Scanning laser apparatus and method with adjusted set of emission control pulses

Abstract

The embodiments described herein provide systems and methods that may improve performance of a scanning laser device (100). Specifically, systems and methods transmit a set of transmit control pulses (222) for detecting when an object (e.g., a person) is within a relatively close safety range. A set of longer-range pulses of higher energy is then conditionally transmitted only when an object is not detected within the safe range with the set of transmission control pulses. The sets of transmit control pulses are transmitted at a variable timing and / or variable energy that is determined at least in part as to whether a previous set of transmit control pulses detects an object within a safe range. Using a set of transmit control pulses with variable timing and / or variable energy may provide improved reliability of object detection in a safe range while still meeting the energy limits required for eye safety.

Description

Background Art

[0001] Scanning laser devices have been developed and implemented for a variety of applications, including object detection. For example, light detection and ranging (LiDAR) systems have been developed to generate 3D maps of surfaces, where the 3D map describes depth variations on the surface. Such object detection and depth maps have been used for a variety of applications, including object and motion sensing, navigation, and control. For example, such LiDAR devices are used for navigation and control of autonomous vehicles, including autonomous vehicles used in transportation and manufacturing.

[0002] One issue in some LiDAR systems is the need to achieve a specific effective range while also providing eye safety. To help achieve this, the international standard IEC 60825.1 describes example laser safety classes. While there are many different laser safety classes, one major distinction between the classes is whether the product is considered "eye safe" or "non-eye safe." Eye safe laser systems are generally considered to be incapable of producing damaging levels of accessible radiation during operation, and are also generally exempt from equipment marking requirements, control measures, or other additional safety measures. IEC 60825.1 classifies eye safe products as Class 1. However, products containing higher powered laser devices may still be classified as eye safe products if the product includes additional safety measures to reduce accessible emissions, where otherwise the product would be classified as non-eye safe.

[0003] Thus, there remains a continuing need for systems and methods that can provide effective sensing at the constructive range while also providing improved eye safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 shows a schematic diagram of a scanning laser device according to various embodiments;

[0005] Figure 2A shows a schematic diagram of a scanning laser device and a scanning field according to various embodiments;

[0006] Figure 2B and Figure 2C A diagram showing exemplary laser light pulses according to various embodiments;

[0007] Figure 3A , Figure 3B and Figure 3C A flowchart illustrating an exemplary method according to various embodiments is shown;

[0008] Figure 4A , Figure 4B , Figure 4C and Figure 4D shows a graph of exemplary pulse set energy over time according to various embodiments;

[0009] Figure 5A Schematic diagrams showing optical assemblies according to various embodiments of the present invention;

[0010] Figure 5B , Figure 5C and Figure 5D Graphs showing optical expansion, scanning trajectory, and energy level adjustment of laser light pulse sets according to various embodiments;

[0011] Figure 5E and Fig. 5F Schematic diagrams showing scanning laser devices with different effective ranges and energy level adjustments of laser light pulse sets according to various embodiments;

[0012] Figure 5G shows a schematic diagram of a scanning laser device with multiple effective ranges according to various embodiments;

[0013] Fig. 6A and Figure 6B shows top and side views of a mobile platform including a LiDAR system and resulting scan field according to various embodiments;

[0014] Fig. 7A and Figure 7B shows side and top views of a scanning laser device according to various embodiments;

[0015] Figure 8 shows a schematic diagram of a LiDAR system according to various embodiments;

[0016] Fig. 9 shows a schematic diagram of a LiDAR system according to various embodiments;

[0017] Fig. 10A and Fig. 10B shows side and top views of a transport module according to various embodiments;

[0018] Fig.11A and Fig. 11B shows a side view and a top view of a receiving module according to various embodiments; and

[0019] Fig.12 A perspective view of an integrated photonics module according to various embodiments of the present invention is shown. DETAILED DESCRIPTION

[0020] Embodiments described herein provide systems and methods that can facilitate improved eye safety while providing effective object detection in light detection and ranging (LiDAR) systems and other scanning laser devices. Specifically, the systems and methods utilize a transmission control system and method to transmit a set of transmission control pulses that are used to detect when an object (e.g., a person) is within a relatively close safety range. Then, a higher energy long range pulse set is conditionally emitted only when the object is not detected within the safety range using the transmission control pulse set. Therefore, the use of the transmission control pulse set provides the ability to prevent the emission of a relatively higher energy long range pulse set when a person or other object is within the safety range, and thereby can provide improved eye safety.

[0021] And according to the embodiments described herein, these emission control pulse sets are emitted with variable timing (e.g., variable time periods or delays between emission control pulse sets) and / or variable energy (e.g., further reduced energy levels). Specifically, the emission control pulse sets are emitted with variable timing and / or variable energy that depends at least in part on whether the previous emission control pulse set detected an object with a safe range. Using emission control pulse sets with variable timing and / or variable energy can provide improved reliability of object detection within the safe range while still meeting the energy limits required for eye safety.

[0022] Specifically, in many scanning laser device applications, the total energy of a pulse set within a specific time frame should be considered to provide effective eye safety. By selectively delaying and / or further reducing the energy level of a set of emission control pulses after an object is detected within a safe range with variable timing, the embodiments described herein help to increase the energy level of other emission control pulse sets while maintaining or improving eye safety. Specifically, selectively delaying and / or further reducing the energy level of a set of emission control pulses after an object is detected within a safe range allows the previous set of emission control pulses (e.g., those emission control pulse sets before an object is detected in a sensing area) to be emitted at a higher energy. Thus, the embodiments can provide an increase in the energy level of a previous set of emission control pulses while maintaining or reducing potential energy exposure to the eye over time. This increased energy in the previous set of emission control pulses provides improved reliability of detecting an object within a safe range while maintaining eye safety for both emission control pulse sets. Therefore, the embodiments described herein can provide improved reliability of detecting an object within a safe range and improved eye safety.

[0023] Now go to Figure 1, a schematic diagram of a scanning laser device 100 according to various embodiments is shown. In one embodiment, the scanning laser device 100 is a light detection and ranging (LiDAR) system for object detection and / or 3D map generation. The scanning laser device 100 includes a light source controller 101, a laser light source 102, an optical assembly 104, and a detector 106. The optical assembly 104 includes various optical elements for laser scanning, including an expansion optical device 108 and a scanning optical device 110. During operation, the laser light source 102 generates laser pulses, which are scanned by the optical assembly 104 along a scanning track 112 within a scanning field 114.

[0024] These laser pulses strike an object in the scan field 114 in a series of scan positions or measurement points along the scan trajectory 112. It is worth noting that each "scan position" or "measurement point" is not an infinitely small point in space, but rather a small and finite continuous portion of the scan trajectory 112. Specifically, during the round-trip transit time of a laser light pulse, the laser beam traverses a finite portion of the scan trajectory 112. Furthermore, each scan position or measurement point area is also a function of the laser spot size (initial size and divergence) at the distance at which it encounters the object.

[0025] The detector 106 is configured to receive reflections of laser light pulses from measurement points or scan positions on objects within the scanning field 114. The received reflections of the laser light pulses can be used to detect objects within the scanning field 114. For example, time-of-flight (TOF) measurements of the received reflections can be used to generate measured distances. As an example, these measured distances can be used to generate a three-dimensional point cloud describing the depth or distance at each point, which can be used to generate a depth map of any detected objects.

[0026] exist Figure 1 In the example of , the scan trajectory 112 in the scan field 114 includes a raster pattern. However, this is merely an example, and in other embodiments, other trajectories or scan line patterns used may be generated. To facilitate the generation of the scan trajectory 112, a drive circuit may be implemented to control the movement of the scanning optical device 110, while the expansion optical device provides any desired optical expansion, including exit pointing angle expansion, beam width expansion, and beam divergence. Detailed examples of such devices are described below.

[0027] In some embodiments, scanning laser device 100 is implemented to include one or more additional detectors in addition to detector 106. For example, a second detector may be implemented to receive reflections through optical assembly 104 from IR laser light pulses within the scanning field.

[0028] The scanning laser device 100 may also include other elements. For example, the scanning laser device 100 may also include time of flight (TOF) circuitry responsive to the detector 106 to measure the distance to an object in the scan field at a depth measurement point.

[0029] According to embodiments described herein, the scanning laser device 100 includes emission control to provide improved eye safety by emitting a higher energy, long-range pulse set only when an object is not detected within a defined safety range. Typically, such improved eye safety is provided by an emission control system (e.g., a light source controller 101 having emission control, emission control circuitry and pulse generation circuitry including or working with such a light source controller, or virtual protective housing circuitry) that causes the laser light source 102 to selectively emit sets of laser light pulses of different energy levels in response to object detection.

[0030] Specifically, the light source controller 101 with emission control causes the laser light source 102 to selectively emit a relatively low energy emission control pulse set for detecting when an object (e.g., a person) is within a relatively close safety range. Then, only when the object is not detected within the safety range, a higher energy long range pulse set is conditionally emitted, thereby improving eye safety. Therefore, when a person or other object is within the safety range, the emission control pulse set can selectively delay or prevent the emission of a relatively higher energy long range pulse set, and thereby can provide improved eye safety.

[0031] And according to the embodiments described herein, these emission control pulse sets are emitted with variable timing (e.g., variable time periods or delays between emission control pulse sets) and / or variable energy (e.g., further reduced energy levels). Specifically, the emission control pulse sets are emitted with variable timing and / or variable energy that depends at least in part on whether the previous emission control pulse set detected an object with a safe range. Using emission control pulse sets with variable timing and / or variable energy can provide improved reliability of object detection within the safe range while still meeting the energy limits required for eye safety.

[0032] Specifically, in a typical embodiment of the scanning laser device 100, the total energy of all pulses within a specific time frame should be considered to provide effective eye safety. By selectively delaying and / or further reducing the energy level of a set of emission control pulses after an object is detected within the safety range with variable timing, the scanning laser device 100 helps increase the energy level of other sets of emission control pulses while maintaining or reducing potential energy exposure to the eye over time.

[0033] For example, under certain safety limit specifications and / or regulatory environments (e.g., regulatory classification limits under IEC 60825.1), a single set of emission control pulses with an energy of 6.60E-07 Joules may be considered eye-safe at 100 mm if no other pulses are emitted within a 5.00E-06 second time frame around the set of emission control pulses (and if the system satisfies various other parameters, such as wavelength, diagonal, beam divergence, and apparent source position). Similarly, two sets of emission control pulses with energies of 3.30E-07 Joules each may be considered eye-safe at 100 mm if no other pulses are emitted within a 5.00E-06 second time frame around the two sets of pulses, and if the pulses themselves do not exceed any other regulatory limits. Thus, in these regulatory environments, the total energy of all sets of emission control pulses over a defined time period determines whether a set of emission control pulses is considered eye-safe at a particular distance. And in such a regulatory environment, selectively delaying and / or further reducing the energy level of a set of transmitted control pulses after an object is detected within a safe range with variable timing allows the energy level of other sets of transmitted control pulses to be increased while maintaining compliance with regulatory classification limits.

[0034] Thus, selectively delaying and / or further reducing the energy level of a set of emission control pulses after an object is detected within the safety range allows prior sets of emission control pulses (e.g., those emission control pulses before an object is detected in the sensing area) to have been emitted at a higher energy. This increased energy in the prior set of emission control pulses provides improved reliability of detecting an object within the safety range while maintaining eye safety for both sets of emission control pulses. Thus, the scanning laser device 100 can provide improved reliability of detecting an object within the safety range and improved eye safety.

[0035] In some applications, it may be desirable to implement the scanning laser device 100 to selectively transmit multiple sets of transmit control pulses prior to transmitting a set of long-range pulses. For example, in some embodiments, it may be desirable to transmit multiple sets of transmit control pulses without resulting object detection within a safe range prior to transmitting a set of ranging pulses. Specifically, two clear sets of transmit control pulses may be desirable in the case where an immediately prior set of transmit control pulses has detected an object within a safe range. Examples of such embodiments are discussed below.

[0036] To facilitate this emission control technology, the light source controller 101 can use various devices and methods to change the energy level of the laser light pulse set. For example, the light source controller 101 can be implemented to dynamically change the pulse duration of each laser light pulse in the pulse set to change the energy of the pulse set. As another example, the light source controller 101 can be implemented to dynamically change the pulse amplitude of each laser light pulse to change the pulse set energy. As another example, the light source controller 101 can be implemented to dynamically change the current used to drive the laser to change the energy of each laser light pulse in the pulse set. As another example, the light source controller 101 can be implemented to dynamically change the number of lasers used to generate each pulse in the pulse set. As another example, the light source controller 101 can be implemented to dynamically change the number of each pulse in each pulse set to change the energy of the resulting pulse set. And various combinations of these technologies can be adopted.

