Patent Description:
In a wide variety of medical procedures, laser light (e.g., a illumination beam, laser treatment beam ("treatment beam"), and/or laser aiming beam ("aiming beam")) is used to assist in surgery and/or treat patient anatomy. For example, in laser photocoagulation, a laser probe propagates a treatment beam to cauterize blood vessels at a laser burn spot across the retina. A treatment beam is typically transmitted from a surgical laser system through an optical fiber cable that proximally terminates in a port adapter, which connects to the surgical laser system, and distally terminates in the laser probe, which is manipulated by the surgeon. Note that, herein, a distal end of a component refers to the end that is closer to a patient's body while the proximal end of the component refers to the end that is facing away from the patient's body or in proximity to, for example, the surgical laser system.

In addition to cauterizing blood vessels at the laser burn spot, the treatment beam may also damage some of the rods and cones that are present in the retina that provide vision, thereby, affecting eyesight. Since vision is most acute at the central macula of the retina, the surgeon arranges the laser probe to generate a laser burn spot in the peripheral areas of the retina. During the procedure, the surgeon drives the probe with a non-burning aiming beam to illuminate the retinal area that is to be photocoagulated. Due to the availability of low-power red laser diodes, the aiming beam is generally a low-power red laser light. Once the surgeon has positioned the laser probe so as to illuminate a desired retinal spot with the aiming beam, the surgeon activates the treatment beam, through a foot pedal or other means, to photocoagulate the illuminated area (or an area encompassing the illuminated area) using the treatment beam. Having burned a retinal spot, 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 until a desired number of burned laser spots are distributed across the retina.

Certain types of laser probes coagulate or burn multiple spots at a time, which may result in a faster and more efficient photocoagulation. For example, a surgical laser system that is coupled to one of such laser probes through an optical fiber may 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 transmits the multiple laser beams to the optical cable, which may include an array of multiple optical fibers or a multi-core fiber that exhibit a corresponding fiber pattern.

For diabetic retinopathy, a pan-retinal photocoagulation (PRP) procedure may be conducted, and the number of required laser photocoagulations for PRP is typically large. For example, <NUM>,<NUM> to <NUM>,<NUM> spots are commonly burned. It may thus be readily appreciated that if the laser probe was a multi-spot probe enabling the burning of multiple spots at a time, the photocoagulation procedure would be faster (assuming the laser source power is sufficient). Accordingly, multi-spot/multi-fiber laser probes have been developed and described in <CIT> and <CIT> as well as <CIT>. In addition to the aiming beam and the treatment beam, vitreoretinal procedures also benefit from illumination light or beam being directed into the eye and onto retinal tissue.

Reference is made to <CIT> and <CIT> considered representative of the state of the art.

The invention is as defined in independent claim <NUM>. Further optional features are provided in the dependent claims.

The present disclosure relates generally to a surgical laser system and more specifically to configuring a surgical laser system to align multi-wavelength laser beams with the cores of a multi-core fiber.

Certain embodiments of the present disclosure provide a surgical laser system comprising a first laser source configured to emit a first laser beam with a first wavelength and a second laser source configured to emit a second laser beam with a second wavelength. The surgical laser system further comprises a first diffraction optical element (DOE) tuned to the first wavelength and a second DOE tuned to the second wavelength, wherein the first DOE is configured to diffract the first laser beam into one or more first diffracted beams at a diffraction angle and the second DOE is configured to diffract the second laser beam into one or more second diffracted beams at the same diffraction angle. The surgical laser system further comprises one or more beam splitters configured to reflect the one or more first diffracted beams and the one or more beams onto a lens. The lens is configured to focus the one or more first diffracted beams and the one or more second diffracted beams onto an interface plane of a proximal end of a cable coupled to the surgical laser system, wherein a distal end of the cable is configured to emit the one or more first diffracted beams and the one or more second diffracted beams onto a target surface.

Aspects of the present disclosure provide a surgical laser system configured to align multi-wavelength laser beams with the cores of a multi-core fiber.

