Dual-gain beam detection

Abstract

Certain 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 configured to execute instructions that cause the processor to control the laser source based on a detection signal received from a circuit comprising: a first amplifier, a second amplifier, and a switch coupled between the second amplifier and a reference potential node, the switch having a state 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

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 090,911, entitled "BEAM DETECTION WITH DUAL GAIN," filed October 13, 2020, inventors Conrad Sawicz and Derek Chen, which is incorporated herein by reference in its entirety as if fully and completely set forth herein.

[0002] The present disclosure relates generally to surgical laser systems, and more particularly to laser beam detection implemented with dual gain. [Background technology]

[0003] In a wide variety of medical procedures, laser light (e.g., an illumination beam, a laser treatment beam ("treatment beam"), a laser aiming beam ("aiming beam"), etc.) is used to assist in surgery and / or treat a patient's body. For example, in laser photocoagulation, a laser probe propagates a treatment beam to ablate blood vessels on the retina at a laser burn spot. The treatment beam is typically transmitted from the surgical laser system via a fiber optic cable that terminates proximally in a port adapter that connects to the surgical laser system and distally in a laser probe operated by the surgeon. It should be noted that, as used herein, the distal end of a component refers to the end closer to the patient's body, and the proximal end of a component refers to the end away from the patient's body, or closer to the surgical laser system, for example.

[0004] In addition to cauterizing blood vessels at the laser burn spot, the treatment beam may also damage some of the rods and cones in the retina that provide vision, thereby affecting vision. Because vision is most acute in the macula, the center of the retina, the surgeon positions the laser probe to generate the laser burn spot in the peripheral part of the retina. During surgery, the surgeon operates the probe using a non-burning aiming beam to illuminate the retinal area to be photocoagulated. Due to the availability of low-power red laser diodes, the aiming beam is typically low-power red laser light. Once the surgeon has positioned the laser probe to illuminate the desired retinal spot with the aiming beam, the surgeon activates the treatment beam via a foot pedal or other means to photocoagulate the illuminated area (or, for example, an area surrounding the illuminated area) with the treatment beam. After burning a spot on the retina, the surgeon repositions the probe to illuminate a new spot with the aiming light, activates the treatment beam to photocoagulate the new spot, repositions the probe, and so on, distributing the desired number of burned laser spots on the retina.

[0005] Some laser probes can coagulate or burn multiple spots at once, making photocoagulation faster and more efficient. For example, a surgical laser system coupled to one such laser probe via an optical fiber can be configured to split a single laser beam into multiple laser beams that exhibit a laser spot pattern. In such an example, the surgical laser system sends the multiple laser beams down an optical cable, which may comprise an array of multiple optical fibers or a multicore fiber that exhibits a corresponding fiber pattern.

[0006] In cases of diabetic retinopathy, panretinal photocoagulation (PRP) may be performed, and the number of laser photocoagulation treatments required in PRP is generally high. For example, 1,000 to 1,500 spots are typically burned. Therefore, it is easy to understand that if the laser probe is a multi-spot probe capable of burning multiple spots at once (assuming the laser source has sufficient power), the photocoagulation treatment will be faster. Accordingly, multi-spot / multi-fiber laser probes are developed and described in U.S. Patent Nos. 8,951,244 and 8,561,280, which are incorporated herein by reference in their entireties as if fully and completely set forth herein. In addition to the aiming and treatment beams, directing an illumination light or beam into the eye or onto retinal tissue is also useful in vitreoretinal surgery. Summary of the Invention [Means for solving the problem]

[0007] The present disclosure relates generally to surgical laser systems, and more particularly to laser beam detection implemented with dual gain.

[0008] Certain embodiments of the present disclosure provide a surgical laser system comprising: a laser source configured to propagate a laser beam; a memory containing 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 comprising: a first amplifier having an output coupled to an input of the first comparator and an input of a second amplifier; a switch coupled between the input of the second amplifier and a reference potential node, the switch state being based on the output of the first comparator; a second comparator having an input coupled to the output of the second amplifier, the first comparator having a first threshold voltage greater than a second threshold voltage of the second amplifier; and a logic gate having a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator. The surgical laser system further comprises a lens configured to focus the laser beam onto an interface surface of a proximal end of an optical fiber coupled to the surgical laser system via a port, the distal end of the optical fiber being configured to project the laser beam onto a target surface.

