Dual gain beam detection

Abstract

Particular embodiments disclosed herein provide a surgical laser system comprising a laser source, a lens, a memory, and a processor in data communication with the memory and configured to execute instructions that cause the processor to control the laser source based on a detection signal received from a circuit. The circuit comprises a first amplifier, a second amplifier, and a switch coupled between the second amplifier and a reference potential node, and a state of the switch is based on an output of a first comparator. The circuit further comprises a second comparator coupled to the second amplifier and a logic gate coupled to the first comparator and the second comparator.

Description

[0001] CLAIM OF PRIORITY

[0002] This application claims the priority benefit of U.S. Provisional Patent Application Serial No. 63 / 090,911, entitled “BEAM DETECTION WITH DUAL GAIN,” filed October 13, 2020, for inventors Conrad Sawicz and Derek Chenn, which is incorporated by reference herein in its entirety as if fully set forth herein, to the extent not inconsistent with the disclosure herein. TECHNICAL FIELD

[0003] The present disclosure relates generally to a surgical laser system, and more particularly, to implementing laser beam detection with dual gain. BACKGROUND

[0004] In a variety of medical procedures, lasers (e.g., an illumination beam, a laser treatment beam (“treatment beam”), a laser aiming beam (“aiming beam”), etc.) are used to assist in surgery and / or to treat patient anatomy. For example, in laser photocoagulation, a laser probe propagates a treatment beam to burn blood vessels at laser burn sites on the retina. The treatment beam is typically transmitted from a surgical laser system through a fiber optic cable that terminates at a proximal end in a port adapter connected to the surgical laser system and at a distal end in a laser probe that is manipulated by a surgeon. It is noted that the distal end of a component refers to the end closer to the patient’s body, while the proximal end of a component refers to the end away from the patient’s body or closer to, for example, the surgical laser system.

[0005] In addition to burning blood vessels at laser burn sites, the treatment beam can also damage rod and cone cells present in the retina that provide vision, thereby affecting vision. Since vision is most acute at the central macula of the retina, the surgeon deploys the laser probe to generate laser burn sites in the peripheral region of the retina. During surgery, the surgeon drives the probe with a non-burning aiming beam to illuminate the region of the retina to be photocoagulated. Due to the availability of low-power red laser diodes, the aiming beam is typically a low-power red laser. Once the surgeon has positioned the laser probe so as to illuminate the desired retinal spot with the aiming beam, the surgeon initiates the treatment beam, either by a foot pedal or other means, to photocoagulate the illuminated region (e.g., or a region surrounding the illuminated region) using the treatment beam. After burning the retinal spot, the surgeon repositions the probe to illuminate a new spot with the aiming beam, initiates the treatment beam to photocoagulate the new spot, repositions the probe, and so on, until a desired number of burn laser spots are distributed across the retina.

[0006] Certain types of laser probes coagulate or burn multiple points at a time, which can enable faster and more effective photocoagulation. For example, a surgical laser system coupled to one of these types of laser probes by an optical fiber can be configured to split a single laser beam into multiple laser beams that exhibit a pattern of laser spots. In such examples, the surgical laser system transmits the multiple laser beams to an optical cable, which can include a multi-fiber array or a multi-core fiber that exhibits a corresponding pattern of optical fibers.

[0007] For diabetic retinopathy, panretinal photocoagulation (PRP) surgery can be performed, and the number of laser coagulations required for PRP is typically large. For example, 1,000 to 1,500 spots are typically burned. Thus, it can be readily appreciated that if the laser probe is a multi-spot probe capable of burning multiple spots at a time, then the coagulation process will be faster (assuming the laser source power is sufficient). Accordingly, multi-spot / multi-fiber laser probes have been developed and described in U.S. Patent Nos. 8,951,244 and 8,561,280, the entire contents of which are incorporated by reference herein as if fully and completely set forth herein. In addition to the aiming beam and the treatment beam, vitreoretinal surgery also benefits from directing an illuminating light or beam onto the eye and retinal tissue. SUMMARY

[0008] The present disclosure relates generally to a surgical laser system, and more particularly, to enabling dual gain laser beam detection.

[0009] Certain embodiments of the present disclosure provide a surgical laser system comprising a laser source configured to propagate a laser beam; a memory comprising executable instructions; and a processor in data communication with the memory and configured to execute the instructions, the instructions causing the processor to control the laser source based on a detection signal received from a circuit. The circuit comprises a first amplifier having an output coupled to an input of a first comparator and an input of a second amplifier; a switch coupled between an input of the second amplifier and a reference potential node, wherein a state of the switch is based on an output of the first comparator; a second comparator having an input coupled to an output of the second amplifier, wherein the first comparator has a first threshold voltage that is greater than a second threshold voltage of the second amplifier; and a logic gate having a first input coupled to an output of the first comparator and a second input coupled to an output of the second comparator. The surgical laser system further comprises a lens configured to focus the laser beam onto an interface plane of a proximal end of an optical fiber coupled to the surgical laser system through a port, wherein a distal end of the optical fiber is configured to project the laser beam onto a target surface.

