Apparatus and method for safe operation of pulsed lasers

Abstract

An apparatus can include an energy rate limiter, an electro-optical transmitter, and an energy monitor. The energy rate limiter limits energy transfer from a power source to an energy storage module based on an energy control signal. The energy storage module is charged based on the energy transfer from the power source. The electro-optical transmitter includes a laser coupled to the local energy storage module. Laser emission of the laser is based on a potential of the energy storage module and a laser enable signal corresponding to the laser. The energy monitor is coupled to the energy storage module and triggers a safety alert signal if a voltage provided by the energy storage module violates a safety condition related to a threshold voltage. The energy rate limiter terminates energy transfer from the power source to the local energy storage module after the safety condition is violated.

Description

[0001] Cross-reference to related applications This application claims priority and interest in U.S. Provisional Patent Application Serial No. 62 / 884,102, entitled “Apparatus and Methods for Optical Power Control for Eye Safe Pulsed Laser Operation”, filed on August 7, 2019 (Agency File No. VLI-032PR), which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure generally relates to apparatus and methods for protecting health during operation of pulsed lasers, and more specifically to apparatus and methods for improving eye safety during both expected and unexpected operating conditions of optical systems such as LiDAR (light detection and ranging) systems. Background Technology

[0003] LiDAR (Light Detection and Ranging) systems measure properties of the environment surrounding a target (e.g., the target's shape, outline, distance to the target, etc.) by illuminating the target with a pulsed laser and using sensors to measure the reflected pulses. The difference between the laser's return time and wavelength can then be used to generate a digital 3D representation of the surrounding environment. LiDAR technology can be used in a variety of applications, including autonomous vehicles, advanced driver assistance systems, mapping, security, surveying, robotics, geology and soil science, agriculture, and unmanned aerial vehicles. Depending on the application and the associated field of view, multi-channel or laser beams can be used to produce images of the desired resolution. LiDAR systems with a greater number of channels can produce a greater number of pixels.

[0004] In a multi-channel LiDAR device, optical transmitters are paired with optical receivers to form multiple “channels.” During operation, the transmitter of each channel emits an optical signal (e.g., a laser) into the device’s environment and detects portions of the signal reflected back to the channel’s receiver from the surrounding environment. In this way, each channel provides a “point” measurement of the environment, which can be aggregated with point measurements from other channels to form a “point cloud” of environmental measurements.

[0005] Measurements collected by the LiDAR channel can be used to determine the distance (“range”) from the device to a surface in the environment that reflects the channel’s emitted optical signal back to the channel’s receiver, and the reflectivity of that surface. The range to the surface can be determined based on the time of flight of the channel’s signal (e.g., the time elapsed from the transmitter emitting the optical signal to the receiver receiving the returned signal reflected by the surface). The reflectivity of the surface can be determined based on the intensity of the returned signal, which typically depends not only on the surface’s reflectivity but also on the range to the surface, the grazing angle of the emitted signal relative to the surface, the power level of the channel’s transmitter, the alignment of the channel’s transmitter and receiver, and other factors.

[0006] "Laser safety" generally refers to the safe design, use, and implementation of lasers to reduce the risk of laser accidents, especially those involving eye damage. "Laser" is an acronym for stimulated emission of light through radiation. The energy produced by lasers is in or near the optical portion of the electromagnetic spectrum. Even relatively small amounts of laser light can cause permanent eye damage. Medium and high-power lasers are potentially dangerous because they can burn the retina or cornea of ​​the eye, or even the skin. The coherence and low divergence angle of lasers (with the help of the eye's lens focusing) cause laser radiation to be concentrated to a very small point on the retina. Sufficiently strong lasers in the visible to near-infrared range (400-1400 nm) can penetrate the eyeball and cause the retina to heat up. In some embodiments, LiDAR systems can operate at a wavelength of 905 nm. Summary of the Invention

[0007] According to one aspect of this disclosure, an apparatus may include a power limiter, an electro-optical emitter, and an energy monitor. The power limiter restricts energy transfer from a power source to an energy storage module based on an energy control signal. The energy storage module is charged based on energy transfer from the power source. The electro-optical emitter includes a laser coupled to the local energy storage module. Laser emission from the laser is based on the potential of the energy storage module and a corresponding laser enable signal. The energy monitor is coupled to the energy storage module and triggers a safety alarm signal if the voltage supplied by the energy storage module violates a safety condition associated with a threshold voltage. After the safety condition is violated, the power limiter terminates energy transfer from the power source to the local energy storage module.

[0008] The foregoing and other preferred features, including various novel details encompassing combinations of implementations and events, will now be described in more detail with reference to the accompanying drawings and pointed out in the claims. It should be understood that the specific systems and methods described herein are shown by way of illustration only and not as limitations. As will be understood by those skilled in the art, the principles and features described herein may be employed in various and numerous embodiments without departing from any scope of the invention. As can be understood from the foregoing and hereinafter description, every and all features described herein, as well as every and all combinations of two or more such features, are included within the scope of this disclosure, provided that the features included in such combinations are not contradictory. Furthermore, any feature or combination of features may be specifically excluded from any embodiment of the invention.

[0009] The foregoing description of the invention is intended to help the reader understand this disclosure and does not limit the scope of any of the claims in any way. Attached Figure Description

[0010] The accompanying drawings, which are included as part of this specification, illustrate presently preferred embodiments and, together with the general description given above and the detailed description of preferred embodiments given below, serve to explain and teach the principles described herein.

[0011] Figure 1 This is a diagram illustrating the operation of an example of a LiDAR system.

[0012] Figure 2A This is another illustration of the operation of an example of a LiDAR system.

[0013] Figure 2B This is an illustration of an example of a LiDAR system with an oscillating mirror.

[0014] Figure 3 This is a block diagram of a transmitter optical subassembly (TOSA) according to some embodiments.

[0015] Figure 4 This is a circuit diagram of a transmitter optical subassembly (TOSA) according to some embodiments.

[0016] Figure 5A This is a flowchart of a method for providing fault-tolerant optical energy limiting according to some embodiments.

[0017] Figure 5B This is a flowchart of another method for providing fault-tolerant optical energy limitation according to some embodiments.

[0018] Figure 6 This is a block diagram of a computing device / information processing system according to some embodiments.

[0019] While this disclosure may have various modifications and alternatives, specific embodiments thereof have been illustrated by way of example in the accompanying drawings and will be described in detail herein. This disclosure should be understood as not being limited to the specific forms disclosed, but rather, the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure. Detailed Implementation

[0020] Apparatus and methods for the safe operation of pulsed laser devices are disclosed. It should be understood that, for the sake of simplicity and clarity, reference numerals may be repeated in the drawings to indicate corresponding or similar elements where deemed appropriate. Furthermore, numerous specific details are set forth to provide a thorough understanding of the exemplary embodiments described herein. However, those skilled in the art will understand that the exemplary embodiments described herein can be practiced without these specific details.

[0021] the term Measurement results, dimensions, quantities, etc., may be presented in range format herein. This range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention. Therefore, a range description should be considered as specifically disclosing all possible sub-ranges and individual values ​​within that range. For example, a range such as 10-20 inches should be considered as specifically disclosing sub-ranges such as 10-11 inches, 10-12 inches, 10-13 inches, 10-14 inches, 11-12 inches, 11-13 inches, etc.

[0022] Furthermore, the connections between the components or systems shown in the accompanying drawings are not intended to be limited to direct connections. Instead, data or signals between these components may be modified, reformatted, or otherwise altered by intermediate components. Additionally, additional or fewer connections may be used. The terms “coupled,” “connected,” or “communically coupled” should be understood to include direct connections, indirect connections via one or more intermediate devices, and wireless connections.

[0023] References to "one embodiment," "preferred embodiment," "embodiment," "some embodiments," or "multiple embodiments" in the specification mean that a particular feature, structure, characteristic, or function described in connection with an embodiment is included in at least one embodiment of the invention, and may be included in more than one embodiment. Furthermore, the appearance of these phrases in various places in the specification does not necessarily refer to the same one or more embodiments.

[0024] The use of certain terms in various places in the specification is for illustrative purposes and should not be construed as limiting. A service, function, or resource is not limited to a single service, function, or resource; the use of these terms may refer to a group of related services, functions, or resources that can be distributed or aggregated.

[0025] In addition, those skilled in the art should recognize that: (1) certain steps may be performed optionally; (2) the steps may not be limited to the specific order set forth herein; (3) certain steps may be performed in a different order; and (4) certain steps may be performed simultaneously.