[0009] Certain embodiments of the present disclosure provide a circuit comprising: a first amplifier having an output coupled to an input of the first comparator and an input of a second amplifier; a switch coupled between the input of the second amplifier and a reference potential node, the switch having a state based on the output of the first comparator; a second comparator having an input coupled to the output of the second amplifier, the first comparator having a first threshold voltage greater than a second threshold voltage of the second amplifier; and a logic gate having a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator.

[0010] Certain embodiments of the present disclosure provide a method for detecting a laser pulse by a circuit, the method including: receiving a laser pulse at an input of the circuit, generating an electrical signal based on the laser pulse, amplifying the electrical signal, performing a first comparison between the amplified electrical signal and a first threshold voltage, where the amplified electrical signal is greater than the first threshold voltage, closing a switch coupled to a node of reference potential. The method further includes performing a second comparison between the amplified electrical signal or the node of reference potential and a second threshold voltage based on the first comparison, where the first threshold voltage is greater than the second threshold voltage, amplifying an output produced by the second comparison, and generating a signal indicative of the detection of a laser pulse based on at least one of the output of the first comparison and the amplified output of the second comparison.

[0011] The following description and the annexed drawings set forth in detail certain illustrative features of the one or more embodiments.

[0012] The accompanying drawings depict certain aspects of one or more embodiments and therefore should not be considered as limiting the scope of the disclosure. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 illustrates an exemplary system for laser beam detection implemented using dual-gain beam detection in accordance with certain aspects of the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating an exemplary surgical laser system and components therein implemented with dual-gain beam detection in accordance with certain aspects of the present disclosure. [Figure 3] FIG. 3 illustrates an exemplary circuit implemented with dual-gain beam detection in accordance with certain aspects of the present disclosure. [Figure 4] FIG. 4 is a flow diagram illustrating an exemplary operation for detecting a laser pulse by a circuit according to certain aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] To facilitate understanding, identical reference numerals have been used, whenever possible, to designate identical elements common to the figures, and it is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further description.

[0015] Aspects of the present disclosure provide a surgical laser system with a laser beam detection circuit implemented with dual gain.

[0016] Exemplary Surgical Laser System FIG. 1 illustrates an exemplary system 100 with laser beam detection implemented with dual gain, according to certain embodiments. 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 surgical laser system 102 may generate a treatment beam at a first wavelength (e.g., about 532 nanometers (nm)), while a second laser source may generate an aiming beam at a second wavelength (e.g., about 635 nm). A user, such as a surgeon, may first trigger surgical laser system 102 (e.g., via a foot switch, voice command, etc.) to emit the aiming beam onto a desired retinal spot. Once the surgeon positions the laser probe to illuminate the desired retinal spot with the aiming beam, the surgeon activates the treatment beam, such as via a foot pedal or other means, to treat the patient's body (e.g., photocoagulate the desired retinal spot using the treatment beam).

[0017] As shown, the surgical laser system 102 includes a connector or port adapter 114 that couples to an optical port of the surgical laser system 102. FIG. 1 also shows a cable 110 having a distal end that couples to and extends through the probe 108 and a proximal end that couples to and extends through the port adapter 114. In some cases, as described further herein, the cable 110 may include two or more cables. In the example of FIG. 1, the port adapter 114 includes a ferrule with an opening that allows the laser beam from the surgical laser system 102 to propagate to an interface (also referred to as a proximal entrance face) at the proximal end of the cable 110. In some examples, the surgical laser system 102 may include two or more port adapters. The interface of the cable 110 includes exposed proximal ends of one or more cores through which the laser beam may be directed. In the example of FIG. 1, the cable 110 is a multicore fiber optic cable (MCF) with four cores. The interface at the proximal end of cable 110 therefore comprises the proximal ends of the four cores exposed through the openings in the ferrule.

[0018] The surgical laser system 102 may be configured to split a single laser beam generated by a laser source into multiple laser beams exhibiting a laser spot pattern. For example, the surgical laser system 102 may split an aiming beam into four aiming beams and then deliver the four aiming beams to the interface of the cable 110 through the ferrule openings of the port adapter 114. Additionally, the surgical laser system 102 may be configured to split a treatment beam into four treatment beams and deliver the four treatment beams to the interface of the cable 110 through the ferrule openings. In such an example, each of the cores of the cable 110 would then transmit a multi-wavelength beam or a combined beam, which may refer to a treatment beam combined with the aiming beam. It should be noted that while certain aspects have been described with the cores of the cable transmitting a combined beam, the cores of the cable 110 may also individually transmit either a treatment beam or an aiming beam depending on which beam is activated and incident on the cable 110.

