photon has been received by the sensing unit.

[0041] For example, the output signal may be generated based on the rate at which pulses (e.g., corresponding to the photons) arrive at the processing means, i.e., whether they arrive within a first predetermined time interval. For example, the processing means may be adapted to generate the output signal when the total number of photons detected by the sensing unit is at least a predetermined number within the first predetermined time interval. For example, the number of pulses may be at least two, preferably at least five, more preferably at least ten pulses within a maximum of 10 nanoseconds, preferably at most 5 nanoseconds, more preferably at most 2 nanoseconds. In other words, the more pulses that arrive within a shorter period of time, the more likely a positive detection is, while the more pulses that arrive within the short period of time, the more likely a false detection is. This is advantageous for obtaining reliable detection and filtering false detections. For example, in the presence of ambient light, it is unlikely that five pulses will be received within 2 nanoseconds. This also enables asynchronous detection, because whenever a number of photons within the first predetermined time interval are detected, a pulse is received and an output signal is generated by the processing means.

[0042] Each processing means is adapted to integrate the output of a corresponding sensing unit to obtain a first integrated output, and the processing means is adapted to generate a first output signal when the first integrated output is at least a first predetermined value (or reaches the first predetermined value). This means that the first integrated output dynamically changes based on the output of the corresponding sensing unit until it reaches the first predetermined value. As described above, the input signal to the processing means and the output signal from the processing means are digital signals, but the signal within the processing means may be an analog signal. For example, in this case, the first integrated output signal is an analog signal, but it is used only within the processing means and not output from the processing means. In practice, when integrating the output from one sensing unit, the first predetermined time interval is usually short, so the integrated output cannot reach the first predetermined value within the first predetermined time interval. Therefore, in practice, the outputs of multiple sensing units, e.g., adjacent sensing units, are connected to each processing means to ensure that the first integrated output reaches the first predetermined value, as described below. Ideally, as shown below, the first integrated output decays over time or is reset at a specific time instance (i.e., allowed to reach the first predetermined value only within the first predetermined time span). That is, the detection of the sensing unit is not limited to single-photon detection. Furthermore, those skilled in the art will understand that the number of photons can be calculated even when using a sensing unit including a typical photodetector that is not a single-photon detector. For example, the total number of photons can also be the total number of detections when at least a certain number, e.g., the predetermined number, is detected within the first predetermined time span.

[0043] Preferably, each sensing unit is adapted to generate a stream of pulses or digital signals (e.g. signals lying within a range of at least two values, e.g. "1" and "0"), e.g. each pulse being the result of the detection of an incident photon. The processing means is also preferably adapted to receive said stream of pulses or digital signals. For example, the input signals to and output signals from the processing means are digital signals. This has the advantage that no analog to digital converters are required. However, processing the signals in the processing means may result in analog signals, e.g. when pulses are integrated in the processing means (see below).

[0044] Preferably, each photodetector is arranged in a reverse bias configuration. Preferably, the photodetector is capable of detecting a single photon incident thereon. Preferably, the photodetector may be adapted to output a logic signal, e.g., an electrical detection signal, upon detection of a photon. For example, the detection signal may be represented by a signal including a logic "1," e.g., detection, while no detection signal may be represented by a signal including a logic "0," e.g., no detection. Alternatively, the 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 back from a logic "1" to a logic "0." Also, no detection may be represented by or result in the absence of such a pulse signal.

[0045] Preferably, the system includes at least one adjacent sensing unit adjacent to the sensing unit. The system includes at least one adjacent processing means adjacent to the processing means. Each sensing unit is connected to the at least one adjacent processing means corresponding to the at least one adjacent sensing unit. In other words, each processing means receives outputs from the sensing unit corresponding to the processing means and at least one, preferably at least two or three, adjacent sensing units. Detection is then performed based on multiple sensing units, e.g., a group of adjacent sensing units. This is advantageous in that it reduces the possibility of false detections resulting from temporally and spatially uncorrelated photon streams, such as ambient light, and instead leads to true detections resulting from light actively projected onto the scene that generates temporally and spatially correlated photon streams in neighboring pixels. For example, if three adjacent sensing units each detect a photon within 2 nanoseconds, this detection is likely to be true.

[0046] Preferably, each of the processing means is adapted to integrate the output of at least one sensing unit and at least one adjacent sensing unit to obtain the first integrated output. The processing means is adapted to generate the first output signal, preferably a digital output signal, if the combined integrated outputs are at least the first predetermined value within the first predetermined time span. Having pulses from multiple sensing units, for example adjacent or closely located sensing units, within a very short period of time makes it less likely to be a false detection.

[0047] Preferably, each of the first integral outputs has a decay rate, which is preferably adjustable. In other words, if there are multiple first and second processing means, each of the processing means can be adjusted independently. The decay rate determines the first predetermined time interval and thus how quickly pulses must follow each other to generate the first output signal. For example, the first integral output continues to decay until enough pulses are received so that the first integral output eventually reaches the first predetermined value. Thus, continuous monitoring is performed to determine whether enough pulses arrive to reach the first predetermined value within a short period of time. Those skilled in the art will understand that determining when too many pulses have been received can be implemented in ways other than by setting a decay rate, such as by resetting the first integral output after a predetermined time interval.

