Apparatus and method for controlling system timing in a LIDAR system

Abstract

Embodiments of the present disclosure relate to apparatus and methods for controlling system timing within a LIDAR system. A method that can be used to control pixel scanning within a range detector. A spatially controllable point light source generates a first light source pulse series associated with a first spatial direction. The first light source pulse series is generated during a first time period. The spatially controllable point light source generates a second light source pulse series associated with a second spatial direction. The second light source pulse series is generated during a second time period overlapping the first time period, such that the second light source pulse series is turned on during the first light source pulse series.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from European Patent Application No. 18208689.2 filed on November 27, 2018, which is incorporated herein by reference. Technical Field

[0003] Embodiments are directed to a method and apparatus for controlling system timing within a LIDAR system. Background Art

[0004] The use of light for range and distance detection is known. These systems, which may be referred to as LIDAR (Light Detection and Ranging), have many applications including consumer electronics, automotive, robotics, surveying, and the like.

[0005] One example LIDAR system uses a light source, such as a vertical cavity surface emitting laser (VCSEL), to generate light pulses that are reflected from a surface and then detected at a receiver or detector, such as a photodiode or a single photon avalanche diode (SPAD) array.

[0006] The time difference between when the light is transmitted and when it is received provides a distance or range value using the simple formula D=S*T, where T is the time difference, S is the speed of light, and D is the distance from the transmitter to the reflecting object and back to the transmitter again.

[0007] A single photon avalanche diode (SPAD) is a semiconductor device capable of detecting light. Photons impinging on the detection region of the SPAD generate electron and hole pairs via the photoelectric effect. The SPAD is reverse biased by a high voltage amplitude so that when electron / hole carriers are generated, the electric field applied across the detection region causes the carriers to be accelerated to relatively high velocities depending on the strength and direction of the applied field. If the kinetic energy of the accelerated carriers is sufficient, additional carriers will be generated from the semiconductor lattice, which are in turn accelerated by the electric field and may release further carriers in an exponentially increasing manner. Therefore, when a sufficiently high electric field is applied across the detection region, a single impinging photon may generate a large number of carriers, resulting in an output current 'pulse', where the current output is proportional to the number of photons detected.

[0008] The minimum voltage required to cause carrier avalanche and thus allow the device to operate as a SPAD is called the breakdown voltage. If the applied voltage is too low, i.e. below the breakdown voltage, the device does not produce any output. However, if the applied voltage is too high, the electric field generated may be sufficient to cause carrier avalanche, even if no photons hit the SPAD, resulting in an erroneous output current. This erroneous output is called "dark current". Summary of the invention

[0009] Embodiments are directed to a method and apparatus for controlling system timing within a LIDAR system. Certain embodiments are directed to a method and apparatus for controlling system timing within a LIDAR system that includes a single photon avalanche diode as a receiver diode.

[0010] According to a first aspect, an apparatus for controlling pixel scanning within a range detector comprises at least one light source configured to provide a spatially controllable point light source. A detector comprising at least one light sensor is configured to receive a reflected spatially controllable point light source. A controller is configured to control the at least one light source. The controller is configured to control the at least one light source to generate a first light source pulse series associated with a first spatial direction, and to control the at least one light source to generate a second light source pulse series associated with a second spatial direction. The second light source pulse series is turned on during the first light source pulse series.

[0011] The controller may be configured to activate the second series of light source pulses a determined time period after activating the first series of light source pulses, wherein the determined time period may be shorter than the time period of the first series of light source pulses.

[0012] The first train of light pulses may be associated with a first row of light sensor elements and the second train of light pulses associated with a second row of light sensor elements.

[0013] The first series of light pulses may be associated with a first row of first light sensor elements of a first row of light sensor elements, and the second series of light pulses may be associated with a second row of first light sensor elements of a second row of light sensor elements.

[0014] The controller may be further configured to control the at least one light source to generate a third series of light source pulses associated with a third spatial direction, which may be associated with a third row of light sensor elements, wherein the third series of light source pulses may operate substantially simultaneously with the first series of light source pulses.

[0015] The controller may also be configured to control the at least one light source to at least one of: spatially dither the at least one light source, and randomly select a spatial direction during at least one of the first series of light pulses and the second series of light pulses.

[0016] The controller can also be configured to control the at least one light source to perform at least one of the following: forming a z-shaped grating pattern using the at least one light source; forming a serpentine grating pattern using the at least one light source; forming an x-shaped grating pattern using the at least one light source; forming a random pattern or a pseudo-random pattern using the at least one light source; and forming a skip-n grating pattern using the at least one light source.

