Laser system for a photoacoustic probe

Abstract

An photoacoustic probe for volumetric photoacoustic imaging is provided. The photoacoustic probe may include a laser system having a power supply configured to provide a constant voltage, and a first capacitor bank coupled to the power supply to receive the constant voltage, the first capacitor bank being configured to power a corresponding first flash lamp upon reaching a first defined charge state. The first capacitor bank may include a first closed-loop feedback configured with a first setpoint determining a first charging time for the first defined charge state, and the first flash lamp may be configured to emit first light along an optical path. The photoacoustic probe may also include an optical window configured to carry the first light to the volume along the optical path.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefits of U.S. non-provisional application No. 18 / 939,149, filed November 6, 2024, entitled “LASER SYSTEM FOR AN OPTOACOUSTIC PROBE”, and U.S. provisional application No. 63 / 597,618, filed November 9, 2023, the entire subject matter of which is expressly incorporated herein by reference. Technical Field

[0003] This invention relates generally to the field of medical imaging, and more specifically to systems related to optoacoustic imaging. Background Technology

[0004] Photoacoustic imaging systems non-invasively visualize thin sections of tissue through the skin at the tissue site. The tissue site can contain various structures, such as tumors, blood vessels, tissue layers, and blood components. In photoacoustic imaging, laser-generated light is used to deliver light energy to a planar section of the tissue site, which generates sound waves due to light absorption by the tissue structures. An image representing the tissue site in space can be generated by performing image reconstruction on the acoustic signal returning to the ultrasound transducer array. Because biological tissue scatters impacting light energy in many directions, the light energy can be absorbed by tissue structures outside the target area, which can generate acoustic return signals that interfere with the imaging of tissue structures within the target area.

[0005] In flash-pumped solid-state lasers, the intensity of the laser output is proportional to the intensity of the light discharged across the flash lamp, which is controlled by the voltage of the capacitor bank. In some applications, such as photoacoustics, multiple laser outputs are continuously generated using different laser systems involving multiple capacitor banks and power supplies. In high-repetition-rate applications such as photoacoustics, charging time becomes a critical parameter for maintaining the desired frame rate. Since the capacitor charging time is directly related to the power supply's output power (j / sec), high power output is typically required.

[0006] Therefore, there is a need for a laser system that provides better control and output when subjected to high repetition rate applications, such as when used in photoacoustic probes. Summary of the Invention

[0007] The appended claims set forth novel and useful systems, apparatuses, and methods for providing photoacoustic imaging. Illustrative embodiments are also provided to enable those skilled in the art to utilize the claimed subject matter.

[0008] The purpose, advantages, and preferred modes of making and using the claimed subject matter can be best understood by referring to the accompanying drawings and the following detailed description of illustrative embodiments.

[0009] According to embodiments herein, a photoacoustic probe for photoacoustic imaging of a volume is provided. The photoacoustic probe may include a laser system having a power supply configured to provide a constant voltage, and a first capacitor bank coupled to the power supply to receive the constant voltage and configured to supply power to a corresponding first flash lamp upon reaching a first defined charge state of the first capacitor bank. The first capacitor bank may include a first closed-loop feedback configured with a first setpoint determining a first charging time for the first defined charge state, and the first flash lamp may be configured to emit first light along an optical path. The photoacoustic probe may also include an optical window configured to carry the first light to the volume along the optical path.

[0010] Optionally, the constant voltage can be a first overvoltage input to the first capacitor bank relative to a first setpoint of the first closed-loop feedback. In one aspect, the laser system may further include a second capacitor bank that can be coupled to a power source to receive the constant voltage and can be configured to power a corresponding second flash lamp when a second defined charge state of the second capacitor bank is reached. The second capacitor bank may include a second closed-loop feedback configured with a second setpoint that determines a second charging time for the second defined charge state, and the second flash lamp may be configured to emit second light along an optical path. In another aspect, the first setpoint may be different from the second setpoint. In one example, the constant voltage can be a second overvoltage input to the second capacitor bank relative to a second setpoint of the second closed-loop feedback. Optionally, the first light from the first flash lamp may have a first wavelength, and the second light from the second flash lamp may have a second wavelength different from the first wavelength. In yet another example, the optical window may also be configured to carry the second light to a volume along an optical path. Alternatively, the first setpoint may be independent of the second setpoint. In another embodiment, the photoacoustic probe may further include an ultrasonic transducer covered by an acoustic lens for receiving a signal associated with the first light carried to the volume.