[0048] By adjusting the decay rate, the length of the time window considered by the processing means can be defined, controlling the system's behavior and adapting it, for example, depending on the available optical power. For example, assume an optical system has a light source that is scanned along different parts of a scene and detected by an optical sensor (described below). Slowing the decay rate (i.e., increasing the observation window) reduces the filtering capability of the processing means, but reducing the optical power reduces the chance of detecting a photon within a given observation window, thereby reducing the power consumption of the light source. Therefore, setting a longer observation window (i.e., a slower decay rate) allows reducing the optical power at the expense of reduced filtering of uncorrelated photon detection.

[0049] Preferably, each processing means is a first processing means connected in series to a second processing means. For example, the output of the first processing means is input to the second processing means. In principle, the first processing means and the second processing means are similar, except that the decay rate of the first processing means is faster than that of the second processing means. This means that the first predetermined time interval during which the total number of pulses must be received is different for the first processing means than for the second predetermined time interval for the second processing means. This allows the two processing means to have different roles. For example, if the first processing means has multiple inputs, the first processing means ensures a matching condition (spatial condition). For example, by projecting a dot onto a scene using the light source and imposing a specific shape on the projected dot, a pixel can be constrained to be flagged as valid only if the imposed kernel corresponding to the expected dot shape is detected in the pixel array within a predetermined time. For example, a 2x1 kernel can be imposed. This means that the projected dot must span at least 2x1 pixels. This is generally suitable for elliptical dot shapes. If we capture a light pulse of length tp, we impose a constraint on the pixels that a 2 × 1 cluster of pixels must fire within tp for a detected photon to be considered to come from an active projection. Preferably, tp is on the order of 1 nanosecond.

[0050] In other words, this condition requires that the inputs of multiple sensing units be positive within a predetermined time before the processing means will generate an output, in which case, for example, if only one input is positive, at least one or two adjacent sensing units must have positive inputs to the processing means, so that the integrated output does not reach a predetermined value.

[0051] The first predetermined value in the first processing means may be different from the predetermined value in the second processing means (hereinafter referred to as the second predetermined value) and may be independently adjustable.

[0052] The second processing means has a different role: ensuring the duration condition (spatiotemporal condition). For example, if a light source is used to project a dot, we can enforce that the dot's trajectory is continuous if the pulse repetition rate is higher than the dot's displacement speed. Let's assume that a 1-ns pulse is repeated every 40 ns. A 41-ns time window can capture two pulses. By requiring that a pixel (or pixel cluster) sees at least two pulses within a 41-ns window, we can filter out a significant portion of the detected disturbance photons, because the photon statistics of the disturbance light are unlikely to produce two consecutive detections within a 42-ns window.

[0053] For example, the second processing means is adapted to integrate the first output signal of the first processing means to obtain a second integrated output, and the second processing means is adapted to generate the second output signal when the second integrated output is at least the second predetermined value. For example, the time required to reach the second predetermined value is a second predetermined time duration that is longer than the first predetermined time duration. For example, the first predetermined time duration is equal to or less than half of the second predetermined time duration.

[0054] In other words, this condition (i.e., persistence) requires that the input to the second processing means contains many pulses (continuous or nearly continuous) within a certain period of time, which means that the input is persistent, i.e., the input is likely to be true. For example, if 9 out of 10 consecutive detections of the sensing unit are positive, it is likely to be positive. The decay rate of the second processing means is long because the second processing means needs to check or monitor the input over a long period of time, while the decay rate of the first processing means is short because the first processing means needs to check or monitor the input (i.e., the output of multiple sensing units) within a short period of time. The combined application of both consistency and persistence creates a powerful filtering strategy that is very efficient in terms of hardware implementation.

[0055] Preferably, the processing means is adapted to associate a weight with each pulse of the sensing unit itself and of connected neighboring sensing units. For example, this can be achieved by giving each pulse of the neighboring sensing units a unique pulse length, which modulates the contribution of each pulse to the integrated signal. Another implementation could be to associate a unique charge with each pulse signal, which is added to or subtracted from the integrated signal in the presence of each pulse. In this way, by assigning different weights, contributions from different types of neighboring signals can be prioritized. For example, diagonal neighbors can be given a lower weight than directly adjacent neighbors. This aims to minimize the possibility that ambient or thermal detections contribute to the true detection as if they were from the activating light.

[0056] Preferably, the processing means is adapted to at least partially reset after generating its output signal. For example, the processing means returns to its initial state after generating the output signal. For example, the value of the integrator output signal is reset. Preferably, two serially connected processing means are reset to different values. For example, the integrator output signal of each processing means is reset to a different value. For example, the first processing means is fully reset. For example, the first integrator output signal is fully reset, e.g., to zero. Meanwhile, the second processing means is partially reset. For example, the second integrator output signal is partially reset. For example, the second integrator output signal is reset to half its value. This is useful when a pulse arrives while the integrator output signal of the processing means has exceeded the threshold and has not yet decayed. For example, a long pulse train is detected and the integrator output quickly reaches the threshold or a predetermined value. In this case, the integrator output needs to be reset to zero so that more pulses can be processed.