[0017] According to a second aspect, a method for controlling pixel scanning in a range detector comprises: providing a spatially controllable point light source, and controlling the spatially controllable point light source. Controlling the spatially controllable light source comprises: generating a first light source pulse series associated with a first spatial direction; and generating a second light source pulse series associated with a second spatial direction. The second light source pulse series is turned on during the first light source pulse series.

[0018] Generating a second series of light source pulses associated with the second spatial direction may include activating the second series of light source pulses a determined time period after activating the first series of light source pulses, wherein the determined time period may be shorter than the time period of the first series of light source pulses.

[0019] The method may further include receiving the reflected spatially controllable point light source at a detector comprising at least one light sensor, wherein the first series of light pulses may be received by a first row of elements of the light sensor and the second series of light pulses may be received by a second row of elements of the light sensor.

[0020] The first series of light pulses may be received by a first row of first elements of the light sensor and the second series of light pulses may be associated with a second row of first elements of the light sensor.

[0021] Controlling the spatially controllable light source may further include generating a third series of light source pulses associated with a third spatial direction, wherein the third series of light source pulses may operate substantially simultaneously with the first series of light source pulses, wherein the third series of light pulses may be received by a third row of elements of the light sensor.

[0022] Controlling the spatially controllable point light source may perform at least one of: spatially vibrating the at least one light source; and randomly selecting a spatial direction during at least one of the first series of light pulses and the second series of light pulses.

[0023] Controlling the spatially controllable point light source may include controlling the at least one light source to form at least one of the following: forming a z-shaped grating pattern using the at least one light source; forming a serpentine grating pattern using the at least one light source; forming an x-shaped grating pattern using the at least one light source; forming a random pattern or a pseudo-random pattern using the at least one light source; and forming a skip n grating pattern using the at least one light source.

[0024] According to a third aspect, a device for controlling pixel scanning within a range detector is provided, the device comprising: a device for providing a spatially controllable point light source; and a device for controlling the spatially controllable point light source, wherein the device for controlling the spatially controllable light source comprises: a device for generating a first light source pulse series associated with a first spatial direction; and a device for generating a second light source pulse series associated with a second spatial direction, wherein the second light source pulse series is turned on during the first light source pulse series.

[0025] The means for generating a second series of light source pulses associated with a second spatial direction may include means for activating the second series of light source pulses a determined time period after activating the first series of light source pulses, wherein the determined time period may be shorter than the time period of the first series of light source pulses.

[0026] The apparatus may further comprise means for receiving a reflected spatially controllable point light source at a detector comprising at least one light sensor, wherein a first series of light pulses may be received by a first row of elements of the light sensor and a second series of light pulses may be received by a second row of elements of the light sensor.

[0027] The first series of light pulses may be received by a first row of first elements of the light sensor, and the second series of light pulses may be associated with a second row of first elements of the light sensor.

[0028] The device for controlling a spatially controllable light source may further comprise a device for generating a third series of light source pulses associated with a third spatial direction, wherein the third series of light source pulses may be operated substantially simultaneously with the first series of light source pulses, wherein the third series of light source pulses may be received by a third row of elements of the light sensor.

[0029] The apparatus for controlling a spatially controllable point light source may perform at least one of: spatially vibrating at least one light source; and randomly selecting a spatial direction during at least one of the first series of light pulses and the second series of light pulses.

[0030] An apparatus for controlling a spatially controllable point light source may include an apparatus for controlling at least one light source to form at least one of the following: forming a z-shaped grating pattern using the at least one light source; forming a serpentine grating pattern using the at least one light source; forming an x-shaped grating pattern using the at least one light source; forming a random pattern or a pseudo-random pattern using the at least one light source; and forming a skip n grating pattern using the at least one light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1schematically illustrates an example LIDAR system in which various embodiments may be implemented, according to some embodiments;

[0032] Figure 2 Schematically shows configurations such as single point, line sensor and image sensor LIDAR;

[0033] Figure 3 An example single-point-single-point timing diagram suitable for controlling laser pulses and pixel pairs is shown;

[0034] Figure 4 Shown based on Figure 3 Example column and row timing diagrams of the single point-to-single point timing diagram shown in ;

[0035] Figure 5 shows an example staggered point timing diagram according to some embodiments;

[0036] Figure 6 Shown based on Figure 5 Example column and row timing diagrams of staggered point timing diagrams shown in ;

[0037] Figure 7 Shown based on Figure 5 Additional example column and row timing diagrams of staggered point timing diagrams are shown, where 2 rows are operated simultaneously;

[0038] Figure 8 shows the use of some embodiments Figure 5 and Figure 6 Example timing operation of the detector according to the timing diagram shown in;

[0039] Fig. 9 Shows the use of Figures 5 to 8 Example improvements of the embodiments shown in with respect to higher signal-to-noise ratio or higher frame rate output;

[0040] Fig.10 Shown is a Figure 3 and Figure 4 A timing diagram for reading an example grating pattern of a SPAD; and

[0041] Figures 11 to 13 According to some embodiments, a method for Figures 5 to 8 Timing diagram to read an example staggered grating pattern of a SPAD. DETAILED DESCRIPTION

[0042] A concept further described in detail according to some embodiments provides a LIDAR system with improved performance by defining a staggered point or vane timing configuration that controls the transmitter and receiver.A concept further discussed in detail relates to at least partially overlapping detector timing ranges.