[0026] The terms “about,” “about equal to,” and other similar phrases (e.g., “X has a value of about Y” or “X is about equal to Y”) used in the specification and claims shall be understood to indicate that a value (X) is within a predetermined range of another value (Y). Unless otherwise specified, the predetermined range may be positive or negative 20%, 10%, 5%, 3%, 1%, 0.1%, or less than 0.1%.

[0027] Unless explicitly indicated to the contrary, the indefinite articles “a” and “an” used in the specification and claims should be understood to mean “at least one”. The phrase “and / or” used in the specification and claims should be understood to mean “any one or two” of the elements so combined, i.e., elements that exist in combination in some cases and separately in others. Multiple elements listed with “and / or” should be interpreted in the same way, i.e., “one or more” of the elements so combined. In addition to the elements specifically indicated by the “and / or” clause, other elements may optionally exist, whether related to or unrelated to those specifically indicated. Thus, as a non-limiting example, a reference to “A and / or B” used in conjunction with open-ended language such as “comprising” may, in one embodiment, refer only to A (optionally including elements other than B); in another embodiment, refer only to B (optionally including elements other than A); in yet another embodiment, refer to both A and B (optionally including other elements); and so on.

[0028] As used in the specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” should be interpreted as inclusive, i.e., including multiple elements or at least one of the elements in the list, but also including more than one, and optionally, additional unlisted items. Only terms that explicitly indicate the opposite (e.g., “only one” or “exactly one”, or, when used in a claim, “consisting of”) will refer to multiple elements or exactly one of the elements in the list. Generally, when preceded by an exclusive term (e.g., “any,” “one of,” “only one,” or “exactly one”), the term “or” should be interpreted only as indicating an exclusive alternative (i.e., “one or the other, but not both”). “Substantially consisting of”, when used in a claim, should have its ordinary meaning as used in the field of patent law.

[0029] As used in the specification and claims, the phrase "at least one" relating to a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the list, but not necessarily including at least one of every and all elements specifically listed in the list, and does not exclude any combination of elements in the list. This definition also allows for the optional presence of elements other than those specifically indicated in the list referred to by the phrase "at least one," whether related to or unrelated to those specifically indicated elements. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B," or equivalently, "at least one of A and / or B") in one embodiment may refer to at least one (optionally including more than one) A, where B is absent (and optionally includes elements other than B); in another embodiment, it refers to at least one (optionally including more than one) B, where A is absent (and optionally includes elements other than A); in yet another embodiment, it refers to at least one (optionally including more than one) A and at least one (optionally including more than one) B (and optionally includes other elements); and so on.

[0030] The use of “includes,” “contains,” “has,” “includes,” “involves,” and their variations implies that the items listed after it and any additional items are included.

[0031] The use of ordinal numbers such as "first," "second," and "third" to modify elements in a claim does not imply that one claim element has any priority, order, or sequence relative to another, or a temporal order of actions of the method. Ordinal terms are used only as labels to distinguish one claim element with a specific name from another element with the same name (but using ordinal terms), thus differentiating claim elements.

[0032] Motivation and benefits of some embodiments In laser-operated environments, the safety of tissues and organs of living organisms (e.g., human eye safety and / or skin safety) depends on laser operating parameters. These operating parameters may include, but are not limited to, the wavelength of the laser beam, the optical power of the laser beam, and the duration of tissue or organ exposure to the laser beam. Limitations on these operating parameters can affect the performance and / or design characteristics of the laser (e.g., emission rate, density, range).

[0033] Therefore, there is a need for laser devices that meet prescribed eye safety standards under both expected and unexpected operating conditions, while also providing acceptable performance under expected operating conditions. In some cases, the light energy emission of a laser device may be higher during unexpected operating conditions, such as failure conditions, than during normal, expected (e.g., failure-free) operation. Some embodiments of the apparatuses and methods described herein favor high (e.g., maximum) light energy emission during expected operating conditions, while simultaneously limiting (e.g., minimizing) light energy emission during unexpected operating conditions.

[0034] LiDAR system Light detection and ranging (“LiDAR”) systems can be used to measure the shape and contours of the environment surrounding the system. LiDAR systems can be applied to many applications, including autonomous navigation of surfaces and aerial mapping. Typically, a LiDAR system emits light pulses, which are then reflected by objects within the environment in which the system operates. The time from emission to reception of each pulse (i.e., time of flight, “TOF”) can be measured to determine the distance between the LiDAR system and the object reflecting the pulse. The science of LiDAR systems is based on the physical properties of light and optical devices.

[0035] In a LiDAR system, light is emitted from a fast-emitting laser. The laser travels through a medium and is reflected from a point on a surface in the environment (e.g., the surface of a building, tree branch, vehicle, etc.). The energy of the reflected light returns to the LiDAR detector, where it can be recorded and used to map the environment.

[0036] Figure 1 The operation of a LiDAR system 100 according to some embodiments is depicted. Figure 1 In this example, LiDAR system 100 includes a LiDAR device 102, which may include a transmitter 104 for transmitting emitted light signals 110, a receiver 106 including a detector, and a control and data acquisition module 108. The LiDAR device 102 may be referred to as a LiDAR transceiver. In operation, the emitted light signal 110 propagates through a medium and is reflected from an object 112, thereby returning a light signal 114 that propagates through the medium and is received by the receiver 106.

[0037] The control and data acquisition module 108 can control the light emission from the transmitter 104 and can record data derived from the returned optical signal 114 detected by the receiver 106. In some embodiments, the control and data acquisition module 108 controls the power level at which the transmitter operates while emitting light. For example, the transmitter 104 can be configured to operate at multiple different power levels, and the control and data acquisition module 108 can select the power level at which the transmitter 104 operates at any given time. Any suitable technique can be used to control the power level at which the transmitter 104 operates. In some embodiments, the control and data acquisition module 108 determines (e.g., measures) the characteristics of the returned optical signal 114 detected by the receiver 106. For example, the control and data acquisition module 108 can use any suitable technique to measure the intensity of the returned optical signal 114.

[0038] A LiDAR transceiver may include one or more optical lenses and / or mirrors (not shown). Transmitter 104 may emit a laser beam with multiple pulses having a specific sequence. Design elements of receiver 106 may include its horizontal field of view (hereinafter, "FOV") and its vertical FOV. Those skilled in the art will recognize that the FOV parameter effectively defines the visible area associated with a particular LiDAR transceiver. More generally, the horizontal and vertical FOVs of a LiDAR system may be defined by a single LiDAR device (e.g., a sensor), or may involve multiple configurable sensors (which may be exclusive LiDAR sensors or may have different types of sensors). FOV can be considered as the scanning area for a LiDAR system. Scanning FOV can be obtained using scanning mirrors or rotating components.

[0039] The LiDAR system may also include a data analysis and interpretation module 109, which can receive output from the control and data acquisition module 108 via connection 116 and perform data analysis functions. Connection 116 can be implemented using wireless or contactless communication technology.

[0040] Figure 2A The illustration depicts the operation of a LiDAR system 202 according to some embodiments. Figure 2A In the example, two reflected light signals 203 and 205 are shown. Laser beams typically tend to diverge as they pass through a medium. Due to this beam divergence, a single laser emission often hits multiple objects, resulting in multiple reflected signals. The LiDAR system 202 can analyze multiple reflected signals and report one of them (e.g., the strongest reflected signal, the last reflected signal, etc.) or more than one of them (e.g., all of them). Figure 2AIn the example, LiDAR system 202 emits laser light in directions toward the near wall 204 and the far wall 208. As shown, most of the beam hits the near wall 204 at region 206, producing a return signal 203, while another portion of the beam hits the far wall 208 at region 210, producing a return signal 205. Return signal 203 can have a shorter time-of-flight (TOF) and a stronger received signal strength compared to return signal 205. In both single-return and multi-return LiDAR systems, it is important that each return signal is accurately correlated with the emitted light signal in order to calculate an accurate TOF.