[0011] According to embodiments herein, a method for imaging a volume using a photoacoustic probe is provided, which may include supplying a constant voltage from a power source to a first capacitor bank having a first flash lamp that emits first light along an optical path upon reaching a first predetermined charge state, and providing first closed-loop feedback using a first setpoint, the first setpoint being a first voltage less than the constant voltage. A first predetermined charging time may be based on the first setpoint, and the method may further include carrying the first light along the optical path to an optical window of the photoacoustic probe.

[0012] Optionally, the method may include supplying a constant voltage from a power source to a second capacitor bank having a second flash lamp that emits second light along an optical path upon reaching a second determined charge state, and providing second closed-loop feedback using a second setpoint, which is a second voltage less than the constant voltage. A second determined charging time may be based on the second setpoint, and the method may further include carrying the second light along the optical path to an optical window of a photoacoustic probe. In one aspect, the first setpoint may be different from the second setpoint. In another aspect, the first light from the first flash lamp may have a first wavelength, and the second light from the second flash lamp may have a second wavelength different from the first wavelength. In one example, the first setpoint may be independent of the second setpoint.

[0013] According to embodiments herein, a laser system for a photoacoustic probe is provided, comprising: a power supply configured to provide a constant voltage; and a first capacitor bank coupled to the power supply to receive the constant voltage and configured to supply power to a corresponding first flash lamp upon reaching a first defined charge state of the first capacitor bank. The first capacitor bank may include a first closed-loop feedback configured with a first setpoint that determines a first charging time for the first defined charge state, and the first setpoint may have a first voltage less than the constant voltage.

[0014] Optionally, the laser system may further include a second capacitor bank coupled to a power source to receive a constant voltage and configured to supply power to a corresponding second flash lamp when a second defined charge state of the second capacitor bank is reached. The second capacitor bank may include a second closed-loop feedback configured with a second setpoint that determines a second charging time for the second defined charge state. Additionally, the second setpoint may have a second voltage less than the constant voltage. In one aspect, the first setpoint may be different from the second setpoint. In another aspect, the first light from the first flash lamp may have a first wavelength, and the second light from the second flash lamp may have a second wavelength different from the first wavelength. In one example, the first setpoint may be independent of the second setpoint. In another example, changing the first setpoint can change the first charging time without changing the constant voltage of the power source. Attached Figure Description

[0015] The above and other objects, features, and advantages of the present invention will become apparent from the following more detailed description of the preferred embodiments shown in the accompanying drawings, wherein reference characters refer to the same parts in the various views. The drawings are not necessarily drawn to scale, but rather focus on illustrating the principles of the invention.

[0016] Figure 1 A schematic block diagram illustrating an implementation of a combined photoacoustic and ultrasonic system that can be used as a platform for the methods and apparatus disclosed herein is shown.

[0017] Figure 2 A schematic orthogonal view of an embodiment of a probe that can be used in conjunction with the methods and other devices disclosed herein is shown.

[0018] Figure 3 A schematic block diagram of a laser system for a photoacoustic probe is shown, which can be used in conjunction with the methods and other devices disclosed herein.

[0019] Figure 4 A graph showing the capacitor voltage as a function of the time constant, as disclosed herein, is shown.

[0020] Figure 5 A graph showing the capacitor current as a function of the time constant, as disclosed herein, is shown.

[0021] Figure 6 A schematic block flowchart of a method for powering a laser system that can be used in conjunction with the systems and devices disclosed herein is shown.

[0022] Figure 7 A graph showing the change of capacitor voltage over time, as disclosed herein, is shown.

[0023] Figure 8 A graph showing the change of capacitor voltage over time, as disclosed herein, is shown.

[0024] Figure 9 A graph showing the change of capacitor voltage over time, as disclosed herein, is shown.

[0025] While the invention can be modified and substituted in various ways, its details have been illustrated by way of example in the accompanying drawings and will be described in detail. However, it should be understood that the purpose is not to limit the invention to the specific embodiments described. Rather, the invention is intended to cover all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Detailed Implementation

[0026] The following description and accompanying drawings are illustrative and should not be construed as limiting. Numerous specific details are described to provide a thorough understanding. However, in some cases, well-known or conventional details have not been described to avoid obscuring the description. References to one or more embodiments of this disclosure are not necessarily references to the same embodiment; and such references refer to at least one.

[0027] In this specification, references to "an embodiment" or "embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this disclosure. The phrase "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. Furthermore, various features that may be manifested by some embodiments but not by others are described. Similarly, various requirements are described that may be required by some embodiments but not by others.