[0043] about Figure 1 , further details an example range or distance measurement system suitable for implementing some embodiments. System 100 includes a light source 103. The light source can be considered as an emitter of light used in distance detection. The light source can be any suitable pulse (or wave) light source. For example, in some embodiments, the light source can be one or more vertical cavity surface emitting laser light sources. The vertical cavity surface emitting laser is suitable because it can produce well-defined pulses of suitable short duration. The light source 103 can also include or be coupled to various optical devices, which are configured to collimate and / or focus the light source to a specific zone or area. In addition, in some embodiments, the light source includes a mechanical guide or a beam guide, which is configured to guide light according to a defined pattern to a target or surface 104. The emitted light 102 can then be incident on the surface 104, and the reflected light 106 is received at the detector 105.

[0044] The system 100 may include a detector 105, which may include or be coupled to various optical devices that are configured to focus the returned light to a specific photosensitive area or region within the detector. The detector can be considered a receiver of light used in distance detection. In addition, in some embodiments, the detector includes or is associated with a mechanical guide or beam guide (in some embodiments, the guide is the same guide used by the light source 103) that is configured to direct the returned light to a specific photosensitive area or region within the detector. In some embodiments, the detector 105 includes a photosensitive area, such as an array of single photon avalanche diodes that are configured to convert the received light into an electronic signal suitable for output.

[0045] In addition, the system may include a timing generator (or controller) 113. In some embodiments, the timing generator 113 may be used to control the detector 105 and the light source 103. The timing generator 113 may be configured to generate various timing or control pulses to control the light source, for example to control when and where the light is emitted. The timing generator 113 may also be configured to further control the detector to activate some areas as photosensitive or active and activate some other areas as inactive.

[0046] In addition, the system may include a distance measurement / distance mapping unit 115. In some embodiments, the distance measurement / distance mapping unit 115 may be configured to receive timing control information from the timing generator 113 and from the detector 105 (and in some embodiments, the light source 103), and determine the distance between the system 100 and the surface 104 based on the time it takes for light to propagate from the light source 103 to the surface 104 and from the surface 104 to the detector 105. The distance measurement / distance mapping unit 115 may, for example, be configured to generate a histogram of detected events (with respect to time) and determine the distance from the histogram. In some embodiments, the distance measurement / distance mapping unit 115 is configured to determine the distance for more than one point or area, and thus determine a distance map.

[0047] In some embodiments, the system 100 may further include a suitable application 111, which is configured to interface with the timing generator 113 and the distance measurement / distance mapping unit 115. For example, the application may be an automobile braking decision unit, an automobile navigation unit, a computer vision unit, or others. The application 111 may, for example, receive a distance map or distance value, and perform a decision or determination based on the distance information to control another device. In some further embodiments, the application 111 may also be configured to control the timing generator to change the distance measurement parameters.

[0048] In some embodiments, the timing generator 113, the distance measurement / distance mapping unit 115 and the application 101 may be implemented on a computer (running suitable software stored on at least one memory and at least one processor), a mobile device, or alternatively, within a specific device utilizing, for example, an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0049] about Figure 2 , example light source (emitter) and detector (receiver) configurations are shown. The first example is a single point or discrete diode configuration 201. The system 201 based on a single point configuration includes an emitter 203 (e.g., a VCSEL or similar controllable light source), which typically uses a 2D scanning mirror or rotating unit 207 as a target and outputs via an optical element 209. The optical element 209 is also configured to receive the reflected light and focus it back to a single point receiver 205 via the 2D scanning mirror or rotating unit 207. The single point receiver 205 typically includes at least one photosensitive area (e.g., SPAD 206) that is configured to detect light and then generate appropriate electronic pulses based on receiving the reflected light. By changing the direction of the 2D scanning mirror or rotating unit 207, the area can be scanned point by point.