[0019] In some examples, the surgical laser system 102 may also propagate an illumination beam to an interface of the cable 110 (e.g., the interface may also include the proximal end of the cladding that retains the core within the cable 110) to illuminate the interior of the eye, particularly the area of ​​the retina 120 that is to be photocoagulated. In certain aspects, the illumination beam may be propagated by a white light emitting diode (LED).

[0020] The cable 110 delivers the combined beam to the probe 108, which propagates a multi-spot pattern (e.g., four spots) of the combined beam onto the retina 120 of the patient's 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. A distal end portion 145 of the probe tip 140 may also house a lens that focuses the combined beam onto the retina 120.

[0021]

[0023] A variety of systems can be implemented using dual-gain laser detection circuits. Figure 2 shows an example of a surgical laser system 202, and components therein, that can be implemented using beam detection circuits with dual gain. The surgical laser system 202 includes a laser source 204 delivering a treatment beam 210, laser sources 206 and 236 delivering aiming beams 212 and 240, respectively, a light source 208 delivering an illumination beam 214, a port selector 219, and beam detection circuits 207 and 216.

[0022] At the beginning of surgery, the surgeon may activate light source 208 to illuminate the inside of the eye to better view the retina. As shown, once emitted by light source 208, illumination beam 214 is received by collimating lens 222 configured to generate a beam with parallel rays. In certain embodiments, collimating lens 222 may be a multi-element achromatic lens including two single lenses and one doublet lens. Thus, as shown, illumination beam 214 emerges from the opposite side of collimating lens 222 with parallel rays and passes through beam splitter 226 to condenser lens 224B. In certain embodiments, condenser lens 224B may be a multi-element achromatic lens including two single lenses and one doublet lens. In such an embodiment, condenser lens 224B has the same design as collimating lens 222, except that the assembly is reversed (e.g., rotated 180 degrees), thereby forming a 1:1 magnification imaging system. Beam splitter 226 may have different coatings on its two sides 226a and 226b. For example, side 226a is coated to allow light propagated thereto to pass through beam splitter 226. Thus, illumination beam 214 propagated to side 226a passes through beam splitter 226. Meanwhile, side 226b is coated to reflect light or laser beams such as treatment beam 210 and aiming beam 212, as described in more detail below. Note, however, that a small portion of illumination beam 214 is reflected by side 226a to sensor 227 configured to detect illumination beam 214.

[0023] Focusing lens 224B then focuses illumination beam 214 onto an interface of a proximal end of a cable, such as cable 110B, that is coupled to port 225B of surgical laser system 202 via port adapter 114B. As described in connection with FIG. 1, cable 110B may have four cores. Thus, focusing lens 224B focuses illumination beam 214 onto an interface of cable 110B such that illumination beam 214 propagates along the entire length of each of cable 110B's four cores to the distal end of a surgical probe (e.g., probe 108 of FIG. 1) coupled to cable 110B. As described above, the interface of each of cables 110A, 110B includes the proximal ends of the four cores of cable 110 that are exposed through openings 217A, 217B of port adapters 114A, 114B, respectively, via ferrules 215A, 215B.

[0024] Once the surgeon is able to view the inside of the eye, the surgeon can project one or more desired aiming beam spots onto the retina from the distal end of the probe. More specifically, after being activated by the surgeon, laser source 206 emits aiming beam 212 onto beam splitter 218, which reflects aiming beam 212 to diffractive optical element (DOE) 220. Similarly, laser source 236 emits aiming beam 240 onto beam splitter 221, which passes a portion of aiming beam 240 toward focusing lens 224A, which focuses aiming beam 240 at an interface of cable 110A, thereby causing aiming beam 240 to propagate along the entire length of each core of cable 110A to the distal end of a surgical probe (e.g., probe 108 of FIG. 1 ) coupled to cable 110A. Diffraction segments may also be referred to herein as "segments." In the example of FIG. 2, DOE 220 is positioned such that aiming beam 212 is aligned with the central segment of DOE 220, and DOE 220 diffracts aiming beam 212 into multiple aiming beams (e.g., four aiming beams). However, the surgeon may reposition 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 surgical laser system 202, the surgeon may position DOE 220 to align aiming beam 212 with a different segment of DOE 220, which may diffract aiming beam 212 into two, one, or other number of beams.