[0028] The system and method for providing photoacoustic imaging with out-of-plane artifact suppression are described below with reference to block diagrams, operational illustrations, and algorithms. It should be understood that each block in the block diagrams, operational illustrations, and algorithms, as well as combinations of blocks in the block diagrams, operational illustrations, and algorithms, can be implemented using analog or digital hardware and computer program instructions.

[0029] These computer program instructions may be stored on a computer-readable medium and provided to a processor of a general-purpose computer, a special-purpose computer, an ASIC, or other programmable data processing apparatus, such that the instructions, which are executed by the processor of the computer or other programmable data processing apparatus, perform the functions / actions specified in the block diagram, one or more operation blocks, and / or algorithms.

[0030] In some cases, frequency-domain based algorithms require zero or symmetric padding for performance reasons. This padding is not essential to the description of the algorithm's implementation and is therefore sometimes omitted from the description of the processing steps. In some cases, even if padding is disclosed in the steps, the algorithm can still be executed without it. However, in other cases, padding is necessary and cannot be removed without corrupting the data.

[0031] In some alternative implementations, the functions / actions indicated in the boxes may not occur in the order shown in the operation diagram. For example, depending on the functions / actions involved, two boxes shown consecutively may actually be executed substantially simultaneously, or these boxes may sometimes be executed in reverse order.

[0032] Reference will now be made in more detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings. Those skilled in the art will understand that the data structures and processing steps described herein can be implemented in many other ways without departing from the spirit of the disclosure and the scope of the invention, and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concepts of this disclosure to those skilled in the art.

[0033] The embodiments described herein may be implemented in conjunction with one or more systems and methods described in one or more of the following patents, publications and / or public applications, the entire contents of which are expressly incorporated herein by reference:

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[0041] U.S. Patent 9,792,686, filed on November 17, 2016, entitled "System and Method For Acquiring Optoacoustic Data and Producing Parametric Maps Using Subband Acoustic Compensation";

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[0088] As used herein, the phrase "constant voltage" refers to a voltage that is supplied and does not change or does not change significantly in response to variations in the circuit. For example, a constant voltage of 1000V may vary minimally between 998V and 1002V based on real-world differences in the device and is still considered a constant voltage. Nevertheless, aside from being a result of real-world differences, a constant voltage does not change proportionally or in response to the charging or discharging of capacitors in the circuit. In one example, the constant voltage may vary by less than 2% of the desired voltage while the voltage supply or power source is operating.

[0089] As used herein, the phrase "determined state of charge" refers to the amount of charge required within the capacitor bank to discharge and supply current to the corresponding flash unit. This determined state of charge can be expressed as a percentage of charge relative to the full capacity of the capacitor bank, and can be, for example, 100%, 99%, 98%, etc. Alternatively, the determined state of charge can be expressed as the amount of charge achieved, rather than as a percentage. Still, upon reaching the determined state of charge, the capacitor bank discharges to provide input to the corresponding flash unit.

[0090] As used herein, the phrase "overvoltage" or "overvoltage input" should be understood to mean that the setpoint of the closed feedback loop in the capacitor bank has a voltage lower than the constant supply voltage. Therefore, if the supply voltage provides a constant voltage of 1000V and the setpoint is set to 999V or lower, the corresponding capacitor bank is operating under overvoltage.

[0091] An optoacoustic system is provided, comprising a laser system with different capacitor bank voltage output setpoints using a single power supply. This is achieved by applying an overvoltage input relative to the desired setpoint and closed-loop feedback. For example, if the capacitor banks receive 1000V (from a single output of the power supply), the closed-loop feedback can be used to set each bank independently without changing the power supply output. Since the capacitor charger output current is related to the charging time via Tc = Cload * Vcharge / Iout, it can be seen that higher output power is typically required for high repetition rates. In RC applications, one can refer to... Figure 4-5The time constant (T) shown represents the time required to reach the voltage setpoint and steady state. Typically, a capacitor takes 5*T to fully charge. Using the example above, if the capacitor bank receives 1000V and a desired setpoint of 500V is controlled using closed-loop feedback, the time required for the capacitor to charge to the setpoint becomes 0.7*T, less than 1 / 5 of the original charging time. Therefore, speed and efficiency are significantly improved.