[0010] Certain embodiments of the present disclosure provide a circuit comprising a first amplifier having an output coupled to an input of a first comparator and an input of a second amplifier; a switch coupled between an input of the second amplifier and a reference potential node, wherein a state of the switch is based on an output of the first comparator; a second comparator having an input coupled to an output of the second amplifier, wherein the first comparator has a first threshold voltage that is greater than a second threshold voltage of the second amplifier, and a logic gate having a first input coupled to an output of the first comparator and a second input coupled to an output of the second comparator.

[0011] Certain embodiments of the present disclosure provide a method of detecting a laser pulse by a circuit, the method comprising receiving the laser pulse at an input of the circuit, generating an electrical signal based on the laser pulse, amplifying the electrical signal, making a first comparison between the amplified electrical signal and a first threshold voltage, wherein when the amplified electrical signal is greater than the first threshold voltage, a switch coupled to a reference potential node is closed. The method further comprises, based on the first comparison, making a second comparison between the amplified signal or the reference potential node and a second threshold voltage, wherein the first threshold voltage is greater than the second threshold voltage; amplifying an output generated by the second comparison; and generating a signal indicating detection of the laser pulse based on at least one of the output of the first comparison and the amplified output of the second comparison.

[0012] The following description and associated drawings set forth certain illustrative features of one or more embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0013] The accompanying drawings depict certain aspects of one or more embodiments, and should not be used to limit or impose upon the scope the present disclosure.

[0014] Figure 1 An exemplary system for laser beam detection with dual gain beam detection is shown in accordance with certain aspects of the present disclosure.

[0015] Figure 2 An example of a surgical laser system with dual gain beam detection and components therein is shown in accordance with certain aspects of the present disclosure.

[0016] Figure 3 An exemplary circuit for laser beam detection with dual gain beam detection is shown in accordance with certain aspects of the present disclosure.

[0017] Figure 4 A flowchart showing exemplary operations for detecting a laser pulse by a circuit in accordance with certain aspects of the present disclosure.

[0018] For ease of understanding, the same reference numbers are used in different drawings to designate the same or similar elements. It is contemplated that elements and features of one embodiment can be beneficially incorporated into other embodiments without further recitation. DETAILED DESCRIPTION

[0019] Aspects of the present disclosure provide a surgical laser system having a laser beam detection circuit with dual gain.

[0020] Exemplary surgical laser system

[0021] Figure 1An exemplary system 100 having laser beam detection with dual gain implemented is shown in accordance with certain embodiments. The system 100 includes a surgical laser system 102 having one or more laser sources for generating laser beams used during ophthalmic surgery. For example, a first laser source within the surgical laser system 102 can generate a treatment beam having a first wavelength (e.g., about 532 nanometers (nm)), while a second laser source can generate an aiming beam having a second wavelength (e.g., about 635 nm). A user, such as a surgeon, can first trigger the surgical laser system 102 (e.g., via a footswitch, voice command, etc.) to emit the aiming beam onto a desired retinal point. Once the surgeon has positioned the laser probe so as to illuminate the desired retinal point with the aiming beam, the surgeon initiates the treatment beam, such as by a foot pedal or other means, to treat the patient anatomical structure (e.g., photocoagulate the desired retinal point using the treatment beam).

[0022] As shown, the surgical laser system 102 includes a connector or port adapter 114 coupled to an optical port of the surgical laser system 102. Figure 1 Also shown is a cable 110 having a distal end coupled to and extending through the probe 108 and a proximal end coupled to and extending through the port adapter 114. In some cases, as described further herein, the cable 110 can include more than one cable. Figure 1 In the example shown, the port adapter 114 includes a ferrule having an opening that allows the laser beam from the surgical laser system 102 to propagate into an interface plane (also referred to as a proximal incidence plane) of the proximal end of the cable 110. In some examples, the surgical laser system 102 can include more than one port adapter. The interface plane of the proximal end of the cable 110 includes exposed proximal ends of one or more cores to which the laser beam can be directed. In some examples, the interface plane of the proximal end of the cable 110 includes exposed proximal ends of all cores of the cable 110. Figure 1 In the example shown, the cable 110 is a multi-core fiber cable (MCF) having four cores. As such, the interface plane of the proximal end of the cable 110 includes proximal ends of the four cores exposed through the opening of the ferrule.

[0023] The surgical laser system 102 can be configured to split a single laser beam generated by the laser source into multiple laser beams exhibiting a pattern of laser spots. For example, the surgical laser system 102 can split the aiming beam into four aiming beams and then deliver the four aiming beams through the openings of the ferrule of the port adapter 114 to the interface plane of the cable 110. The surgical laser system 102 can be further configured to split the treatment beam into four treatment beams and deliver the four treatment beams through the openings of the ferrule to the interface plane of the cable 110. In this example, each core of the cable 110 will transmit a multi-wavelength or combined beam, which can refer to the treatment beam combined with the aiming beam. While certain aspects are described with respect to the cable cores transmitting a combined beam, note that the cores of the cable 110 can also transmit the treatment beam or the aiming beam individually, depending on which beam is activated and incident on the cable 110.