[0037] In some embodiments, the light source controller 101 emission control can be implemented as part of a pulse generation circuit and / or an emission control circuit. In these embodiments, the pulse generation circuit and / or the emission control circuit are used as a light source controller to cause the laser light source to selectively emit a relatively low energy emission control pulse set for detecting when an object (e.g., a person) is within a relatively close safety range. Then, only when the object is not detected within the safety range, a higher energy long range pulse set is conditionally emitted, thereby improving eye safety. Detailed examples of such pulse generation circuits and emission control circuits will be described in more detail below.

[0038] In one embodiment, the light source controller 101 can be implemented using emission control to: emit a first emission control pulse set at a reduced first energy level; in response to no object being detected within a safe range using the first emission control pulse set, emit a ranging pulse set at a higher energy level, wherein the higher energy level is greater than the reduced first energy level; in response to no object being detected within the safe range using the first emission control pulse set, emit a second emission control pulse set after a first time period following the first emission control pulse set and at a reduced second energy level; and in response to an object being detected within the safe range using the first emission control pulse set, emit an adjusted second emission control pulse set, wherein the adjusted second emission control pulse set includes at least one of an extended first time period following the first emission control pulse set and a further reduced second energy level relative to the reduced second energy level.

[0039] In another embodiment, the light source controller 101 can also be implemented as: in response to no object being detected within a safe range using the second emission control pulse set or the adjusted second emission control pulse set, emitting a third emission control pulse set, wherein the third emission control pulse set includes a second time period following the second emission control pulse set or the adjusted second emission control pulse set and a reduced third energy level; and in response to an object being detected within a safe range using the second emission control pulse set or the adjusted second emission control pulse set, emitting an adjusted third emission control pulse set, wherein the adjusted third emission control pulse set includes at least one of an extended second time period following the second emission control pulse set or the adjusted second emission control pulse set and a further reduced third energy level relative to the reduced third energy level.

[0040] In another embodiment, the light source controller 101 may be further implemented such that the further reduced second energy level relative value is dynamically adjusted for each of the plurality of adjusted emission control pulse sets. In another embodiment, the light source controller 101 may be further implemented to dynamically determine the extended first time period such that the first emission control pulse set and the adjusted second emission control pulse set have a combined energy below an energy limit of the laser light pulse within the defined time frame. In such an embodiment, the energy limit may be a regulatory classification limit implemented for safety purposes, a limit intended to protect sensitive materials from damage, or a limit to provide operational reliability, to name a few examples.

[0041] In this application, the term "pulse collection" is defined as a group of one or more laser pulses emitted together within a relatively short period of time, where the received reflections are used together to provide object detection and / or ranging. In this definition, a single pulse generally corresponds to an individual burst of laser light emitted within one on / off cycle of a laser light source.

[0042] A pulse set including one or more pulses can produce reflections that can be used together for object detection and ranging in a variety of different ways. For example, multiple pulses in a pulse set can be implemented to provide multiple independent object detection opportunities. In other embodiments, the results of multiple pulses can be combined (e.g., averaged, integrated) to provide an increased probability of detection and / or increased accuracy.

[0043] As another example, a pulse set having multiple pulses may be modulated using any of a variety of different techniques, including amplitude modulation, frequency modulation, phase modulation, etc. In these examples, the pulse set may be modulated to include a signature that may increase detection reliability and / or effective range of the pulse set.

[0044] As a detailed example, a ranging pulse set can be modulated to include one of a plurality of different possible signatures by changing the relative timing of individual pulses. In some embodiments, a ranging pulse set including a plurality of pulses can be modulated using a channel signature, and then the received reflection can be used for ranging only when the received reflection is modulated to the same channel signature. Otherwise, the light received at the detector can be rejected. In such an embodiment, modulation of multiple pulses can therefore be used to reject noise and improve the signal-to-noise ratio (SNR). This can increase the effective range of the ranging pulse set without requiring additional energy in each individual pulse. Similarly, multiple pulses can be used in one transmit control pulse set to reject noise and improve the range and / or reliability of the transmit control pulse set. Examples of such modulation techniques can be found in U.S. Patent No. 11,402,476, entitled "Method and Apparatus for LIDAR Channel Encoding".

[0045] Now go to Figure 2A , shows a schematic diagram of a scanning laser device 200. In one embodiment, the scanning laser device 200 is a LiDAR system for object detection and / or 3D map generation. Figure 2A As shown, the scanning laser device is implemented to scan an object in a scanning field 210. In the illustrated embodiment, the scanning field 210 is defined in part by an effective range 212 and an output scanning angle 214. Other factors may also define the scanning field 210, including orthogonal scanning angles ( Figure 2A ) and the optics of the scanning laser device 200 (e.g., laser pulse power variation, expansion optics 108, scanning optics 110). It should be noted that this is a simplified example and more complex implementations of the scanning field are possible and will be discussed below.

[0046] As described above, the scanning laser device 100 includes emission control to provide improved eye safety by emitting higher energy long range pulse sets (e.g., to the effective range 212) only when no object is detected within a relatively close safety range (e.g., the safety range 222). Typically, to provide eye safety, the safety range 222 is implemented so that the higher energy long range pulse sets are considered eye safe at and beyond the outer edge of the safety range. Again, it should be noted that the safety range 222 is a simplified example and more complex embodiments are possible.

[0047] During operation, the emission control system causes the laser light source to selectively emit a relatively low energy emission control pulse set for detecting when an object (e.g., a person) is located within the relatively close safety range 222. Then, only when no object is detected within the safety range, a higher energy long range pulse set (having an effective range 212) is conditionally emitted, thereby improving eye safety. Thus, when a person or other object is located within the safety range 222, the emission control pulse set provides the ability to selectively delay or prevent the emission of a relatively high energy long range pulse set, and can thereby provide improved eye safety.

[0048] To provide such safety, the set of emission control pulses is generated to have a reduced energy level that reduces accessible emissions and provides eye-safe operation over at least a portion of the safety range 222. For example, if the set of emission control pulses meets the Class 1 level accessible emission limits under IEC 60825.1 over at least a portion of the safety range 222, then that portion can be expected to be eye-safe. As a specific example, in some embodiments, the energy levels of the set of emission control pulses can be implemented to meet the Class 1 level limits, thereby providing eye-safe operation beginning at 100 mm from the scanning laser device 200 while providing reliable object detection outside the edge of the safety range 222. For example, in very bright sunlight, a set of emission control pulses that is eye-safe at 100 mm may have a reduced energy level at a safety range distance of 10 meters. -10 The probability of failing to detect an object with 20% reflectivity is 0.1%. And such a set of emission control pulses will have a lower probability of failing to detect an object at a distance closer to the safety range 222. Of course, this is just one example, and in other embodiments, the pulse set energy level can be set so that the accessible emission results in eye-safe operation starting at a distance greater than 100 mm from the scanning laser device 200.

[0049] As described above, in some embodiments, when a platform using a scanning laser device (e.g., LiDAR or other scanning laser device 100) is in motion, the energy of the set of transmitted control pulses can be increased. For example, when the speed of a car is above a threshold, the energy of the set of transmitted control pulses can be set to a level that causes the accessible emission to be at an eye-safe level at a minimum distance of more than 100 mm. The energy of the set of transmitted control pulses can then be increased as the speed of the platform increases. For example, when the platform accelerates to between 2.5 meters per second (m / s) and 25 m / s, the energy of the set of transmitted control pulses can be gradually increased.

[0050] Increasing the energy level of the set of transmitted control pulses in response to speed may again result in an increased probability of detecting an object within a safe range and / or increasing the range at which an object may be detected using the set of transmitted control pulses.

[0051] Now go to Figure 2B , shows an exemplary laser pulse train that together constitutes a transmission control pulse set and a ranging pulse set according to various embodiments of the present invention. Specifically, Figure 2B Pulses 228, 229 are shown constituting an exemplary transmit control pulse set, and pulses 230, 231 are shown constituting an exemplary ranging pulse set. As noted above, the term "pulse set" is defined as a group of one or more laser pulses emitted together within a relatively short period of time, wherein the received reflections are used together to provide object detection and / or ranging.

[0052] In this example, the first transmit control pulse set (consisting of pulse 228) is transmitted before the first ranging pulse set (consisting of pulse 230), and the second transmit control pulse set (consisting of pulse 229) is transmitted before the second ranging pulse set (consisting of pulse 231). In such an embodiment, pulse 230 of the first ranging pulse set is transmitted only if pulse 228 of the first transmit control pulse set does not result in the detection of an object within the safety range 222. Similarly, pulse 231 of the second ranging pulse set is transmitted only if pulse 229 of the second transmit control pulse set does not result in the detection of an object within the safety range 222.

[0053] In this example, each transmit control pulse set includes only one pulse 228, 229, while each long range ranging pulse set includes five pulses 230, 231 that are spaced closely in time to effectively function as one pulse set. For example, a ranging pulse set of five pulses 230 may be emitted in a time period between 30-90 ns. Thus, pulses 228, 229, 231, and 231 are examples of the types of emissions that may be emitted by a LiDAR or other scanning laser device (e.g., scanning laser device 100, 200) for each scanning position or measurement point in scanning field 210.

[0054] As described above, a set of transmit control pulses (consisting of pulses 228, 229) is transmitted to detect any possible objects within the relatively short safety range 222, and then the system conditionally transmits a set of long range ranging pulses (consisting of pulses 230, 231) based on whether an object is detected. Specifically, Figure 2BAn example is shown in which each of the two pulses 228, 229 of the emission control pulse does not result in an object being detected within the safety range 222, and therefore pulses 230, 231 for the ranging pulse set are emitted for long range detection of the effective range 212. It should be noted that pulse 228 and pulse 230 do not effectively form part of the same pulse set, but rather provide separate detection events. However, it should also be noted that because the time between each pulse 228 and the subsequent pulse 230 is short enough that they all effectively scan the same scanning position or measurement point defined by the emission direction portion of the laser light pulse set. This means that pulse 228 can reliably detect whether an object is within the safety range at the effective same scanning position or measurement point that the subsequent pulse 230 will hit. As a non-limiting example, pulse 228 can be separated from pulse 230 in time by 90-500 ns.

[0055] Next, it should also be noted that in this example, first pulse 228 and subsequent pulse 230 will correspond to a first scanning position or measurement point, while second pulse 229 and subsequent pulse 231 will correspond to the next scanning position or subsequent measurement point in scanning field 210.

[0056] Again, the set of transmit control pulses (e.g., pulses 228, 229) are generated to have energy levels that provide a very high probability of detecting an object within the designed short safety range 222, while also providing eye safety within the short safety range 222. The set of long range ranging pulses (e.g., pulses 230, 231) can then be generated to have energy levels that are eye safe at the short safety range 222 and beyond, while providing reliable long range detection for the effective range 212.

[0057] It should be noted that although Figure 2BA set of one pulse 228, 229 for each transmit control pulse set and five pulses 230, 231 transmitted for each ranging pulse set are shown, but any suitable number of pulses may be used in each pulse set. For example, a single pulse with a relatively high energy level may be used in place of a set of multiple pulses 230, 231 for ranging to each scan position. As another example, multiple pulses of relatively lower energy for each transmit control pulse set may be used in place of one pulse 228, 229 for each transmit control pulse set. Additionally, in some embodiments, different numbers of pulses with the same energy level per pulse may be employed to provide multiple ranges. For example, a short range for a transmit control pulse set may be provided by the energy of a single pulse, while a long range for a ranging pulse set may be provided by the energy of multiple pulses, wherein each of the multiple pulses has the same energy as a single pulse for the transmit control pulse set. As another example, a short range of emitted control pulses may be defined by the energy of a single short range pulse, while a medium range may be defined by multiple pulses, each having the same energy as the short range pulse, and a long range may be defined by more pulses having the same or greater energy than the short range pulse.

[0058] In some applications, it may be desirable to implement a system to selectively transmit multiple sets of transmit control pulses prior to transmitting a set of ranging pulses. Figure 2C , shows another exemplary laser pulse train that constitutes a transmission control pulse set and a ranging pulse set according to various embodiments of the present invention. In this example, two transmission control pulse sets (the first consisting of pulse 232 and the second consisting of pulse 234) are transmitted before the first ranging pulse set (consisting of pulse 236), while only one transmission control pulse set (consisting of pulse 238) is transmitted before the second ranging pulse set (consisting of pulse 240). Again, in such an embodiment, the first set of pulses 236 of the first ranging pulse set is only transmitted when neither pulse 232 nor 234 of the transmission control pulse set results in an object being detected within the safety range 222. It should be noted that in this embodiment, the two pulses 232 and 234 are separated in time, and the reflections are received and processed separately to provide two separate transmission control pulse sets with two separate object detection opportunities. However, the time between pulses 232 and 234 is also short enough that they both effectively scan the same scanning position or measurement point defined by the transmission direction portion of the laser light pulse set. As a non-limiting example, the two pulses 232 and 234 may be separated in time by between 90-500 ns.