[0057] In this case, the first processing means is fully reset, since it requires multiple sensing units to detect pulses over a short period of time. In such a case, the first predetermined value is reached quickly. However, the second processing means is partially reset, since it requires one sensing unit to detect pulses over a longer period of time. In such a case, the second predetermined value is reached slowly. A full reset would mean that for a pulse train that repeats faster than the decay rate of the processing means, only one in two pulses would produce a pulse at the output of the processing means. A partial reset avoids this and can provide a continuous pulse train at the output of the processing means, where only the first pulse does not result in a pulse at the output (see Figures 4, 5 and 9).

[0058] Preferably, the system includes a switching element for each processing means, the switching element being adapted to bypass the processing means. For example, the system can be programmed so that one of the first processing means or the second processing means is bypassed by the switching element. This allows the optimal processing means to be selected depending on conditions, such as ambient light conditions or the active signal strength. For example, if the signal strength is too low, it may not be desirable to use two processing means in series. As an example, when using two processing means sequentially, there are three scenarios: (1) the first processing means is ON and the second processing means is OFF, (2) the first processing means is OFF and the second processing means is ON, and (3) the first processing means is ON and the second processing means is ON.

[0059] For example, when ambient light is negligible, it may be advantageous to use only the second processing means (scenario 2), thus reducing power consumption (i.e., of the first processing means) and increasing processing speed. However, when ambient light is significant, it may be advantageous to use the first processing means (scenario 1) to further filter out noisy detections due to ambient light. Finally, when highly reliable detection is required, it may be advantageous to use both the first and second processing means (scenario 3), which allows for two-layer filtering and high detection reliability.

[0060] In another example, this may also depend on the bandwidth of the received signal; for example, if the bandwidth is very wide, it may be appropriate to use the first processing means (i.e., a short time window), and if the bandwidth is narrow, it may be appropriate to use the second processing means (i.e., a long time window).

[0061] Preferably, each processing means is a neuron, preferably a leaky integrate-and-fire (LIF) neuron. However, those skilled in the art will understand that other types of neural networks, such as convolutional networks and spike networks, may also be used. All implementations described above regarding the processing means are also applicable when the processing means is a neuron. For example, the system preferably includes a first neuron and a second neuron connected in series. The first neuron has at least two or at least three inputs. The inputs are, for example, the outputs of one sensing unit and one or two adjacent sensing units. The second neuron has one input, which is the output of the first neuron. Also, similar to the above description, the first neuron has inputs from the sensing unit and the adjacent sensing unit, which enables simultaneous detection, i.e., detection of photons from adjacent pixels within a certain time span, i.e., a first time window. The first window is typically short and has the same size as the light pulse to be detected. Meanwhile, the second neuron enables sustained detection, repeatedly detecting photons or neuron firings at the same pixel within a second time window, i.e., within a second time window. The second time window is typically long, preferably equal to or slightly longer than the repetition time of the light pulse. One or both neurons can be selected to operate using switching means depending on the light conditions, allowing for programmable filter behavior by operating the switch. The advantage of using neurons is that this architecture allows for very low power consumption and compact implementation. Also, as above, the neurons are adapted to integrate at least one input, and each neuron is adapted to generate an output signal, preferably a digital output signal or a digital pulse, when the integrated value is at least the predetermined value. However, in practice, for the first neuron (i.e., the neuron performing coincidence detection), if a pulse arrives from only one sensing unit, the pulse is integrated in the first neuron, but not enough to reach the predetermined value.Therefore, in practice, it is necessary to integrate the outputs from multiple sensing units to reach a predetermined value. As above, each neuron is adapted to at least partially reset after generating an output signal. In some implementations, the neuron resets itself after firing. In other implementations, the neuron partially (e.g., half) resets. This avoids cases where a pulse arrives while the neuron is still above the predetermined value or threshold. This is because the neuron can integrate the outputs of the sensing units to obtain an integrated output, which leaks (i.e., decays) over time, allowing the neuron to fire when the integrated output reaches the predetermined value.

[0062] In a configuration in which two neurons are connected in series, the first neuron is preferably fully reset because it has a faster decay rate. That is, the decay rate of the first neuron is short, e.g., at most 10 ns, preferably at most 5 ns, more preferably at most 2 ns or 1 ns. In other words, if a predetermined number of pulses arrive within the short time frame, the detection of the first neuron is almost instantaneous. For example, this is the case when the sensing unit and one or two of its neighbors detect an incident photon within a short time frame. On the other hand, the second neuron is preferably partially reset because it has a slower decay rate. That is, the decay rate of the second neuron is long, e.g., at least 10 ns, preferably at least 20 ns or at least 50 ns. For example, the decay rate of the first neuron (or generally the first processing means) is at least twice, or at least three or four times, or generally much faster than the decay rate of the second neuron (or generally the second processing means). The second neuron is not affected by the disturbing light because it has already been filtered by the first neuron. Therefore, the second neuron has a long time window. This is because the second neuron is responsible for detecting whether the detection is sustained, i.e., whether the detection is positive or "1" in at least M, preferably consecutive, observation windows out of the past N observation windows, where M is greater than 1 and at most equal to N. For example, in ten consecutive time windows, the second neuron detects whether the detection is positive in the majority or all, e.g., nine or eight, of the ten consecutive time windows. The second neuron provides a second level of filtering in addition to the first level of filtering provided by the first neuron.