[0024] In some examples, the surgical laser system 102 can also propagate an illumination beam into the interface plane of the cable 110 (e.g., the cable can also include a proximal end of a cladding that holds the cores within the cable 110) in order to illuminate the interior of the eye, particularly the area of the retina 120 to be photocoagulated. In certain aspects, the illumination beam can be propagated by a white light emitting diode (LED).

[0025] The cable 110 delivers the combined beam to the probe 108, which propagates the multi-spot pattern (e.g., four spots) of the combined beam to the retina 120 of the patient eye 125. The probe 108 includes a probe body 112 that houses and protects the distal end of the cable 110 and a probe tip 140. The distal portion 145 of the probe tip 140 can also house a lens that focuses the combined beam on the retina 120.

[0026] Various systems can implement dual gain laser detection circuitry. Figure 2 One example of a surgical laser system 202 and components therein that can implement beam detection circuitry with dual gain is shown. The surgical laser system 202 includes a laser source 204 that propagates a treatment beam 210, laser sources 206, 236 that respectively propagate aiming beams 212, 240, a light source 208 that propagates an illumination beam 214, a port selector 219, and beam detection circuitry 207, 216.

[0027] At the beginning of a procedure, a surgeon can activate the light source 208 to illuminate the interior of the eye and make it easier to view the retina. As shown, once emitted by the light source 208, the illumination beam 214 (dotted section) is received by the collimating lens 222, which is configured to produce a beam of light having parallel rays. In certain embodiments, the collimating lens 222 can be a multi-element achromatic lens comprising two singlets and one doublet. Thus, as shown, the illumination beam 214 exits with parallel rays from the other side of the collimating lens 222 and passes through the beam splitter 226 to the converging lens 224B. In certain embodiments, the converging lens 224B can be a multi-element achromatic lens comprising two singlets and one doublet. In such embodiments, the converging lens 224B has the same design as the collimating lens 222 except that the components are inverted (e.g., rotated 180 degrees), thereby creating a one-to-one magnification imaging system. The beam splitter 226 can have different coatings on both sides 226a and 226b of the beam splitter. For example, side 226a is coated so that it allows light propagating on that side to pass through the beam splitter 226. As such, the illumination beam 214 propagating onto side 226a passes through the beam splitter 226. On the other hand, side 226b is coated to reflect light or laser beams, such as the treatment beam 210 and the aiming beam 212, as further described below. Note, however, that a negligible portion of the illumination beam 214 is reflected by side 226a onto a sensor 227, which is configured to sense the illumination beam 214.

[0028] The converging lens 224B then converges the illumination beam 214 into the interface plane of the proximal end of the cable (such as cable 110B) that is coupled to the port 225B of the surgical laser system 202 through the port adapter 114B. As described with respect to Figure 1 the cable 110B can have four cores. As such, the converging lens 224B focuses the illumination beam 214 into the interface plane of the cable 110B so that the illumination beam 214 propagates along the entire length of each of the four cores of the cable 110B to the distal end of the surgical probe (e.g., the probe 108 of FIG. 1) that is coupled to the cable 110B. Figure 1 As described above, the interface plane of each cable 110A, 110B includes the proximal ends of the four cores of the cable 110 that are exposed via the ferrules 215A, 215B through the openings 217A, 217B of the port adapters 114A, 114B, respectively.

[0029] Once the surgeon has access to the inside of the eye, they can project one or more desired aiming beams onto the retina from the distal end of the probe. More specifically, after initiation by the surgeon, laser source 206 emits aiming beam 212 onto beam splitter 218, which reflects aiming beam 212 onto diffractive optics (DOE) 220. Similarly, laser source 236 emits aiming beam 240 onto beam splitter 221, which directs a portion of aiming beam 240 toward converging lens 224A, which focuses aiming beam 240 onto the interface plane of cable 110A, such that aiming beam 240 propagates along the entire length of each core of cable 110A to the surgical probe coupled to cable 110A (e.g., Figure 1 The distal end of probe 108. The diffraction segment may also be referred to as the "segment" in this paper. Figure 2 In the example, DOE 220 is positioned such that aiming beam 212 is aligned with the middle section of DOE 220, which diffracts aiming beam 212 into several aiming beams (e.g., four aiming beams). However, the surgeon can change the position of DOE 220 to diffract the beam into a different number of beams (e.g., two or one). For example, using voice commands or some other feature of the surgical laser system 202, the surgeon can position DOE 220 to align aiming beam 212 with different sections of DOE 220, which can diffract aiming beam 212 into two, one, or another number of beams.

[0030] Once diffracted, the resulting aiming beam is reflected by beam splitter 226 onto converging lens 224B. Converging lens 224B then focuses the four aiming beams onto the interface plane at the proximal end of cable 110B, such that each aiming beam propagates along the entire length of its corresponding core to the surgical probe (e.g., Figure 1 The distal end of the probe (108) allows the surgeon to project four desired targeting beam points onto the retina from the distal end of the probe.