[0025] Once diffracted, the resulting aiming beams are reflected by beam splitter 226 to focusing lens 224B. Focusing lens 224B then focuses the four aiming beams onto the interface of the proximal end of cable 110B, such that each of the aiming beams propagates along the entire length of a corresponding core of cable 110B to the distal end of a surgical probe (e.g., probe 108 of FIG. 1 ). This allows the surgeon to project four desired aiming beam spots onto the retina from the distal end of the probe.

[0026] As described above, once the surgeon positions and activates the laser probe to project an aiming beam spot onto the retina, the surgeon activates the laser source 204, such as via a foot pedal or other means, to treat the patient's body (e.g., photocoagulate the desired retinal spot with the treatment beam). When activated, the laser source 204 emits a polarized treatment beam 210, the polarization axis of which may be altered by the polarization rotator 232. For example, in some embodiments, the polarization rotator 232 filters the treatment beam 210 to produce a vertically polarized treatment beam that is s-polarized relative to the plane of incidence of the beam splitter 226.

[0027] A polarized treatment beam 210 may be advantageous because beam splitter 226 may have a polarization-sensitive coating so that, for example, an s-polarized beam may reflect from beam splitter 226 with a small wavelength spread. As described above, beam splitter 226 is coated to allow illumination beam 214 to pass while reflecting treatment beam 210 and aiming beam 212. Therefore, to provide the surgeon with a high quality and high throughput illumination beam 214A, it is advantageous to polarize treatment beam 210, which allows beam splitter 226 to isolate and reflect treatment beam 210 in a narrower wavelength band.

[0028] The surgical laser system may also include a shutter 234 disposed between the laser source 204 and the port selector 219. The shutter 234 may be configured to alternately block or allow the treatment laser beam to reach the port selector 219. The surgeon or surgical staff may control the shutter 234 (e.g., via a foot switch, voice command, etc.) to emit the laser aiming beam and fire the treatment laser beam (i.e., open the shutter 234) to treat (e.g., photocoagulate) the patient's body. In each case, the beam splitter 221 and the beam splitter 218 may direct the laser beam toward the first port adapter 114A and the second port adapter 114B, respectively.

[0029] Once polarized, treatment beam 210 reaches beam splitter 213, which is configured to transmit a significant portion of treatment beam 210 while reflecting a small portion 231 to sensor 223. Sensor 223 is an optical sensor configured to detect whether laser source 204 is active. After passing through beam splitter 213, treatment beam 210 is received at port selector 219, which is configured to reflect treatment beam 210 to beam splitter 218 or beam splitter 221 if shutter 234 is in an open position allowing treatment beam 210. Beam splitter 218 is configured to reflect a small portion 233 of treatment beam 210 to beam detection circuit 216 while transmitting a significant portion of treatment beam 210. As described further herein, beam detection circuit 216 is an optical detection circuit implemented using dual gain. Beam splitter 221 is configured to reflect a portion of treatment beam 210 to focusing lens 224A while passing another portion of treatment beam 210 to beam detection circuit 207, which may be similar to beam detection circuit 216.

[0030] As shown, linearly polarized treatment beam 210 passes through beam splitter 221 at an angle relative to beam splitter 221 that is equal to the angle at which aiming beam 240 is passed by beam splitter 221. Thus, once laser source 204 is activated, transmitted treatment beam 210 and reflected aiming beam 240 are combined (e.g., overlapping one another) to produce combined beam 242 before reaching focusing lens 224A. Focusing lens 224A focuses combined beam 242 at an interface at the proximal end of cable 110A so that combined beam 242 propagates along the entire length of the core of cable 110A to the distal end of a surgical probe (e.g., probe 108 of FIG. 1 ).

[0031] As shown, linearly polarized treatment beam 210 passes through beam splitter 218 at an angle relative to beam splitter 218 that is equal to the angle at which aiming beam 212 is reflected by beam splitter 218. Thus, when laser source 204 is activated, transmitted treatment beam 210 and reflected aiming beam 212 are combined (e.g., overlap each other) to form combined beam 211 before reaching DOE 220. DOE 220 then diffracts combined beam 211 into combined beams 211a-211d. Each of combined beams 211a-211d refers to a diffracted treatment beam and a diffracted aiming beam that overlap each other.