<FIG> illustrates an example system <NUM> for creating a multi-spot pattern of laser beams on the surface of the retina, according to certain embodiments of the present invention. System <NUM> includes a surgical laser system <NUM> having one or more laser sources for generating laser beams used during ophthalmic procedures. For example, a first laser source within surgical laser system <NUM> may generate a treatment beam with a first wavelength (e.g., -<NUM> nanometers (nm)) while a second laser source may generate an aiming beam with a second wavelength (e.g., -<NUM>). A user, such as a surgeon, may trigger the surgical laser system <NUM> (e.g., via a foot switch, voice commands, etc.) to emit the aiming beam onto a desired retinal spot. Once the surgeon has positioned the laser probe so as to illuminate the desired retinal spot with the aiming beam, the surgeon activates the treatment beam, such as through a foot pedal or other means, to treat the targeted patient anatomy (e.g., photocoagulate the desired retinal spot using the treatment beam).

As shown, surgical laser system <NUM> includes a connector or port adapter <NUM> that couples to an optical port (not shown) of surgical laser system <NUM>. <FIG> also shows a cable <NUM> having a distal end that couples to and extends through a probe <NUM> and a proximal end that couples to and extends through port adapter <NUM>. In the example of <FIG>, port adapter <NUM> includes a ferrule with an opening that allows laser beams from surgical laser system <NUM> to be propagated into an interface plane (also referred to as a proximal entrance plane) of the proximal end of cable <NUM>. The interface plane of cable <NUM> comprises the exposed proximal ends of the one or more cores where laser beams may be directed to. In the example of <FIG>, cable <NUM> is a multi-core optical fiber cable (MCF) with four cores. As such, the interface plane of the proximal end of cable <NUM> comprises the proximal ends of the four cores that are exposed through the opening of the ferrule of port adapter <NUM>.

Surgical laser system <NUM> may be configured to split a single laser beam that is generated by a laser source into multiple laser beams that exhibit a laser spot pattern. For example, surgical laser system <NUM> may split a single aiming beam into four aiming beams and then deliver the four aiming beams to the interface plane of cable <NUM> through the opening of the ferrule of port adapter <NUM>. Surgical laser system <NUM> may further be configured to split a single treatment beam into four treatment beams and deliver the four treatment beams to the interface plane of cable <NUM> through the opening of the ferrule. In such an example, each of the cores of cable <NUM> would then be transmitting both an aiming beam and a treatment beam, which may be referred to, collectively, as a combined beam or a multi-wavelength beam (due to the fact that the aiming beam and treatment beam have different wavelengths). In some examples, surgical laser system <NUM> may also propagate an illumination beam into an interface plane of cable <NUM> (e.g., which may also include a proximal end of a cladding that holds the cores within cable <NUM>) in order to illuminate the inside of the eye, especially areas of the retina <NUM> that are to be photocoagulated. In certain aspects, an illumination beam may be generated by a white light-emitting diode (LED).

Cable <NUM> delivers the combined beams to probe <NUM>, which propagates a multi-spot pattern (e.g., four spots) of combined beams to the retina <NUM> of a patient's eye <NUM>. Probe <NUM> includes a probe body <NUM> at its proximal end and a probe tip <NUM> at its distal end. Probe body <NUM> and probe tip <NUM> house and protect the distal end of cable <NUM>. A distal end portion <NUM> of the probe tip <NUM> may also contain a lens that focuses the combined beams on the retina <NUM>.

Various systems can be employed to create a multi-spot pattern of combined laser beams. <FIG> illustrates one example of a surgical laser system, and the components therein, that may be used for creating a multi-spot pattern of combined laser beams. Surgical laser system <NUM> comprises a laser source <NUM>, which generates a treatment beam <NUM>, a laser source <NUM>, which generates an aiming beam <NUM>, and a light source <NUM>, which generates an illumination beam <NUM>.