[0031] As described above, once the surgeon has positioned and activated the laser probe to project the aiming beam point onto the retina, the surgeon activates the laser source 204, for example via a foot pedal or other device, to address the patient's anatomy (e.g., photocoagulate the desired retinal point using the therapeutic beam). Upon activation, the laser source 204 emits a polarized therapeutic beam 210, the polarization axis of which can be altered by a polarization rotator 232. For example, in some embodiments, the polarization rotator 232 filters the therapeutic beam 210 to produce a vertically polarized therapeutic beam, which is s-polarized relative to the incident plane of the beam splitter 226.

[0032] Polarizing the treatment beam 210 can be advantageous because the beam splitter 226 can have a coating that is sensitive to polarization such that, for example, s-polarized light beams can be reflected off the beam splitter 226 with less wavelength broadening. As described above, the beam splitter 226 is coated such that the beam splitter allows the illumination beam 214 to pass through while reflecting the treatment beam 210 and the aiming beam 212. Thus, to provide the surgeon with a high quality and throughput illumination beam 214A, it is advantageous to polarize the treatment beam 210, which allows the beam splitter 226 to isolate and reflect the treatment beam 210 with a narrower wavelength band.

[0033] The surgical laser system can also include a shutter 234 disposed between the laser source 204 and the port selector 219. The shutter 234 can be configured to alternately block or allow the treatment laser beam from reaching the port selector 219. The surgeon or surgical staff can control the shutter 234 (e.g., via a foot pedal, a voice command, etc.) to emit the laser aiming beam and to fire the treatment laser beam (i.e., open the shutter 234) to treat the patient anatomy (e.g., photocoagulation). In each case, the beam splitter 221 and the beam splitter 218 can direct the laser beam to the first port adapter 114A and the second port adapter 114B, respectively.

[0034] Once polarized, the treatment beam 210 reaches the beam splitter 213, which is configured to allow a majority of the treatment beam 210 to pass through while reflecting an insignificant portion 231 onto a sensor 223. The sensor 223 is a light sensor configured to detect whether the laser source 204 is active. After passing through the beam splitter 213 and as long as the shutter 234 is in an open position to allow the treatment beam 210 to enter, the treatment beam 210 is received at the port selector 219, which is configured to reflect the treatment beam 210 onto the beam splitter 218 or the beam splitter 221. The beam splitter 218 is configured to reflect an insignificant portion 233 of the treatment beam 210 onto a beam detection circuit 216 while allowing a majority of the treatment beam 210 to pass through. As described further herein, the beam detection circuit 216 is a light sensing circuit that is implemented with dual gain. The beam splitter 221 is configured to reflect a portion of the treatment beam 210 onto a focusing lens 224A while allowing another portion of the treatment beam 210 to pass through to a beam detection circuit 207, which can be similar to the beam detection circuit 216.

[0035] As shown, linearly polarized treatment beam 210 passes through beamsplitter 221 at an angle relative to beamsplitter 221 that is equal to the angle at which aiming beam 240 passes through beamsplitter 221. Thus, once laser source 204 is active, the transmitted treatment beam 210 combines (e.g., so that they overlap one another) with the reflected aiming beam 240, creating a combined beam 242 that subsequently reaches converging lens 224A. Converging lens 224A focuses combined beam 242 onto an interface plane at the proximal end of cable 110A, such that combined beam 242 propagates along the entire length of the core of cable 110A to the distal end of the surgical probe (e.g., probe 108) of FIG. 1. Figure 1

[0036] As shown, linearly polarized treatment beam 210 passes through beamsplitter 218 at an angle relative to beamsplitter 218 that is equal to the angle at which aiming beam 212 is reflected by beamsplitter 218. Thus, once laser source 204 is active, the transmitted treatment beam 210 combines (e.g., so that they overlap one another) with the reflected aiming beam 212, creating a combined beam 211 that subsequently reaches DOE 220. DOE 220 then diffracts combined beam 211 into combined beams 211a-211d. Each of combined beams 211a-211d is a diffracted treatment beam that overlaps a diffracted aiming beam.

[0037] Combined beams 211a-211d are then received at beamsplitter 226, which reflects combined beams 211a-211d onto converging lens 224B. Converging lens 224B focuses combined beams 211a-211d onto an interface plane at the proximal end of cable 110B, such that each combined beam 211a-211d propagates along the entire length of a corresponding core of cable 110B to the distal end of the surgical probe (e.g., probe 108) of FIG. 1. More specifically, in the example of FIG. 1, cable 110B is an MCF having four cores (such as cores A, B, C, and D). In such examples, converging lens 224B focuses combined beams 211a-211d onto the interface plane at the proximal end of cable 110B such that, for example, combined beam 211a propagates onto core A, combined beam 211b propagates onto core B, combined beam 211c propagates onto core C, and combined beam 211d propagates onto core D. Figure 1 Figure 2

[0038] Example dual-gain beam detection

[0039] ​​​Aspects of the present disclosure provide a surgical laser system having a laser beam detection circuit that achieves dual gain. Specifically, certain aspects provide techniques for measuring pulse duration, such as short (e.g., 50 ps (picoseconds)) laser pulses that can have a wide dynamic range (e.g., 1 mW (milliwatt) to 3.3 W (watts)).