[0032] The combined beams 211a-211d are then received at beam splitter 226, which reflects the combined beams 211a-211d to collecting lens 224B. Collecting lens 224B focuses the combined beams 211a-211d at an interface of the proximal end of cable 110B such that each of the combined beams 211a-211d propagates along the entire length of a corresponding core of cable 110B to the distal end of a surgical probe (e.g., probe 108 of FIG. 1). More specifically, in the example of FIG. 2, cable 110B is an MCF with four cores, such as cores A, B, C, and D. In such an example, focusing lens 224B focuses combined beams 211a-211d at an interface at the proximal end of cable 110B, such that, for example, combined beam 211a propagates to core A, combined beam 211b propagates to core B, combined beam 211c propagates to core C, and combined beam 211d propagates to core D.

[0033] Exemplary Beam Detection with Dual Gain Aspects of the present disclosure provide a surgical laser system with a laser beam detection circuit implemented with dual gain. In particular, certain aspects provide techniques for measuring pulse durations, such as short (e.g., 50 μs (microseconds)) laser pulses, that can have a wide dynamic range (e.g., 1 mW (milliwatt) to 3.3 W (watts)).

[0034] Currently, measuring short laser pulses can generally be achieved using circuits that ignore the pulse amplitude by simply limiting the circuit's gain. Gain-limiting circuits typically have recovery times (e.g., 10 μs or more) that are a significant fraction of the laser pulse duration (e.g., 50 μs). As a result, such recovery times can introduce errors into the measurement of the actual laser pulse duration. Photodiode beam detectors are often implemented in such circuits for two separate purposes. The first purpose is to detect the laser pulse when it is on to ensure that the laser beam is steered to the correct output port. The duration of the detected signal can be measured to confirm the pulse duration. The second purpose is to detect unwanted output, which can occur when micropulsing is used to generate pulses. For example, laser energy can be directed to the incorrect port or the laser can appear to be on when it is meant to be off. Improper or inaccurate detection of a laser beam can be dangerous to patients during medical procedures involving laser beams.

[0035] The dynamic range of laser beams can be large; that is, maximum powers can be as high as 3.3 W and as low as 1 mW. Accommodating the relatively large dynamic range of laser beams can be further complicated by uncertainties in the beam splitter used to sample the laser beam itself. For example, manufacturing variations in beam splitters can be as high as 100%. It may be desirable for the circuitry used to detect the output of the photodiode receiving the laser pulse to be able to handle the large dynamic range while still being able to accurately measure the pulse duration.

[0036] Conventional gain-limiting circuits typically impact the ability to accurately measure pulse duration. While several methods exist for amplifying photodiode signals, using a transimpedance (TIM) amplifier is typically optimal for fast response. As long as the amplifier remains within its operating limits, pulse fidelity is generally high. However, if the output signal is too large, the amplifier may saturate, causing unpredictable or very long recovery times. Using a Zener diode can limit the voltage gain to the breakdown voltage of the Zener diode, but the saturated recovery time of the Zener diode can be 10 μs or longer. Thus, a circuit that can handle the dynamic range of the laser beam and does not saturate is desired for proper and accurate pulse measurements.

[0037] Accordingly, certain aspects of the present disclosure provide techniques related to a beam detection circuit implemented with dual gain. In particular, certain aspects relate to using two amplifiers with different gains in series in a beam detection circuit. The gain of the first amplifier can be set so that the largest laser pulse is within the operating limits of the first amplifier. The second amplifier can have a gain to further amplify the signal so 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 cut off 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). Cutting off the signal to the second amplifier can prevent the second amplifier from exceeding its operating limits, especially when large signals are passing through the circuit. In certain aspects, the output of the first amplifier and / or the second amplifier can be used to measure pulse duration so that amplifier switching does not affect the measurement. In other words, by implementing a beam detection circuit with two amplifiers in the manner described above, it is possible to detect the laser beam more accurately.

[0038] 3 shows an example circuit 300 implemented with dual-gain beam detection. As shown, the circuit 300 may include a photodiode 302, amplifiers 304, 310, comparators 308, 312, a switch 314, a resistor 318, and a logic gate 322.

[0039] As shown, photodiode 302 may be coupled between an input of amplifier 304 and a reference potential node 316 (e.g., electrical ground). In some embodiments, reference potential node 316 may instead be a voltage source or a current source. Another input of amplifier 304 may be coupled to reference potential node 316. In certain aspects, amplifier 304 may amplify the photodiode signal as much as possible without exceeding the operational limits of amplifier 304. An output of amplifier 304 may be coupled to an input of amplifier 310, which may have another input coupled to reference potential node 316. In certain aspects, the gain of amplifier 310 may be greater than the gain of amplifier 304. As shown, resistor 318 may be coupled between amplifiers 304, 310. Additionally, switch 314 may be coupled between node 319 (between resistor 318 and amplifier 310) and reference potential node 316.