At the outset of the surgery, a surgeon may activate light source <NUM> in order to illuminate the inside of the eye's globe and make it easier to view the retina. As shown, once emitted by light source <NUM>, illumination beam <NUM> is received by collimating lens <NUM>, which is configured to produce a beam with parallel (collimated) rays of light. In certain embodiments, collimating lens <NUM> may be a multi-element achromat comprising two singlet lenses and one doublet lens. Therefore, as shown, illumination beam <NUM> emerges with parallel rays of light from the other side of collimating lens <NUM> and passes through beam splitter <NUM> to reach a condensing lens <NUM>. In certain embodiments, condensing lens <NUM> may be a multi-element achromat comprising two singlet lenses and one doublet lens. In such embodiments, condensing lens <NUM> has the same exact design as collimating lens <NUM>, except that the assembly is revered (e.g., rotated by <NUM> degrees), thereby creating a one-to-one magnification imaging system. Beam splitter <NUM> may have different coatings on its two sides, 226a and 226b. For example, side 226a is coated such that it allows light propagated thereon to pass through beam splitter <NUM>. As such, illumination beam <NUM>, which is propagated onto side 226a passes beam splitter <NUM>. On the other hand, side 226b is coated to reflect light or laser beams such as treatment beam <NUM> and aiming beam <NUM>, as further described below. Although, note that a trivial portion of illumination beam <NUM> is reflected by side 226a onto sensor <NUM>, which is configured to sense illumination beam <NUM>.

Condensing lens <NUM> then converges illumination beam <NUM> into an interface plane of a proximal end of a cable, such as cable <NUM> shown in <FIG>, that is coupled to a port <NUM> of surgical laser system <NUM> through port adapter <NUM>. As described in relation to <FIG>, cable <NUM> is a cable with four cores. As such, condensing lens <NUM> focuses illumination beam <NUM> into an interface plane of cable <NUM> such that illumination beam <NUM> is propagated, along an entire length of each of the four cores of cable <NUM>, to the distal end of a surgical probe (e.g., probe <NUM> of <FIG>) that is coupled to cable <NUM>. As described above, the interface plane of cable <NUM> comprises the proximal ends of the four cores of cable <NUM> that are exposed through an opening <NUM> of ferrule <NUM> of port adapter <NUM>.

Once the surgeon is able to view inside the eye's globe, the surgeon may project from the distal end of the probe one or more desired aiming beam spots onto the retina. More specifically, after activation by the surgeon, laser source <NUM> emits aiming beam <NUM> onto beam splitter <NUM>, which reflects aiming beam <NUM> onto diffraction optical element (DOE) <NUM>. As further described in relation to <FIG>, DOE <NUM> may comprise different diffraction segments (e.g., three segments), each configured to diffract or split a beam into a different number of beams. A diffraction segment may also be referred to as a "segment" herein. In the example of <FIG>, DOE <NUM> is positioned such that aiming beam <NUM> is aligned with the middle segment of DOE <NUM>, which diffracts aiming beam <NUM> into aiming beams (e.g., four aiming beams). However, a surgeon may change the position of DOE <NUM> in order to diffract a beam into a different number of beams (e.g., one or two). For example, using voice command or some other feature of surgical laser system <NUM>, a surgeon may position DOE <NUM> to align aiming beam <NUM> with a different segment of DOE <NUM>, which may diffract aiming beam <NUM> into one, two, or other numbers of beams.

Once diffracted, the resulting aiming beams are reflected by beam splitter <NUM> onto condensing lens <NUM>. Condensing lens <NUM> then focuses the four aiming beams onto the interface plane of a proximal end of cable <NUM> such that each of the aiming beams is propagated, along an entire length of a corresponding core of cable <NUM>, to the distal end of a surgical probe (e.g., probe <NUM> of <FIG>). This allows the surgeon to project from the distal end of the probe four desired aiming beam spots onto the retina.