[0040] Currently, measuring short laser pulses can be accomplished with circuits that typically ignore the pulse amplitude by limiting the circuit gain only. Gain limiting circuits typically have a recovery time (e.g., 10 ps or longer) that takes up a large portion of the laser pulse duration (e.g., 50 ps). Thus, this recovery time can cause an error in measuring the actual laser pulse duration. A photodiode beam detector can be implemented in such circuits, typically for two different purposes. The first purpose is to detect the laser pulse when it is on to verify that the laser beam is being steered to the correct output port. The duration of the detection signal can be measured to verify the pulse duration. The second purpose is to detect unwanted outputs, which can occur when using micro-pulse generation pulses. For example, laser energy can be directed to an incorrect port, or the laser appears to be on when it should be off. In medical procedures involving laser beams, improper or inaccurate detection of the laser beam can cause harm to the patient.

[0041] The dynamic range of the laser beam can be large. That is, the maximum output can be as high as 3.3 W, and as low as 1 mW. Adapting to the relatively large dynamic range of the laser beam can be further complicated by the uncertainty of a beam splitter used to sample the laser beam itself. For example, manufacturing variations of the beam splitter can be as high as 100%. It is desirable for the circuit used to detect the output of the photodiode that receives the laser pulse to be able to handle the large dynamic range while still being able to accurately measure the pulse duration.

[0042] Conventional gain limiting circuits typically impact the ability of the circuit to accurately measure the pulse duration. There are several ways to amplify the photodiode signal; however, high speed response is typically best achieved using a trans-impedance (TIM) amplifier. As long as the amplifier stays within its operating limits, the pulse fidelity is typically high. However, when the output signal is too large, the amplifier can saturate, resulting in an unpredictable or very long recovery time. A Zener diode can be used to limit the voltage gain to the gain of the Zener diode breakdown voltage, but the saturation recovery time of the Zener diode can be equal to or greater than 10 ps. Thus, to make a correct and accurate pulse measurement, a circuit is needed that can handle the dynamic range of the laser beam and not saturate.

[0043] Accordingly, certain aspects of the present disclosure provide techniques for implementing a dual-gain optical beam detection circuit. In particular, certain aspects involve using two amplifiers with different gains in series in an optical beam detection circuit. The gain of the first amplifier can be set such that the largest laser pulse will be within the operating limits of the first amplifier. The second amplifier can have a gain to further amplify the signal such that low amplitude pulses can be measured by the circuit. The output of the first amplifier can control a switch that can be configured to block the signal to the second amplifier when a large pulse (e.g., greater than a threshold voltage) is detected. In other words, the output from the first amplifier can be shunted (e.g., shorted) to a reference potential node (e.g., ground). By blocking the signal to the second amplifier, the second amplifier can be prevented from exceeding its operating limits when a particularly large signal passes through the circuit. In certain aspects, the output of the first amplifier and / or the second amplifier can be used to measure the pulse duration such that switching the amplifiers does not affect the measurement. In other words, implementing an optical beam detection circuit with two amplifiers in the manner described above allows for more accurate detection of a laser beam.

[0044] Figure 3 An exemplary circuit 300 implementing dual-gain optical beam detection is shown. As shown, the circuit 300 can include a photodiode 302, amplifiers 304, 310, comparators 308, 312, a switch 314, a resistor 318, and a logic gate 322.

[0045] As shown, the photodiode 302 can be coupled between an input of the amplifier 304 and a reference potential node 316 (e.g., electrical ground). In some embodiments, the reference potential node 316 can instead be a voltage or current source. Another input of the amplifier 304 can be coupled to the reference potential node 316. In certain aspects, the amplifier 304 can amplify the photodiode signal as much as possible without exceeding the operating limits of the amplifier 304. The output of the amplifier 304 can be coupled to an input of the amplifier 310, which can have another input coupled to the reference potential node 316. In certain aspects, the gain of the amplifier 310 can be greater than the gain of the amplifier 304. As shown, a resistor 318 can be coupled between the amplifiers 304, 310. Further, a switch 314 can be coupled between a node 319 (between the resistor 318 and the amplifier 310) and the reference potential node 316.