[0040] The output of amplifier 304 may be coupled to an input of comparator 308, which may be compared to voltage V1. As shown, the output of amplifier 310 may be coupled to an input of comparator 312, which may be compared to voltage V2. In certain aspects, V1 may be greater than V2, and V2 may be selected to be large enough so that noise does not cause false triggering (e.g., a value greater than when the laser pulse exceeds 1 mW). V1 may be selected to be greater than V2 because comparator 312 may be configured to detect low-power beams (e.g., as low as a 1 mW laser beam) and may be saturated by higher power beams, while comparator 308 may be configured to detect higher power beams (e.g., up to 3.3 W laser beams) without saturating. When the input to comparator 308 exceeds voltage V1, comparator 308 may output a logic high voltage signal (e.g., 3.3 V or 5 V) to logic gate 322 and switch 314, as indicated by dashed line 320. When the input to comparator 312 exceeds voltage V2, comparator 312 may output a logic high voltage signal (e.g., 3.3V or 5V) to logic gate 322. When the output of comparator 308 is logic high, for example, switch 314 may close, coupling (e.g., shorting) the input of amplifier 310 to reference potential node 316. In particular aspects, logic gate 322 may be an OR gate or any other suitable logic gate.

[0041] In certain embodiments, it may be advantageous to amplify the photodiode signal so that a signal of approximately 1 mW exceeds the threshold. However, signals whose power is significantly higher than 1 mW (e.g., high-level signals), when amplified by amplifier 304, would cause amplifier 310 to exceed its operating limits. Therefore, voltage V1 of comparator 308 may be selected so that voltage V1 is less than the saturation voltage of amplifier 310. If a high-level signal is then passed through circuit 300, such a signal can generate a logic high output from the comparator before amplifier 310 reaches its saturation voltage, subsequently closing switch 314. A low-level laser pulse (e.g., a low-power laser pulse) can be applied to the photodiode and amplified by both amplifiers 304 and 310. This technique can prevent amplifier 310 from significantly overloading, allowing it to return to zero output quickly enough so as not to affect, for example, pulse measurements. Because amplifier 304 has a finite rise time, comparator 312 may output a logic-high signal before the signal has sufficient amplitude to trigger comparator 308, thereby closing switch 314. If one or more of comparators 308, 312 outputs a logic-high signal, logic gate 322 may output a logic-high signal. The output of logic gate 322 may, for example, start a timer to measure the duration of a laser pulse. Thus, the start of a laser pulse may be measured with similar accuracy for both large and small amplitude pulses (e.g., high or low signals). In some implementations, the laser pulse may be timed and / or controlled independently of circuit 300. For example, this may be done by a shutter (e.g., shutter 234 in FIG. 2) or a power supply. In this case, circuit 300 may be used as a double-check for laser pulse timing. Furthermore, in some examples of independent pulse timing / control, photodiode timing may be measured by two independent circuits, such that the clocks used to generate / measure the pulses are independent.

[0042] 4 is a flow diagram illustrating an example operation 400 for detecting a laser pulse by a circuit. Operation 400 can be understood and implemented within circuit 300 of FIG.

[0043] The operations 400 begin by receiving a laser pulse at an input of the circuit at block 405. At 410, the circuit generates an electrical signal based on the laser pulse (e.g., via photodiode 302). At 415, the circuit amplifies the electrical signal (e.g., via amplifier 304).

[0044] At 420, the circuit performs a first comparison (e.g., via comparator 308) between the amplified electrical signal and a first threshold voltage (e.g., voltage V1) and closes a switch (e.g., switch 314) coupled to a reference potential node (e.g., reference potential node 316) if the amplified electrical signal is greater than the first threshold voltage.

[0045] At 425, based on the first comparison, the circuit either re-amplifies the amplified electrical signal (e.g., via amplifier 310) or amplifies the voltage associated with the reference potential node. In certain embodiments, if the voltage of the amplified electrical signal is less than the first threshold voltage, the amplified electrical signal may be re-amplified. If the voltage of the amplified electrical signal is greater than the first threshold voltage, the amplified electrical signal is coupled to the reference potential, thereby effectively shunting / short-circuiting the amplified electrical signal. Thus, the amplified electrical signal does not pass to the second amplifier. Rather, as a result, the voltage associated with the reference potential node (e.g., ground) may be input to the second amplifier.