[0092] Go to Figure 1 Typically, device 100 provides a photoacoustic system, which can also be used as a multimodal, combined photoacoustic and ultrasonic system. In one embodiment, device 100 includes a probe 102 connected to system chassis 101 via optical path 132 and electrical path 108. System chassis 101 houses a photonic system 129 and a computing subsystem 128. Computing subsystem 128 includes one or more computing components for ultrasonic control and analysis, and photoacoustic control and analysis; these components may be discrete or integrated. In embodiments, the computing subsystem includes a relay system 110, a triggering system 135, a photoacoustic processing and superposition system 140, and an ultrasonic instrument 150. In one embodiment, triggering system 135 is configured to actuate and control the operation of primary light sources 130, 131 and secondary signal source 134, in one example, the secondary signal source 134 being a secondary light source. In other examples, the secondary signal source may be an acoustic signal source, a piezoelectric-based signal source, an ultrasonic signal source, etc. The main light sources 130 and 131 are used to generate signals for imaging purposes, while the auxiliary signal source 134 is not used to generate signals for imaging purposes. In this example, the triggering system 135 prevents the actuation of the main light sources 130 and 131 before the actuation of the auxiliary signal source 134. Therefore, the triggering system 135 prevents the actuation of the main light sources 130 and 131 until a light-indicating probe detected from the auxiliary signal source 134 on the tissue is in contact with volume 160.

[0093] In one embodiment, the photonic system 129 is capable of generating light pulses of at least two different wavelengths. In another embodiment, the photonic system 129 includes two separate main light sources 130 and 131 and an auxiliary signal source 134. In one embodiment, the main light sources 130 and 131 are Nd:YAG and Alexandrite lasers. In an example embodiment, the auxiliary signal source 134 may be a light-emitting diode, a photodiode, a low-power laser, etc. The outputs of the main light sources 130 and 131 of the photonic system 129 are transmitted to the probe 102 via an optical path 132. In another example embodiment, the auxiliary signal source 134 is located within the housing of the probe 102 and generates light exiting the probe 102 through one or more optical windows 103. Alternatively, the auxiliary signal source 134 is located outside the probe housing. Specifically, whether inside or outside the probe housing, the auxiliary light source is positioned to emit light onto organic tissue, a phantom, or other volume 160 to induce reflected light that can be received by one or more photodetectors. In one example, the photodetector is located at the distal end of the probe 102 and receives reflected light through the optical window 103.

[0094] One or more displays 112, 114 (which may be touchscreen displays) are provided for displaying images and all or part of the user interface of device 100. One or more other user input devices (not shown), such as keyboards, mice, and various other input devices (e.g., dials and switches), may be provided for receiving input from the operator.

[0095] Now go to Figure 2 The probe 102 includes an ultrasonic transducer covered by an acoustic lens 205. The probe 102 includes a distal end and a proximal end. The probe surface 217 of the probe 102 is located at the distal end 208. The probe 102 also includes one or more optical windows 103 through which light carried on the optical path 132 can be transmitted to the surface of volume 160 (e.g., a three-dimensional volume). Specifically, the probe 102 can be positioned in close proximity to another volume 160, such as organic tissue, a phantom, or other tissue that may have one or more inhomogeneities 161, 162 (e.g., a tumor). Ultrasonic gel (not shown) or other materials can be used to improve acoustic coupling between the probe 102 and the surface of volume 160 and / or improve light energy transfer. When the probe 102 is close to the surface of volume 160, the probe 102 can transmit light from an auxiliary signal source 134 (… Figure 1Light is emitted onto the surface of volume 160 and reflected and detected by one or more photodetectors. The computational subsystem 128 can then use the method described herein to determine whether probe 102 is in contact with volume 160 based on the reflected light. Upon determining contact between probe 102 and the volume, the computational subsystem 128 permits actuation of main light sources 130, 131 to generate otoacoustic feedback.

[0096] Go to Figure 3 A laser system 300 for a photoacoustic probe is shown. The laser system 300 may include a power source 302 (such as a battery, generator, etc.) that supplies voltage to flash lamps 304A or 304B via a first capacitor bank 306 (associated with a first flash lamp 304A) and a second capacitor bank 308 (associated with a second flash lamp). In one example, the power source generates a constant voltage that is an overvoltage required to power flash lamps 304A and 304B. Therefore, in this example, when the required voltage is 750V, the constant overvoltage supplied by the power source is 1000V. Furthermore, in other examples, the power source may provide constant voltages of 500V, 750V, 1250V, 2000V, etc., depending on the required voltage of flash lamps 304A and 304B. Additionally, although only the first capacitor bank 306 and the second capacitor bank 308 are shown, in other embodiments, additional capacitor banks may be used to regulate the power supplied by the power source.