[0063] The reference to one or two processing means (or neurons) in the present invention should not be understood as limiting. Those skilled in the art will understand that additional layers of neurons can be used, for example to achieve further filtering. For example, a third neuron can check whether a neighboring neuron has fired within a certain time in the past.

[0064] Preferably, the system further comprises at least one light source and a scanning means adapted to scan a light beam from the light source at least partially over the scene along a trajectory. This is advantageous for enabling triangulation and determining a depth profile of the field of view. For example, the depth profile can be estimated by triangulating the points of the at least one object in the scene detected by the optical sensor with data on the light emitted by the at least one light source. This is similar to triangulating the outputs of two optical sensors, since the data on the light emitted by the light source is known, i.e., it is known which part of the scene the light illuminates at a given time. An advantage of this invention is that the light source and the light sensor are asynchronous, i.e., the generation and detection of light are asynchronous, resulting in asynchronous detection. However, the light source and the optical sensor must be calibrated, e.g., so that the pattern and projection angle at each timestamp are known.

[0065] Preferably, the system comprises at least one optical sensor, and distance is estimated by the 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, where the displacement is referred to as an expected position based on prior knowledge of a light source and / or the displacement is referred to as the 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, which is advantageous in that the distance between each object and the sensor can be easily determined.

[0066] Scanning the light beam from the light source is advantageous in enabling triangulation. For example, when using a system including a light source that irradiates a light beam onto a scene (e.g., an environment) and two optical sensors, for example, positioned at different orientations, and the two optical sensors (i.e., their sensing units) have a shared field of view of the scene, triangulation can be used to convert the xy-time data of the two sensors (i.e., their sensing units) into xyz-time data. For example, the light source is adapted to irradiate the light beam onto the scene in an illumination trace. The light source includes means adapted to scan the light beam over the scene (preferably continuously). The optical sensor monitors a light spot generated by the light beam and outputs the position of at least one object point in the scene (e.g., a point on the surface of the object) along the trace at multiple instances. The xy-time data of the two optical sensors (i.e., their sensing units) can be converted into xyz-time data using triangulation. The light source can, for example, serve as a reference point and synchronize the position of the point of the object on the first optical sensor with the point on the second optical sensor, creating a depth or z-dimension. The light source can illuminate and scan the light beam over the scene to be imaged, such as in a Lissajous pattern or raster scan. This illumination trajectory is advantageous in that after several illumination cycles, a significant portion of the image is already illuminated, allowing for efficient and fast image detection. Other illumination patterns are also envisioned.

[0067] Preferably, the scanning is continuous so that objects in a scene are continuously scanned and identified. For example, a light source generates a light beam, which generates a light spot on an object. The light beam is continuously scanned over the scene along the trajectory. For example, at each time, the beam has scanned all or almost all of the scene. Then, reflected signals are received by at least one sensing unit. The scanning may be, for example, a Lissajous pattern or a raster scan. The scanning means may be, for example, a MEMS scanner, a mirror, an optical phase array, a metasurface approach beam scanning, or the like.

[0068] For example, the light source is adapted to a wavelength detectable by the sensing unit, for example between 100 nanometers and 10 micrometers, preferably between 100 nanometers and 1 micrometer. For example, the optical sensor comprises a photodetector or a matrix of photodetectors capable of detecting photons incident on each detector within a wavelength detection window in the range of 100 nanometers to 10 micrometers, preferably in the range of 100 nanometers to 1 micrometer.

[0069] Preferably, the scanning is accomplished by discrete steps of the scan angle, and typically the sensing sampling frequency of the sensor is faster than the step frequency of the scanner.

[0070] Preferably, the optical energy emitted along the scanning trajectory is pulsed, meaning that the scanning arrangement scans the beam across the scene in a discrete or continuous manner, and the beam energy profile in time is pulsed. For example, the beam may be a pulse train of 1 nanosecond pulses repeated every 40 nanoseconds. In this case, the preferred time constant of the first processing means, taking into account consistency, is 1 nanosecond to 2 nanoseconds, and the time constant associated with the second processing means is 41 nanoseconds to 42 nanoseconds or slightly longer.

[0071] Preferably, each optical sensor comprises a matrix of pixel sensors connected to a matrix of processing means. For example, the system may comprise more than 100 pixel sensors, preferably more than 1,000 pixel sensors, more preferably more than 10,000 pixel sensors, even more preferably more than 100,000 pixel sensors, and most preferably more than 1,000,000 pixel sensors. For example, the system may comprise the optical sensors arranged in a matrix fashion comprising rows of 1,000 pixel sensors and columns of 1,000 pixel sensors.

[0072] Preferably, the system comprises image representation means, for example in the form of a screen or other image representation device, for reconstructing the positions of the points of said object in said scene.

[0073] Preferably, the system is used for 3D vision applications, for example to visualize objects in three dimensions, or the sensor(s) may allow analyzing the scene without necessarily generating an image of the scene, for example by extracting features of objects in the scene.

[0074] Preferably, the system further comprises multiple optical sensors (e.g., at least two optical sensors) and / or multiple light sources. This is advantageous for creating 3D vision and allows triangulation (e.g., between one sensing unit of a first optical sensor and one sensing unit of a second optical sensor) to obtain depth data. For example, each optical sensor may be oriented differently such that triangulation of the outputs of two optical sensors provides a 3D perception of the scene being imaged.