As described above, once the surgeon has positioned and activated the laser probe so as to project one or more aiming beam spots onto the retina, the surgeon may then activate laser source <NUM>, such as through a foot pedal or other means, to treat the targeted patient anatomy (e.g., photocoagulate the desired retinal spot using the treatment beam). When activated, laser source <NUM> emits polarized treatment beam <NUM>, whose polarization axis may be changed by a polarization rotator <NUM>. For example, in some embodiments, polarization rotator <NUM> filters treatment beam <NUM> to produce a vertically-polarized treatment beam which is s-polarized relative to the plane of incidence of beam splitter <NUM>.

A polarized treatment beam <NUM> may be advantageous because, in some embodiments, beam splitter <NUM> may have coatings that are sensitive to polarization such that, for example, an s-polarized beam may reflect off of beam splitter <NUM> with less broadening of the wavelength. As described above, beam splitter <NUM> is coated such that it allows illumination beam <NUM> to pass through while reflecting treatment beam <NUM> and aiming beam <NUM>. Therefore, to provide the surgeon with a high quality and throughput illumination beam <NUM>, it is advantageous to polarize treatment beam <NUM>, which allows beam splitter <NUM> to isolate and reflect treatment beam <NUM> with a narrower band of wavelength.

Once polarized, treatment beam <NUM> reaches beam splitter <NUM>, which is configured to allow a substantial portion of treatment beam <NUM> to pass through, while reflecting a trivial portion <NUM> onto sensor <NUM>. Sensor <NUM> is a light sensor configured to detect whether laser source <NUM> is active or not. After passing through beam splitter <NUM>, treatment beam <NUM> is received at beam splitter <NUM>, which is configured to reflect treatment beam <NUM> onto beam splitter <NUM>. Beam splitter <NUM> is configured to reflect a trivial portion <NUM> of treatment beam <NUM> onto sensor <NUM> while allowing a substantial portion of treatment beam <NUM> to pass through. Sensor <NUM> is a light sensor configured to detect whether treatment beam <NUM> has reached beam splitter <NUM>.

As shown, linearly polarized treatment beam <NUM> passes through beam splitter <NUM> at an angle with respect to beam splitter <NUM> that is equal to the angle with which aiming beam <NUM> is reflected by beam splitter <NUM>. Therefore, once laser source <NUM> is active, transmitted treatment beam <NUM> and reflected aiming beam <NUM> are combined (e.g., such that they overlay each other), creating combined beam <NUM>, before reaching DOE <NUM>. DOE <NUM> then diffracts combined beam <NUM> into combined beams 211a-211d. Each one of combined beams 211a-211d refers to a diffracted treatment beam and a diffracted aiming beam that overlay each other.

Combined beams 211a-211d are then received at beam splitter <NUM>, which reflects combined beams 211a-211d onto condensing lens <NUM>. Condensing lens <NUM> focuses combined beams 211a-211d onto an interface plane of the proximal end of cable <NUM> such that each of the combined beams 211a-211d is propagated, along an entire length of a corresponding core of cable <NUM>, to the distal end of a surgical probe (e.g., probe <NUM> of <FIG>). More specifically, in the example of <FIG>, cable <NUM> is an MCF with four cores, such as cores A, B, C, and D. In such an example, condensing lens <NUM> focuses combined beams 211a-211d onto an interface plane of a proximal end of cable <NUM> such that, for example, combined beam 211a is propagated onto core A, combined beam 211b is propagated onto core B, combined beam 211c is propagated onto core C, and combined beam 211d is propagated onto core D.

In the example of <FIG>, both aiming beam <NUM> and treatment beam <NUM> are diffracted by the same DOE <NUM>. However, in optics, the angle at which light is diffracted by a DOE is dependent upon the light's wavelength. This is because a DOE's diffraction grating is generally configured or tuned to diffract light at a certain angle only for a given wavelength. In the example of <FIG>, DOE <NUM> may be tuned to ensure that any diffracted beam with a wavelength λ<NUM>, which is equal to the wavelength of treatment beam <NUM> (e.g., -<NUM> nanometers (nm)), is diffracted at an angle Θ<NUM> with respect to the incident beam direction. Accordingly, DOE <NUM> is effectively able to diffract treatment beam <NUM> at angle Θ<NUM> for each diffracted beam. But, because aiming beam <NUM> has a different wavelength λ<NUM> (e.g., -<NUM>), DOE <NUM> may diffract aiming beam <NUM> at angle Θ<NUM> with respect to the incident beam direction, which may be slightly different than angle Θ<NUM>.