[0097] The first capacitor bank 306 includes circuitry for regulating or switching the input from the power supply 302 for use by the corresponding first flash lamp 304A. The circuitry may include a first transistor 309A that receives the input from the power supply 302. The circuitry also includes a plurality of capacitors 310A coupled in parallel with a plurality of resistors 312A, which store and release charge for the circuitry. Connected in parallel with the plurality of capacitors 310A and the plurality of resistors 312A are an auxiliary resistor 314A and a second transistor 316A. In one example, the second transistor is an insulated-gate bipolar transistor (IGBT); alternatively, the second transistor may be a MOSFET, or another transistor operating with a diode 318A to act as a switch for a circuit that controls when power is supplied to the first flash lamp 304A. In one example, the second transistor 316A and the diode 318A operate as a switch and block current from flowing through the first flash lamp until a defined charge state of the first capacitor bank is reached. In one example, the charge state is determined to be 98% charged, while in other examples, the charge state could be 99% charged, 100% charged, etc. Specifically, the charge state can be determined using a provided threshold, where the first capacitor bank 306 is considered fully charged. Meanwhile, the auxiliary resistor 314A provides a path to the feedback loop 320A, which supplies voltage from the circuit to the comparator 322A, which also receives a setpoint voltage source 324A, such that the comparator provides the final feedback voltage 326A to the first transistor 309A.

[0098] The second capacitor bank 308 can provide the same circuitry as the first capacitor bank 306. In this way, the second capacitor bank 308 can include circuitry for regulating or switching the input from the power supply 302 for use by the corresponding second flash lamp 304B. The circuitry can include a first transistor 309B that receives input from the power supply 302. The circuitry also includes multiple capacitors 310B coupled in parallel with multiple resistors 312B, which store and release charge for the circuitry. Connected in parallel with the multiple capacitors 310B and the multiple resistors 312B are an auxiliary resistor 314B and a second transistor 316B. In one example, the second transistor is an insulated-gate bipolar transistor (IGBT); alternatively, the second transistor can be a MOSFET, or another transistor operating with a diode 318B to act as a switch for a circuit that controls when power is supplied to the second flash lamp 304B. In one example, the second transistor 316B and the diode 318B operate as a switch, blocking current from flowing through the second flash lamp until a defined charge state of the second capacitor bank is reached. In one example, the charge state is determined to be 98% charged, while in other examples, the charge state could be 99% charged, 100% charged, etc. Specifically, the charge state can be determined using a provided threshold, where the second capacitor bank 308 is considered fully charged. Meanwhile, the auxiliary resistor 314B provides a path to the feedback loop 320B, which supplies the voltage from the circuit to the comparator 322B. The comparator 322B also receives a setpoint voltage source 324B, causing the comparator to supply the resulting feedback voltage 326B to the first transistor 309B.

[0099] Therefore, by applying an overvoltage input relative to the desired setpoint and closed-loop feedback, different capacitor bank voltage output setpoints 330A and 330B can be provided using a single power supply 302. In one example, capacitor banks 306 and 308 are supplied with 1000V (from a single output of power supply 302), and closed-loop feedback can be used to set each capacitor bank 306, 308 independently of each other without changing the power supply output. Thus, in one example, the first closed-loop feedback could be 500V for the first capacitor bank 306, and the second closed-loop feedback could be 450V for the second capacitor bank 308. Therefore, lower power requirements can be achieved for higher repetitive applications (such as photoacoustic monitoring using flashes 304A, 304B). Furthermore, faster charging times are achieved, along with reduced costs, as only a single capacitor charger is required. As used herein, charging time refers to the amount of time between the discharge of a capacitor bank (e.g., when the second transistor and diode allow current to flow to the corresponding flash due to the circuit reaching a defined charge state) and the capacitor bank reaching a defined charge state for the next discharge. In addition, feedback can provide improved pulse-to-pulse output for the 304A and 304B flash units, thereby improving the entire photoacoustic system.

[0100] Figure 4 A graph 400 showing the capacitor voltage 402 versus a time constant 404 is shown. The time constant represents a defined time period (such as one second, ten seconds, one minute, etc.), such that if 1T represents ten seconds, then 5T represents fifty seconds. As shown, the current laser system, utilizing a varying voltage source and not overvoltage, has a transition period 406 that lasts until 4T is reached, and during the steady-state period 410, a capacitor is not fully charged until point 408 (e.g., at 5T). In contrast, based on the use of... Figure 3 In the experiments with the described laser system, the capacitor was fully charged at point 412 (e.g., 0.7T) or less than one-fifth of the time required to reach a fully charged state. Furthermore, the capacitor voltage at which the fully charged state is reached is significantly lower compared to previous laser systems.