[0046] The output of amplifier 304 can be coupled to an input of comparator 308, and the input can be compared to voltage VI. As shown, the output of amplifier 310 can be coupled to an input of comparator 312, and the input can be compared to voltage V2. In certain aspects, VI can be greater than V2, and V2 can be selected to be large enough (e.g., a value that is exceeded when a laser pulse exceeds 1 mW) so that noise does not cause a false trigger. VI can be selected to be greater than V2 because comparator 312 can be configured to detect low power beams (e.g., laser beams as low as 1 mW) and can saturate due to higher power beams, while comparator 308 can be configured to detect higher power beams without saturating (e.g., laser beams as high as 3.3 W). If the input to comparator 308 exceeds voltage VI, then comparator 308 can output a logic high voltage signal (e.g., 3.3 V or 5 V) to logic gate 322 and switch 314, as shown by dashed line 320. If the input to comparator 312 exceeds voltage V2, then comparator 312 can output a logic high voltage signal (e.g., 3.3 V or 5 V) to logic gate 322. For example, when the output of comparator 308 is logic high, switch 314 can close and couple (e.g., short) the input of amplifier 310 to reference potential node 316. In certain aspects, logic gate 322 can be an OR gate, or any other suitable logic gate.

[0047] In certain aspects, it can be advantageous to amplify the photodiode signal so that a signal of approximately 1 mW exceeds the threshold. However, a signal with significantly more than 1 mW of power (e.g., a high-level signal) when amplified by the amplifier 304 will cause the amplifier 310 to exceed its operating limits. Thus, the voltage VI of the comparator 308 can be selected so that VI is less than the saturation voltage of the amplifier 310. When a high-level signal is subsequently passed through the circuit 300, such a signal can cause a logic high output of the comparator and subsequently close the switch 314 before the amplifier 310 reaches the saturation voltage. A low-level laser pulse (e.g., a low-power laser pulse) can be applied to the photodiode and amplified by both of the amplifiers 304, 310. This technique can prevent the amplifier 310 from being significantly overloaded, so the amplifier 310 can return to zero output, for example, quickly enough not to affect the pulse measurement. Because the amplifier 304 has a finite rise time, the comparator 312 can output a logic high signal before the signal has a sufficient amplitude to trigger the comparator 308 and thus cause the switch 314 to close. In the event that one or more of the comparators 308, 312 output a logic high signal, the logic gate 322 can output a logic high signal. The output of the logic gate 322 can cause a timer to start, for example, to measure the duration of the laser pulse. Thus, for both large and small amplitude pulses (e.g., high-level or low-level signals), the start of the laser pulse can be measured with similar accuracy. In some embodiments, the laser pulse can be timed and / or controlled independently of the circuit 300. For example, this can be done by a shutter (e.g., the shutter 234 of Figure 2 FIG. 1) or a power supply. In such a case, the circuit 300 can serve as a double check for laser pulse timing. Furthermore, in some examples of independent pulse timing / control, the timing of the photodiode can be measured by two independent circuits so that the clock used to create / measure the pulse is independent.

[0048] Figure 4 is a flowchart illustrating exemplary operations 400 for detecting a laser pulse by a circuit. The operations 400 can be understood and implemented in the context of the circuit 300 of Figure 3 FIG. 1.

[0049] At block 405, the operations 400 begin by receiving a laser pulse at an input of the circuit. At 410, the circuit generates an electrical signal based on the laser pulse (e.g., via the photodiode 302). At 415, the circuit amplifies the electrical signal (e.g., via the amplifier 304).

[0050] At 420, the circuit makes a first comparison (e.g., via comparator 308) between the amplified electrical signal and a first threshold voltage (e.g., voltage VI), where when the amplified electrical signal is greater than the first threshold voltage, a switch (e.g., switch 314) coupled to a reference potential node (e.g., reference potential node 316) is closed.

[0051] At 425, based on the first comparison, the circuit (e.g., via amplifier 310) again amplifies the amplified electrical signal or a voltage associated with the reference potential node. In certain aspects, the amplified electrical signal can be amplified again when the voltage of the amplified electrical signal is less than the first threshold voltage. When the voltage of the amplified electrical signal is greater than the first threshold voltage, the amplified electrical signal is coupled to the reference potential, effectively shunting / shorting the amplified electrical signal. Thus, the amplified electrical signal is not passed to the second amplifier. Rather, therefore, a voltage associated with the reference potential node (e.g., ground) can be input to the second amplifier.

[0052] At 430, based on the first comparison, the circuit performs a second comparison (e.g., via comparator 312) between the amplified electrical signal or a voltage associated with the reference potential node and a second threshold voltage (e.g., voltage V2), where the first threshold voltage is greater than the second threshold voltage.

[0053] At 435, the circuit generates (e.g., via logic gate 322) a signal indicating detection of a laser pulse based on at least one of an output of the first comparison and an output of the second comparison.

[0054] The foregoing description is provided for purposes of illustration and is not intended to limit the various embodiments as described herein. Multiple variations of the embodiments described herein are possible, and some of these are described, and others are omitted so as to not obscure the novelty of the various embodiments. The order or sequence of any process or method can be different, and the use or type of any specific elements can be changed by those skilled in the art depending on the particular device or feature. Certain embodiments can be implemented in software, hardware, or a combination thereof. The various embodiments disclosed herein can be implemented as computer programs or program modules including, but not limited to, wireless communication modules, firmware, resident software, microcode, etc. Furthermore, the various embodiments can take other forms that are within the scope of the embodiments as described herein. Accordingly, the claims are not intended to be limited to the precise embodiments disclosed herein.