[0050] The second example configuration is a line sensor / blade scanning configuration 211. The blade scanning configuration 211 typically includes a (linear) array of emitting elements, such as an array of VCSELs or other controllable light source elements. The light from the emitting elements is then passed to a 1D scanning mirror or rotating unit 217, which is then output via a suitable optical element 219. The optical element receives the reflected light and passes the emitted light to a receiver 215 via the 1D scanning mirror or rotating unit 217. The receiver 215 typically includes an array of SPAD elements (e.g., a linear array of SPAD elements) or a linear photosensitive array. In this way, 'blades' or lines of light can be generated, which are then received to generate image lines. These lines can then be stepped by changing the direction of the 1D scanning mirror or rotating unit 217 to scan the area 218 (line by line 214). In some embodiments, the blade scanning configuration 211 can be implemented by a series of offset linear arrays or emitting elements and a static mirror.

[0051] The third type of operation is a flash configuration, in which an emitter (which may include one or more light sources) generates a single flash that can be output via a suitable optical element (or in some cases an optical window) 229, and received via a further optical element 228 (or an optical element 229 in the same path as the emission), at an image sensor 225 including an array of sensitive areas 226. Thus, the flash configuration is capable of generating a single image 224 generated by a single exposure.

[0052] about Figure 2 The difference between the configurations shown is that the flash configuration, while capable of generating fast frame rates, is limited in accuracy due to safety light level restrictions, whereas the single point and line sensor configuration is limited in frame rate due to scanning, but is capable of using higher light levels and therefore producing more accurate image depth maps. Many applications such as automotive navigation and automatic object detection would benefit from the high frame rate and accurate depth map configurations that would be produced by the embodiments discussed below.

[0053] One of the aspects that slows down the frame rate of a single point / single point configuration is the way the light sources / pixels are individually activated. Figure 3 A typical time pattern for operating a pixel is shown in FIG. Figure 3 A timing diagram is shown showing the activation of a laser pulse or transmitter 301 which generates laser pulses 302, 304, 306 separated by an integration time period Tint 341. The integration time defines the expected maximum range of the system, in other words the expected maximum time for a light pulse to propagate from the transmitter to the target and reflect from the target back to the receiver.

[0054] Figure 3Also shown is a timing diagram for a series of pixels 311, 321, 331, where the photosensitive regions are activated sequentially for an integration time.

[0055] Thus, the first pixel 311 is shown as being activated for a TOF range time 313 following the laser pulse 302, and then being deactivated or insensitive for a series of subsequent integration time periods 317. During the TOF range time 313, reflected light may be detected as indicated by the event detection arrow 315. Additionally, during the TOF range time 313, pixel 2 321 and pixel 3 331 are insensitive.

[0056] The second pixel 321 is shown as being activated for a TOF range time 323, which is immediately after the second laser pulse 304 and also follows the end of the first pixel 311 TOF range time 313. A detected event 325 is shown within the TOF range time 323. The second pixel is shown as being deactivated or in a non-sensitive time 327, which is the same period as the first pixel 311 TOF range time 313 and within a period after the TOF range time 323.

[0057] The third pixel 331 is shown as being activated for a TOF range time 333, which is immediately after the third laser pulse 306 and also follows the end of the first pixel 311 TOF range time 313 and the second pixel 323 TOF range time 323. A detected event 335 is shown within the TOF range time 333. The second pixel is shown as being deactivated or in a non-sensitive time 337, which is the same period as the first pixel 311 TOF range time 313 and the second pixel 321 TOF range time 323.

[0058] Thus, as shown, each pixel is activated sequentially and requires a separate Tint period 341 (typically around 2 μs).

[0059] Then, this Figure 4 The scan timing diagram is repeatedly shown, Figure 4 Column and row activations are shown, where each column 401 (or pixel) is sequentially activated for a separate Tint or Tshot time, as shown in a close-up view 403 of the sequential activation of pixel 1 405, pixel 2 407, and pixel 3 409 for the first row (row 1 413). The same sequential column activations are then shown for subsequent rows (row 2 415, row 3 417 to row N).

[0060] Therefore, in such a system, the frame period is limited by the Tshot or Tint time period.

[0061] Thus, the following examples illustrate embodiments where the frame period is not limited by the Tshot or Tint time periods. A concept discussed previously is one where the timing ranges of pixels are configured to at least partially overlap. For example, this can be implemented using a staggered offset or staggered point timing system where, instead of activating pixels independently and sequentially, the pixels are activated according to a staggered offset pattern for each channel.

[0062] about Figure 5 , which shows in more detail an example staggered point timing system used in some embodiments. In this example, laser pulse timing 501 shows a sequence of laser pulses 503, 505, 507, where each successive pulse is associated with a pixel, but is spaced apart according to a staggered offset period.