[0101] Similarly, Figure 5 Graph 500 is shown, illustrating the capacitor current 502 at the same time constant 504. As shown, using the current laser system, the current does not approach zero until point 508 (e.g., at 5T), while for... Figure 3 The laser system has a current close to zero at point 512 (e.g., at 0.7T). As a result, improved functionality is provided.

[0102] Figure 6A block flowchart of a method 600 for powering a laser system for a photoacoustic probe is shown. The photoacoustic probe can be... Figure 1-2 The photoacoustic probe shown is illustrated, and the laser system can be as follows: Figure 1 and Figure 3 Any laser system shown.

[0103] At point 602, the power supply supplies power to one or more capacitor banks. In one example, the supplied power comprises a constant voltage that does not change. In another example, the constant voltage may be an overvoltage greater than at least one set point of the capacitor bank. In one embodiment, the constant voltage is 1000V. In another example, two capacitor banks are provided in the laser system. In yet another example, more than two capacitor banks are provided in the laser system.

[0104] At point 604, it is determined whether a defined charge state has been reached. Specifically, each capacitor bank is used to operate the corresponding flash based on feedback from a setpoint. Specifically, the constant voltage supplied by the power source can be greater than the setpoint for each capacitor bank to provide an overvoltage to each capacitor bank until each capacitor bank reaches a defined charge state (e.g., fully charged). As a result, the time period for each capacitor bank to fully charge is reduced compared to currently used laser systems for photoacoustic probes. In one example, when the first capacitor bank reaches a first defined charge state, the first capacitor bank is ready to discharge. Similarly, when the second capacitor bank reaches a second defined charge state, the second capacitor bank is ready to discharge. Both the first and second defined charge states represent the corresponding capacitor banks that are fully charged. In one example, full charging does not necessarily mean 100% charging, but rather a threshold charge percentage can be selected, such as 99%, 98%, 95%, etc., and once reached, discharge can proceed. In this way, the charge state threshold can be determined before using the capacitor banks and is therefore a defined charge state. In one example, one or more processors can continuously make determinations related to the state of each capacitor bank, and can determine to change the determined charge state (e.g., from 99% to 98%) based on the determinations made. In another example, a switch such as a transistor is used within the circuit, and when a threshold charge state is reached, the transistor allows current to flow through the transistor to the flash lamp.

[0105] At point 606, once the capacitor bank reaches a defined charge state, it discharges to power the corresponding flash unit. This process continues to repeat during laser system operation until the flash unit is no longer in use. By providing a laser system that combines a constant power supply voltage with a setpoint within the capacitor bank to provide feedback in cases where the constant voltage is an overvoltage, the time it takes for the capacitors to reach full charge is significantly reduced, while also lowering the voltage required to reach full charge. Therefore, an improved method is provided.

[0106] Figure 7-9 Several graphs 700, 800, and 900 are shown, illustrating the variation of capacitor bank voltages 702, 802, and 902 over time 704, 804, and 904. The first graph 700 shows the variation according to... Figure 6 Methods and Figure 3 The laser system utilizes an overvoltage input. In this example, the overvoltage input is 600V, with the first capacitor bank 706 having a setpoint voltage of 360V and the second capacitor bank 708 having a setpoint voltage of 310V. In this example embodiment, the first capacitor bank 706 has an initial charge at 0.5 seconds and then begins to excite every 200 milliseconds (ms) starting at 3.5 seconds. Simultaneously, the second capacitor bank 708 also shows an initial charge at 0.5 seconds and begins to excite every 200 ms starting at 3.5 seconds. The first graph 700 also shows the current consumption 710 of the laser system, which has a peak current 712 of only 4 amps at 0.5 seconds and only 2 amps during the 200 ms recharge period.

[0107] With Figure 8 The laser system shown is compared to one without overcharging. Similarly, the first capacitor bank 806 has a setpoint voltage of 360V, while the second capacitor bank 808 has a setpoint voltage of 310V. Again, as previously stated, both the first capacitor bank 806 and the second capacitor bank 808 show initial charging at 0.5 seconds and begin excitation every 200ms at 3.5 seconds. In such a system, when no overvoltage is provided, the peak current 812 increases to 7 amps as current draw 810 provides it. Therefore, as shown, Figure 3 and Figure 6 The laser system reduces the peak ampere by almost half. Additionally, compared to the method and system described herein, the first capacitor bank 806 takes an additional 500 ms to reach its initial setpoint. Therefore, when the current limiter is fixed to allow the second capacitor bank 808 to have the same initial charging time, it is insufficient to recharge the first capacitor bank 806 (e.g., the voltage does not reach the desired setpoint once the 200 ms ignition sequence is initiated). Therefore, the current system and method provide significantly improved results.