[0059] Now go to Figure 3A, a flow chart illustrates a method 300 according to various embodiments. In some embodiments, the method 300 or portions thereof are performed by a LiDAR or other scanning laser device (e.g., scanning laser device 100, 200). For example, the method 300 may be performed by a series of circuits or electronic systems that are part of, communicate with, or are otherwise associated with the scanning laser device. The method 300 is not limited by a particular type of device that performs the method.

[0060] At step 302, a set of emission control (EC) pulses is emitted for the next scan position. As described above, the set of emission control pulses includes one or more laser light pulses emitted at a reduced energy level to determine whether any object is within a relatively close safety range (e.g., Figure 2A The set of laser light pulses is thus implemented at an energy level that is considered eye-safe within at least a portion of the safety range. It should be noted that in some embodiments, one set of emission control pulses (e.g., a set of laser light pulses) is emitted for each scanning position in step 302. Figure 2B In other embodiments, more than one set of transmit control pulses (e.g., consisting of pulses 228) is transmitted for at least some scanning positions in step 302. Figure 2C In addition, in other embodiments, the number of emission control pulse sets emitted for each scanning position in step 302 may be variable and may change during operation based on various factors. As will be described in more detail below, the embodiments described herein allow In step The energy level of the emission control pulse set emitted in 302 is relatively high To improve detection reliability while maintaining eye safety.

[0061] At step 304, a determination is made as to whether an object is detected within a safe range using the set of transmitted control pulses. As described above, in one embodiment, a detector (e.g., Figure 1 The detector 106 of the scanning field is configured to receive reflections of the laser light pulses from objects within the scanning field. The received reflections of the laser light pulses can then be used to detect these objects and determine the distance to these objects (e.g., using time of flight (TOF) measurements and calculating the distance based on these TOF measurements). In one embodiment, step 304 may include comparing the TOF measurements to a threshold, wherein the value of the threshold corresponds to a desired safety range based on various suitable factors. Therefore, the received reflections of the set of transmit control pulses can be used to determine whether there are objects with a specified safety range.

[0062] If no object is detected within the safety range, the method 300 proceeds to step 306. At step 306, one or more ranging pulse sets are transmitted, and any received reflections of the ranging pulse sets are used to generate a distance measurement. It should also be noted that in typical embodiments, the time between the transmission of the transmission control pulse set in step 302 and the transmission of the subsequent ranging pulse set in step 306 is short enough that both the transmission control pulse set and the ranging pulse set effectively strike and reflect from the same measurement point or scanning location.

[0063] The ranging pulse set transmitted in step 306 is provided for relatively long range object detection and distance measurement. Therefore, the energy of the ranging pulse set is generally much greater than the energy level of the prior transmit control pulse set transmitted in the previous step 302. In other words, the ranging pulse set is transmitted at a higher energy level, wherein the higher energy level is greater than the reduced first energy level of the first transmit control pulse set.

[0064] Therefore, at step 306, the control pulse set transmitted in step 302 is used only when it is within a safe range (e.g., Figure 2A The signal is then emitted when no object is detected within the safety range 222 of the transmitter. Figure 2A Thus, method 300 provides improved eye safety by transmitting a relatively high energy set of ranging pulses only when no object has been detected within the safe range for a given scan position or measurement point by a previously transmitted set of control pulses.

[0065] The received reflections of the ranging pulse set are used to generate distance measurements. Again, in one embodiment, the IR detector is configured to receive reflections of the ranging pulse set from objects within the scan field. The received reflections of the ranging pulse set can then be used to detect those objects and determine the distance to those objects (e.g., using TOF measurements). In one embodiment, multiple calculated distances are used to generate a point cloud of data (e.g., 3D point (X, Y, Z) cloud data that can be written to a memory or other data storage device). And as described above, in some embodiments, modulation techniques can be applied to the ranging pulse set to increase the SNR and effective range.

[0066] Using the distance measurement generated from any received reflections in step 306, method 300 returns to step 302, where a next set of transmit control (EC) pulses is transmitted for the next scan position, and the process continues. Specifically, when repeating step 302, when no object is detected within the safety range during the previous step 302, a second set of transmit control pulses is transmitted at a reduced second energy after a first time period following the first set of transmit control pulses.

[0067] Thus, as long as no object is detected within the safety range, steps 302, 304, and 306 may be continuously repeated to generate measured distances for different scanning positions in the scanning field. However, if it is determined at any step 304 that the set of emission control pulses results in the detection of an object within the safety range, the method moves to an adjusted emission control process 312 including steps 308 and 310. At step 308, an adjusted emission control (AEC) pulse set is emitted. The adjusted emission control pulse set is again a set of laser light pulses with a reduced energy level that is used to determine whether any object is within a relatively close safety range (e.g., Figure 2A However, in this step 308, the adjusted emission control pulse set If no object is detected within the safety range in step 304, the next step will be The set of emission control pulses emitted in 302 has been modified .

[0068] Specifically, the transmitted adjusted transmission control pulse set includes at least one of an extended first time period following the first transmission control pulse set and a further reduced second energy level relative to the reduced second energy level. Therefore, the transmitted adjusted transmission control pulse set in step 308 is adjusted to have an extended time delay period before its transmission and / or to have an energy level further reduced compared to the transmission control pulse set to be transmitted in the next step 302 if no object is detected within the safety range in step 304.

[0069] For example, in some embodiments, the transmitted adjusted transmission control pulse set in step 308 is adjusted to have an energy level that is further reduced compared to the transmission control pulse set that will be transmitted in the next step 302 if no object is detected within the safety range in step 304. Likewise, in some embodiments, the transmitted adjusted transmission control pulse set in step 308 is adjusted to have an extended time delay period before its transmission compared to the transmission control pulse set that will be transmitted in the next step 302 if no object is detected within the safety range in step 304. Finally, in some embodiments, the transmitted adjusted transmission control pulse set in step 308 is adjusted to have an energy level that is further reduced compared to the transmission control pulse set that will be transmitted in the next step 302 if no object is detected within the safety range in step 304. now that having an extended time delay period before its emission, also With a further reduced energy level.

[0070] Each of these embodiments can provide significant performance improvements over past techniques for providing eye safety. Specifically, by selectively delaying and / or further reducing the energy level of the adjusted set of transmitted control pulses after an object is detected within the safety range with variable timing, these embodiments help increase the energy level of the previously transmitted control pulse set while maintaining the desired eye safety level. As described above, in order to provide a certain level of eye safety, the total energy of the set of transmitted control pulses within a specific time frame should be considered. For example, the IEC 60825.1 specification defines the eye safety of pulses at least in part by the amount of energy emitted by two or more pulses within a set of specific time frames when there is still the possibility of an object within the safety range.

[0071] In such a regulatory environment, selectively delaying and / or further reducing the energy level of the adjusted set of emission control pulses after an object is detected within the safety range allows the previous set of emission control pulses to be emitted at a higher energy while maintaining eye safety for the two sets of pulses taken together. In other words, because the adjusted set of emission control pulses emitted in step 308 is delayed and / or the energy is further reduced, the set of emission control pulses emitted in step 302 can have a relatively higher energy while maintaining eye safety for the two sets of pulses taken together. In addition, this increased energy in the set of emission control pulses emitted in step 302 provides improved reliability in detecting objects within the safety range. Therefore, the improved reliability of object detection within the safety range itself provides improved eye safety.

[0072] At step 310, it is determined whether an object is detected within the safety range using the adjusted set of emission control pulses. Again, in one embodiment, the detector is configured to receive reflections of the laser light pulses from objects within the scan field. The received reflections of the laser light pulses can then be used to detect these objects and determine the distance to these objects. Thus, any received reflection of the set of emission control pulses can be used to determine whether an object with a specified safety range exists.

[0073] If no object is detected within the safety range, the method 300 returns to step 302, where the next set of transmit control (EC) pulses is transmitted. When performing step 302, the set of transmit control pulses may include a second time period following the second set of transmit control pulses or the adjusted second set of transmit control pulses and a reduced third energy level. Steps 302, 304, and 306 may then be continuously repeated to generate measured distances for different scan positions in the scan field, as long as no object is detected within the safety range.

[0074] If an object is detected within the safety range at step 310, the method 300 returns to step 308. At step 308, an adjusted set of emission control (AEC) pulses is again emitted. And again, the adjusted set of emission control pulses is a set of laser light pulses having a combined reduced energy level that is provided for determining whether there are any objects within a relatively close safety range. However, in this additional execution of step 308, the adjusted set of emission control pulses is Compared to If no object is detected within the safety range in step 310, the transmission control signal transmitted in the next step 302 is The pulse set is modified In this execution of step 308, the adjusted set of emission control pulses may include at least one of an extended second time period following the second set of emission control pulses or the adjusted second set of emission control pulses and a further reduced third energy level relative to the reduced third energy level.

[0075] Therefore, the adjusted set of transmit control pulses transmitted in step 308 is adjusted to have an extended time delay period before its transmission and / or to have an energy level further reduced compared to the set of transmit control pulses to be transmitted in the next step 302 if no object is detected within the safety range in step 310.

[0076] Therefore, again, in some embodiments, the transmitted adjusted set of transmit control pulses in step 308 is again adjusted to have a further reduced energy level compared to the set of transmit control pulses that would be transmitted in the next step 302 if no object was detected within the safety range in step 310. Likewise, in some embodiments, the transmitted adjusted set of transmit control pulses in step 308 is adjusted to have an extended time delay period before its transmission compared to the set of transmit control pulses that would be transmitted in the next step 302 if no object was detected within the safety range in step 310. Finally, in some embodiments, the transmitted adjusted set of transmit control pulses in step 308 is adjusted to have an extended time delay period before its transmission compared to the set of transmit control pulses that would be transmitted in the next step 302 if no object was detected within the safety range in step 310. now that having an extended time delay period before its emission, also With a further reduced energy level.

[0077] Each of these embodiments can provide significant performance improvements by facilitating an increase in the energy level of a previous set of transmit control pulses while maintaining the required eye safety level. This increased energy in the set of transmit control pulses emitted in step 302 again provides improved reliability of detecting objects within the safety range.

[0078] It should be noted that when an object is repeatedly detected within the safety range, the adjusted emission control process 312 (i.e., steps 308 and 310) can be continuously performed. In this case, in response to detecting an object within the safety range in the corresponding step 310, an adjusted emission control pulse set is emitted in each step 308. And in each case, the adjustment amount (e.g., the time period before the pulse set and / or the change in the energy level of the pulse set) can be modified. For example, the adjustment amount can be based on the number of times these steps are performed. This adjustment allows the combined energy of all emission control pulse sets emitted when an object may be in the sensing area to be lower than the limit within the corresponding total time period of the emission control pulse set.

[0079] Finally, it should be noted that in method 300, two sets of transmit control pulses are required without other detections after an object is detected within the safety range before a set of ranging pulses is transmitted. Specifically, after a detection in step 304 or 310, before a set of ranging pulses can be transmitted in step 306, a set of transmit control pulses must be transmitted in steps 308 and 302 without a resulting detection. Requiring two clear sets of pulses after detection can further increase the reliability of the transmit control system by increasing the probability of detecting an object within the safety range before transmitting a set of ranging pulses.

[0080] Now go to Figure 4A-4D , show exemplary graphs of exemplary pulse set energy changes over time. Specifically, these graphs show the energy of various transmission control pulse sets and ranging pulse sets according to exemplary operating scenarios and according to various embodiments described herein.

[0081] Specifically, go to Figure 4A , a graph 400 shows the relative energy and timing of the transmitted control pulse set and the ranging pulse set in an exemplary operating scenario when no object is detected within the safety range. Specifically, the graph 400 shows the energy 402, 406 and 410 of the three transmitted control pulse sets, and the energy 404, 408 and 412 of the three corresponding ranging pulse sets.

[0082] In this illustrated example, a first set of transmit control pulses having energy 402 is followed by a first set of ranging pulses having energy 404, a second set of transmit control pulses having energy 406 is followed by a second set of ranging pulses having energy 408, and a third set of transmit control pulses having energy 410 is followed by a third set of ranging pulses having energy 412. As will be described in more detail below, therefore, Figure 4A It shows that Figure 3A Steps 302, 304, and 306 of the method 300 shown in FIG.

[0083] Again, each of the first emission control pulse set, the second emission control pulse set, and the third emission control pulse set includes one or more pulses closely spaced in time to provide an object detection and / or ranging event. Likewise, each of the first ranging pulse set, the second ranging pulse set, and the third ranging pulse set includes one or more pulses closely spaced in time to provide an object detection and / or ranging event. In this case, the timing of the pulse set can be referenced to the leading edge of the first pulse, the center time of multiple pulses, or the trailing edge of the last pulse, to give three non-limiting examples. And it is worth noting that in this illustrated example, energies 402, 406, 410, 404, 408, and 412 are the combined energies of all pulses in the corresponding pulse set with timing based on the start of the first pulse in each set.