[0041] Some embodiments of LiDAR systems can capture distance data in a two-dimensional (“2D”) (e.g., single-plane) point cloud manner. These LiDAR systems can be used in industrial applications or can be repurposed for surveying, mapping, autonomous navigation, and other uses. Some embodiments of these systems rely on the use of a single laser emitter / detector pair combined with a moving mirror to achieve scanning across at least one plane. The mirror can reflect emitted light from the emitter (e.g., a diode) and / or reflect returned light to the receiver (e.g., a detector). Using a wobbling mirror in this way allows the LiDAR system to achieve an azimuth (horizontal) view of 90–180–360 degrees, while simultaneously simplifying both system design and manufacturability. Many applications require more data than just a single 2D plane. The 2D point cloud can be expanded to form a three-dimensional (“3D”) point cloud, where multiple 2D clouds are used, each pointing at a different elevation (vertical) angle. Design elements of the receiver for LiDAR system 202 may include a horizontal FOV and a vertical FOV.

[0042] Figure 2B A LiDAR system 250 with a wobbling mirror according to some embodiments is depicted. Figure 2B In the example, LiDAR system 250 uses a single laser emitter / detector combined with a wobbling mirror 256 to efficiently scan across a plane. The distance measurements obtained by such a system can be effectively two-dimensional (e.g., planar), and the captured distance points can be rendered as a 2D (e.g., single-plane) point cloud. In some embodiments, but not limited to, the wobbling mirror 256 can wobble at a very high speed (e.g., thousands of cycles per minute).

[0043] The LiDAR system 250 may include a laser electronics 252, which may include a single light emitter and a photodetector. The emitted laser signal 251 may be directed to a fixed mirror 254, which may reflect the emitted laser signal 251 to a wobbling mirror 256. As the wobbling mirror 256 "wobbles," the emitted laser signal 251 may be reflected off the object 258 in its propagation path. The reflected signal 253 may be coupled to a detector in the laser electronics 252 via the wobbling mirror 256 and the fixed mirror 254. Design elements of the receiver in the LiDAR system 250 include a horizontal field of view (FOV) and a vertical field of view (FOV), which define the scanning area.

[0044] Eye safety in laser environments Eye damage is a major concern for those who use or operate around laser beams. The extent of eye damage from laser beam exposure depends on the portion of the eye exposed and the exposure parameters (e.g., the wavelength of the laser beam, the power or pulse energy of the laser beam, the duration of exposure, etc.). These factors can be used to determine the maximum permissible exposure, or MPE. The MPE is the safe biological limit. It can be considered as the level of laser radiation that a person can be exposed to without adverse biological changes in the eyes or skin.

[0045] Laser safety encompasses the safe design, use, and implementation of lasers to reduce (e.g., minimize) the risk of laser accidents, particularly those involving eye injury. Lasers are potentially dangerous because they can burn the retina of the eye or even the skin. Therefore, the sale and operation of laser devices are strictly regulated by government regulations (such as Section 21 of the US and international standard IEC 60825, Federal Regulation (CFR) Part 1040). These regulations define laser classifications based on their power and wavelength, as well as the longest reasonably foreseeable exposure duration. More specifically, the objectives of IEC 60825 include: 1) classifying lasers and laser devices that emit radiation in the range of 180 nm to 1 mm based on the degree of optical radiation hazard posed by the lasers and laser devices to aid in hazard assessment and determination of user control measures; 2) establishing requirements for laser device manufacturers to provide information so that appropriate preventative measures can be taken; 3) providing adequate warnings to individuals with laser device hazards through labeling and instructions; and 4) reducing the likelihood of injury by reducing (e.g., minimizing) unnecessary accessible radiation and by providing improved control over laser radiation hazards through protective features associated with accessible radiation from laser devices.

[0046] Laser devices can be classified based on a combination of one or more output powers and one or more wavelengths of available emission (laser radiation) across the entire range of their capabilities during any operational period after manufacturing, resulting in their assignment to the highest appropriate category. This assessment may include consideration of any reasonably foreseeable single-failure conditions during operation. A laser device can be assigned to a specific category when it meets all the requirements within that category, such as engineering controls, marking requirements, and the provision of relevant information to the user.

[0047] Each laser used in a LiDAR system is typically referred to as a "laser designator" and is classified as either FDA Class IIIa or IEC Class 3R. Within these categories, depending on power and beam area, a laser designator may be temporarily dangerous when viewed directly with the naked eye or when the beam is directly observed. The risk of damage increases when viewed with optical instruments.

[0048] IEC 60825 also includes considerations for repetitive pulsed lasers used in systems such as LiDAR. Exposure to any group of pulses (or subgroups of pulse trains) delivered at any given time should not exceed the Maximum Permissible Exposure (MPE) specification. IEC 60825 contains specific MPE provisions for eye exposure at wavelengths less than 400 nm and greater than 1400 nm, as well as MPE provisions for skin exposure. Additionally, IEC 60825 includes different specific MPE provisions for eye exposure at wavelengths from 400 nm to 1400 nm, including retinal thermal limitations.

[0049] The eye can absorb more light energy with shorter pulse widths than with longer pulse widths, but longer pulse widths can generate more heat. Generally, the energy level increases with increasing pulse width. Both the FDA and IEC specify the joules per second that laser pointers (e.g., LiDAR emitters) can transmit during continuous emission.

[0050] Laser absorption and its effects on various parts of the eye are wavelength-dependent. For example, wavelengths in the ultraviolet range (approximately 180 to 400 nm) can cause damage to the cornea and lens, but generally do not penetrate to the retina. Visible light (approximately 400 to 700 nm) can be transmitted through the cornea and lens and focused onto the retina. Light in the near-infrared range (approximately 700 to 1400 nm) can also reach the retina and has the potential to cause damage. Finally, light in the mid-infrared and far-infrared ranges (approximately 1400 nm to one million nanometers or one millimeter) can be absorbed by the cornea and lens and converted into heat, which can potentially cause damage.

[0051] In some embodiments, the laser in a LiDAR system operates in the near-infrared range, for example, at a wavelength of approximately 905 nm. Because this wavelength is close to that of visible light (red light begins around 780 nm), excessive laser activity in the near-infrared range can cause eye damage to the sensitive light-detecting cells on the retina. Therefore, as previously mentioned, the power levels of 905 nm lasers in the United States and other jurisdictions are strictly regulated by government regulations.

[0052] In some other embodiments, the laser of the LiDAR system can operate at approximately 1550 nm, outside the visible light range. The interior of the eye is transparent to 905 nm light, so a LiDAR system at that wavelength can reach the vulnerable retina. The eye is opaque to 1550 nm light, preventing the wavelength from reaching the retina, thus allowing the use of higher-powered LiDAR without endangering the retina. However, as mentioned above, the generation of heat in the cornea and lens may pose safety concerns.

[0053] There is typically a trade-off between laser safety (in practice or as defined by applicable government regulations) and laser flexibility. Key factors can include 1) the laser's emission speed (e.g., pulse rate, transmission frequency, etc.); 2) the density of the laser device design (e.g., physical density, channel spacing, spot diameter, optical power density, etc.); and 3) the laser's emission range. These factors can all increase the complexity of multiple LiDAR systems.

[0054] Transmitter Optical Subassembly (TOSA) Laser devices are expected to operate in a way that meets prescribed eye safety standards under both expected and unexpected operating conditions. In some cases, the light energy emission of a laser device may be higher during unexpected operating conditions, such as failure conditions, than during normal, expected (e.g., failure-free) operation. Some embodiments of the apparatuses and methods described herein favor high (e.g., maximum) light energy emission during expected operating conditions while simultaneously limiting (e.g., minimizing) light energy emission during unexpected operating conditions.

[0055] According to one aspect of this disclosure, the amount of energy that can be supplied to a laser diode under one or more single-point-of-failure criteria can be precisely limited. A “single-point-of-failure criterion” refers to a failure condition that results in one failure at a time. Such a criterion can be defined by applicable regulations and / or standards (e.g., FDA, IEC).

[0056] The electro-optical efficiency of a laser diode is the ratio of the light energy emitted to the electrical energy dissipated. The electro-optical efficiency of a laser diode can be determined by simultaneous measurements of both light and electrical energy. Within empirical statistical constraints: 1) the electro-optical efficiency of a laser diode can be constant or decrease during its operating lifetime; and 2) the electro-optical efficiency of a laser diode does not increase during its lifetime. Therefore, after verifying the electro-optical efficiency E0 at the initial start of laser diode operation, the maximum light energy emission of the laser diode during its operating lifetime can be estimated based on the measurement of the laser diode's electrical energy dissipation and the initial electro-optical efficiency E0, without the need for simultaneous light energy measurements. Similarly, after verifying the electro-optical efficiency E0 at any time t... P The electro-optic efficiency E of the laser diode operation P Subsequently, based on the measured power dissipation of the laser diode and the previous electro-optical efficiency E of the laser diode, P To estimate the remaining operating lifetime of the laser diode (t > t) P Maximum light energy emission without the need for simultaneous light energy measurement.