[0108] at the same time, Figure 9 It shows the relationship with Figure 7 and Figure 8The same circuit is used, except that the peak current is set to allow recharging at ignition. Therefore, the first capacitor bank 906 has a setpoint of 360V, the second capacitor bank 908 has a setpoint of 310V, and both capacitor banks have initial charge at 0.5 seconds and begin firing every 200ms starting at 3.5 seconds. In this case, the peak current 912 of the current consumption 910 is close to 16 amps, or... Figure 6 Methods and Figure 3 The peak current of the laser system is almost four times that of the laser system described herein. Therefore, without a variable current, the initial current charge can provide a peak current of almost 50 amperes compared to 4 amperes using the method described herein and the laser system.

[0109] In summary, by utilizing the overvoltage method described herein, a reduced current consumption is provided compared to methods that provide a setpoint voltage to maintain the same repetition rate. Furthermore, compared to setpoint-based systems, the current method and laser system can have reduced cost and complexity. Therefore, despite the associated costs of current limiters, the current reduction does not occur by providing overvoltage, even with the use of current limiters. Thus, an improved system and method are provided.

[0110] The above references, including block diagrams and operational descriptions of methods and apparatus for photoacoustic probes, describe this system and method. It should be understood that each block in the block diagram or operational illustration, and combinations of blocks in the block diagram or operational illustration, can be implemented by means of analog or digital hardware and computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, ASIC, FPGA, or other programmable data processing device, such that the instructions, executed via the processor of the computer or other programmable data processing device, implement the function / action specified in the block diagram or one or more operational blocks. In some alternative embodiments, the functions / actions indicated in the blocks may not occur in the order shown in the operational illustration. For example, depending on the functions / actions involved, two blocks shown consecutively may actually be executed substantially simultaneously, or these blocks may sometimes be executed in reverse order.

[0111] As used in this specification and the appended claims, unless otherwise stated, “a” or “an” means “at least one” or “one or more”. Additionally, the singular forms “a,” “an,” and “the” include plural indicators unless explicitly stated otherwise. Thus, for example, a reference to a composition containing “a compound” includes a mixture of two or more compounds.

[0112] As used in this specification and the appended claims, the term "or" is generally used in its meaning as including "and / or" unless otherwise expressly stated in the content.

[0113] The numerical ranges described in this article by endpoints include all numbers contained within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0114] Unless otherwise specified, all numerical values ​​of quantities, measures of characteristics, etc., of all expressive elements used in the specification and claims should in all cases be understood to be modified by the term "about," unless the context clearly indicates otherwise. Therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, which may vary according to the desired characteristics sought by those skilled in the art using the teachings of the invention. At least, and without attempting to limit the scope of the claims, each numerical parameter should be interpreted at least according to the number of significant figures reported and by applying ordinary rounding techniques. However, any numerical value inherently contains certain errors, which are necessarily caused by the standard deviation found in their respective test measurements.

[0115] Those skilled in the art will recognize that the methods and systems of this disclosure can be implemented in many ways and are therefore not limited to the foregoing exemplary embodiments and examples. In other words, functional elements and various functions performed by one or more components of various combinations of hardware and software or firmware can be distributed across a software application at the client level or the server level or both. In this regard, any number of features of the different embodiments described herein can be combined into one or more embodiments, and alternative embodiments having fewer or more features than all those described herein are possible. Functionality can also be distributed, in whole or in part, across multiple components in a manner now known or in the future. Thus, numerous software / hardware / firmware combinations are possible in implementing the functions, features, interfaces, and preferences described herein. Furthermore, the scope of this disclosure covers conventionally known methods for performing the described features and functions and interfaces, as well as those variations and modifications that can be made to the hardware or software or firmware components described herein, as those skilled in the art will understand now and thereafter.

[0116] Furthermore, the embodiments of the methods presented and described as flowcharts in this disclosure are provided by way of example to provide a more complete understanding of the technology. The disclosed methods are not limited to the operations and logical flows presented herein. Alternative embodiments are contemplated in which the order of various operations is changed, and in which sub-operations described as part of a larger operation are performed independently.