Diffracting treatment beam <NUM> and aiming beam <NUM> at different diffraction angles, however, may cause a misalignment among one or more of the diffracted beams, as further shown in <FIG>. In addition, in the example of <FIG>, the inter-spot power non-uniformity of the major beams diffracted from DOE <NUM> may be minimized only for the wavelength of treatment beam <NUM> because the DOE grating design of DOE <NUM> is only optimized for treatment beam <NUM>'s wavelength. Inter-spot power non-uniformity is the maximum individual-spot power deviation from the average power of the major beam spots. DOE <NUM>, therefore, may able to minimize the inter-spot power non-uniformity across only the four diffracted treatment beams but not across the four diffracted aiming beams. In addition, DOE <NUM> being only tuned to the wavelength of treatment beam <NUM> may result in an out-of-order leakage of aiming beam <NUM>. In other words, DOE <NUM> may diffract aiming beam <NUM> into undesired spots, including the zero-order spot which is the portion of the incident beam that transmits, undiffracted, directly through DOE <NUM>.

The angular deviation (Θ<NUM> - Θ<NUM>) between each diffracted beam 211a-d at the aiming beam wavelength and its corresponding diffracted beam 211a-d at the treatment wavelength is Fourier-transformed by condensing lens <NUM> into a spatial deviation r<NUM> - r<NUM> of the spatial lateral position of each diffracted aiming beam 212a-d on interface plane <NUM> and its corresponding treatment beam <NUM>-a-d on interface plane <NUM>, such as in the example misalignment of <FIG> More specifically, <FIG> illustrates input into an interface plane <NUM> of the proximal end of cable <NUM>, which is exposed through an opening <NUM> of ferrule <NUM>. Interface plane <NUM>, as described above, comprises the exposed proximal ends of the four cores 344a-344d of the MCF cable <NUM> that extend through port adapter <NUM>. As shown, because DOE <NUM> diffracts treatment beam <NUM> and aiming beam <NUM> at different angles, aiming beam 212a is not aligned with the center of treatment beam 210a, which may correspond to the center of core 344a. As a result, aiming beam 212a is not centered in core 344a. Note that the other three combined beams 211b-211d are not shown in <FIG> for simplicity.

In the case of surgical laser system <NUM>, the tolerance stack-up of lateral misalignments of the overall laser/probe optical system may cause one or more aiming beams 212a-d at interface plane <NUM> to not couple fully into its respective fiber core <NUM>, while other aiming beams 212a-d may fully couple into their respective fiber cores. This may greatly increase the inter-spot power non-uniformity of the multiple aiming beams 212a-d projected out of the probe and focused onto the retina. As such, one or more of the aiming beam spots projected on the retina may be dim relative to the other spots, which may be irritating or distracting to the surgeon. Further, the misalignment between the treatment beam and the aiming beam significantly reduces the allowed margin for any further misalignment that may occur due to an optical drift or other types of environmental conditioning and/or perturbations. As such, any further misalignment of an already misaligned pair of treatment and aiming beams may further reduce the accuracy of the corresponding surgical laser system.

Accordingly, certain embodiments of the present disclosure relate to a surgical laser system that is configured to diffract a treatment beam and an aiming beam such that each of the diffracted aiming beams (e.g., four diffracted aiming beams) is aligned more closely with each of the corresponding diffracted treatment beams (e.g., four diffracted treatment beams).