[0057] Figure 3 A functional block diagram of a transmitter optical subassembly (TOSA) 300 according to some embodiments is depicted. Figure 3 In this example, the TOSA 300 includes a power limiter 302, an electro-optic modulator 303, and a local energy monitor 306. The electro-optic modulator 303 may also include a local energy storage device 305. In some embodiments, the TOSA 300 allows one or more laser diodes to operate safely within defined safety thresholds.

[0058] exist Figure 1 In this example, power supply V1 is configured to provide electrical power to one or more components of the TOSA 300 via power limiter 302. Specifically, power supply V1 can be configured to provide electrical power to internal node 304 of electro-optic modulator 303. The electrical power supplied to internal node 304 can be used to charge the energy storage components of local energy storage device 305. Power supply V1 can be internal or external to the TOSA 300. Any suitable type of power supply V1 can be used.

[0059] The power limiter 302 can control (e.g., limit) the rate of electrical power transfer from power source V1 (e.g., from the positive terminal of power source V1) to one or more components of TOSA 300 (e.g., to internal node 304 of electro-optic modulator 303). In this way, the power limiter 302 can control the charging of energy storage components (e.g., capacitors, inductors, batteries, etc.) of the local energy storage device 305. In some cases, the power limiter 302 transfers electrical energy from power source V1 to internal node 304 at an appropriate rate and for an appropriate duration to charge the energy storage components of the local energy storage device 305 to the power supply voltage V1 or any other suitable voltage.

[0060] The operation of the power limiter 302 can be controlled by the power control signal 316. Based on the power control signal 316, the power limiter 302 can operate in a "connected state" or a "disconnected state". In the "disconnected state", the power limiter 302 can disconnect the power supply V1 from the electro-optic modulator 303, so that no electrical energy is transferred from the power supply V1 to the electro-optic modulator 303 via the power limiter 302. In the "connected state", the power limiter 302 can connect the power supply V1 to the electro-optic modulator 303, so that electrical energy is transferred from the power supply V1 to the electro-optic modulator 303 via the power limiter 302. In some embodiments, the power limiter 302 operates in the connected state based on (e.g., in response to) the power control signal 316 having a specific value (e.g., a voltage greater than a specific threshold TV1, or a voltage less than a specific threshold TV2). Similarly, in some embodiments, the power limiter 302 operates in the off state based on (e.g., in response to) an energy control signal 316 having a specific value (e.g., a voltage less than a specific threshold TV1, or a voltage greater than a specific threshold TV2).

[0061] When the power limiter 302 is in the connected state, the amount or rate of energy transferred from the power supply V1 to the electro-optic modulator 303 through the power limiter 302 can vary based on the energy control signal 316. For example, the amount or rate of energy transferred through the power limiter 302 can be a function of the voltage of the power supply V1, the voltage of the energy control signal 316, and the threshold voltage TV.

[0062] The electro-optic modulator 303 may have one or more lasers (e.g., "n" lasers). Any suitable number of lasers can be used, such as 1-64 lasers, 8 lasers, etc. In some embodiments, each laser is implemented using a laser diode. In some embodiments, each laser control signal (318-320) enables current to flow through the corresponding laser diode, thereby causing the electro-optic modulator to emit the corresponding laser signal (L1 to Ln). Similarly, in some embodiments, each of the laser control signals 318-320 can prevent current from flowing through the corresponding laser diode, thereby causing the electro-optic modulator to terminate the emission of the corresponding laser signal (L1 to Ln).

[0063] In some embodiments, the local energy monitor 306 monitors the voltage of internal node 304 and compares the monitored voltage with an input safety threshold signal 322 to generate an output safety alarm signal 308. Monitoring the voltage of internal node 304 may involve measuring the voltage of internal node 304. Monitoring and / or comparison may be performed continuously, persistently, periodically, intermittently, or in response to a control signal. In some embodiments, the local energy monitor 306 asserts (e.g., enables) the safety alarm signal 308 in response to determining that the voltage of internal node 304 violates a safety condition. The safety condition may relate to the relationship between the voltage of internal node 304 and a safety threshold voltage. For example, a safety condition may be violated if the voltage of internal node 304 exceeds the safety threshold voltage 322 or if the voltage of internal node 304 is below the safety threshold voltage 322. After the safety alarm signal is asserted, the safety alarm signal 308 may remain asserted until any appropriate safety criterion is met (e.g., until a reset signal is received, until the voltage of the internal node meets the safety condition, etc.).

[0064] In some embodiments, the local energy monitor 306 provides a safety alarm signal 308 to the power limiter 302 as an energy control signal 316. In some embodiments, the energy control signal 316 is generated (e.g., asserted and / or deasserted) based on the safety alarm signal 308. Optionally, the energy control signal 316 may also be generated based on one or more other signals. The energy control signal 316 may be generated by any suitable component, including (but not limited to) the local energy monitor 306, another component of the TOSA 300, or a control device 350 external to the TOSA 300 (e.g., a programmable processing device or digital logic circuit). In some embodiments, the component generating the energy control signal 316 may assert (e.g., enable) the energy control signal 316 when the safety alarm signal 308 (and optionally, one or more other signals) indicates that one or more conditions for safely stimulating (e.g., charging) the local energy storage device 305 are met (e.g., when no single point of failure criterion is met). In some embodiments, when a safety alarm signal 308 (and optionally, one or more other signals) indicates that one or more conditions for safely activating the local energy storage device 305 are not met (e.g., when a set of single-point-of-failure criteria are met), the component generating the energy control signal 316 can deassert (e.g., disable) the energy control signal 316. Similarly, in some embodiments, when a safety alarm signal 308 (and optionally, one or more other signals) indicates that one or more conditions for safely operating the laser are not met, the component generating the laser control signal (e.g., signals 318-320) can deassert the laser control signal. When the energy control signal 316 is deassertified (disabled), the power limiter 302 can change from a connected state to a disconnected state to prevent the power limiter 302 from supplying additional energy from the power source V1 to the local energy storage device 305.

[0065] In some embodiments, the internal node 304 may be coupled (e.g., conductive coupling, direct connection, etc.) to the output of the power limiter 302 and the input of the local energy monitor 306 via the electro-optic modulator 303. In some embodiments, the terminals (e.g., the anodes) of the laser diode of the electro-optic modulator may also be coupled to the internal node 304.

[0066] Still referencing Figure 3During the intended operation of the laser diodes of the electro-optic modulator 303, the power dissipation and therefore light emission of each laser diode can be determined by the amount and duration of the current flowing through the laser diode, which can be controlled by (1) the corresponding laser control signals (318-320) and (2) the voltage at the terminals of the laser diode (e.g., the voltage at the anode of the laser diode, which is the voltage of the internal node 304). The duration of the light pulse emitted by the laser diode can be determined by the duration of the current flowing through the laser diode. The light pulse power can be determined based on the light pulse duration and the amount of current flowing through the laser diode during the light pulse, which depends on the voltage at the terminals (e.g., the anode) of the laser diode (e.g., the voltage of the internal node 304) and the internal circuitry of the electro-optic modulator 303 during the light pulse.

[0067] During unexpected operation of the laser diode, the internal circuitry of the local energy monitor 306 or the laser control signals 318-320 may malfunction. Similarly, the internal circuitry of the power limiter 302 or the electro-optic modulator 303 may also malfunction. However, when a single component fails, the TOSA 300 can limit the light energy emitted by the electro-optic modulator 303. More specifically, in the event of such a malfunction, the local energy storage device 305 can limit the amount of energy supplied to the laser of the electro-optic modulator 303. That is, if a malfunction exists in the TOSA 300, the voltage at the internal node 304 may violate one or more safety conditions (e.g., may rise above a safety threshold), thereby asserting (enabling) the safety alarm signal 308. In response to the assertion of the safety alarm signal 308, the energy control signal 316 can be deasserted, causing the power limiter 302 to restrict the transfer of energy from the power supply V1 to the local energy storage device 305. In some embodiments, when the energy control signal 316 is deasserted, the amount of energy transferred from the power supply V1 to the local energy storage device 305 is less than or equal to a threshold amount (e.g., 0 kWh or 10 μJ). In some embodiments, when the energy control signal 316 is deasserted, the rate at which energy is transferred from the power supply V1 to the local energy storage device 305 is less than or equal to a threshold rate (e.g., 0 W). Therefore, after the energy control signal 316 is deasserted, the operation (emission) of the laser can be limited to the remaining energy stored in the local energy storage device 305. The capacity of the energy storage component in the local energy storage device 305 can be selected such that even if the energy storage component is fully charged when the energy control signal 316 is deasserted, the remaining energy can be consumed after a few (e.g., 1-10) laser emissions. After a safety alarm signal is asserted, the TOSA 300 or the controller 350 can disable the assertion of the energy control signal 316 until specified conditions are met (e.g., the TOSA is power-cycled, a service procedure is executed, etc.).