[0084] In this example, a first set of transmit control pulses having energy 402 is transmitted to detect any possible objects within the safety range (e.g., executing step 302 of method 300), and if no objects are detected within the safety range (e.g., step 304), a first set of ranging pulses having energy 404 is transmitted (e.g., step 306). It should be noted again that because the time between the first set of transmit control pulses and the first set of ranging pulses is relatively short, the pulse sets are both transmitted in substantially the same direction and both effectively scan the same scanning position or measurement point.

[0085] Then, in a first time period after transmitting the first set of transmit control pulses, a second set of transmit control pulses with energy 406 is transmitted to detect any possible objects within the safety range, and if no object is detected within the safety range, a second set of ranging pulses with energy 408 is transmitted (e.g., another execution of steps 302, 304, 306).

[0086] Then, in a second time period after transmitting the second transmission control pulse set, a third transmission control pulse set with energy 410 is transmitted to detect any possible objects within the safety range, and if no object is detected within the safety range, a third ranging pulse set with energy 412 is transmitted (e.g., another execution of steps 302, 304, 306).

[0087] It should also be noted that in this example, the first set of transmit control pulses and the first set of ranging pulses will correspond to a first scanning position or measurement point, while the second set of transmit control pulses and the second set of ranging pulses will correspond to the next scanning position or subsequent measurement point in the scanning field, and so on.

[0088] Typically, the set of transmit control pulses is generated to have energies 402, 406, and 410 that provide a very high probability of detecting an object within a designed short safety range, while also providing eye safety within at least a portion of the safety range (e.g., eye safety from the output of the scanning laser device to the outer edge of the safety range of 100 mm). In contrast, the set of ranging pulses is generated to have energies 404, 408, and 410 that are eye safe from the outer edge of the safety range and beyond, while providing reliable long range detection to an effective range outside the safety range.

[0089] Specifically, a first set of transmit control pulses may be generated to have an energy at a first reduced energy level 402. A second set of transmit control pulses may be generated to have an energy at a second reduced energy level 406. A third set of transmit control pulses may be generated to have an energy at a third reduced energy level 410. It should be noted that in various embodiments, the first, second, and third reduced energy levels may be the same energy level or different energy levels. However, in each case, the reduced energy level is less than a higher energy level of a subsequent set of ranging pulses.

[0090] Now go to Figure 4B , a graph 420 shows the energy and timing of a transmit control pulse set and a ranging pulse set in an exemplary operating scenario when an object is detected within a safe range using a transmit control pulse set. Specifically, the graph 420 shows the energy 422, 426 and 430 of three transmit control pulse sets, and the energy 432 of a subsequent ranging pulse set. As will be described in more detail below, Figure 4B Shown in Figure 3A Another example of a set of pulses transmitted during method 300 .

[0091] In this example, a first set of transmit control pulses having energy 422 is transmitted to detect any possible objects within the safe range (e.g., performing step 302 of method 300). This results in detection of an object 424 within the safe range (e.g., step 304). Therefore, a set of ranging pulses is not transmitted following the first set of transmit control pulses, and an adjusted second set of transmit control pulses having energy 426 is transmitted (e.g., step 308). In this illustrated example, the adjusted second set of transmit control pulses is transmitted after a delay (i.e., after the extended first time period).

[0092] The adjusted second set of transmit control pulses does not result in an object being detected within the safe range (e.g., step 310). Therefore, a third set of transmit control pulses having energy 430 is transmitted to detect any possible objects within the safe range (e.g., step 302). This again does not result in an object being detected within the safe range (e.g., step 304). Therefore, a set of ranging pulses having energy 332 is transmitted (e.g., step 306).

[0093] As mentioned above, in Figure 4B In an example, the adjusted second set of transmission control pulses is transmitted after the extended first time period. Specifically, the extended first time period is longer than the corresponding first time period when no object is detected (e.g., Figure 4A Selectively delaying the adjusted set of emission control pulses after an object is detected within the safety range helps to emit the previous set of emission control pulses at a higher energy while maintaining eye safety for the two pulse sets taken together. This increased energy in the previous set of emission control pulses provides improved reliability of detecting an object within the safety range, thereby providing improved eye safety.

[0094] Finally, it should be noted that in Figure 4B In the example of FIG. 1 , after detecting an object within the safe range using a first set of transmit control pulses, two sets of transmit control pulses are required without another detection before transmitting a set of ranging pulses again. Again, requiring two clear sets of pulses after detection can further increase the reliability of the transmit control system by increasing the probability of detecting an object within the safe range before transmitting a set of ranging pulses.

[0095] Now go to Figure 4C , graph 440 shows the energy and timing of a transmit control pulse set and a ranging pulse set in another exemplary operating scenario when an object is detected within a safe range using a transmit control pulse set. In this example, a first transmit control pulse set having an energy 442 is transmitted to detect any possible object within the safe range (e.g., performing step 302 of method 300). This results in the object being detected within the safe range (e.g., step 304). Therefore, a ranging pulse set is not transmitted following the first transmit control pulse set, and an adjusted second transmit control pulse set having an energy 446 is transmitted (e.g., step 308). In this illustrated example, the adjusted second transmit control pulse set is transmitted at a further reduced energy level.

[0096] The adjusted second set of transmit control pulses does not result in an object being detected within the safe range (e.g., step 310). Therefore, a third set of transmit control pulses having energy 450 is transmitted to detect any possible object within the safe range (e.g., step 302). This again does not result in an object being detected within the safe range (e.g., step 304). Therefore, a set of ranging pulses having energy 452 is transmitted (e.g., step 306).

[0097] As mentioned above, in Figure 4C In the example of , the adjusted second set of transmission control pulses is transmitted at a further reduced energy level. Specifically, the reduced energy level is less than the corresponding energy level when no object is detected (e.g., Figure 4A Selectively further reducing the energy of the adjusted transmit control pulse set after the object is detected within the safety range facilitates transmitting the previous transmit control pulse set at a higher energy while maintaining eye safety for the two pulse sets taken together. This increased energy in the previous transmit control pulse set again provides improved reliability of detecting the object within the safety range, and thereby can provide improved eye safety.

[0098] Finally, it should be noted that Figure 4C In the example of FIG. 5 , after an object is detected within a safe range using a first set of transmitted control pulses, two sets of transmitted control pulses are required without another detection before transmitting a set of ranging pulses again.

[0099] Now go to Figure 4D , graph 460 shows the energy and timing of a transmit control pulse set and a ranging pulse set when an object is detected within a safe range using a transmit control pulse set in another exemplary operating scenario. In this example, a first transmit control pulse set having an energy 462 is transmitted to detect any possible object within the safe range (e.g., performing step 302 of method 300). This results in the object being detected within the safe range (e.g., step 304). Therefore, a ranging pulse set is not transmitted following the first transmit control pulse set, and an adjusted second transmit control pulse set having an energy 466 is transmitted (e.g., step 308). In this illustrated example, the adjusted second transmit control pulse set is transmitted after a delay, i.e., after an extended first time period.

[0100] In this example, the adjusted second set of transmit control pulses again results in the object being detected within the safe range (e.g., step 310). Therefore, an adjusted third set of transmit control pulses having energy 470 is transmitted (e.g., step 308 is re-executed). In this illustrated example, the adjusted third set of transmit control pulses includes both an extended delay and a further reduced energy level.

[0101] The adjusted third set of transmit control pulses does not result in an object being detected within the safe range (e.g., step 310). Therefore, a fourth set of transmit control pulses having energy 472 is transmitted to detect any possible objects within the safe range (e.g., step 302). This again does not result in an object being detected within the safe range (e.g., step 304). Therefore, a set of ranging pulses having energy 474 is transmitted (e.g., step 306).

[0102] As mentioned above, in Figure 4D In the example of , the adjusted second set of transmission control pulses is transmitted with an extended delay and a further reduced energy level. Specifically, the extended second time period is longer than the corresponding second time period when no object is detected (e.g., Figure 4A Likewise, the further reduced energy 470 is less than the corresponding energy level when no object is detected (e.g., Figure 4A The reduced third energy level 410). Selectively extending the time period and Further reducing the energy of the adjusted emission control pulse set after the object is detected within the safety range helps to emit the previous emission control pulse set at a higher energy while maintaining eye safety for the two pulse sets taken together. This increased energy in the previous emission control pulse set again provides improved reliability of detecting the object within the safety range, thereby providing improved eye safety.

[0103] Now go to Figure 3B , a flowchart shows a method 350 according to various other embodiments. The method 350 is Figure 3A Thus, method 350 or a portion thereof is performed by a LiDAR or other scanning laser device (eg, scanning laser device 100, 200).

[0104] Method 350 differs in that an adjusted emission control process 352 including steps 308 and 310 also includes step 354, which determines whether an additional adjusted emission control check is required. In such an embodiment, method 350 may require an additional set of emission control pulses without an object detected within the safety range before returning to step 302. If an additional adjusted emission control check is required, the method returns to step 308. If an additional adjusted emission control check is not required, the method returns to step 302.

[0105] Such an embodiment can be implemented in a variety of ways. For example, the technique can be implemented by providing a count variable to track the number of adjusted emission control pulse sets that have been emitted since the last object was detected within the safety range. Only when the required number of adjusted emission control pulse sets have been emitted without additional objects being detected within the safety range does the method return to step 302 instead of step 308. In some embodiments, the number of additional emission control pulse sets required can be dynamically changed based on various operating parameters, including the measured distance to the last detected object within the safety range, the number of previous object detections within the safety range, environmental conditions, the speed of the vehicle using the scanning laser device, etc.

[0106] Now go to Figure 3C , a flowchart illustrating a method 360 according to various other embodiments. The method 360 is again Figure 3A Thus, method 360 or a portion thereof is performed by a LiDAR or other scanning laser device (eg, scanning laser device 100, 200).

[0107] Method 360 differs in that the set of ranging pulses transmitted in step 306 is also used to detect objects within the safe range and trigger the execution of the adjusted transmission control process 312 including steps 308 and 310. Therefore, method 360 provides an additional check for objects within the safe range.

[0108] Specifically, the method 360 includes step 362. At step 362, it is determined whether an object is detected within the safety range using the ranging pulse set. If the object is detected within the safety range using the ranging pulse set, the method 360 proceeds to the adjusted emission control process 312 including steps 308 and 310. At step 308, an adjusted emission control (AEC) pulse set is transmitted. As described above, if the object is not detected within the safety range in step 304, the adjusted emission control pulse set is modified relative to the emission control pulse set that has been transmitted in the next step 302. If the object is not detected within the safety range using the ranging pulse set, the method returns to step 302, where the method 362 continues to the next scanning position.

[0109] It should be noted that in some embodiments, it may be desirable to include variations of method 360 and variations of method 362, thereby including additional steps 354 and 362 in the method. And these are just some examples of the types of variations that may be included in the techniques described herein.

[0110] Now turn to Figure 5 - Fig.12 , various detailed examples of exemplary scanning laser devices will be described. These examples include various specific embodiments of the types of scanning laser devices that can implement emission control according to the embodiments described herein. However, it should be noted that these are only non-limiting examples of the types of scanning laser devices that can be implemented using the above-described emission control methods.

[0111] Now go to Figure 5A , a more detailed embodiment of an optical assembly 500 is shown. The optical assembly 500 includes optical elements for scanning laser beam pulses over a scanning field. The optical assembly 500 is an example of the type of optical assembly that can be used in a LiDAR or other scanning laser device (e.g., scanning laser devices 100, 200) according to embodiments described herein. Figure 5A The optical elements shown in the figure include beam shaping optics 502, a first scanning mirror 504, expansion optics 506, and a second scanning mirror 508, although this is only a non-limiting example. Again, during operation of the scanning laser device, the laser light source generates laser light pulses that are scanned by the optical assembly 500 into a scanning track (e.g., scanning track 112) on a scanning field (e.g., scanning field 114).

[0112] For example, the laser light source may include one or more infrared (IR) lasers implemented to generate IR laser light pulses. In one specific example, pulses from multiple IR laser light sources are combined and shaped by beam shaping optics 502. Beam shaping optics 502 may include any optical device for changing the beam shape of laser light pulses. For example, beam shaping optics 502 may include optical elements for changing beam shape, changing beam collimation, combining multiple beams, and opening a beam.