<FIG> illustrates an example surgical laser system <NUM> that may be used for creating a multi-spot pattern of combined laser beams. Surgical laser system <NUM> comprises a laser source <NUM>, which generates a treatment beam <NUM>, a laser source <NUM>, which generates an aiming beam <NUM>, and a light source <NUM>, which generates an illumination beam <NUM>. Surgical laser system <NUM> also comprises DOE <NUM>, which is tuned to diffract laser beams with a wavelength of λ<NUM> (e.g., treatment beam <NUM>), at an angle Θ<NUM>. Surgical laser system <NUM> also comprises DOE <NUM>, which is tuned to diffract laser beams with a wavelength of λ<NUM> (e.g., aiming beam <NUM>), at the same angle Θ<NUM>. Utilizing two DOEs allows surgical laser system <NUM> to diffract treatment beam <NUM> and aiming beam <NUM> both at the same angle and, thereby, ensure that the combined beams are aligned closely. As shown, surgical laser system <NUM> also comprises two different beam splitters <NUM> and <NUM>, one to reflect beams diffracted by DOE <NUM> and another to reflect beams diffracted by DOE <NUM>.

When activated by the surgeon, laser source <NUM> emits aiming beam <NUM>, which is diffracted by DOE <NUM> at angle Θ<NUM>, into aiming beams 412a-412d. Aiming beams 412a-412d then reflect off of beam splitter <NUM> onto condensing lens <NUM>. As described above, beam splitter <NUM> is coated such that light propagated onto side 226a is able to pass through beam splitter <NUM>. As such, aiming beams 412a-412d are able to efficiently transmit through beam splitter <NUM> without any change to their angular directions in the collimated-space region before lens <NUM>, or their angles of incidence onto interface plane <NUM> in <FIG>. The angle of incidence refers to an angle which an incident line or ray makes with a line perpendicular to the surface at the point of incidence. Condensing lens <NUM> then focuses aiming beams 412a-412d onto an interface plane of a proximal end of cable <NUM> such that each of the aiming beams 412a-412d is propagated, along an entire length of a corresponding core of cable <NUM>, to the distal end of a surgical probe (e.g., probe <NUM> of <FIG>).

Once the surgeon has illuminated the desired retinal spots with aiming beams 412a-412d, the surgeon activates laser source <NUM>, which then emits treatment beam <NUM>. Treatment beam <NUM> may take the same path described in relation to <FIG> and reach DOE <NUM>, which is configured to diffract treatment beam <NUM>, at the same angle Θ<NUM>, into treatment beams 210a-210d. Treatment beams 210a-<NUM>0d then reflect off of beam splitter <NUM> onto condensing lens <NUM>, which focuses treatment beams 210a-210d onto the interface plane of the proximal end of cable <NUM> such that each of the treatment beams 210a-210d is propagated, along an entire length of a corresponding core of cable <NUM>, to the distal end of a surgical probe (e.g., probe <NUM> of <FIG>).

As shown in <FIG>, because the path of treatment beam <NUM> is decoupled from the path of aiming beam <NUM> (at least before they are reflected by beam splitters <NUM> and <NUM>), the diffraction angles for the two beams <NUM> and <NUM>, which have different wavelengths, can be the same or even changed independent of each other. As described above, what enables this configuration is the use of two DOEs <NUM> and <NUM>. As shown, both DOEs <NUM> and <NUM> are configured or positioned to diffract beams <NUM> and <NUM> into the same number of beams. In the example of <FIG>, both DOEs <NUM> and <NUM> are positioned such that beams <NUM> and <NUM> are aligned with the middle segments of both DOEs <NUM> and <NUM>, which are configured to diffract each of beams <NUM> and <NUM>, respectively, into four beams. However, in some embodiments, a surgeon may cause both DOEs <NUM> and <NUM> to be repositioned such that beams <NUM> and <NUM> are diffracted into another number of diffracted beams (e.g., one or two). Repositioning DOEs <NUM> and <NUM>, in some embodiments, may involve mechanically or electromechanically moving the location of DOEs <NUM> and <NUM> within surgical laser system <NUM>. In certain embodiments, both DOEs <NUM> and <NUM> may be mounted on the same linear element (e.g., a carriage or stage (not shown)) such that by repositioning the linear element, both DOEs <NUM> and <NUM> are set to the same desired segment at the same time.