[0117] Various modifications and alterations to this invention will be apparent to those skilled in the art without departing from its scope and spirit. It should be understood that this invention is not intended to be unduly limited to the specific embodiments and examples described herein, and that these embodiments and examples are provided merely for illustrative purposes. The scope of this invention is intended to be limited only by the appended claims. Therefore, although the invention has been specifically shown and described with reference to preferred embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A photoacoustic probe for photoacoustic imaging of volume, said photoacoustic probe include: A laser system, comprising: A power source configured to provide a constant voltage; A first capacitor bank, coupled to the power source to receive the constant voltage, is configured to supply power to a corresponding first flash lamp when a first defined charge state of the first capacitor bank is reached. The first capacitor bank includes a first closed-loop feedback configured with a first setpoint, the first setpoint determining a first charging time for the first determined charge state; and The first flash is configured to emit a first light along the optical path; and An optical window configured to carry the first light into the volume along the optical path.

2. The photoacoustic probe according to claim 1, wherein, The constant voltage is the first overvoltage input of the first capacitor bank relative to the first set point of the first closed-loop feedback.

3. The photoacoustic probe according to claim 1, wherein, The laser system also includes: A second capacitor bank, coupled to the power source to receive the constant voltage, is configured to supply power to a corresponding second flash lamp when a second defined charge state of the second capacitor bank is reached. The second capacitor bank includes a second closed-loop feedback configured with a second setpoint, the second setpoint determining a second charging time for determining the second charge state; and The second flash is configured to emit a second light along the light path.

4. The photoacoustic probe according to claim 3, wherein, The first set point is different from the second set point.

5. The photoacoustic probe according to claim 3, wherein, The constant voltage is a second overvoltage input of the second capacitor bank relative to the second set point of the second closed-loop feedback.

6. The photoacoustic probe according to claim 3, wherein, The first light from the first flash lamp has a first wavelength, and the second light from the second flash lamp has a second wavelength different from the first wavelength.

7. The photoacoustic probe according to claim 3, wherein, The optical window is also configured to carry the second light into the volume along the optical path.

8. The photoacoustic probe according to claim 3, wherein, The first setpoint is independent of the second setpoint.

9. The photoacoustic probe according to claim 1, further comprising: An ultrasonic transducer, covered by an acoustic lens, is used to receive a signal associated with the first light carried into the volume.

10. A method for imaging a volume using a photoacoustic probe, comprising: A constant voltage is supplied from a power source to a first capacitor bank having a first flash lamp, the first flash lamp emitting first light along an optical path when it reaches a first defined charge state; A first setpoint is used to provide a first closed-loop feedback, wherein the first setpoint is a first voltage that is less than the constant voltage; Wherein, the first determined charging time is based on the first set point; and The first light is carried along the optical path to the optical window of the photoacoustic probe.

11. The method of claim 10, further comprising: The constant voltage is supplied from the power source to the second capacitor bank having the second flash lamp, the second flash lamp emitting second light along the light path when it reaches the second defined charge state; A second setpoint is used to provide a second closed-loop feedback, wherein the second setpoint is a second voltage that is less than the constant voltage; Wherein, the second determination of charging time is based on the second set point; and The second light is carried along the optical path to the optical window of the photoacoustic probe.

12. The method according to claim 11, wherein, The first set point is different from the second set point.

13. The method according to claim 11, wherein, The first light from the first flash lamp has a first wavelength, and the second light from the second flash lamp has a second wavelength different from the first wavelength.

14. The method according to claim 11, wherein, The first setpoint is independent of the second setpoint.

15. A laser system for a photoacoustic probe, comprising: A power source configured to provide a constant voltage; A first capacitor bank, coupled to the power source to receive the constant voltage, and configured to supply power to a corresponding first flash lamp when a first defined charge state of the first capacitor bank is reached; The first capacitor bank includes a first closed-loop feedback configured with a first setpoint, the first setpoint determining a first charging time for the first determined charge state; and Wherein, the first set point has a first voltage that is less than the constant voltage.

16. The laser system according to claim 15, further comprising: A second capacitor bank, coupled to the power source to receive the constant voltage, is configured to supply power to a corresponding second flash lamp when a second defined charge state of the second capacitor bank is reached. The second capacitor bank includes a second closed-loop feedback configured with a second setpoint, the second setpoint determining a second charging time for determining the second charge state; and The second set point has a second voltage that is less than the constant voltage.

17. The laser system according to claim 16, wherein, The first set point is different from the second set point.

18. The laser system according to claim 16, wherein, The first light from the first flash lamp has a first wavelength, and the second light from the second flash lamp has a second wavelength that is different from the first wavelength.

19. The laser system according to claim 16, wherein, The first setpoint is independent of the second setpoint.

20. The laser system according to claim 15, wherein, Changing the first setpoint alters the first charging time without changing the constant voltage of the power supply.

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