[0113] The output of the beam shaping optics 502 is passed to a first scanning mirror 504. Typically, the first scanning mirror 504 provides one axis of motion (e.g., horizontal) while the second scanning mirror 508 provides another, generally orthogonal axis of motion (e.g., vertical). Thus, the first scanning mirror 504 scans the laser beam pulses in one direction (e.g., horizontal) while the second scanning mirror 508 scans in another direction (e.g., vertical). Furthermore, in a typical implementation of such an embodiment, the first scanning mirror 504 is operated to provide scanning motion at one rate (e.g., a relatively slow scanning rate) while the second scanning mirror 508 is operated to provide motion at a different rate (e.g., a relatively fast scanning rate). Together, this results in the laser light pulses being scanned into a scanning trajectory (e.g., scanning trajectory 112). It is also noted that the labels "vertical" and "horizontal" used herein are somewhat arbitrary, as rotating the scanning laser device 90 degrees will effectively switch the horizontal and vertical axes.

[0114] The output of the first scanning mirror 504 is passed to the expansion optics 506. Typically, the expansion optics 506 are implemented to provide an expansion of the scan field in one or more directions. For example, the expansion optics 506 can be implemented to provide an angular expansion along the axis of motion of the first scanning mirror 504. Thus, in an example where the first scanning mirror 504 provides a relatively slow scan along a horizontal axis, the expansion optics 506 can be implemented to increase the scan angle along the horizontal direction. As a specific example, the first scanning mirror 504 can be implemented to provide a scan angle of 40 degrees in the horizontal direction, and the expansion optics 506 can be implemented to expand the scan angle to 110 degrees, thereby expanding the size of the resulting scan trajectory and scan field.

[0115] To provide this expansion, the expansion optics 506 can be implemented with one or more lenses, where the one or more lenses are configured to provide the desired angular expansion together. In a specific example, the expansion optics 506 is implemented with three separate lenses. A description of this embodiment will be described in more detail below.

[0116] The output of the expansion optics 506 is passed to a second scanning mirror 508. Again, the first scanning mirror 504 provides one axis of motion (e.g., horizontal), while the second scanning mirror 508 provides another generally orthogonal axis of motion (e.g., vertical). In addition, the first scanning mirror 504 and the second scanning mirror 508 operate at different scanning rates. In a particular embodiment, the second scanning mirror 508 provides vertical high-rate scanning, while the first scanning mirror 504 provides horizontal low-rate scanning.

[0117] During operation, the optical assembly 500 thus operates to receive laser light pulses and scan those laser light pulses into a scanning trajectory pattern within a scanning field.

[0118] Now turn to Figure 5B , graph 510 shows a representation of the optical spread in the scan field. Specifically, graph 510 shows the exit pointing angle spread as a function of the scan angle along a first axis, where the first axis also corresponds to the first axis in the resulting scan field. The exit angle spread is determined by the expansion optics of the scanning laser device (e.g., Figure 1 Extended optical device 108, Figure 5A 506) can provide an example of the type of optical expansion that can be provided by the expansion optics. The optical expansion shown in the graph 510 is non-uniform with respect to the first axis, and more specifically, results in a non-linear optical expansion with respect to the axis in the scan field. This non-uniform and non-linear optical expansion results in a higher rate of change of optical expansion in the side regions of the scan field along the first axis compared to a lower rate of change of optical expansion in the central region. This is indicated by the slope of the function curve becoming steeper as the distance from the center increases.

[0119] Now go to Figure 5C , graph 512 shows an exemplary scanning trajectory 513. During operation of the scanning laser device, laser light pulses strike the object in a series of scanning positions or measurement points along scanning trajectory 513. Scanning trajectory 513 is an example of the type of scanning trajectory that can be generated by a scanning laser device that includes an expansion optic that provides non-uniform optical expansion relative to a first axis (e.g., Figure 1 Extended optical device 108, Figure 5A More specifically, the scanning trajectory 513 is an optical expansion (such as Figure 5B An example of the type of trajectory that can be generated by scanning the scanned field 513 is shown in FIG. 510 , which shows an example of an optical expansion (shown in FIG. 511 ) of FIG. 512 . Thus, the scanned trace 513 shows the result of non-uniform and non-linear optical expansion, where a higher rate of change of the exit angle spread is created in the side regions of the scanned field along the first axis compared to a lower rate of change of the exit angle spread created in the central region.

[0120] The scanning trajectory 513 is generated by the movement of one or more scanning mirrors, wherein the mirrors provide deflection of the laser light pulses along a first axis and a second axis, with non-uniform spreading provided by one or more spreading optics. In this illustrated example, the scanning motion in the first axis is a relatively slow motion, while the scanning motion in the second axis is a relatively fast motion. Furthermore, in this example, the motion in the first axis is horizontal, while the motion in the second axis is vertical (although again, it should be noted that the labels "vertical" and "horizontal" are somewhat arbitrary).

[0121] Finally, it should be noted that scanning trajectory 513 is only one example trajectory caused by non-uniform changes in optical expansion, and many other implementations are possible.

[0122] As mentioned above, such as Figure 5B and Figure 5C The changes in optical expansion shown will result in changes in the effective range of the scanning laser detector. Specifically, changes in optical expansion will result in changes in beam width and beam divergence, which in turn result in changes in the effective range of the scanning laser device. Therefore, in some embodiments, the light source controller (e.g., light source controller 101) is configured to change the energy level of the set of laser light pulses to provide the desired effective range of the sensor by at least partially compensating for the effects of the non-uniform optical expansion provided by the expansion optical device.

[0123] Now go to Figure 5D , a graph 514 shows a representation of the energy level adjustment of a set of laser light pulses. Specifically, the graph 514 shows the energy level adjustment as a function of the scanning angle along a first axis, where the first axis also corresponds to the first axis in the resulting scan field. It is worth noting that the energy level adjustment of this diagram can be considered as a percentage increase in energy level from a low power state, or a percentage decrease in energy level from a high power state.

[0124] Again, in one embodiment, the light source controller (e.g., light source controller 101) is configured to vary the energy in a manner proportional to the non-uniform change in optical expansion. Again, this variation can be applied to the long range ranging pulse set, the short range emission control pulse set, or both. Thus, the laser light pulses subjected to greater optical expansion are generated with greater energy levels, and vice versa. The increase in energy level compensates for the reduction in effective range due to the increase in optical expansion, thereby providing the desired effective range of the detector and scanning laser device.

[0125] As described above, in some embodiments, a scanning laser device (e.g., scanning laser device 100) is implemented to provide an improved effective range that varies across a scan field, with different effective ranges in different regions of the scan field. In these embodiments, these different effective ranges are achieved by varying the energy level of a set of laser light pulses in a manner that adjusts both the energy level of the desired effective range in the scan field region and the optical etendue in the scan field region.

[0126] Now go to Figure 5E , shows a schematic diagram of a scanning laser device 520. Specifically, Figure 5E A scanning laser device 520 is shown implemented with three different exemplary scanning fields 522, 524, and 526, wherein the three different scanning fields 522, 524, and 526 each have a different effective range and a different field of view angle. As an example, these different effective ranges can be provided by implementing the scanning laser device 520 to operate at different times and in different modes during operation, wherein each different mode has a different range and / or a different field of view angle. For example, the scanning laser device 520 can be implemented to alternate or otherwise switch between different range modes in response to various factors. In other embodiments, which will be discussed in more detail below, the scanning laser device 520 can be implemented to provide these different ranges during different portions of the same scanning trajectory.

[0127] exist Figure 5E In the example of , there are three range modes, namely, a close range mode, a medium range mode, and a long range mode. In this example, the close range mode provides a scanning field 526 with an effective range of 60 meters and a scanning field angle of 110 degrees. The medium range mode provides a scanning field 524 with an effective range of 120 meters and a scanning field angle of 50 degrees. Finally, the long range mode provides a scanning field 522 with an effective range of 200 meters and a scanning field angle of 25 degrees. Of course, these are just examples, and other implementations are possible.

[0128] To achieve these different range modes in the scanning laser device 520, the light source controller (e.g., light source controller 101) will change the energy level of the set of laser light pulses to achieve the desired range. By dynamically changing the angular extent of the mirror deflection, the three different angular ranges of the scanning fields 522, 524, and 526 for these three modes can be achieved. In other embodiments, the angular extent of the mirror deflection can be kept constant and the angular extent of the scanning fields 522, 524, and 526 can be changed by selectively not transmitting laser light pulses when the mirror is outside the desired angular extent of the desired scanning field angle. In either case, the scanning laser device 520 can provide the desired effective range and the desired scanning field angular extent for each different operating mode.

[0129] It should be noted that each of the close range mode, the mid-range mode, and the long range mode can be implemented as the same or different safety ranges for the transmit control. Therefore, in some examples, the safety range of objects detected by the transmit control pulse set may be different for each range. Therefore, the energy of the transmit control pulse set can be changed to provide these different safety ranges.

[0130] Now go to Fig. 5F , a representation of the energy level of the laser light pulses is shown in graph 530. Graph 530 shows the energy level of the laser light pulses for three range modes, namely, long range mode, medium range mode, and short range mode. These modes correspond to Figure 5E 526. Thus, in the long range mode, the scanning laser device 520 has an operating range of 200 meters with a relatively narrow 25 degree field of view. In the medium range mode, the scanning laser device 520 has an operating range of 120 meters and a 50 degree field of view. In the close range mode, the scanning laser device 520 has an operating range of 60 meters and a relatively wide 110 degree field of view. Thus, the energy levels of the sets of laser light pulses are adjusted to provide these desired ranges while also taking into account any non-uniform optical expansion provided by the expansion optics.

[0131] Graph 530 shows energy level adjustments for three different modes as a function of scan angle along a first axis, where the first axis also corresponds to the first axis in the resulting scan field. In this case, the light source controller (e.g., light source controller 101) is configured to provide a relatively constant high energy level for the long range mode because the relatively narrow field of view limits the optical spread of these pulses. In this example, the energy level of the set of laser light pulses is 100% or close to 100% of the full pulse energy.

[0132] However, for the mid-range and near-range modes, the light source controller is configured to vary the energy in a manner proportional to the non-uniform change in optical extension over the angular range covered by the mode. This allows the desired range to be achieved in both modes while compensating for the effects of non-uniform optical extension.

[0133] Figure 5E and Fig. 5FThe examples show a scanning laser device 520 embodiment in which there are separate modes with different effective ranges and different scanning field angles 522, 524, and 526. Again, in such an embodiment, the scanning laser device 520 can be implemented to switch between modes in various patterns and / or based on various factors. In these examples, each mode has a relatively constant range across its respective scanning field. However, in other embodiments, the scanning laser device 520 can be implemented to provide these different ranges during different portions of the same scanning frame, effectively providing dynamic range shaping across the scanning field. For ease of implementation, the scanning laser device 520 can be implemented to vary the effective range at various points within each scanning trajectory or scanning frame. Thus, at these points within the scanning trajectory, the effective range can be increased or decreased to dynamically achieve the desired range across the scanning field.

[0134] Now go to Figure 5G , shows a schematic diagram of a scanning laser device 520 having multiple effective ranges. Specifically, Figure 5G It is shown implemented to provide a scan field 532 having three different effective ranges, with different ranges over different angular regions of the scan field 532. Again, this dynamic range shaping can be accomplished by implementing the scanning laser device 520 to adjust the pulse energy at different points within the scan trajectory.

[0135] Specifically, in Figure 5G In the example of , scanning field 532 has a near range region 534 having a range of 60 meters and corresponding to an extended output angle between 25 to 55 degrees and -25 to -55 degrees. Scanning field 532 also has a mid range region 536 having a range of 120 meters and corresponding to an extended output angle between 12.5 to 25 degrees and -12.5 to -25 degrees. Finally, scanning field 532 has a long range region 538 having a range of 200 meters and corresponding to an extended angle between 0 to 12.5 degrees and 0 to -12.5 degrees. Thus, scanning laser device 520 provides three different ranges on each scanning trajectory or scanning frame.

[0136] It should be noted that Figure 5G An example of Figure 5E. Specifically, the example also provides a "long range zone" (e.g., a central zone with a range of 200 meters), a "mid-range zone" (e.g., a middle zone with a range of 120 meters), and a "near range zone" (e.g., an outer zone with a range of 60 meters) on each scan trajectory. The scanning laser device 520 can accomplish this dynamic range shaping by varying the pulse set energy to vary the effective range at 25, 12.5, -12.5, and -25 degrees, while also varying the pulse set energy to compensate for any effects of non-uniform optical expansion provided by the expansion optics.

[0137] Again, it should be noted that the scanning laser device can be implemented to use the same or different safety ranges for each of these different zones or angular regions. Therefore, in some examples, the safety range for detecting an object by transmitting a set of control pulses can be different for each of these different zones or angular regions. Therefore, the energy of the set of transmitted control pulses can be varied to provide these different safety ranges.