[0063] Thus, the system shows a first laser pulse 503 associated with a first pixel (pixel 1), a second laser pulse 505 associated with a second pixel (pixel 2), a third laser pulse 507 associated with a third pixel (pixel 3), and so on, to a Yth laser pulse associated with a Yth pixel. The system then repeats such that there are also additional cycles of first laser pulses 553 associated with the first pixel (pixel 1), additional cycles of second laser pulses 555 associated with the second pixel (pixel 2), additional cycles of third laser pulses 557 associated with the third pixel (pixel 3), and so on, to an additional cycle of Yth laser pulses associated with the Yth pixel. This can be repeated for a desired number of ranging cycles.

[0064] As shown by timing line 511, the first pixel (Pixel 1) can be configured such that it is active after the first laser pulse 503. During this active time, any return event 515 associated with the first laser pulse 503 can be detected within the TOF range 513, which continues until the first laser pulse 553 of an additional cycle, which starts an additional TOF range period until a determined number of ranging cycles are completed.

[0065] Additionally, for the second pixel (Pixel 2, as shown by timing line 521), it can be configured so that it is active after the second laser pulse 505. During this active time, any return event 525 associated with the second laser pulse 505 can be detected within the TOF range 523, which continues until an additional cycle of the second laser pulse 555, which starts an additional TOF range period until a determined number of ranging cycles are completed. In some embodiments, the second pixel is deactivated (shown by the hatched area 512) until the second laser pulse occurs.

[0066] For the third pixel (pixel 3, as shown by timing line 531), it can be configured so that it is activated after the third laser pulse 507. During this activation time, any return event 535 associated with the third laser pulse 505 can be detected within the TOF range 533, which continues until an additional cycle of the third laser pulse 557, which starts an additional TOF range period until a determined number of ranging cycles are completed. In some embodiments, the third pixel is deactivated (shown by the hatched area 522) until the third laser pulse occurs.

[0067] In implementing the timing of laser (light source) pulses, such an embodiment may be able to implement an integration time (Tint) for Y pulses within the range of (Y-1)×(time of the light range period) (the integration time (Tint) may be approximately 2 μs).

[0068] about Figure 6 , which shows that relative to Figure 5 611 and column 601 of the staggered point timing shown in FIG. In this example, with respect to the first row 613, a first sequence 603 of staggered pixel activation is shown, where each pixel is sampled multiple times and then a histogram is read out. For example, as shown in FIG. Figure 6 As shown in the dashed box, pixel 1 is sampled as 604 a 、604 b 、604 c , then read out 6042. In the interleaved period after each pixel 1, pixel 2 is sampled as 606 a ,606 b ,606 c , then read out 6062. After another interleaving period, pixel 3 is sampled as 608 a 、608 b 、608 c , then read out 6082.

[0069] Additionally, once the histogram of pixel 1 of row 1 is read out, the next row (row 2 615) can be activated and pixel 1 can be sampled, and then, after an interleaved delay thereafter, pixel 2 of row 2 can be activated, and so on.

[0070] In this way, row 2 615 can be active while row 1 613 is active (e.g. Figure 6 613 and 615).

[0071] In some embodiments, the rows can be run substantially simultaneously (with staggered delays between them) without the possibility of overlap between the rows. Figure 7In the example shown, the pair of row 1 713 and row 2 715 are activated substantially simultaneously, with pixel 1 of row 1 being activated as indicated by sequence 706. a ,706 b is activated as shown, followed by a sequence 708 of pixels 1 of row 2 after an interleaved delay. a ,708 b After a further interleaving delay, this may again be followed by a sequence 710 of pixels 2 of row 1 a ,710 b , followed by a sequence 712 of pixels 2 of row 2 after an interleaved delay a ,712 b .

[0072] Once the histogram of pixel 1 of row 1 is read out, then, Figure 6 In this manner, row 3 717 with pixel 1 is turned on, followed by row 4 719 with pixel 1 after a staggered delay.

[0073] In this way, the frame rate can be further increased, as Figure 8 As shown in Figure 8 A series of histogram timing outputs are shown. A first timing line 801 is shown, which opens 803 at the start of a histogram generation period 805 for pixel 1 of row 1. At the end of histogram generation for pixel 1 of row 1 (in other words, after a defined number of range finding cycles using pixel 1 from row 1), a reading of the histogram for pixel 1 of row 1 occurs 807. Thereafter, a histogram generation period 809 for pixel 1 of row 2 opens.