[0075] Preferably, the processing means, e.g., the first processing means, generates an output signal, e.g., the first output signal, when multiple inputs to the first processing means, e.g., inputs from multiple sensing units, are positive within a certain period of time, e.g., the first predetermined time width. Alternatively, the processing means, e.g., the second processing means, generates an output signal, e.g., the second output signal, when inputs to the second processing means, e.g., the input from the first processing means, comprise consecutive pulses within a certain period of time, e.g., the second predetermined time width. This can be generalized as described below. The processing means generates an output when multiple inputs to the processing means are positive within a certain period of time, or the processing means generates an output when one input to the processing means comprises consecutive (or semi-consecutive) pulses within a certain period of time.

[0076] Preferably, each processing means is a first processing means connected in series with a second processing means, the second processing means adapted to integrate the first output signal of the first processing means to obtain a second integrated output, and the second processing means adapted to generate the second output signal when the second integrated output is at least a second predetermined value within a second predetermined time interval, similar to that described above, except that instead of relying on the decay rate of each processing means, the first processing means is reset after the first predetermined time interval and the second processing means is reset after the second predetermined time interval, the first predetermined time interval being half of the second predetermined time interval.

[0077] In a second aspect, the present invention relates to a method for optical sensing, the method comprising (a) receiving a plurality of optical signals using a plurality of sensing units, for example according to the first aspect.

[0078] The method further includes (b) integrating, in parallel for each optical signal, the optical signal to obtain a first integrated output. For example, a processing unit may be associated with each of the sensing units, and each processing unit may integrate the optical signal input to the processing unit to obtain the first integrated output. The method further includes (c) generating a first output signal when the first integrated output is at least a first predetermined value within a first predetermined time period.

[0079] Preferably, the method further comprises adapting the plurality of sensing units to output a signal in response to detecting a photon. Preferably, the method further comprises a damping step of damping the integrated output over time, the rate of said damping preferably being adjustable.

[0080] Preferably, the method further comprises the steps of (d) in parallel with each first output signal, integrating said signal to obtain a second integrated output, and (e) generating a second output signal when the second integrated output is at least a second predetermined value, wherein the rate of decay in steps (a) to (c) is faster than the rate of decay in steps (d) to (e).

[0081] Preferably, the method further comprises the steps of resetting a first integral output after generating the first output signal, and resetting a second integral output after generating the second output signal.

[0082] The features of the second aspect (method) are as described in the first aspect (system).

[0083] In a third aspect, the present invention relates to the use of a system according to the first aspect and / or a method according to the second aspect for optical sensing.

[0084] Further features and advantages of embodiments of the present invention will now be described with reference to the 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 is limited only by the claims.

[0085] FIG. 1 shows an optical sensing system (1) according to an embodiment of the present invention. The optical sensing system (1) comprises an optical sensor (30) including a plurality of sensing units (2′, 2″, 2′″). The optical sensing system (1) further comprises an optical system (3) capable of generating an image of a scene (4) on the optical sensor (2′, 2″, 2′″). The optical sensing system (1) further comprises a light source (14) that emits a light beam (16) that generates a light spot or dot on the scene (4). The optical sensing system (1) further comprises a scanning means (15) adapted to scan the light beam (16) over the scene (4). For example, the scanning means (15) may be a reflector or a MEMS mirror or the like that can scan the light beam (16) over the scene (4), for example, over different parts of the scene (4). The light beam (16) is scanned along an illumination trajectory, for example, in a Lissajous manner. Then, the reflected signals from the scene (4) are captured by the sensing units (2', 2'', 2'').

[0086] The optical sensing system (1) further comprises a plurality of processing means (5', 5", 5'", 5'", 5'"), i.e., a first processing means (5', 5") adapted to receive the outputs (7', 7", 7'") of the sensing units (2', 2", 2'"). The optical sensing system (1) comprises at least one adjacent sensing unit (2", 2'") adjacent to the sensing unit (2'). Similarly, the optical sensing system (1) comprises at least one adjacent processing means (5") adjacent to the processing means (5'). Each sensing unit (2', 2", 2'") is connected to its corresponding processing means (5', 5") and to the adjacent processing means (5") corresponding to the adjacent sensing unit (2", 2'".

[0087] The outputs (7' 7'', 7''') of the sensing units (2', 2'', 2''') are input to the first processing means (5', 5''). The first processing means (5', 5'') are connected in series to the second processing means (5''', 5''''), and the outputs of the first processing means (5', 5'') are connected to the inputs of the second processing means (5''', 5'''').

[0088] The outputs (7', 7'', 7''') of the sensing units (2', 2'', 2''', the output (8) of the first processing means (5', 5''), and the output of the second processing means (5''', 5'''') are digital outputs, e.g., trains of pulses. As shown, the first processing means (5', 5'') is adapted to receive multiple inputs of multiple sensing units (2', 2'', 2'''), e.g., sensing unit (2') and at least one adjacent sensing unit (2'', 2'''). The second processing means (5''', 5'''') is adapted to receive only one input, which is the output of the first processing means (5', 5'').

[0089] The processing means (5') is shown in Figure 1 as being located outside the sensing unit (2'). However, the processing means (5') may also be part of the sensing unit (2'). If the processing means (5') is a neuron, said neuron is preferably directly connected to the sensing unit (2').