[0046] At 430, based on the first comparison, the circuit performs a second comparison (e.g., via comparator 312) between the re-amplified electrical signal or the 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.

[0047] At 435, the circuit generates (eg, via logic gate 322) a signal indicative of the detection of a laser pulse based on at least one of the output of the first comparison and the output of the second comparison.

[0048] The foregoing description is provided to enable those skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Accordingly, the claims are not intended to be limited to the embodiments shown herein, but are to be accorded the full scope consistent with the language of the claims.

[0049] Illustrative Embodiments

[0013] Embodiment 1: A surgical laser system comprising: a laser source configured to propagate a laser beam; a memory containing executable instructions; and a processor in data communication with the memory configured to execute the instructions, the instructions causing the processor to control the laser source based on a detection signal received from the circuit, the circuit comprising: a first amplifier having an output coupled to an input of the first comparator and an input of a second amplifier; a switch coupled between the input of the second amplifier and a reference potential node, the switch having a state based on the output of the first comparator; a second comparator having an input coupled to the output of the second amplifier, the first comparator having a first threshold voltage greater than a second threshold voltage of the second amplifier; and a logic gate having a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator. The surgical laser system further comprises a lens configured to focus the laser beam onto an interface surface of a proximal end of an optical fiber coupled to the surgical laser system via a port, the distal end of the optical fiber being configured to project the laser beam onto a target surface.

[0050] Embodiment 2: A surgical laser system as described in embodiment 1, wherein the circuit further includes a photodiode coupled between the input of the first amplifier and a reference potential node, the photodiode being configured to receive the laser beam.

[0051] Embodiment 3: A surgical laser system as described in embodiment 1 or 2, wherein the processor is configured to start a timer upon receiving a detection signal from the circuit, and the processor is configured to stop propagation of the laser beam when the timer reaches a timing threshold.

[0052] Embodiment 4: A surgical laser system described in any of embodiments 1 to 3, wherein the processor is configured to stop propagation of the laser beam except when it determines, 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 directed to propagate the laser beam, the laser beam is not propagated when the surgical system is not directed to propagate the laser beam, and the laser beam is propagated within a threshold duration.

[0053] Embodiment 5: A surgical laser system described in any one of embodiments 1 to 4, further comprising a photodiode coupled between the input of the first amplifier and a reference potential node.

[0054] Embodiment 6: A surgical laser system according to any one of embodiments 1 to 5, wherein the first amplifier has a first gain that is smaller than the second gain of the second amplifier.

[0055] Embodiment 7: A surgical laser system according to any one of embodiments 1 to 6, wherein the saturation voltage level of the second amplifier is greater than the first threshold voltage of the first comparator.

[0056] Embodiment 8: A surgical laser system according to any one of embodiments 1 to 7, wherein the second threshold voltage of the second comparator is at least 1 mW.

[0057] Embodiment 9: A surgical laser system described in any of embodiments 1 to 8, wherein the switch is configured to short-circuit the input of the second amplifier to a reference potential node when the voltage at the input of the first comparator exceeds the first threshold voltage of the first comparator.

[0058] Embodiment 10: A surgical laser system described in any one of embodiments 1 to 9, wherein the switch is one of an analog switch or a metal oxide semiconductor field effect transistor (MOSFET).

[0059] Embodiment 11: A surgical laser system according to any one of embodiments 1 to 10, wherein the first amplifier is a transimpedance amplifier.

[0060] Embodiment 12: A surgical laser system according to any one of embodiments 1 to 11, wherein the logic gate is an OR gate.

[0061] Embodiment 13: A surgical laser system described in any of embodiments 1 to 12, further comprising a resistor coupled between the output of the first amplifier and the input of the second amplifier.

[0062] Embodiment 14: A method of detecting a laser pulse by a circuit, comprising: receiving a laser pulse at an input of the circuit; generating an electrical signal based on the laser pulse; amplifying the electrical signal; performing 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, closing a switch coupled to a reference potential node; re-amplifying the amplified electrical signal or shunting the amplified electrical signal to the reference potential node based on the first comparison; when the amplified electrical signal is re-amplified, performing a second comparison between the re-amplified electrical signal and a second threshold voltage, wherein the first threshold voltage is greater than the second threshold voltage; and generating a signal indicative of detection of a laser pulse based on at least one of an output of the first comparison and an output of the second comparison.