[0055] Exemplary Embodiments

[0056] Embodiment 1: A surgical laser system comprising a laser source configured to propagate a laser beam; a memory comprising executable instructions; a processor in data communication with the memory and configured to execute the instructions, the instructions causing the processor to control the laser source based on a detection signal received from a circuit. The circuit comprises: a first amplifier having an output coupled to an input of a first comparator and an input of a second amplifier; a switch coupled between an input of the second amplifier and a reference potential node, wherein a state of the switch is based on an output of the first comparator; a second comparator having an input coupled to an output of the second amplifier, wherein the first comparator has a first threshold voltage that is greater than a second threshold voltage of the second amplifier; and a logic gate having a first input coupled to an output of the first comparator and a second input coupled to an output of the second comparator. The surgical laser system further comprises a lens configured to focus the laser beam onto an interface plane of a proximal end of an optical fiber coupled to the surgical laser system through a port, wherein a distal end of the optical fiber is configured to project the laser beam onto a target surface.

[0057] Embodiment 2: The surgical laser system of embodiment 1, wherein the circuit further comprises a photodiode coupled between an input of the first amplifier and the reference potential node, the photodiode configured to receive the laser beam.

[0058] Embodiment 3: The surgical laser system of embodiment 1 or 2, wherein the processor is configured to start a timer when the processor receives the detection signal from the circuit, and the processor is configured to stop propagation of the laser beam when the timer reaches a timing threshold.

[0059] Embodiment 4: The surgical laser system of any of embodiments 1-3, wherein the processor is configured to stop propagation of the laser beam in addition to when it is determined based on the detection signal that: the laser beam is directed to the port; the laser beam is propagated when the surgical laser system is instructed to propagate the laser beam and is not propagated when the surgical system is not instructed to propagate the laser beam; and the laser beam is propagated for a threshold duration of time.

[0060] Embodiment 5: The surgical laser system of any of embodiments 1-4, further comprising a photodiode coupled between an input of the first amplifier and the reference potential node.

[0061] Embodiment 6: The surgical laser system of any of embodiments 1-5, wherein the first amplifier has a first gain that is less than a second gain of the second amplifier.

[0062] Embodiment 7: The surgical laser system of any of embodiments 1-6, wherein a saturation voltage level of the second amplifier is greater than a first threshold voltage of the first comparator.

[0063] Embodiment 8: The surgical laser system of any of embodiments 1-7, wherein a second threshold voltage of the second comparator is at least 1 mW.

[0064] Embodiment 9: The surgical laser system of any of embodiments 1-8, wherein the switch is configured to short the input of the second amplifier to the reference potential node if a voltage at the input of the first comparator exceeds the first threshold voltage of the first comparator.

[0065] Embodiment 10: The surgical laser system of any of embodiments 1-9, wherein the switch is one of an analog switch or a metal oxide semiconductor field effect transistor (MOSFET).

[0066] Embodiment 11: The surgical laser system of any of embodiments 1-10, wherein the first amplifier is a transimpedance amplifier.

[0067] Embodiment 12: The surgical laser system of any of embodiments 1-11, wherein the logic gate is an OR gate.

[0068] Embodiment 13: The surgical laser system of any of embodiments 1-12, further comprising a resistor coupled between an output of the first amplifier and an input of the second amplifier.

[0069] Embodiment 14: A method of detecting a laser pulse by a circuit, the method comprising: receiving the laser pulse at an input of the circuit; generating an electrical signal based on the laser pulse; amplifying the electrical signal; making a first comparison between the amplified electrical signal and a first threshold voltage, wherein when the amplified electrical signal is greater than the first threshold voltage, a switch coupled to a reference potential node is closed; based on the first comparison: amplifying the amplified electrical signal again; or shunting the amplified electrical signal to the reference potential node; when the amplified electrical signal is amplified again, making a second comparison between the amplified electrical signal and a second threshold voltage, wherein the first threshold voltage is greater than the second threshold voltage; and generating a signal indicating that the laser pulse is detected based on at least one of an output of the first comparison and an output of the second comparison.

[0070] Embodiment 15: A circuit, the circuit comprising: a first amplifier having an output coupled to an input of a first comparator and an input of a second amplifier; a switch coupled between an input of the second amplifier and a reference potential node, wherein a state of the switch is based on an output of the first comparator; a second comparator having an input coupled to an output of the second amplifier, wherein the first comparator has a first threshold voltage that is greater than a second threshold voltage of the second amplifier; and a logic gate having a first input coupled to an output of the first comparator and a second input coupled to an output of the second comparator.

[0071] Embodiment 16: The circuit of embodiment 15, further comprising a photodiode coupled between an input of the first amplifier and the reference potential node.

[0072] Embodiment 17: The circuit of embodiment 15 or 16, wherein the first amplifier has a first gain that is less than a second gain of the second amplifier.

[0073] Embodiment 18: The circuit of any one of embodiments 15 to 17, wherein a saturation voltage level of the second amplifier is greater than the first threshold voltage of the first comparator.