[0068] Figure 4 Circuitry for implementing a transmitter optical subassembly (TOSA) 400 according to some embodiments is depicted. Figure 4 In the example, the TOSA 400 includes a power supply V1, a power limiter 410, an electro-optic modulator 412, and a local energy monitor 414. These components of the TOSA 400 will be described in further detail below.

[0069] Power supply V1 can have both positive and negative voltage terminals. Figure 4 In the example, the positive terminal of power supply V1 is coupled to resistor R1 of power limiter 410.

[0070] The power limiter 410 may include a resistor R1, an inductor (e.g., an inductive ferrite) L1, and an electrical switch SC1 for limiting the rate of power transfer from the positive power supply terminal to the internal node 403. In some embodiments, the electrical switch SC1 selectively connects the internal node 404 to the internal node 403 based on a charging signal 416. Terminals of one or more lasers of the electro-optic modulator 412 (e.g., the anodes of one or more laser diodes) may be coupled (e.g., conductive coupling, direct connection, etc.) to the internal node 404. The charging signal 416 may be provided by a control device 450 external to the TOSA 400 (e.g., a programmable processing device or digital logic circuitry).

[0071] The electro-optic modulator 412 may include one or more laser diodes DL1 to DLn, each laser diode having an anode terminal and a cathode terminal. Each laser diode can be selectively excited by conducting current from its anode to its cathode. Figure 4 In the example, the anodes of laser diodes DL1 to DLn are coupled to internal node 404, which is coupled to internal node 403 via electrical switch SC1. During normal (e.g., fault-free) operation, switch SC1 can be closed for a sufficient period of time so that the voltage measured at internal node 404 is equivalent to (e.g., substantially equal to) the voltage measured at internal node 403 before switch SC1 is opened, thereby isolating power supply V1 from the laser circuitry.

[0072] The electro-optic modulator 412 may also include one or more electrical switches SDL1 to SDLn for connecting corresponding terminals (e.g., cathodes) of one or more laser diodes DL1 to DLn to one or more reference terminals (e.g., negative voltage terminals of power supply V1). Each of the electrical switches SDL1 to SDLn can be configured (e.g., controlled) by a corresponding enable signal (e.g., signals 418-420). The laser enable signal may be provided by one or more components external to TOSA 400 (e.g., control device 450). Each electrical switch SDL1 to SDLn can operate in a manner substantially similar to a “dimmer” in the sense that a variable current can be conducted through each switch (SDL1-SDLn) based on the corresponding enable signal 418-420. In some embodiments, the amount of current flowing through the electrical switch (SDL1-SDLn) and thus through the laser diode (DL1-DLn) corresponding to that switch can be controlled by rapidly turning the switch on and off. In some embodiments, the switching speed of each of the electrical switches SDL1 to SDLn may be approximately one billionth of a second or faster. In some embodiments, the amount of current flowing through the electrical switches (SDL1-SDLn) and thus through the laser diodes (DL1-DLn) corresponding to those switches may depend at least in part on the duty cycle of the enable signals (418-420) controlling the switches. In some embodiments, each enable signal may control not only the duration of the period during which the corresponding electrical switch (SDL) conducts current, but also the resistance of the switch during current conduction.

[0073] A local energy storage mechanism is provided within the electro-optic modulator 412. The local energy storage mechanism may include one or more energy storage components (e.g., capacitors, batteries, etc.) C1 to Cn. One terminal of each energy storage component may be connected (e.g., conductive coupling, direct connection, etc.) via internal node 404 to one or more terminals (e.g., anodes) of lasers DL1-DLn, and another terminal of each energy storage component may be connected to a reference terminal (e.g., the negative voltage terminal of power supply V1).

[0074] The local energy monitor 414 may include a filter (e.g., a low-pass filter) that provides a filtered measurement of the voltage measured at internal node 404, which in many scenarios is actually the voltage of internal node 403. The filter may include a resistor RLPF1 and a capacitor CLPF1. The voltage measured at internal node 404 may be the voltage across the energy storage components (C1-Cn) of the electro-optic modulator 412. Figure 4In the example, voltage comparator circuit U1 406 compares the filtered voltage at internal node 404 with a voltage threshold (e.g., a safety threshold voltage 422) and provides the comparison result as a safety alarm signal 408. The voltage threshold 422 can be provided by a component external to TOSA 400 (e.g., control device 450). Figure 4 In the example, the voltage threshold 422 and the filtered voltage of the internal node 404 are provided to the positive and negative terminals of comparator U1, respectively. Therefore, in Figure 4 In the example, when the filtered voltage of internal node 404 exceeds the voltage threshold 422, the polarity of the safety alarm signal 408 can be negative.

[0075] Still referencing Figure 4 During the intended operation of the laser diodes (DL1 to DLn), the energy dissipation and therefore light emission of the laser diodes are controlled by (1) enable signals 418 to 420 that control the duration and resistance of the conduction current of switches SDL1 to SDLn, and (2) the voltage across the terminals of the laser diodes (e.g., the voltage at the anode of the laser diode coupled to internal node 404). The duration of the light pulse emitted by the laser diode (DL) can be determined by the switch contact duration (the duration of the corresponding period of conduction current of switch SDL), and the power of the light pulse is controlled by the magnitude of the current conducted through the laser diode (DL), which is determined by the resistance of the corresponding switch SDL and the anode voltage of the laser diode. During the unintended operation of the laser diodes, one of the switches SDL1 to SDLn or control signals 418-420 may fail. The TOSA 400 provides a mechanism to limit the amount of light energy emitted by the laser diode in the event of a single component failure. For example, when a safety alarm signal 408 (and optionally, one or more other signals) indicates that one or more conditions for safely energizing the local storage capacitors (C1 to Cn) are not met (e.g., when a set of single-point-of-failure criteria are met), the control device 450 may deassert the charging signal 416 (e.g., disable it). Similarly, in some embodiments, when a safety alarm signal 408 (and optionally, one or more other signals) indicates that one or more conditions for safely operating the laser are not met, the control device 450 may deassert the laser control signals (e.g., signals 418-420).

[0076] In some embodiments, n equals 8, so the electro-optic modulator 412 has 8 laser diodes (DL1-DLn) and 8 energy storage components (C1-Cn). Such embodiments can provide 8 operating channels for a LiDAR system. Other embodiments can provide other combinations of laser diodes, energy storage components, and channels. Some other embodiments may include 1-64 channels, 16 channels, 32 channels, 64 channels, etc.

[0077] To enhance (e.g., maximize) performance, the TOSA 400 may have a common feed that provides efficient connectivity between the power limiter 410, the electro-optic modulator 412, and the local energy monitor 414. In some embodiments, an internal node 404 provides direct connectivity between these components, including interfaces to energy storage components C1 to Cn and laser diodes DL1 to DLn. This means that the power limiter 410, the electro-optic modulator 412, and the local energy monitor 414 share a common feed, namely internal node 404. This common feed extends to internal node 403 when switch SC1 is activated.

[0078] Furthermore, in some embodiments, energy storage components (e.g., capacitors) C1 to Cn are physically positioned sequentially between corresponding laser diodes DL1 to DLn. For shorter pulses, positioning energy storage components (e.g., capacitors) C1 to Cn near corresponding laser diodes DL1 to DLn can reduce (e.g., minimize) the time delay and impedance of the current from a given energy storage element (e.g., capacitor) to the corresponding laser diode.

[0079] Those skilled in the art will recognize that the polarity of the circuit elements in the TOSA 400 can be "flipped" without substantially affecting the function. Moreover, the order of components R1, L1, and SC1 in the TOSA 400 has no substantial impact on the function of the TOSA 400.