[0063] Embodiment 15: A circuit comprising: a first amplifier having an output coupled to an input of the first comparator and an input of the second amplifier; a switch coupled between the input of the second amplifier and a reference potential node, the state of the switch being based on the output of the first comparator; a second comparator having an input coupled to the output of the second amplifier, the first comparator having a first threshold voltage greater than a second threshold voltage of the second amplifier; and a logic gate having a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator.

[0064] Embodiment 16: The circuit of embodiment 15, further comprising a photodiode coupled between the input of the first amplifier and the reference potential node.

[0065] Embodiment 17: The circuit of embodiment 15 or 16, wherein the first amplifier has a first gain that is smaller than the second gain of the second amplifier.

[0066] Embodiment 18: The circuit according to any one of embodiments 15 to 17, wherein the saturation voltage level of the second amplifier is greater than the first threshold voltage of the first comparator.

[0067] 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.

[0068] Embodiment 20: A circuit described in any of embodiments 15 to 19, wherein the switch is configured to short-circuit the input of the second amplifier to a reference potential node when the voltage at the input of the first comparator exceeds a first threshold voltage of the first comparator.

[0069] Embodiment 21: The circuit of any of embodiments 15 to 20, wherein the switch is one of an analog switch or a metal oxide semiconductor field effect transistor (MOSFET).

[0070] Embodiment 22: The circuit according to any one of embodiments 15 to 21, wherein the first amplifier is a transimpedance amplifier.

[0071] Embodiment 23: The circuit according to any one of embodiments 15 to 22, wherein the logic gate is an OR gate.

[0072] Embodiment 24: The circuit of any one of embodiments 15 to 23, further comprising a resistor coupled between the output of the first amplifier and the input of the second amplifier.

Claims

1. 1. A surgical laser system comprising: a laser source configured to propagate a laser beam; a memory containing executable instructions; 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 comprising: a first amplifier having an output coupled to an input of the first comparator and to an input of the second amplifier; a switch coupled between the input of the second amplifier and a reference potential node, the state of the switch being controlled based on the output of the first comparator; a second comparator having an input coupled to the output of the second amplifier, the first comparator having a first threshold voltage greater than a second threshold voltage of the second amplifier; a logic gate having a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator, the output of the logic gate being the detection signal; and a lens configured to focus the laser beam onto an interface of a proximal end of an optical fiber coupled to the surgical laser system through a port, the distal end of the optical fiber configured to project the laser beam onto a target surface; A surgical laser system comprising:

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

3. the processor is configured to start a timer upon receiving the detection signal from the circuit; 10. The surgical laser system of claim 1, wherein the processor is configured to stop propagation of the laser beam when the timer reaches a timing threshold.

4. The processor, based on the detection signal, The laser beam is directed toward the port. and stopping propagation of the laser beam except when it is determined that the laser beam is propagated when the surgical laser system is oriented to propagate the laser beam, and the laser beam is not propagated when the surgical system is not oriented to propagate the laser beam; the laser beam is propagated within a threshold duration; 10. The surgical laser system of claim 1.

5. 1. A method for 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; performing a first comparison between the amplified electrical signal and a first threshold voltage, closing a switch coupled to a reference potential node when the amplified electrical signal is greater than the first threshold voltage; Based on the first comparison, amplifying the amplified electrical signal; or shunting the amplified electrical signal to the reference potential node; When the amplified electrical signal is reamplified, performing a second comparison between the reamplified electrical signal and a second threshold voltage, the first threshold voltage being greater than the second threshold voltage; generating a signal indicative of the 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 first amplifier having an output coupled to an input of the first comparator and to an input of the second amplifier; a switch coupled between the input of the second amplifier and a reference potential node, the state of the switch being controlled based on the output of the first comparator; a second comparator having an input coupled to the output of the second amplifier, the first comparator having a first threshold voltage greater than a second threshold voltage of the second amplifier; a logic gate having a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator; A circuit comprising:

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

8. 7. 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. 7. 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. 7. The circuit of claim 6, wherein the second threshold voltage of the second comparator is a value above which the circuit detects a laser beam having a power output of at least 1 mW.

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

12. 7. 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. 7. The circuit of claim 6, wherein the logic gate is an OR gate.

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

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