[0074] Embodiment 19: The circuit of any one of embodiments 15 to 18, wherein the second threshold voltage of the second comparator is at least 1 mW.

[0075] Embodiment 20: The circuit of any one of embodiments 15-19, wherein the switch is configured to short the input of the second amplifier to the reference potential node if a voltage at the input of the first comparator exceeds a first threshold voltage of the first comparator.

[0076] Embodiment 21 : The circuit of any one of embodiments 15-20, wherein the switch is one of an analog switch or a metal oxide semiconductor field effect transistor (MOSFET).

[0077] Embodiment 22: The circuit of any one of embodiments 15-21, wherein the first amplifier is a transimpedance amplifier.

[0078] Embodiment 23: The circuit of any one of embodiments 15-22, wherein the logic gate is an OR gate.

[0079] Embodiment 24: The circuit of any one of embodiments 15-23, further comprising a resistor coupled between an output of the first amplifier and an input of the second amplifier.

Claims

1. A surgical laser system, comprising: a laser source configured to propagate a laser beam; a memory comprising executable instructions; a processor in data communication with the memory and configured to execute the instructions, the instructions causing the processor to control the laser source based on a detection signal received from a circuit, the circuit comprising: a first amplifier having an output coupled to an input of a first comparator and an input of a second amplifier; a switch coupled between an input of the second amplifier and a reference potential node, wherein a state of the switch is controlled based on an output of the first comparator; a second comparator having an input coupled to an output of the second amplifier, wherein the first comparator has a first threshold voltage that is greater than a second threshold voltage of the second comparator; and a logic gate having a first input coupled to an output of the first comparator and a second input coupled to an output of the second comparator, wherein an output of the logic gate is the detection signal; a lens configured to focus the laser beam onto an interface plane of a proximal end of an optical fiber coupled to the surgical laser system through a port, wherein a distal end of the optical fiber is configured to project the laser beam onto a target surface.

2. The surgical laser system of claim 1, wherein, the circuit further comprising a photodiode coupled between an input of the first amplifier and the reference potential node, the photodiode configured to receive the laser beam.

3. The surgical laser system of claim 1, wherein: the processor is configured to start a timer when the processor receives the detection signal from the circuit; and the processor is configured to stop propagation of the laser beam when the timer reaches a timing threshold.

4. The surgical laser system of claim 1, wherein, the processor is configured to stop propagation of the laser beam in addition to when it is determined based on the detection signal that: the laser beam is directed to the port; the laser beam is propagated when the surgical laser system is instructed to propagate the laser beam and is not propagated when the surgical laser system is not instructed to propagate the laser beam; and the laser beam is propagated for a threshold duration of time.

5. A method of detecting a laser pulse by a circuit, comprising: receiving the laser pulse at an input of the circuit; generating an electrical signal based on the laser pulse; amplifying the electrical signal; making a first comparison between the amplified electrical signal and a first threshold voltage, wherein a switch coupled to a reference potential node is closed when the amplified electrical signal is greater than the first threshold voltage; based on the first comparison: amplifying the amplified electrical signal again; or shunting the amplified electrical signal to the reference potential node; when the amplified electrical signal is amplified again, making a second comparison between the amplified again electrical signal and a second threshold voltage, wherein the first threshold voltage is greater than the second threshold voltage; and generate a signal indicating detection of the laser pulse based on at least one of an output of the first comparison and an output of the second comparison.

6. A circuit comprising: a first amplifier having an output coupled to an input of a first comparator and an input of a second amplifier; a switch coupled between an input of the second amplifier and a reference potential node, wherein a state of the switch is controlled based on an output of the first comparator; a second comparator having an input coupled to an output of the second amplifier, wherein the first comparator has a first threshold voltage that is greater than a second threshold voltage of the second comparator; and a logic gate having a first input coupled to an output of the first comparator and a second input coupled to an output of the second comparator.

7. The circuit of claim 6, further comprising a photodiode coupled between an input of the first amplifier and the reference potential node.

8. The circuit of claim 6, wherein, the first amplifier has a first gain that is less than a second gain of the second amplifier.

9. The circuit of claim 6, wherein, a saturation voltage level of the second amplifier is greater than the first threshold voltage of the first comparator.

10. The circuit of claim 6, wherein, the second threshold voltage of the second comparator is a value that is exceeded when the circuit detects a laser beam having a power of at least 1 mW.

11. The circuit of claim 6, wherein, the switch is configured to short the input of the second amplifier to the reference potential node if a voltage at the input of the first comparator exceeds the first threshold voltage of the first comparator.

12. The circuit of claim 6, wherein, the switch is one of an analog switch or a metal oxide semiconductor field effect transistor (MOSFET).

13. The circuit of claim 6, wherein, the first amplifier is a transimpedance amplifier.

14. The circuit of claim 6, wherein, the logic gate is an OR gate.

15. The circuit of claim 6, further comprising a resistor coupled between an output of the first amplifier and an input of the second amplifier.

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