[0074] in addition, Figure 8 A second timing line 811 is shown which performs a histogram read 813 of the pixels 2 of row X (where X is the number of rows) at the time of opening 803. Following this histogram read (equivalent to an interleaving delay), there is a histogram generation period 815 for the pixels 2 of row 1. At the end of the histogram generation for the pixels 2 of row 1 (in other words, after a defined number of ranging cycles using the pixels 2 from row 1), a histogram read 817 for the pixels 2 of row 1 occurs at this time. Thereafter, a histogram generation period 819 for the pixels 2 of row 2 is opened.

[0075] This process can be repeated for additional histograms, so that Figure 8As shown in FIG. 8 , there is a third timing line 821, which, at the time of opening 803, is at the end of performing histogram generation 822 of pixels 3 of row X, and a histogram reading 823 of pixels 3 of row X occurs. After this histogram reading, there is a generation period 825 of the histogram of pixels 3 of row 1. At the end of the histogram generation of pixels 3 of row 1 (in other words, after a defined number of ranging cycles using pixels 3 from row 1), a histogram reading 827 of pixels 3 of row 1 occurs at this time. Thereafter, a histogram generation period 829 of pixels 3 of row 2 is opened.

[0076] A further histogram line 831 is shown, which shows that at the time of the start 803, the histogram generation 822 of the pixels ... in row X, and the histogram reading 833 of the pixels ... in row X occurs. After this histogram reading, there is a generation period 835 of the histogram of the pixels ... in row 1. At the end of the histogram generation of the pixels ... in row 1 (in other words, after a defined number of ranging cycles using the pixels ... from row 1), the histogram reading 837 of the pixels ... in row 1 occurs at this time. Thereafter, the histogram generation period 839 of the pixels ... in row 2 is turned on.

[0077] The final histogram line 841 is shown, which opens 803 at the start of the histogram generation period 842 for pixels Y of row X. At the end of the histogram generation for pixels Y of row X (in other words, after a defined number of ranging cycles using pixels Y from row X), a histogram reading 843 for pixels Y of row X now occurs. Thereafter, a histogram generation period 845 for pixels Y of row 1 opens.

[0078] about Fig. 9 , illustrating the advantages of using the staggered delay method as described herein. Fig. 9 The upper portion 901 of shows a situation where each pixel is activated one by one. Thus, a number of samples (4 in this example case) are used to generate 903 a histogram associated with pixel 1 before moving to pixel 2 905 and continuing until the last pixel (pixel N 907). After all pixels have been used, the frame is complete, as shown by the frame time 904.

[0079] Fig. 9The middle portion 911 of shows a case where an interleaved delay is used between activating each pixel and for the same frame time the signal to noise ratio can be improved since more samples can be used for each pixel. Thus, using a number of samples (16 in this example case), sampling of the histogram associated with pixel 1 is turned on 913. The interleaved delay period is turned on after pixel 1, then pixel 2 915 is turned on, and so on until the last pixel (pixel N 917) is turned on. After all pixels are completed, the frame is complete, as shown by the frame time 914.

[0080] Fig. 9 The lower portion 921 shows a situation where an interleaved delay is used between activating each pixel and for the same number of samples shown in the upper portion 901, the pixels can be sampled using a shorter frame time 924.

[0081] Thus, using a number of samples (4 in this example case), a sample of the histogram associated with pixel 1 is turned on 923. An interleaved delay period is turned on after pixel 1, then pixel 2 925 is turned on, and so on until the last pixel (pixel N 927) is turned on. After all pixels are completed, the frame is complete, as shown by frame time 924, which is shorter than frame time 904.

[0082] In some embodiments, spatial vibration / randomization can be employed to switch from pixel to pixel in sequence to allow higher power per point and longer integration per receiving pixel as the spatial vibration / randomization moves light out of the eye's field of view.

[0083] Using examples and about Fig.10 , further illustrating some of the patterns associated with moving from pixel to pixel using staggered delay operations. Fig.10 The upper portion of shows a first example raster pattern for operating a pixel-by-pixel scan. This is a conventional single-dot raster pattern where the first row (row 1 1001) is scanned from side to side, a scan line return 1002 is implemented before scanning the second row (row 2 1003), another scan line return 1004 is implemented before scanning the third row (row 3 1005), and so on. This can be applied to the staggered delay operation described herein, where each pixel scan turns on a staggered delay after each other.

[0084] Fig.10The lower portion of shows a second example raster pattern for operating a pixel-by-pixel scan. This is a serpentine single-dot raster pattern where the first row (row 1 1011) is scanned from side to side, before the second row (row 2 1013) is scanned in the opposite direction to the first row, a scan line jump 1012 is implemented. After another scan line jump 1014 is implemented, the third row (row 3 1005) is scanned in the opposite direction to the second row (and the same direction as the first row), and the pattern repeats. This can also be applied to the staggered delay operation described herein, where each pixel scan turns on a staggered delay after each other.