[0138] Although Figure 5G The scanning laser device 520 shown in FIG. 5 provides a scanning field 532 with three different effective ranges, but this is only an example embodiment, and other embodiments are also possible. For example, the scanning laser device can be implemented with a greater number of effective ranges. In addition, the number and range of ranges can be asymmetric, horizontal and / or vertical.

[0139] Now turn to Fig. 6A and Figure 6B , shows an application of a scanning laser device (eg, scanning laser device 100). Specifically, Fig. 6A and Figure 6B A mobile platform with a scanning LiDAR system is shown according to various embodiments. Car 602 is a mobile platform on which a LiDAR system 604 is mounted. The LiDAR system is a mobile platform that uses the various embodiments discussed above (e.g., Figure 1 This can be accomplished by a scanning laser device 100) or any scanning laser device and LiDAR system discussed herein.

[0140] The LiDAR system 604 generates an exemplary scan field, where different horizontal areas have different effective ranges. Fig. 6A and Figure 6B As shown, the LiDAR system 604 can be implemented to selectively facilitate a long range region 606, a mid range region 608, and a near range region 610, each of which has a different degree of angle. Again, this can be achieved by operating the LiDAR system 604 in three different range modes, wherein the three different range modes have different field of view angles, such as Figure 5EAlternatively, this can be accomplished by operating the LiDAR system 604 to provide dynamic range shaping, where different areas have different effective ranges, such as Figure 5G and as shown in Figures 5I-4L.

[0141] To achieve these different ranges in the LiDAR system 604, the light source controller will vary the energy levels of the laser light pulses and pulse sets (including ranging and emission control pulse sets) to compensate for the optical spread of the expansion optics and the different desired ranges. It is worth noting that in some embodiments, significant and / or non-uniform optical spread may be provided in one or both axes. In these embodiments, any energy changes to compensate for optical spread will only occur in the axis with significant optical spread.

[0142] Now turn to Fig. 7A and Figure 7B , side and top views of an exemplary scanning laser device 700 are shown. The scanning laser device 700 is an example of a device type that can be implemented using the above-described emission control techniques (e.g., methods 300, 350, 360). Therefore, the scanning laser device 700 can be implemented to selectively emit a relatively low-energy emission control pulse set for detection when there is an object (e.g., a person) within a relatively close safety range, and then conditionally emit a long-range ranging pulse set only when the object is not detected within the safety range, thereby improving eye safety. And according to embodiments described herein, these emission control pulse sets are emitted with variable timing (e.g., a variable time period or delay between emission control pulse sets) and / or variable energy (e.g., a further reduced energy level) based in part on the detection of an object within the safety range.

[0143] In one embodiment, scanning laser device 700 is a light LiDAR system for object detection and / or 3D map generation. Scanning laser device 700 includes laser light source 702 and optical assembly 704. Optical assembly 704 is an example of the type of optical assembly that can be used for LiDAR or other scanning laser devices (e.g., scanning laser device 100) according to embodiments described herein. Thus, optical assembly 704 includes various optical elements for facilitating scanning. It should be noted that Fig. 7A and Figure 7B are simplified examples and therefore do not show all elements or features of a fully implemented scanning laser device or optical assembly.

[0144] Fig. 7AThe optical assembly 704 shown in the figure includes a beam shaping optical device 714, a first prism 716, a first scanning mirror assembly 717, a first scanning mirror 718, an expansion optical device including three expansion lenses 720, 722, and 724, a second prism 726, a second scanning mirror assembly 727, and a second scanning mirror 728.

[0145] During operation of scanning laser device 700, laser light source 702 generates laser light pulses that are scanned into a scanning trajectory by optical assembly 704. For example, laser light source 702 may include one or more infrared (IR) lasers driven by field effect transistors (FETs) to generate IR laser light pulses.

[0146] Typically, pulses from multiple IR laser light sources are first combined and shaped by beam shaping optics 714 and associated optical elements. Thus, beam shaping optics 714 may include any optical device for changing the beam shape of laser light pulses. For example, beam shaping optics 714 may include collimating lenses, polarization combiners, pairs of anamorphic prisms for improved divergence, and other such elements. In one embodiment, a pick-up beam splitter or prism 703 is implemented within beam shaping optics 714 to direct reflections to a detector configured for relatively short range pulse detection ( Fig. 7A and Figure 7B not shown).

[0147] The output of the beam shaping optics 714 is passed to a first prism 716 which launches the beam upward to a first scanning mirror 718. In the illustrated embodiment, the first scanning mirror 718 provides a horizontal scanning motion, while the second scanning mirror 728 provides a vertical scanning motion. Furthermore, in this example, the first scanning mirror 718 is driven to provide a scanning motion at a relatively slow scanning rate, while the second scanning mirror 728 is driven to provide a motion at a relatively slow scanning rate. However, these are merely examples, and other embodiments are possible. In summary, the scanning mirror motion causes the laser light pulses to be scanned into a scanning trajectory. Again, it should be noted that the labels "vertical" and "horizontal" used herein are somewhat arbitrary, as a 90 degree rotation of the scanning laser device will effectively switch the horizontal and vertical axes.

[0148] The output of the first scanning mirror 718 is passed to three expansion lenses 720, 722, 724, which together provide expansion optics. Typically, the expansion optics are implemented to provide expansion of the scan field in the horizontal direction.

[0149] Specifically, in this illustrated example, three expansion lenses 720, 722, 724 are implemented to image the output of the first scanning mirror 718 onto the second scanning mirror 728 while providing non-uniform expansion in the horizontal direction. As a specific example, the first scanning mirror 718 can be implemented to provide a scanning angle of 40 degrees in the horizontal direction, and the expansion lenses 720, 722, 724 can be implemented to provide non-uniform expansion to expand the scanning angle to 110 degrees.

[0150] In one specific example, three expander lenses 720, 722, 724 implement a 4F optical system that images the output of the first scanning mirror 718 onto the second scanning mirror 728. Specifically, the three expander lenses 720, 722, 724 provide a 4F optical system whose magnification varies with the angle from the first scanning mirror 718. The result of the three expander lenses 720, 722, 724 is a non-uniform variation in the optical expansion of the outgoing scanning angle provided by the first scanning mirror 718. The second prism 726 receives the output of the third expander lens 724 and directs the beam to the second scanning mirror 728.

[0151] Now go to Figure 8 , a scanning light detection and ranging (LiDAR) system 800 is shown according to various embodiments. The system 800 includes a pulse generation circuit 890, an infrared (IR) laser light source 830, a scanning mirror assembly 814 with a scanning mirror 816, and a mirror drive and control circuit 854. The system 800 also includes a first infrared (IR) detector 842, a first time of flight (TOF) measurement circuit 844, a 3D point cloud storage circuit 886, a first comparator 848, and a transmission control circuit 880. The system 800 also includes a second IR detector 1842, a second TOF measurement circuit 1844, and a second comparator 1848. As will be described in more detail below, the second IR detector 1842 can be implemented to provide redundant relatively short range detection.

[0152] LiDAR system 800 is another example of a type of scanning laser device that can be implemented according to embodiments described herein (e.g., methods 300, 350, 360). In this example, the emission control circuit 880 and the pulse generation circuit 890 are used as all or part of the light source controller, thereby controlling the laser light source 830 to selectively emit a relatively low-energy emission control pulse set for detection when there is an object (e.g., a person) within a relatively close safety range. Then, a long-range ranging pulse set is conditionally emitted only when an object is not detected within the safety range, thereby improving eye safety. And according to embodiments described herein, these emission control pulse sets are emitted with variable timing (e.g., a variable time period or delay between emission control pulse sets) and / or variable energy (e.g., a further reduced energy level) based in part on the detection of an object within the safety range.

[0153] The laser light source 830 can be a laser light source such as a laser diode, etc., which is capable of emitting a laser beam pulse 862. The beam pulse 862 strikes the scanning mirror assembly 814, which in some embodiments is part of a scanner based on a micro-electromechanical system (MEMS), etc., and is reflected from the scanning mirror 816 to generate a controlled output beam pulse 834. In some embodiments, an optical element is included in the optical path between the laser light source 830 and the mirror 816. For example, the system 800 can include a collimating lens, a dichroic mirror, an expansion optical device, or any other suitable optical element. And as described above, during operation of the system 800, the scanning mirror, the expansion optical device, and other elements can cause the reflection of the laser light pulse toward the second IR detector 1842.

[0154] The scanning mirror drive and control circuit 854 provides one or more drive signals 855 to control the angular movement of the scanning mirror 816 so that the output beam pulse 134 passes through the scanning track 840 in the scanning field 828. In operation, the laser light source 830 generates modulated light pulses in the invisible spectrum, and when the beam pulse 834 passes through the scanning track 840, the scanning mirror 816 reflects the light pulses.

[0155] In some embodiments, the scanning trajectory 840 is formed by a combination of a sawtooth component on the horizontal axis and a sinusoidal component on the vertical axis. In further embodiments, the horizontal scan is also sinusoidal. Various embodiments of the present invention are not limited by the waveforms used to control the vertical and horizontal scans or the resulting scanning trajectory patterns. One axis (e.g., horizontal) is a slow scan axis and the other axis is a fast scan axis.

[0156] Although scanning mirror 816 is illustrated as a single mirror that scans along two axes, this is not a limitation of the present invention. For example, in some embodiments, mirror 816 is implemented as two separate scanning mirrors, one scanning in one axis and the second scanning in the second axis.

[0157] In some embodiments, the scanning mirror 816 includes one or more sensors to detect the angular position or degree of angular deflection of the mirror (in one or two dimensions). For example, in some embodiments, the scanning mirror assembly 814 includes a piezoresistive sensor that transmits a voltage proportional to the deflection of the mirror on the fast scan axis. In addition, in some embodiments, the scanning mirror assembly 814 includes an additional piezoresistive sensor that transmits a voltage proportional to the deflection of the mirror on the slow scan axis. The mirror position information is provided back to the mirror drive and control circuit 854 as one or more SYNC signals 815. In these embodiments, the mirror drive and control circuit 854 includes one or more feedback loops to modify the drive signal in response to the measured angular deflection of the mirror. In addition, in some embodiments, the mirror drive and control circuit 854 includes one or more phase-locked loop circuits that estimate the instantaneous angular position of the scanning mirror based on the SYNC signal.

[0158] The mirror drive and control circuit 854 can be implemented using functional circuits, such as a phase-locked loop (PLL), a filter, an adder, a multiplier, a register, a processor, a memory, etc. Therefore, the mirror drive and control circuit 854 can be implemented in hardware, software, or any combination. For example, in some embodiments, the control circuit 854 is implemented in an application specific integrated circuit (ASIC). In addition, in some embodiments, some faster data path control is performed in the ASIC, and the overall control is software programmable.

[0159] The system 800 includes two separate IR detectors, a TOF measurement circuit, and a comparator for detecting IR laser pulses. Specifically, the system 800 includes a first IR detector 842 and a second IR detector 1842. Typically, the first IR detector 842 is implemented to detect reflections from both a transmit control (e.g., relatively short range) and a ranging pulse set (e.g., relatively long range), while the second IR detector provides redundant detection of reflections from a low-power transmit control pulse set to provide increased eye safety.

[0160] The first IR detector 842 includes one or more photosensitive devices capable of detecting reflections of an IR laser light pulse. For example, the first IR detector 842 may include one or more PIN photodiodes, silicon photomultipliers (SiPMs), avalanche photodiodes (APDs), etc. Each point in the field of view that is illuminated by an IR laser light pulse (referred to herein as a "measurement point") may or may not reflect a certain amount of incident light back to the first IR detector 842. If the first IR detector 842 detects a reflection, the IR detector 842 provides a signal 843 to the first TOF measurement circuit 844.

[0161] The first TOF measurement circuit 844 measures the time of flight (TOF) of the IR laser light pulses to determine the distance to an object in the field of view. In some embodiments, the emission control circuit 880 provides a timing signal (not shown) corresponding to the emission time of a particular IR laser light pulse to the first TOF measurement circuit 844, and the first TOF measurement circuit 844 measures the TOF of the IR laser light pulse by determining the elapsed time between the emission of the pulse and the receipt of a reflection of the same pulse.

[0162] The first TOF measurement circuit 844 can be implemented using any suitable circuit. For example, in some embodiments, the first TOF measurement circuit 844 includes an analog integrator that is reset when the IR pulse is started and stopped when the reflected pulse is received. The first TOF measurement circuit 844 can also include an analog-to-digital converter to convert the analog integrator output to a digital value corresponding to the time of flight (TOF) of the IR laser pulse, which in turn corresponds to the distance between the system 800 and the object in the field of view reflected by the laser light pulse.