[0090] FIG. 2 illustrates an optical sensing system (1) according to an embodiment of the present invention. The optical sensing system (1) includes multiple sensing units (2′, 2″, 2′″) and multiple processing means (5′, 5″). Each sensing unit (2′, 2″, 2′″) is connected in parallel to its corresponding processing means (5′, 5″). The processing means (5′, 5″) includes a first neuron (12) and a second neuron (13) connected in series. As in FIG. 1, the output (6) of the first neuron (12) is input to the second neuron (13). The inputs (7′, 7″, 7′″) and outputs (6, 8) of each neuron (12, 13) are digital, e.g., pulses. For example, a stream of photons enters the sensing units (2′, 2″, 2′″), which in turn output a pulse train. In FIG. 2, a first neuron (12) functions as the first processing means (5', 5'') of FIG. 1, and a second neuron (13) functions as the second processing means (5''', 5'''') of FIG. 1.

[0091] FIG. 3 shows a processing means (5) according to an embodiment of the present invention. The input (7) to the processing means (5) is a stream of pulses. The processing means (5) is adapted to generate a pulse (21) at the output (8) of the processing means (5) when the total number of pulses (11) is at least a predetermined number (11) within a predetermined time span (Δt). In this figure, the total number of pulses (11) is shown only from one input (7). However, in practice, the total number of pulses (11) preferably takes multiple inputs into account. This allows filtering out ambient light or false detections, since it is more difficult to obtain a total number of X false detections from a sensing unit and its neighboring sensing units within Y time spans. For example, if there are three inputs to the processing means (5) corresponding to three adjacent sensing units (2', 2'', 2'''), and a total of nine pulses need to arrive within two nanoseconds to enable the processing means to generate an output pulse (21), then approximately three pulses per sensing unit (2', 2'', 2''') need to arrive within two nanoseconds. This is a very effective way to reduce false positives and obtain reliable detection.

[0092] FIG. 4 illustrates an example of a processing means (5) including a first neuron (12) and a second neuron (13) according to an embodiment of the present invention. An example of an output (7'') of a sensing unit (2'') is shown in (a), where the output (7'') is a train of pulses (19) corresponding to events of the sensing unit (2''). These pulses (19) are input to the first neuron (12). Similar pulses of neighboring sensing units (2', 2''') are also output (7', 7''') by the neighboring sensing units (2', 2''') and input to the first neuron (12). The first neuron (12) is adapted to integrate its input (7', 7'', 7'''), as shown in (b). For example, at a first time instance (t1), a pulse is received and the integrated output (10) jumps in value. The integrated output (10) of the first neuron (12) decays according to a decay rate. At a second time instance (t2), another pulse is received, causing the integrator output (10) to again jump above the threshold (9) or the first predetermined value. As the integrator output (10) exceeds the threshold (9) limit (within the first predetermined time interval (Δt)), an output pulse (17) is generated by the first neuron (12) at a third time instance (t3), as shown in (c). This occurs again at a fourth time instance (t4) and a fifth time instance (t5), generating another output pulse at a sixth time instance (t6).

[0093] The integrated output (10) is not only the result of integrating the output (7'') of one sensing unit (2''), but also the result of integrating the outputs (7', 7''') of the neighboring sensing units (2', 2'''). Therefore, if a pulse comes from only one sensing unit (2'') and the pulse is likely the result of a false detection, the integrated output (10) of the one sensing unit (2'') will not be high enough to reach the threshold (9). Therefore, the outputs (7', 7'', 7''') of one sensing unit (2'') and its neighboring sensing units (2', 2''') need to reach the threshold (9) to ensure reliable detection and filter out false detections.

[0094] The output (6) of the first neuron (12), which includes a pulse (17), is input to the second neuron (13). Unlike the first neuron (12), the second neuron (13) has only one input (6). The second neuron (13) is also adapted to integrate the input (6). However, the integrated output (23) decays at a different rate than the first neuron (12). This is shown in (d), where the integrated output (23) of the second neuron (13) decays at a slower rate than the first integrated output (10) of the first neuron (12). The slower decay rate of the integrated output (23) of the second neuron (13) indicates whether the detection is a sustained detection. For example, the first neuron (12) can detect reliable detections and filter out false detections by relying on the detection of neighboring sensing units, or so-called coincidence detection. Meanwhile, the second neuron (12) can detect a sustained detection, e.g., a detection occurring continuously within a period of time (herein referred to as a second predetermined time interval (Δt2)), or so-called sustained detection. Because the pulse (17) at the input of the second neuron (13) is sustained and the second integrated output (23) of the second neuron (13) reaches the threshold (9), a pulse (18) is generated by the second neuron (13) at the seventh time instance (t7), as shown in (e). For better understanding, Figure 5(ae) shows a similar situation to Figure 4(ae) in a vertical view.