[0085] Fig.11 A third example is shown of a modified raster pattern for operating a pixel-by-pixel scan using staggered delays in the manner described herein. In this scan pattern, the first row (row 1 1101) is scanned from side to side and loops back Y times 1102. After the Yth loop is complete, a scan line loop is performed 1104 before scanning the second row (row 2 1103) in the same direction as row 1.

[0086] Row 2 1103 loops Y times 1106 and after the Yth loop is complete, a scan line return 1108 is performed before scanning the third row (row 3 1105) in the same direction as row 2.

[0087] Row 3 1105 loops Y times 1110, and after the Yth loop is completed, the scan line is returned 1112 for the next row scan, and so on.

[0088] Fig.10 and Fig.11 The pattern shown in has equal spatiotemporal sampling per pixel.

[0089] Fig.12 Two other patterns are shown. Fig.12 The upper portion of FIG. 1 shows a fourth example of a modified serpentine raster pattern for operating a pixel-by-pixel scan using staggered delays in the manner described herein. In this scan pattern, the first row (row 1 1201) is first scanned from one side to the other side 1251, and then scanned from the other side back to the starting point 1253. Thereafter, the cycle is repeated Y times 1202. After the Yth cycle is completed, a scan line return 1212 is performed.

[0090] The cycle is repeated for the second row (row 2 1203), which is scanned in the same manner as row 1 (in other words, in a first direction, then back again, then repeated Y times 1204 before implementing a scan line return 1214).

[0091] The process is repeated again for the third row (row 3 1205) and additional rows.

[0092] Fig.12 The lower portion of shows a fifth example of a modified X-shaped raster pattern for operating a pixel-by-pixel scan using staggered delays in the manner described herein. In this scan pattern, pairs of rows are grouped and the scan is organized so that pixel 1 of the first row (row 1 1211) is scanned first, then the second pixel of the second row (row 2 1213) is scanned, and then the spatial X pattern is followed to the end of the scan line, which ends at the end pixel of row 1, and then starts again from the end pixel of row 2, back to the first pixel of row 2. This can then be repeated 2Y times 1216.

[0093] After the last loop is complete, the next pair of rows is scanned in the same manner.

[0094] The raster pattern attempts to increase the spatial distance between adjacent pixels.

[0095] In some embodiments, a pattern may be formed from groups of more than two rows.

[0096] Fig.13 The pattern shown in shows a sixth example, which is a skip pattern. In this scan pattern, the first row (row 1 1301) is first scanned from one side to the other side 1351, wherein in this scan, skips are performed, each skip missing a pixel. When the end is reached, then scan back to the beginning from the other side, performing a similar skip pattern. When the beginning of the row is reached, the loop is looped Y times 1312. After the Yth loop is completed, a scan line return 1302 is implemented.

[0097] The loop is repeated for the second row (row 2 1303) in the same manner as row 1 (and then repeated Y times 1314 before performing a scan line return 1304).

[0098] The process is repeated again for the third row (row 3 1305) and additional rows.

[0099] This approach similarly increases the spatial distance between neighboring pixels.

[0100] Although a skip 1 pattern is shown, other skip patterns may be implemented.

[0101] The above examples show various spatial patterns, however any suitable spatial pattern may be implemented, where the spatial pattern may be deterministic, pseudo-random, or random.

[0102] The above apparatus and method can be implemented in any device or apparatus utilizing a single photon avalanche detector. For example, the above apparatus and method can be implemented in a LIDAR system. It should be understood that this non-limiting embodiment is merely exemplary, and the apparatus and method can be implemented in any manner for other light detection applications.

[0103] It should be understood that the above-described arrangements may be implemented at least in part by an integrated circuit, a chipset, one or more dies packaged together or in different packages, discrete circuits, or any combination of these options.

[0104] Various embodiments with different variations have been described above. It should be noted that those skilled in the art can combine various elements of these various embodiments and variations.

[0105] Such changes, modifications, and improvements are intended to be part of this disclosure and are intended to fall within the scope of the invention. Therefore, the foregoing description is only exemplary and is not intended to be limiting. The present invention is limited only by the appended claims and their equivalents.

Claims

1. An apparatus for controlling pixel scanning in a range detector, the apparatus comprising: A single point diode light source configured to provide spatially controllable point light pulses; a detector including a light sensor configured to receive the reflected spatially controllable point light pulse; A controller configured to control the single-point diode light source, wherein the controller is configured to: controlling the single point diode light source to generate a first series of light source pulses during a first time period, the first series of light source pulses being associated with a first spatial direction; as well as During a second time period that is turned on after the first time period is turned on, the single-point diode light source is controlled to generate a second light source pulse series, wherein the second light source pulse series is associated with a second spatial direction, wherein the first time period and the second time period overlap, so that the second light source pulse series is turned on during the first light source pulse series.