[0163] The 3D point cloud storage device 846 receives X, Y data from the mirror drive and control circuit 854, and receives the distance (Z) data on the node 845 from the first TOF measurement circuit 844. For each detected reflection, a triplet (X, Y, Z) is written to the 3D point cloud storage device, thereby generating a series of 3D points, referred to herein as a "point cloud". Not every X, Y measurement point in the field of view has a corresponding Z measurement. Therefore, the resulting point cloud may be sparse or dense. The amount of data contained in the 3D point cloud is not a limitation of the present invention.

[0164] The 3D point cloud storage device 846 can be implemented using any suitable circuit structure. For example, in some embodiments, the 3D point cloud storage device 846 is implemented in a dual-port memory device that can write on one port and read on a second port. In other embodiments, the 3D point cloud storage device 846 is implemented as a data structure in a general-purpose memory device. In further embodiments, the 3D point cloud storage device 846 is implemented in an application-specific integrated circuit (ASIC).

[0165] The first comparator 848 compares the distance data (Z) on node 845 to a threshold value, and if the distance is less than the threshold value, the first comparator 848 asserts a safe range object detection signal on the input of an OR gate 882. The safe range object detection signal is passed to the transmit control circuit 880 through the OR gate 882 to indicate that an object has been detected within a "safe range", where the "safe range" is determined by the value of the threshold value on node 847. For example, if the threshold value is set to a value corresponding to a distance of five meters, and the detected distance is below the threshold value, an object less than five meters has been detected, and the transmit control circuit 880 will be notified via the safe range object detection signal on node 884.

[0166] The threshold value and corresponding safety range distance at node 847 may be modified by the transmit control circuit 880 based on any criteria. For example, the threshold value may be a function of IR laser pulse power, pulse duration, pulse density, wavelength, scanner speed, required laser safety level, etc. The manner in which the threshold value is determined is not a limitation of the present invention.

[0167] The second IR detector 1842, the second TOF measurement circuit 1844, and the second comparator 1848 operate to provide a redundant detection capability for reflections of the emission control pulse set from objects within the safety range. The redundant detection of the emission control pulse set provides an additional safety measure. For example, if one of the IR detector, the TOF measurement circuit, or the comparator fails, the redundancy will ensure continued safe operation.

[0168] It is noteworthy that the first IR detector 842 and the second IR detector 1842 receive the reflected light pulses through different optical paths. Specifically, the first IR detector 842 receives the reflected light along a separate path shown at 835, while the second IR detector 1842 shares at least a portion of the optical path with the transmitted light pulse. Specifically, the reflected light from the scan field is reflected back by at least some of the mirror 816, the expansion optical device, and other elements in the optical assembly to reach the second IR detector 1842 along path 1835.

[0169] The second TOF measurement circuit 1844 measures the time of flight (TOF) of the IR laser light pulses to determine the distance to objects within the field of view in a similar manner as the first TOF measurement circuit 844. Thus, the second TOF measurement circuit 1844 may be implemented using any suitable circuitry, as may the first TOF measurement circuit 844.

[0170] Likewise, the second comparator 1848 compares the distance data (Z) on node 845 to a threshold value, and if the distance is less than the threshold value, the second comparator 1848 asserts a safe range object detection signal on the input of the OR gate 882. Again, this safe range object detection signal is passed to the transmit control circuit 880 via the OR gate 882 to indicate that an object has been detected within a relatively short "safe range," where the "safe range" is determined by the value of the threshold value on node 1847. For example, if the threshold value is set to a value corresponding to a distance of five meters and the detected distance is below the threshold value, the transmit control circuit 880 will be notified via the safe range object detection signal on node 884.

[0171] Again, the threshold at node 1847 and the corresponding safety range distance can be modified by the transmit control circuit 880 based on any criteria. For example, the threshold can be a function of IR laser pulse power, pulse duration, pulse density, wavelength, scanner speed, required laser safety level, etc.

[0172] In some embodiments, both the detection and TOF measurement circuits are used to detect short-range objects (e.g., objects within a safe range), and only one of the detection and TOF measurement circuits is used to measure long-range distances and / or write to a 3D cloud storage device. Figure 8 In the illustrated embodiment, the flight time measured by TOF measurement circuit 1844 or TOF measurement circuit 1844 may be used to detect objects within a safe range using a set of transmit control pulses, but only the flight time measured by TOF measurement circuit 844 is used to populate the 3D point cloud.

[0173] The transmit control circuit 880 operates in a manner that manages the accessible transmit level to allow the overall operation to remain eye-safe. For example, in some embodiments, the transmit control circuit 880 controls whether to generate a short-range transmit control pulse set or a long-range ranging pulse set by setting a pulse set energy value on node 885. The transmitted pulse set energy can be controlled by one or more of pulse power, pulse duration, or pulse count. The transmit control circuit 880 can also control the timing of the transmit pulses via a timing signal on node 857. For example, the transmit control circuit can control the timing and energy of the transmit control pulse set and the ranging pulse set. And according to the embodiments described herein, these transmit control pulse sets are transmitted with variable timing (e.g., variable time periods or delays between transmit control pulse sets) and / or variable energy (e.g., further reduced energy levels) based in part on the detection of objects within the safe range.

[0174] The transmit control circuit 880 may be implemented using any suitable circuit structure. For example, in some embodiments, the transmit control circuit 880 may include one or more finite state machines implemented using digital logic to respond to object detection within the safety range and conditionally signal the pulse generation circuit 890 to transmit a long-range pulse set. In addition, in some embodiments, the transmit control circuit 880 may include a processor and memory to provide software programmability of transmit control and ranging pulse set energy, thresholds, etc. The manner in which the transmit control circuit 880 is implemented is not a limitation of the present invention.

[0175] Now go to Fig. 9 , shows a scanning light detection and ranging (LiDAR) system 1300 according to various embodiments. The LiDAR system 1300 includes a transmission control circuit 1384, a pulse generation circuit 1390, a 3D point cloud storage device 1346, an OR gate 1380, and a control circuit 1354. The LiDAR system 1300 also includes a transmission module 1310, a receiving module 1330, a TOF and short range detection circuit 1340, and a TOF and short range detection circuit 1350.

[0176] LiDAR system 1300 is another example of a type of scanning laser device that can be implemented according to embodiments described herein (e.g., methods 300, 350, 360). In this example, emission control circuit 1384, pulse generation circuit 1390 acts as a light source controller, and specifically controls transmission module 1310 to selectively emit a relatively low energy emission control pulse set for detection when there is an object (e.g., a person) within a relatively close safety range. Then, a higher energy long-range pulse set is conditionally emitted only when an object is not detected within the safety range, thereby improving eye safety. And according to embodiments described herein, these emission control pulse sets are emitted with variable timing (e.g., a variable time period or delay between emission control pulse sets) and / or variable energy (e.g., a further reduced energy level) based in part on the detection of an object within the safety range.

[0177] The LiDAR system 1300 includes two independent IR detectors and TOF and short range detection circuits for detecting reflections of IR laser pulses. Specifically, the receiving module 1330 includes a first IR detector implemented to detect reflections from both a short range pulse set (e.g., a transmit control pulse set) and a long range pulse set (e.g., a ranging pulse), while the transmitting module 1310 includes a second IR detector that provides redundant detection of reflections from a relatively low energy short range transmit control pulse set to provide increased eye safety.

[0178] The transmission module 1310 includes an IR laser light source to generate a pulsed laser beam, collimation and focusing optics, and one or more scanning mirror assemblies, which are implemented together in an optical assembly to scan the pulsed laser beam in two dimensions in the field of view. The transmission module 1310 also includes an IR laser light detector that shares an optical path with the emitted IR laser light pulses. Example embodiments of the transmission module will be described more fully below with reference to the following drawings.

[0179] The receiving module 1330 includes optics and one or more scanning mirror assemblies to scan in two dimensions to direct light reflected from the field of view to an included IR light detector. Example embodiments of the receiving module are described more fully below with reference to the following figures.

[0180] Each of the TOF and short range detection circuits 1340 and 1350 includes a TOF measurement circuit and a comparator. For example, the TOF and short range detection circuit 1340 may include a TOF circuit 1844 and a second comparator 1848, while the TOF and short range detection circuit 1350 may include a TOF measurement circuit 844 and a comparator 848 ( Figure 8 ).

[0181] The control circuit 1354 controls the movement of the scanning mirror in the transmitting module 1310, as described above with reference to Figure 8 The control circuit 1354 also controls the movement of the scanning mirror within the receiving module 1330. In operation, the control circuit 1354 receives mirror position feedback information (not shown) from the transmitting module 1310 and also receives mirror position feedback information (not shown) from the receiving module 1330. The mirror position feedback information is used to phase lock the operation of the mirror.

[0182] The control circuit 1354 drives a microelectromechanical (MEMS) assembly with a scanning mirror within the transmit module 1310 with a drive signal 1345, and also drives a MEMS assembly with a scanning mirror within the receive module 1330 with a drive signal 1347, which moves the mirror through an angular degree of mirror deflection that defines the size and position of the scan trajectory 1342 and the scan field 1328. The synchronization of the transmit and receive scans allows the receive aperture to accept photons only from the portion of the field of view where the transmit energy is transmitted. This results in significant ambient light noise immunity.

[0183] The emission control circuit 1384 and the pulse generation circuit 1390 control the timing and energy of the pulses emitted by the transmission module 1310. For example, the pulse generation circuit 1390 may include a laser light source controller configured to change the energy level of the laser light pulses emitted by the transmission module 1310. Therefore, the emission control circuit 1384 may be implemented to control the timing and energy of the emitted emission control pulse set and the ranging pulse set to implement the above-mentioned emission control methods 300, 350 and 360.

[0184] Now go to Fig. 10A and Fig. 10B , Fig. 10A A side view of the transmitting module 1400 is shown and Fig. 10B A top view of a transmitting module 1400 is shown. Transmitting module 1400 is an example of a transmitting module that can be used in a LiDAR system (e.g., Fig. 9 1400). Thus, transmit module 1400 is another example of a device type that can be implemented using the above-described emission control techniques (e.g., methods 300, 350, 360). Transmit module 1400 includes a laser light source 1410, a beam shaping optical device 1420, a receive energy pick-up device 1460, a mirror 1462, a beam shaping device 1464, an IR detector 1466, a scanner 1428, and an exit optical device 1450.

[0185] In some embodiments, the laser light source 1410 source generates non-visible light, such as infrared (IR) light. In these embodiments, the IR detector 1466 detects the same wavelength of non-visible light as the IR detector in the receiving module 1600 (FIG. 11, discussed below). For example, in some embodiments, the laser light source 1410 may include a laser diode that generates infrared light having a wavelength of approximately 905 nanometers (nm), and the IR detector 1466 detects reflected light pulses having a wavelength of approximately 905 nm. Also, for example, in some embodiments, the laser light source 1410 may include a laser diode that generates infrared light having a wavelength of approximately 940 nanometers (nm), and the IR detector 1466 detects reflected light pulses having a wavelength of approximately 940 nm. The wavelength of light is not a limitation of the present invention. Any wavelength, visible or invisible, may be used without departing from the scope of the present invention.

[0186] Laser light source 1410 may include any number or type of emitters suitable for generating a pulsed laser beam. For example, in some embodiments, laser light source 1410 includes Fig. 10B1514, 1516, and 1518 are shown in FIG. The pulsed laser light generated by the laser light source 1410 is combined, collimated, and focused by the beam shaping optical device 1420 to generate a pulsed laser beam. For example, the optical devices 1522, 1524, 1526, and 1528 can collimate the laser beam on the fast axis, the polarization rotator 1523 and the beam combiner 1520 can combine the laser beam, and the optical device 1522 can fan the pulsed laser beam on the slow axis. The beam size and divergence are not necessarily uniform in various embodiments of the present invention; some embodiments have higher values, while some embodiments have lower values.

[0187] Scanner 1428 receives the pulsed laser beam from optical device 1420 and scans the pulsed beam in two dimensions. Fig. 10A and 10B In the illustrated embodiment, the scanner 1428 includes two independent scanning mirror assemblies 1430, 1440, each assembly including scanning mirrors 1432, 1442, wherein each scanning mirror scans the beam in one dimension. For example, scanning mirror 1432 scans the pulsed beam in a fast scanning direction, while scanning mirror 1442 scans the pulsed beam in a slow scanning direction.

[0188] Although scanner 1428 is shown to include two scanning mirror assemblies, each of which scans in a separate dimension, this is not a limitation of the present invention. For example, in some embodiments, scanner 1428 is implemented using a single dual-axis scanning mirror assembly that scans in two dimensions. In some embodiments, the scanning device is implemented using an electromagnetic drive, using a small subassembly including a MEMS chip and a permanent magnet, and a micro-assembly of an electrical interface, but various embodiments are not limited in this regard.