[0095] FIG. 6 shows the processing means (5), where in (a) a first neuron (12) and a second neuron (13) are connected in series. Another advantageous implementation is shown in (b), in which a switching means (22′, 22″) precedes each of the first neuron (12) and the second neuron (13). For example, the first switching means (22′) precedes the first neuron (12), and the second switching means (22″) precedes the second neuron (13). Each switching means (22′, 22″) allows the corresponding neuron (12, 13) to be bypassed. For example, the first switching means (22′) can bypass the first neuron (12), and the output (7′) of the sensing unit (2′) is immediately input to the second neuron (13). Similarly, the second switching means (22'') allows the output of the first neuron (12) to bypass the second neuron (13), which becomes the output of the processing means (5). Only one switching means (22', 22'') may operate at a time (or none at all), otherwise the processing means (5) would not be able to process the input and produce a useful output.

[0096] The switching means (22', 22'') are advantageous when only one neuron is required to perform an operation. For example, when ambient light or noise is very low, the first neuron (12) can be bypassed without compromising the reliability of the system. Similarly, it is advantageous to bypass the second neuron (13) when the output of the first neuron does not require further filtering. Bypassing the neurons (12, 13) is also advantageous, for example, to reduce power consumption and increase processing speed.

[0097] FIG. 7 shows an example of synchronous detection, which is common in the prior art. In this example, assume that a pulse train (24) is input to the system as shown in (a), and observation windows (25) are set at intervals of a fixed period (t) as shown in (b). Because the observation windows (25) only cover a fixed time instance, pulses outside the observation windows (25) are not detected. For example, since only two pulses (24) coincide with two observation windows (25), the output (26) contains only those two pulses, and the other two pulses are not detected. However, the present invention provides asynchronous detection, which overcomes the drawbacks of synchronous detection.

[0098] FIG. 8 shows detection examples under different ambient light conditions according to an embodiment of the present invention. In (a), detection is performed under strong ambient light conditions. Therefore, it is desirable to use not only the sensing unit (2') but also two adjacent sensing units (2'', 2'''). The outputs of the sensing unit (2') and the two adjacent sensing units (2'', 2''') are supplied to the first neuron (12) or the first processing system (5'). However, in (b), detection is performed under weak ambient light conditions. Therefore, one sensing unit (2') and one adjacent sensing unit (2'') are sufficient. The outputs of the one sensing unit (2') and one adjacent sensing unit (2'') are input to the first neuron (12) or the first processing means (5'). An implementation that allows switching between (a) and (b) can be obtained by using switching elements (22', 22''): under strong ambient light conditions, the first switching element (22') is inactive and the first neuron (12) processes its input. However, under weak ambient light conditions, the first switching element (22') is activated, bypassing the first neuron (12) and providing the input directly to the second neuron (13). Other configurations can be envisioned based on the intensity of the activating light and other conditions such as bandwidth.

[0099] 9 shows an example of asynchronous detection according to an embodiment of the present invention. A pulse (29) of a different sensing unit is received in a first time window (T1, e.g., 1 nanosecond) and a pulse (27) is generated by the first processing means whenever the integrated output exceeds a predetermined value for the processing means (i.e., the number of pulses exceeds a predetermined number). This is followed by a second time window (T2, e.g., 20 nanoseconds) associated with the second processing means, which is much longer. The first processing means (5', 5'') is connected to the second processing means (5''', 5''''). A pulse (28) is generated by the second processing means whenever a pulse of the first processing means is received in the second time window (T2) and the integrated output exceeds a predetermined value for said processing means (i.e., the number of pulses exceeds a predetermined number).

[0100] Other arrangements for achieving the objectives of the methods and apparatus embodying the present invention will be apparent to those skilled in the art. Details of specific embodiments of the present invention will now be described. However, no matter how detailed the above description may appear in text, it will be apparent that the present invention can be applied in many ways. It should be noted that the use of a particular term in describing a particular feature or aspect of the present invention should not be construed as meaning that the term herein be redefined so as to be limited to the particular feature or aspect of the invention with which the term is associated. [Explanation of symbols]

[0101] 1. Optical Sensing System 2', 2'', 2''' sensing unit and adjacent sensing unit 3 Optical system 4 Scenes 5',5'' Processing means / first processing means 5''',5'''' Second processing means 6. Output signal of (first) processing means / output signal of first neuron 7 Optical sensor output signal 8. Output signal of (first) processing means / output signal of second neuron 9. First predetermined value 10 Optical sensor first integral output 11 Number of pulses from the optical sensor within a given time 12 First neuron 13 Second neuron 14 Light source 15 Scanning means 16 Light Beam 17 Digital output signal of the first neuron 18 Digital output signal of the second neuron 19 Digital input signal to processing means / digital output signal of optical sensor 20 Neuronal decay rate 21 Digital output signal of processing means 22 Switching element 23 Second integral output of the first neuron 24 Pulse train input to synchronous detection system 25 Observation window 26 Synchronous detection system output 27 First neuron or processing output 28 Second neuron or processing output 29 Pulses from different sensing units 30 Optical Sensor t1 First time instance t2 Second time instance t3 Third time instance t4 4th hour instance t5 5th hour instance t6 6th hour instance t7 7th hour instance 31 Second output signal / output signal of second processing means 32 Second predetermined value

Claims

1. An optical sensing system (1) for optical sensing, comprising: at least one optical sensor (30) including a plurality of sensing units (2'), preferably in a matrix configuration, each of said sensing units (2') being preferably a pixel sensor (2'), each sensing unit (2') including a photodetector, each photodetector adapted to output a signal in response to detecting a photon; an optical system (3) capable of generating an image of a scene (4) on said optical sensor (30); a plurality of processing means (5) each connected to at least one corresponding sensing unit (2'); and Each of said processing means (5') is adapted to receive at least one input corresponding to at least one output (7') of a corresponding sensing unit (2'); each of said processing means (5', 5'') adapted to integrate the output (7', 7'', 7''') of a corresponding sensing unit (2', 2'', 2''') to obtain a first integrated output (10); the processing means (5', 5'') is adapted to generate a first output signal (8) when the first integral output (10) reaches at least the first predetermined value (9) within a first predetermined time period (Δt); The optical sensing system (1) further comprises at least one light source (14) and a scanning means (15); the scanning means (15) being adapted to scan the light beam (16) from the light source (14) along a trajectory over the scene (4), preferably continuously; Optical sensing system (1).