2. The apparatus of claim 1, wherein the first series of light source pulses is associated with a first row of light sensor elements and the second series of light source pulses is associated with a second row of light sensor elements.

3. The apparatus of claim 2, wherein the first series of light source pulses is associated with a first row of first light sensor elements in the first row of light sensor elements, and the second series of light source pulses is associated with a second row of first light sensor elements in the second row of light sensor elements.

4. An apparatus according to claim 2, wherein the controller is further configured to control the single-point diode light source to generate a third light source pulse series associated with a third spatial direction, the third spatial direction being associated with a third row of light sensor elements, wherein the third light source pulse series is generated during a time period substantially simultaneously with the first time period.

5. The apparatus of claim 1, wherein the controller is configured to spatially vibrate the single point diode light source.

6. The apparatus of claim 1, wherein the controller is configured to randomly select a spatial direction for the first and second series of light source pulses.

7. The apparatus of claim 1, wherein the controller is configured to control the single point diode light source to form a zigzag grating pattern using the first light source pulse series.

8. The apparatus of claim 1, wherein the controller is configured to control the single point diode light source to form a serpentine grating pattern using the first light source pulse series.

9. The apparatus of claim 1, wherein the controller is configured to control the single point diode light source to form an x-shaped grating pattern using the first light source pulse series.

10. The apparatus of claim 1, wherein the controller is configured to control the single point diode light source to form a random pattern or a pseudo-random pattern using the first light source pulse series.

11. The apparatus of claim 1, wherein the controller is configured to control the single point diode light source to form a skip-n raster pattern using the first light source pulse series.

12. A method for controlling pixel scanning in a range detector, the method comprising: generating a first series of light source pulses associated with a first spatial direction using a spatially controllable single point diode light source, wherein the first series of light source pulses is generated during a first time period; as well as The spatially controllable single-point diode light source is used to generate a second light source pulse series associated with a second spatial direction, wherein the second light source pulse series is generated during a second time period overlapping the first time period so that the second light source pulse series is turned on during the first light source pulse series.

13. The method according to claim 12, further comprising: receiving, at a first row of elements of a light sensor, a reflected version of each light source pulse in the first series of light source pulses; as well as At a second row of elements of the light sensor, a reflected version of each of the light source pulses of the second series of light source pulses is received.

14. The method of claim 13, wherein the first series of light source pulses are received by a first row of first elements of the light sensor and the second series of light source pulses are associated with a second row of first elements of the light sensor.

15. The method according to claim 13, further comprising: A third series of light source pulses associated with a third spatial direction is generated, wherein the third series of light source pulses is generated during a time period substantially concurrent with the first time period, and wherein the third series of light source pulses is received by a third row of elements of the light sensor.

16. The method of claim 12, wherein the spatially controllable single-point diode light source is controlled by spatially vibrating the light source.

17. The method of claim 12, wherein the spatially controllable single-point diode light source is controlled by randomly selecting a spatial direction for the first light source pulse train or the second light source pulse train.

18. The method of claim 12, wherein the spatially controllable single-point diode light source is controlled to form a z-shaped grating pattern using the first light source pulse series.

19. The method of claim 12, wherein the spatially controllable single-point diode light source is controlled to form a serpentine grating pattern with the light source.

20. The method of claim 12, wherein the spatially controllable single-point diode light source is controlled to form an x-shaped grating pattern using the first light source pulse series.

21. The method of claim 12, wherein the spatially controllable single-point diode light source is controlled to form a random pattern or a pseudo-random pattern using the first light source pulse series.

22. The method of claim 12, wherein the spatially controllable single-point diode light source is controlled to form a skip-n grating pattern using the first light source pulse series.

23. A method for controlling pixel scanning in a range detector, the method comprising: generating, by a single point diode light source, a first series of light source pulses associated with a first spatial direction, wherein the first series of light source pulses is generated during a first time period; generating, by the single point diode light source, a second series of light source pulses associated with a second spatial direction, wherein the second series of light source pulses is generated during a second time period overlapping the first time period; generating, by the single point diode light source, a third series of light source pulses associated with a third spatial direction, wherein the third series of light source pulses is generated during a time period substantially concurrent with the first time period; receiving, at a first row of elements of a light sensor, a reflected version of each light source pulse in the first series of light source pulses; receiving, at a second row of elements of the light sensor, a reflected version of each light source pulse in the second series of light source pulses; as well as At a third row of elements of the light sensor, a reflected version of each light source pulse in the third series of light source pulses is received.

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