[0189] The exit optics 1450 operates the scanned pulsed laser beam as it leaves the transmission module. In some embodiments, the exit optics 1450 performs field expansion. For example, the scanner 1428 can scan an angular extent of up to 20 degrees on the fast scan axis and can scan an angular extent of up to 40 degrees on the slow scan axis, and the exit optics 1450 can expand the field of view to 30 degrees on the fast scan axis and 120 degrees on the slow scan axis. The relationship between the scanning angle of the scanning mirror and the amount of field expansion provided by the exit optics 1450 is not a limitation of the present invention.

[0190] The received energy pick-up device 1460 deflects the received light (shown as a dashed line) that shares at least a portion of the transmitted light path with the transmitted light pulse (shown as a solid line). The deflected received light is then reflected by the mirror 1462, focused by the optical device 1064, and detected by the IR detector 1466. In some embodiments, the pick-up device 1460 includes a "window" that transmits the pulsed beam generated by the IR laser light source, and reflects the outer portion to deflect the received energy outside the window. In other embodiments, the pick-up device 1460 is a partial reflector that transmits a portion of the incident light and reflects the rest. For example, a reflector that transmits 90% of the incident light and reflects 10% of the incident light will provide the IR detector 1466 with 10% of the light reflected from the object in the field of view. In further embodiments, the pick-up device 1460 may include a polarization beam splitter that transmits a pulsed laser beam (in a first polarization) and picks up received light of a different polarization. This is effective to some extent because the reflection is randomly polarized due to Lambertian reflection. In further embodiments, the outgoing laser beam and the received energy may be directed to different portions of the scanning mirror, and the pickup device 1460 may be an offset mirror positioned to reflect one but not the other.

[0191] Again, in order to facilitate reliable detection of low energy emission control pulse sets, the IR detector 1466 can be implemented with multiple sensors that are configured to receive reflections through at least some of the same optical components used to send laser light pulses into the scanning field. Specifically, the IR detector 1466 can be configured to receive laser light pulses through the same scanning mirrors 1432, 1142, exit optical devices 1450 and other optical elements used to send laser light pulses into the scanning field. Since the same optical components are used by multiple sensors to receive laser reflections, any damage or obstruction that prevents multiple sensors from receiving reflections from the emission control pulse set may also prevent the laser light pulse from scanning into the scanning field. Therefore, the IR detector 1466 can more reliably detect objects that have hit the safe range of the scanning field and reflected back toward the emission control pulse set of the detector, and can therefore be used to reliably determine when it is safe to emit a long range pulse set. In addition, the multiple sensors in the IR detector 1466 are configured to at least partially eliminate the effects of back reflections within the optical components. Eliminating the effects of back reflections within the optical assembly can improve the sensitivity of the detector, especially for detecting low energy emissions within the scan field to control reflections.

[0192] As described above, the transmission module 1400 can be implemented using a laser light source controller that is configured to change the energy level of a set of laser light pulses according to the position along the first axis of the scanning field. The change in the energy level of the set of laser light pulses is performed to provide the required effective range of the sensor while at least partially compensating for the effects of the non-uniform optical expansion provided by the expansion optical device. For example, in one embodiment, the light source controller is configured to change the energy in a manner proportional to the non-uniform change in optical expansion. Therefore, laser light pulses that are subjected to greater optical expansion generate laser pulses with greater energy levels. In addition, the laser light source controller can be configured to change the energy to achieve different effective ranges for different scanning areas of the scanning field.

[0193] Now go to Fig.11A and Fig. 11B , Fig.11A A side view of the receiving module 1600 is shown and Fig. 11B 1 shows a top view of a receiving module 1600. The receiving module 1600 is an example of a receiving module that can be used in a LiDAR system (e.g., Fig. 9 Receive module 1600 is another example of a device type that can be implemented using the above-described emission control techniques (e.g., methods 300, 350, 360). Receive module 1600 includes IR detector 1610, folding mirror 1612, imaging optics 1620, bandpass filter 1622, scanner 1628, and exit optics 1650.

[0194] Scanning mirror assemblies 1630 and 1640 are similar or identical to scanning mirror assemblies 1430 and 1440, and exit optics 1650 are similar or identical to exit optics 1450. Bandpass filter 1422 passes wavelengths of light generated by laser light source 1410 and blocks ambient light of other wavelengths. For example, in some embodiments, the laser light source generates 905 nm light, and bandpass filter 1622 passes 905 nm light.

[0195] Imaging optics 1620 images a portion of the field of view onto IR detector 1610 after reflection from fold mirror 1612. Since scanner 1628 scans synchronously with scanner 1428, detector 1610 always collects light from the measurement point illuminated by the scanning pulse beam.

[0196] Fig.12 1800 shows a perspective view of an integrated photon module according to various embodiments of the present invention. The integrated photon module 1800 includes a transmitting module 1400 ( Fig. 10A and Fig. 10B ) and receiving module 1600 ( Fig.11A and Fig. 11B) Both. The integrated photonic module 1800 is shown to have a rectangular housing in which the transmitting module 1400 and the receiving module 1600 are placed side by side. In some embodiments, the transmitting module 1400 and the receiving module 1600 are placed one on top of the other.

[0197] In the previous detailed description, reference is made to the accompanying drawings, which show by way of example specific embodiments in which the present invention can be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention. It should be understood that the various embodiments of the present invention, although different, are not necessarily mutually exclusive. For example, a specific feature, structure or characteristic associated with one embodiment herein may be implemented in other embodiments without departing from the scope of the present invention. In addition, it should be understood that the position or arrangement of the various elements in each disclosed embodiment may be modified without departing from the scope of the present invention. Therefore, the previous detailed description should not be considered restrictive, and the scope of the present invention is defined only by the appended claims, appropriate interpretations, and the full range of equivalents that the claims have. In the accompanying drawings, the same reference numerals represent the same or similar functions in several views.

[0198] Although the present invention has been described in conjunction with certain embodiments, it should be understood that those skilled in the art can easily understand that modifications and variations can be made without departing from the scope of the present invention. Such modifications and variations are considered to be within the scope of the present invention and the appended claims.

Claims

1. A device comprising: a laser light source configured to generate laser light pulses; an optical assembly comprising beam scanning optics to scan the laser light pulses into a scan field; a detector that detects reflections of the laser light pulses from within the scanning field; as well as a light source controller coupled to the laser light source and the detector, the light source controller being adapted to control the laser light source: transmitting a first set of emission control pulses at a reduced first energy level; In response to not detecting an object within a safe range using reflections of the first set of transmit control pulses, transmitting a set of ranging pulses at a higher energy level, wherein the higher energy level is greater than the reduced first energy level; In response to not detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting a second set of transmit control pulses after a first time period following the first set of transmit control pulses and at a second, reduced energy level; and In response to detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting an adjusted second set of transmit control pulses, wherein the adjusted second set of transmit control pulses includes at least one of an extended first time period following the first set of transmit control pulses and a further reduced second energy level relative to the reduced second energy level.

2. The device according to claim 1, wherein The light source controller is further adapted to control the laser light source: in response to no object being detected within the safety range using reflections of the second transmit control pulse set or the adjusted second transmit control pulse set, transmitting a third transmit control pulse set, wherein the third transmit control pulse set includes a second time period subsequent to the second transmit control pulse set or the adjusted second transmit control pulse set and a reduced third energy level; and In response to detecting an object within the safety range using reflections of the second emission control pulse set or the adjusted second emission control pulse set, an adjusted third emission control pulse set is emitted, wherein the adjusted third emission control pulse set includes at least one of an extended second time period following the second emission control pulse set or the adjusted second emission control pulse set and a further reduced third energy level relative to the reduced third energy level.

3. The device according to claim 1, wherein The light source controller is further adapted to control the laser light source: In response to detecting an object within the safety range using reflections of the adjusted second set of transmit control pulses, a plurality of adjusted sets of transmit control pulses are transmitted, wherein each of the plurality of adjusted sets of transmit control pulses includes at least one of an extended first time period following the first set of transmit control pulses and a further reduced second energy level relative to the reduced second energy level.

4. The device according to claim 3, wherein For each of the plurality of adjusted transmit control pulse sets, the further reduced second energy level relative value is dynamically adjusted.

5. The device according to claim 1, wherein The light source controller is further adapted to control the laser light source: In response to detecting an object within the safety range using reflections of the ranging pulse set, transmitting the adjusted second set of transmit control pulses, wherein the adjusted second set of transmit control pulses includes at least one of an extended first time period following the first set of transmit control pulses and a further reduced second energy level relative to the reduced second energy level.

6. The device according to claim 1, wherein By adapting to: dynamically determining the extended first time period so that the first set of transmit control pulses and the adjusted second set of transmit control pulses have a combined energy below an energy limit for a set of pulses within a defined time frame, The light source controller is adapted to control the laser light source to emit the adjusted second emission control pulse set.

7. The device according to claim 6, wherein The energy limits are regulatory classification limits.

8. The device according to claim 1, wherein By adapting to: dynamically determining the further reduced second energy level relative to the reduced second energy level such that the first set of transmit control pulses and the adjusted second set of transmit control pulses have a combined energy below an energy limit for a set of pulses within a defined time frame, The light source controller is adapted to control the laser light source to emit the adjusted second emission control pulse set.

9. The device according to claim 1, wherein The apparatus also includes time-of-flight (TOF) circuitry responsive to the detector to determine a distance to a depth measurement point in the scan field from the detected reflection.

10. The device according to claim 1, wherein The ranging pulse set includes a plurality of pulses modulated with a signature.

11. A device comprising: a laser light source configured to generate laser light pulses; an optical assembly comprising beam scanning optics to scan the laser light pulses into a scan field; a detector that detects reflections of the laser light pulses from within the scanning field; time-of-flight (TOF) circuitry responsive to the detector to determine a distance to a depth measurement point in the scan field from the detected reflection; a light source controller coupled to the laser light source and the TOF circuit system, the light source controller being adapted to control the laser light source: emitting a first set of emission control pulses at a reduced first energy level; In response to not detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting a set of ranging pulses at a higher energy level, wherein the higher energy level is greater than the lowered first energy level; responsive to not detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting a second set of transmit control pulses after a first time period following the first set of transmit control pulses and at a second, reduced energy level; In response to detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting an adjusted second set of transmit control pulses, wherein the adjusted second set of transmit control pulses includes an extended first time period subsequent to the first set of transmit control pulses and a second energy level further reduced relative to the reduced second energy level; in response to no object being detected within the safety range using reflections of the second transmit control pulse set or the adjusted second transmit control pulse set, transmitting a third transmit control pulse set, wherein the third transmit control pulse set includes a second time period subsequent to the second transmit control pulse set or the adjusted second transmit control pulse set and a reduced third energy level; and In response to detecting an object within the safety range using reflections of the second emission control pulse set or the adjusted second emission control pulse set, an adjusted third emission control pulse set is emitted, wherein the adjusted third emission control pulse set includes an extended second time period following the second emission control pulse set or the adjusted second emission control pulse set and a further reduced third energy level relative to the reduced third energy level.

12. A transmission control method, wherein: The method comprises: transmitting a first set of emission control pulses at a reduced first energy level; In response to not detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting a set of ranging pulses at a higher energy level, wherein the higher energy level is greater than the lowered first energy level; In response to not detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting a second set of transmit control pulses after a first time period following the first set of transmit control pulses and at a second, reduced energy level; and In response to detecting an object within the safety range using reflections of the first set of transmit control pulses, transmitting an adjusted second set of transmit control pulses, wherein the adjusted second set of transmit control pulses includes at least one of an extended first time period following the first set of transmit control pulses and a further reduced second energy level relative to the reduced second energy level.

13. The method according to claim 12, further comprising: in response to no object being detected within the safety range using reflections of the second transmit control pulse set or the adjusted second transmit control pulse set, transmitting a third transmit control pulse set, wherein the third transmit control pulse set includes a second time period subsequent to the second transmit control pulse set or the adjusted second transmit control pulse set and a reduced third energy level; and In response to detecting an object within the safety range using reflections of the second emission control pulse set or the adjusted second emission control pulse set, an adjusted third emission control pulse set is emitted, wherein the adjusted third emission control pulse set includes at least one of an extended second time period following the second emission control pulse set or the adjusted second emission control pulse set and a further reduced third energy level relative to the reduced third energy level.

14. The method according to claim 12, further comprising: In response to detecting an object within the safety range using reflections of the adjusted second set of transmit control pulses, a plurality of adjusted sets of transmit control pulses are transmitted, wherein each of the plurality of adjusted sets of transmit control pulses includes at least one of an extended first time period following the first set of transmit control pulses and a further reduced second energy level relative to the reduced second energy level.

15. The method according to claim 12, further comprising: In response to detecting an object within the safety range using reflections of the ranging pulse set, transmitting the adjusted second set of transmit control pulses, wherein the adjusted second set of transmit control pulses includes at least one of an extended first time period following the first set of transmit control pulses and a further reduced second energy level relative to the reduced second energy level.

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