2. 2. The optical sensing system (1) according to claim 1, the optical sensing system (1) comprises at least one adjacent sensing unit (2'', 2''') adjacent to the sensing unit (2') and at least one adjacent processing means (5'') adjacent to the processing means (5'); Each sensing unit (2') is connected to said at least one adjacent processing means (5'') corresponding to said at least one adjacent sensing unit (2'', 2'''); Optical sensing system (1).

3. 3. The optical sensing system (1) according to claim 2, each of the processing means (5', 5'') is adapted to integrate the outputs (7', 7'', 7''') of the corresponding sensing unit (2', 2'', 2''') and at least one of the adjacent sensing units (2'', 2''') to obtain the first integrated output (10); Optical sensing system (1).

4. An optical sensing system (1) according to any one of claims 1 to 3, Each of the first integral outputs (10) has a damping factor (20); Each of the attenuation rates (20) is adjustable. Optical sensing system (1).

5. 5. The optical sensing system (1) according to claim 4, each processing means (5', 5'') is a first processing means (5', 5'') connected in series with a second processing means (5''', 5''''); the decay rate of the first processing means (5', 5'') is at least twice as fast as the decay rate of the second processing means (5''', 5''''); Optical sensing system (1).

6. 6. An optical sensing system (1) according to claim 5, the second processing means (5''', 5'''') is adapted to integrate the first output signal (8) of the first processing means (5', 5'') to obtain a second integrated output (23); the second processing means (5''', 5''') is adapted to generate a second output signal (31) when the second integral output (23) reaches at least a second predetermined value (32) within a second predetermined time period; Optical sensing system (1).

7. 7. An optical sensing system (1) according to claim 5 or 6, each processing means (5', 5'', 5''', 5'''') is adapted to at least partially reset after generating said output signal (8, 31); the first processing means (5', 5'') are fully reset and the second processing means (5''', 5'''') are partially reset; Optical sensing system (1).

8. An optical sensing system (1) according to any one of claims 1 to 4, the processing means (5', 5") is a first processing means (5', 5") connected in series with a second processing means (5'", 5""), the second processing means (5'", 5"") being adapted to integrate the first output signal (8) of the first processing means (5', 5") to obtain a second integrated output (23); the second processing means (5''', 5''') is adapted to generate a second output signal (31) when the second integral output (23) reaches at least a second predetermined value (32) within a second predetermined time interval, the first processing means being reset after the first predetermined time interval and the second processing means being reset after the second predetermined time interval, the first predetermined time interval being half of the second predetermined time interval; Optical sensing system (1).

9. An optical sensing system (1) according to any one of claims 1 to 8, the optical sensing system (1) comprises a switching element (22', 22'') for each processing means (5', 5'', 5''', 5'''''', the switching elements (22', 22'') are adapted to be able to bypass the processing means (5', 5'', 5''', 5''''); Optical sensing system (1).

10. An optical sensing system (1) according to any one of claims 1 to 9, each processing means (5', 5'', 5''', 5'''') is an artificial neuron (12, 13), preferably a leaky integrate and fire LIF neuron; Optical sensing system (1).

11. An optical sensing system (1) according to any one of claims 1 to 10, at least two optical sensors (30); adapted to triangulate data from the sensing unit (2) of one optical sensor (30) with data from the sensing unit (2) of another optical sensor (30); Optical sensing system (1).

12. An optical sensing system (1) according to any one of claims 1 to 11 or any one of claims 6 to 12, the processing means (5', 5") generates the first output signal (8) when a plurality of inputs are positive within the first predetermined time interval, or the processing means (5''', 5"") generates the second output signal (31) when successive pulses are input within the second predetermined time interval; Optical sensing system (1).

13. 1. An optical sensing method, comprising: a- using an optical system (3) to generate an image of a scene (4) on an optical sensor (30) comprising a plurality of sensing units (2); b- receiving a plurality of optical signals (7') from said plurality of sensing units (2); c- an integration step, in parallel for each optical signal, of integrating said optical signal (7') to obtain a first integrated output (10); d- generating a first output signal (8) when said first integral output (10) reaches at least a first predetermined value (9) within a first time period (Δt); e- a scanning step by means of at least one light source (14) and a scanning means (15) for scanning a light beam (16) from said light source (14) along a trajectory over said scene (4); characterized in that it has Optical sensing methods.

14. 14. The optical sensing method according to claim 13, The method further includes a damping step of damping the first integral output (10) over time, the damping rate being adjustable. Optical sensing methods.

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