[0080] An example has been described where the front end of the TOSA is implemented using a voltage source V1 connected in series with the power limiter 302. (See example...) Figure 4 As shown, the power limiter 410 can be implemented as a circuit with a resistor R1, an inductor L1, and an electrical switch SC1, which limits the rate (or amount) of electrical power transfer from the power supply V1 to the internal node 404, which is the input terminal of the electro-optic modulators (303, 412). Other implementations of the TOSA front end are possible.

[0081] Figure 5A A method 500A for providing fault-tolerant optical energy limiting according to some embodiments of the present disclosure is illustrated graphically. Method 500A may include processing blocks 501-509, some embodiments of which are described below.

[0082] In block 501, a controller (e.g., control device 350 or 450) sets the values ​​of one or more laser control signals (e.g., signals 318-320 or 418-420) to a disabled state to disable one or more lasers (e.g., the laser of electro-optic modulator 303 or 412). Disabling a laser can stop the laser from emitting and / or prevent the laser from initiating the emission of a new pulse while the laser remains in the disabled state.

[0083] In block 503, a controller (e.g., control device 350 or 450) sets the value of an energy control signal (e.g., 316 or 416) to an enabled state (or "connected" state) to enable power supply to charge local energy storage components (e.g., local energy storage device 305, capacitors C1-Cn, etc.). The energy control signal can remain enabled for any appropriate duration (e.g., during a predetermined period of time expected to be sufficient to charge the local energy storage device to a specific potential; before the local energy storage device reaches a predetermined potential; etc.).

[0084] In block 505, the controller (e.g., control device 350 or 450) sets the value of one or more of the laser control signals to an enabled state, allowing current to pass through one or more corresponding lasers. Allowing current to pass through the lasers results in laser emission.

[0085] In block 507, a controller (e.g., control device 350 or 450) sets the value of one or more laser control signals to a disabled state to disable the corresponding laser. Disabling a laser can cause the laser to stop emitting and / or prevent the laser from initiating the emission of a new pulse while the laser remains in the disabled state.

[0086] In block 509, which can be performed during the operation of blocks 501-507, an energy monitor (e.g., local energy monitor 306 or 414) can monitor the voltage across a local energy storage unit (e.g., the voltage at node 304 in TOSA 300 or node 404 in TOS 400) and compare the monitored voltage to a threshold voltage (e.g., a threshold voltage represented by safety threshold signals 322 or 422). Monitoring and / or comparison can be performed continuously, persistently, periodically, intermittently, or in response to a control signal. The energy monitor can assert (e.g., enable) an alarm signal (e.g., safety alarm signal 308 or 408) in response to determining that the voltage across the local energy storage unit violates a safety condition. For example, the energy monitor can assert an alarm signal when a fault condition is detected. In some embodiments, a fault condition is detected when the voltage across the local energy storage unit drops below a threshold voltage (indicating over-discharge of the local energy storage unit). In some embodiments, a fault condition is detected when the voltage across the local energy storage component rises above a threshold voltage (which indicates overcharging of the local energy storage component).

[0087] Referring again to block 509, the controller (e.g., control device 350 or 450) can monitor alarm signals. If an alarm signal is asserted at any time, the controller can set the energy control signal to a disabled (or "off") state to prevent additional energy from reaching the local energy storage component from the power supply. In some embodiments, if an alarm signal is asserted, the controller can also set the laser control signal (e.g., signal 318-320 or 418-420) to a disabled state.

[0088] Figure 5B Another method 500B for providing fault-tolerant optical energy limiting according to some embodiments of the present disclosure is illustrated graphically. Method 500B may include processing blocks 511-519, some embodiments of which are described below.

[0089] In block 511, the controller (e.g., control device 450) sets the values ​​of one or more laser control signals (e.g., signals 318-320 or 418-420) to a disabled state to disable one or more laser diodes DL1 to DLn (e.g., by disconnecting discharge switches SDL1 to SDLn).

[0090] In block 513, the controller (e.g., control device 450) sets the value of the energy control signal (e.g., charging signal 416) to an enabled state (or "connected") to connect the capacitor charging switch SC1 for a minimum duration, allowing the local energy storage capacitors C1 to Cn to be charged to 100% of their capacity or an acceptable proportion of the supply voltage V1 via the energy transfer rate limiting resistor R1 and the inductor (e.g., inductive ferrite). The acceptable proportion of the supply voltage can be determined based on the applied laser pulse energy and pulse repetition rate requirements.

[0091] In block 515, the controller (e.g., control device 450) sets the values ​​of one or more laser control signals (e.g., signals 318-320 or 418-420) to an enabled state to connect discharge switches SDL1 to SDLn, thereby enabling current to flow through one or more laser diodes DL1 to DLn.

[0092] In block 517, the controller (e.g., control device 450) sets the values ​​of one or more laser control signals (e.g., signals 318-320 or 418-420) to a disabled state to disable laser diodes DL1 to DLn (e.g., by disconnecting discharge switches SDL1 to SDLn).

[0093] In block 519, which can be performed during the operation of blocks 511-519, an energy monitor (e.g., local energy monitor 414) can monitor the voltage across capacitors C1 to Cn (e.g., the voltage at node 404 in TOSA 400) and compare the monitored voltage with a threshold voltage (e.g., the threshold voltage represented by safety threshold signal 422). Monitoring and / or comparison can be performed continuously, persistently, periodically, intermittently, or in response to a control signal. Monitoring can be performed by voltage comparator circuit U1. The energy monitor can assert (e.g., enable) an alarm signal (e.g., safety alarm signal 408) in response to determining that the voltage across the local energy storage component violates a safety condition. For example, the energy monitor can assert an alarm signal when a fault condition is detected. In some embodiments, a fault condition is detected when the voltage across the local energy storage component drops below a threshold voltage (indicating over-discharge of the local energy storage component, e.g., capacitors C1 to Cn). In some embodiments, a fault condition is detected when the voltage across the local energy storage component rises above a threshold voltage (which indicates excessive power delivery to the local energy storage component).

[0094] Referring again to box 519, the controller (e.g., control device 450) can monitor safety alarm signals. If a safety alarm signal is asserted at any time, the controller can set the energy control signal to a disabled (or "off") state to prevent additional energy from power supply V1 to local energy storage capacitors C1 to Cn. In some embodiments, if the alarm signal is asserted, the controller can also set the laser control signal (e.g., signal 318-320 or 418-420) to a disabled state.

[0095] Use cases, benefits, and applications of some embodiments When the power limiter 302 is disconnected from the electro-optic modulator 303 (e.g., when switch SC1 is open), some embodiments limit the maximum optical energy dissipation of lasers LD1 to LDn to: in, It is the sum of the capacitances of the local energy storage components (e.g., C1 to Cn). It is the voltage of power supply V1. It is the optical threshold voltage of the laser diode, and It refers to the electro-optic efficiency of the laser diode.

[0096] In some embodiments, the safety methods and apparatus described herein can be tested by simulating one or more fault conditions in the TOSA (300, 400) (e.g., a fault in one or more components of the TOSA), measuring (or estimating) the optical energy dissipation of the laser, and determining whether the optical energy dissipation of the laser remains within safe limits during the fault. For example, a fault condition can be simulated by forcing one or more lasers to remain enabled regardless of any alarm signals provided by the local energy monitor (306, 414). The laser can be forced to remain enabled by keeping the laser's discharge switch in the connected state and / or by keeping the laser's control signal in the "enabled" state. The simulation of such a fault condition can be initiated (1) before the local energy storage component of the electro-optic modulator (303, 412) begins charging, (2) while the local energy storage component of the electro-optic modulator is charging (e.g., which charging switch SC1 is in the connected state), or (3) during an interruption of charging of the local energy storage component of the electro-optic modulator (e.g., after the energy storage component has been charged and the charging switch SC1 has been switched to the off state). The above describes some examples of techniques for measuring (or estimating) the optical energy dissipation of a laser during fault conditions.

[0097] In the event of a failure of one or more of the discharge switches (SDL1-SDLn) or laser control signals (e.g., signals 318-320 or 418-420) when the power supply is connected to the electro-optic modulator 303 via the power rate limiter 302 (e.g., when the charging switch SC1 is closed), some embodiments limit the maximum optical energy dissipation of lasers LD1 to LDn to approximately: in, It is the total capacitance of the local energy storage device 305 (e.g., the sum of capacitances C1 to Cn). It is the voltage of power supply V1. It is the optical threshold voltage of the laser diode. Isc1 is the electro-optic efficiency of the laser diode, Isc1 is the average current supplied to the electro-optic modulator 303 via the power limiter 302 (e.g., via the charging switch SC1) during time Tsc1 when SC1 remains connected after a failure of one or more discharge switches (SDL1-SDLn) or laser control signals (e.g., signals 318-320 or 418-420), and Ediff is the differential efficiency of the laser per ampere-watt.

[0098] By disconnecting the power supply V1 from the electro-optic modulator 303, the safety alarm 414 can reduce (e.g., minimize) the additional fault energy generated by the product of Isc1 and Tsc1. In some embodiments, the power limiting components of the power limiter (e.g., resistor R1 and inductor L1) control (e.g., limit) the magnitude of the additional fault current Isc1, and the response time of the safety alarm 414 controls the duration of the additional fault current.

[0099] In some embodiments, one or more components (e.g., circuitry) outside the TOSA (300, 400) ensure that the voltage of the power supply V1 and the safety threshold voltage are set within appropriate limits. In some embodiments, after the TOSA (300, 400) is powered on, the controller (e.g., control device 350 or 450) may allow the power limiter (302, 410) to initiate charging of the local energy storage component of the electro-optic modulator (303, 412) only if the voltage of the power supply V1 and the safety threshold voltage supplied to the local energy monitor (306, 414) are set to appropriate values.

[0100] In summary, an apparatus for controlling (e.g., maximizing) light energy emission during expected operating conditions and limiting light energy emission during unexpected operating conditions may include: a rate limiter operable to limit the rate of energy transfer from a power source to one or more local energy storage components based on an energy control signal; the local energy storage component operable to be charged based on the energy transfer from the rate limiter; and an electro-optic modulator including one or more lasers coupled to the local energy storage component. Laser emission from the one or more lasers may be based on a voltage provided by the local energy storage component and one or more corresponding laser enable signals. The apparatus may also include a local energy monitor coupled to the local energy storage component. If a safety condition is violated based on the voltage provided by the local energy storage component, the local energy monitor is operable to trigger a safety alarm. When the safety condition is violated, subsequent emission from the one or more lasers is limited. Specifically, if the safety condition is violated, the energy control signal is disabled, thereby causing termination of energy transfer from the power source to the local energy storage component. With the termination of energy transfer from the power source to the local energy storage component, the energy available for subsequent laser emission is limited by the existing potential of the local energy storage component, which can be determined based on the capacitance of the local energy storage component and the voltage across these components.

[0101] In some embodiments, the power limiter includes a resistor, an inductor (e.g., an inductive ferrite), and a switch controlled by an energy control signal. The switch can be enabled for a duration sufficient to charge the local energy storage component through the resistor and inductor (e.g., to a specific potential or full capacity). The local energy storage component may include one or more (N) capacitors, and the electro-optic modulator may include one or more (N) laser diodes. The N capacitors may be physically positioned sequentially between corresponding laser diodes. The output of the power limiter, a terminal of the N capacitors, a terminal of the N laser diodes, and the input to the local energy monitor may share (e.g., be coupled or connected to) a common internal node. The electro-optic modulator may also include one or more corresponding laser discharge switches that control the emission of one or more lasers based on one or more laser enable signals. The local energy monitor can compare a low-pass filtered measurement of the voltage of the local energy storage component with a safety threshold.

[0102] System Implementation Examples In the embodiments, aspects of the techniques described herein may be directed to or implemented on an information processing system / computing system. For the purposes of this disclosure, a computing system may include any means or aggregation of means operable to compute, calculate, determine, classify, process, transmit, receive, retrieve, generate, route, switch, store, display, communicate, indicate, detect, record, reproduce, process, or utilize any form of information, intelligence, or data for commercial, scientific, control, or other purposes. For example, a computing system may be a personal computer (e.g., a laptop computer), a tablet computer, a tablet PC, a personal digital assistant (PDA), a smartphone, a smartwatch, a smart package, a server (e.g., a blade server or a rack server), a network storage device, or any other suitable device, and may vary in size, shape, performance, functionality, and price. A computing system may include random access memory (RAM), one or more processing resources (such as a central processing unit (CPU), or hardware or software control logic), ROM, and / or other types of memory. Additional components of a computing system may include one or more disk drives, one or more network ports for communicating with external devices, and various input and output (I / O) devices such as a keyboard, mouse, touchscreen, and / or video display. The computing system may also include one or more buses operable to transmit communication between various hardware components.

[0103] Figure 6 A simplified block diagram of a computing device / information processing system (or computing system) according to embodiments of the present disclosure is depicted. It will be understood that the functionality shown for system 600 can operate to support various embodiments of the information processing system—although it should be understood that the information processing system can be configured differently and include different components.

[0104] like Figure 6 As shown, system 600 includes one or more central processing units (CPUs) 601, which provide computing resources and control the computer. CPU 601 may be implemented using a microprocessor or the like, and may also include one or more graphics processing units (GPUs) 617 and / or floating-point coprocessors for mathematical calculations. System 600 may also include system memory 602, which may be in the form of random access memory (RAM), read-only memory (ROM), or both.

[0105] like Figure 6As shown, multiple controllers and peripheral devices may also be provided. Input controller 603 represents an interface to one or more various input devices 604 (e.g., keyboard, mouse, or pen). A scanner controller 605 may also be provided to communicate with scanner 606. System 600 may also include a storage controller 607 for interfacing with one or more storage devices 608, each storage device including a storage medium such as magnetic tape or disk, or an optical medium that may be used to record instructions for operating systems, utilities, and applications (which may include embodiments of programs implementing various aspects of the techniques described herein). One or more storage devices 608 may also be used to store processed data or data to be processed according to some embodiments. System 600 may also include a display controller 609 for providing an interface to a display device 611, which may be a cathode ray tube (CRT), thin-film transistor (TFT) display, or other type of display. Computing system 600 may also include an automatic signal controller 612 for communicating with automatic system 613. The communication controller 614 can interface with one or more communication devices 615, enabling the system 600 to connect to remote devices via any of a variety of networks, including the Internet, cloud resources (e.g., Ethernet cloud, Ethernet Fibre Channel (FCoE) / Data Center Bridge (DCB) cloud, etc.), local area network (LAN), wide area network (WAN), storage area network (SAN), or via any suitable electromagnetic carrier signal including infrared signals.

[0106] In the illustrated system, all major system components can be connected to bus 616, which may represent more than one physical bus. However, the various system components may be physically close to each other or physically distant. For example, input data and / or output data can be remotely transferred from one physical location to another. Additionally, programs implementing various aspects of some embodiments can be accessed from a remote location (e.g., a server) via a network. Such data and / or programs can be transmitted via any of a variety of machine-readable media, including but not limited to: magnetic media such as hard disks, floppy disks, and magnetic tapes; optical media such as CD-ROMs and holographic devices; magneto-optical media; and hardware devices specifically configured to store or store and execute program code, such as application-specific integrated circuits (ASICs), programmable logic devices (PLDs), flash memory devices, and ROM and RAM devices. Some embodiments may be encoded on one or more non-transitory computer-readable media having instructions for one or more processors or processing units to cause steps to be executed. It should be noted that the one or more non-transitory computer-readable media should include volatile and non-volatile memory. It should be noted that alternative implementations, including hardware implementations or software / hardware implementations, are possible. The hardware implementation of the functionality can be achieved using one or more ASICs, programmable arrays, digital signal processing circuits, etc. Therefore, the term "component" in any claim is intended to cover both software and hardware implementations. Similarly, the term "computer-readable medium or media" as used herein includes software and / or hardware, or a combination thereof, on which a program of instructions is contained. In light of these implementation alternatives, it should be understood that the accompanying drawings and description provide functional information that would be necessary for someone skilled in the art to write program code (i.e., software) and / or manufacture circuitry (i.e., hardware) to perform the desired processing.

[0107] It should be noted that some embodiments may also relate to computer products having a non-transitory tangible computer-readable medium having computer code on it for performing operations of various computer implementations. The medium and computer code may be specifically designed and constructed for the purposes described herein, or they may be of a kind known or available to those skilled in the art. Examples of tangible computer-readable media include, but are not limited to: magnetic media, such as hard disks, floppy disks, and magnetic tapes; optical media, such as CD-ROMs and holographic devices; magneto-optical media; and hardware devices specifically configured to store or store and execute program code, such as application-specific integrated circuits (ASICs), programmable logic devices (PLDs), flash memory devices, and ROM and RAM devices. Examples of computer code include machine code generated by a compiler, and files containing higher-level code executed by a computer using an interpreter. Some embodiments may be implemented, wholly or partially, as machine-executable instructions, which may reside in program modules executed by a processing device. Examples of program modules include libraries, programs, routines, objects, components, and data structures. In a distributed computing environment, program modules may be physically located in a local, remote, or both setting.

[0108] Those skilled in the art will recognize that no computing system or programming language is critical to the practice of the techniques described herein. They will also recognize that the aforementioned elements may be physically and / or functionally divided into sub-modules or combined together.

[0109] Those skilled in the art should understand that the foregoing examples and embodiments are exemplary and not intended to limit the scope of this disclosure. It is intended that all substitutions, enhancements, equivalents, combinations, and improvements that will become apparent to those skilled in the art upon reading the specification and studying the accompanying drawings are included within the true spirit and scope of this disclosure. It should also be noted that the elements of any claim can be arranged differently, including having multiple dependencies, configurations, and combinations.

Claims

1. A control device, comprising: A power limiter operable to limit energy transfer from a power source to a local energy storage module, including local energy storage capacitors (C1, ..., Cn), based on an energy control signal; The local energy storage module is operable to be charged based on energy transfer from the power source; An electro-optical emitter includes one or more lasers coupled to the local energy storage module, wherein laser emission from the one or more lasers is based on a potential of the local energy storage module and one or more laser enable signals corresponding to the one or more lasers; and A local energy monitor, coupled to the local energy storage module, is operable to trigger a safety alarm signal if the voltage supplied by the local energy storage module violates a safety condition related to a safety threshold voltage. The power limiter is operable to terminate energy transfer from the power source to the local energy storage module after a violation of the safety conditions. The safety condition is violated when the voltage across the local energy storage capacitors (C1, ..., Cn) is less than a first threshold, indicating over-discharge of the local energy storage capacitors (C1, ..., Cn), or when the voltage across the local energy storage capacitors (C1, ..., Cn) is greater than a second threshold, indicating over-charging of the local energy storage capacitors (C1, ..., Cn). The power limiter is further operable to terminate energy transfer from the power source to the local energy storage module based on the energy control signal being in a disabled state. The energy control signal is placed in the disabled state in response to the violation of the safety condition. After the power limiter terminates the energy transfer from the power source to the local energy storage module, the amount of energy available for subsequent laser emission is limited to the amount of electrical energy stored in the local energy storage module before the termination of the energy transfer.

2. The apparatus according to claim 1, wherein, The power limiter includes a resistor, an inductor, and a switch controlled by the power control signal.

3. The apparatus according to claim 2, wherein, The energy control signal is configured to enable the switch for a duration sufficient to allow the local energy storage module to charge to a predetermined potential through the resistor and the inductor.

4. The apparatus according to claim 1, wherein, The local energy storage module includes N capacitors, and the one or more lasers are N laser diodes, where N ≥ 1.

5. The apparatus according to claim 4, wherein, The N capacitors are physically positioned sequentially between adjacent laser diodes.

6. The apparatus according to claim 4, wherein, The output terminal of the power limiter, the corresponding terminal of each of the N capacitors, the corresponding terminal of each of the N laser diodes, and the input terminal of the local energy monitor are connected to a common internal node.

7. The apparatus according to claim 1, wherein, The electro-optical transmitter also includes one or more corresponding laser discharge switches, which control the laser emission of the one or more lasers based on the one or more laser enable signals.

8. The apparatus according to claim 1, wherein, The local energy monitor is operable to: The low-pass filtered measurement of the voltage provided by the local energy storage module is compared with the safety threshold voltage; as well as The safety alarm signal is triggered based on the comparison result.

9. The apparatus of claim 1, further comprising a control device operable to provide the energy control signal at least in part based on the safety alarm signal.

10. The apparatus according to claim 9, wherein, The control device is further operable to provide a signal indicating the safety threshold voltage to the local energy monitor.

11. The apparatus of claim 1, further comprising generating the energy control signal at least in part based on the safety alarm signal.

12. A control method, comprising: Energy transfer from the power source to the local energy storage module, which includes local energy storage capacitors (C1, ..., Cn), is controlled based on energy control signals. The one or more lasers are emitted based on the potential of the local energy storage module and one or more laser enable signals corresponding to one or more lasers; The system monitors the voltage provided by the local energy storage module and triggers a safety alarm signal when the voltage provided by the local energy storage module violates a safety condition related to a safety threshold voltage. The violation occurs when the voltage across the local energy storage capacitors (C1, ..., Cn) is less than a first threshold, indicating over-discharge of the local energy storage capacitors (C1, ..., Cn), or when the voltage across the local energy storage capacitors (C1, ..., Cn) is greater than a second threshold, indicating over-charging of the local energy storage capacitors (C1, ..., Cn). After the safety alarm signal is triggered, energy transfer from the power source to the local energy storage module is terminated based on the energy control signal being in a disabled state, wherein the energy control signal is placed in the disabled state in response to the violation of the safety condition. Wherein, after the energy transfer from the power source to the local energy storage module is terminated, the amount of energy emitted in the subsequent laser emission is limited to the amount of electrical energy stored in the local energy storage module before the termination of the energy transfer.

13. The method of claim 12, further comprising comparing a measurement of the voltage provided by the local energy storage module with the safety threshold voltage, wherein, The safety alarm signal is triggered based on the comparison result.

14. A control method, comprising: (a) Setting one or more laser control signals to a disabled state to disable the emission of one or more lasers, wherein the one or more laser control signals are provided to the control terminals of one or more corresponding laser control switches, and wherein each of the laser control switches is operable to control the amount of current conducted through the corresponding laser corresponding to the laser control switch based on one or more characteristics of the laser control signals provided to the laser control switch. (b) Set the energy control signal to the enabled state to connect the power supply to the local energy storage module, which includes local energy storage capacitors (C1, ..., Cn), for a duration of time; (c) Set the control signal of the one or more lasers to an enabled state to enable the emission of the one or more lasers; (d) Set the control signals of the one or more lasers to the disabled state again to disable the emission of the one or more lasers; and (e) During operations (a)-(d), a safety alarm signal provided by a local energy monitor is monitored, and when the safety alarm signal is asserted, the energy control signal is set to a disabled state to disconnect the power supply from the local energy storage module. Specifically, when safety conditions are violated, the safety alarm signal is asserted, and The safety condition is violated when the voltage across the local energy storage capacitor (C1, ..., Cn) is less than a first threshold, indicating over-discharge of the local energy storage capacitor (C1, ..., Cn), or when the voltage across the local energy storage capacitor (C1, ..., Cn) is greater than a second threshold, indicating over-charging of the local energy storage capacitor (C1, ..., Cn).

15. The method according to claim 14, wherein, The energy control signal is provided to the control terminal of the energy control switch.

16. A control device, comprising: One or more processing devices; as well as One or more computer-readable storage devices storing instructions, which, when executed by the processing device, cause the processing device to perform operations, the operations including: (a) Setting one or more laser control signals to a disabled state to disable the emission of one or more lasers, wherein the one or more laser control signals are provided to the control terminals of one or more corresponding laser control switches, and wherein each of the laser control switches is operable to control the amount of current conducted through the corresponding laser corresponding to the laser control switch based on one or more characteristics of the laser control signals provided to the laser control switch. (b) Set the energy control signal to the enabled state to connect the power supply to the local energy storage module, which includes local energy storage capacitors (C1, ..., Cn), for a duration of time; (c) Set the control signal of the one or more lasers to an enabled state to enable the emission of the one or more lasers; (d) Set the control signals of the one or more lasers to the disabled state again to disable the emission of the one or more lasers; and (e) During operations (a)-(d), a safety alarm signal provided by a local energy monitor is monitored, and when the safety alarm signal is asserted, the energy control signal is set to a disabled state to disconnect the power supply from the local energy storage module. Specifically, when safety conditions are violated, the safety alarm signal is asserted, and The safety condition is violated when the voltage across the local energy storage capacitor (C1, ..., Cn) is less than a first threshold, indicating over-discharge of the local energy storage capacitor (C1, ..., Cn), or when the voltage across the local energy storage capacitor (C1, ..., Cn) is greater than a second threshold, indicating over-charging of the local energy storage capacitor (C1, ..., Cn).

17. The control device according to claim 16, wherein, The energy control signal is provided to the control terminal of the energy control switch.

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