Note that, in certain embodiments, DOE <NUM> and <NUM> may instead be placed in a parallel manner with respect to each other. In such embodiments, DOE <NUM> and <NUM> are placed such that each respective segment of DOE <NUM> is aligned with a respective segment of DOE <NUM>. For example, the DOE <NUM> and <NUM> may be stacked (e.g., vertically or horizontally) on top of one another. In such embodiments, DOE <NUM> diffracts treatment beam <NUM> into a number of diffracted treatment beams (e.g., one, two, four) and DOE <NUM> diffracts aiming beam <NUM> into the same number of diffracted aiming beams. Further, in such embodiments, DOE <NUM> and <NUM> would diffract treatment beam <NUM> and aiming beam <NUM>, respectively, onto a single beam splitter, which then reflects the diffracted treatment beams and the diffracted aiming beams onto a condensing lens. For example, the single beam splitter may be designed to have two narrow-spectral-band high-reflectance notches, one for reflecting the diffracted treatment beams and one for reflecting the diffracted aiming beams. Further, the single beam splitter may be tall enough (e.g., vertically) to simultaneously reflect the diffracted aiming beams and the diffracted treatment beams to the condensing lens, which then focuses each of the treatment beams and its corresponding aiming beam to the interface plane of cable <NUM>.

<FIG> illustrates an example input into an interface plane <NUM> of the proximal end of cable <NUM>, which is exposed through an opening <NUM> of ferrule <NUM>. Because DOEs <NUM> and <NUM> are configured to diffract treatment beam <NUM> and aiming beam <NUM>, respectively, at the same angle, the center of aiming beam 412a is now aligned with the center of treatment beam 210a, which may correspond to the center of core 344a. Note that the combination of aiming beam 412a and treatment beam 210a corresponds to combined beam 511a. The other three combined beams are not shown for simplicity. Because aiming beams 412a-d are more centered in treatment beams 210a-d, such as partly shown in <FIG>, the inter-spot uniformity across the aiming beams 212a-d is increased. In addition, surgical laser system <NUM> has a higher margin for any potential misalignment that may be caused due to an optical drift or other types of environmental conditioning and/or perturbations. Also, because the inter-spot power non-uniformity of DOE <NUM> is minimized by optimizing its grating design for the wavelength of treatment beam <NUM> and the inter-spot power non-uniformity of DOE <NUM> is minimized by optimizing its grating design for the wavelength of aiming beam <NUM>, the beam power uniformity across the four diffracted treatment beams and the four diffracted aiming beams can be optimized. Using DOE <NUM>, which is tuned to the wavelength of aiming beam <NUM>, also reduces the out-of-order leakage of aiming beam <NUM>.

Further, surgical laser system <NUM> has a higher angular stability and is less prone to misalignment, as compared to surgical laser system <NUM>, because beam splitter <NUM> no longer reflects aiming beam <NUM>. Generally, alignment sensitivity is much higher for reflection than for transmission. Since beam splitter <NUM> of surgical laser system <NUM> is only used for transmission of laser beams (i.e., treatment beam <NUM>), it is not a major source of potential beam angular stability and alignment. Because even if environmental conditioning and/or perturbations cause slight misalignments to beam splitter <NUM>, the angle at which treatment beam <NUM> is transmitted may not be significantly impacted. In surgical laser system <NUM>, however, beam splitter <NUM> is used for both reflection (i.e., reflection of aiming beam <NUM>) and transmission (i.e., transmission of treatment beam <NUM>). As such, any small misalignment of beam splitter <NUM> may significantly impact the angle with which aiming beam <NUM> is reflected. In addition, the arrangement of components in surgical laser system <NUM>, allows for a more optimal placement of sensor <NUM>. As shown in <FIG>, sensor <NUM> is placed such that it is less likely to receive any scattered light from treatment beam <NUM>. Sensor <NUM> may be sensitive to green light (e.g., treatment beam <NUM>) when attempting to sense the presence of white light (e.g., illumination beam <NUM>) and, therefore, by receiving scattered light from treatment beam <NUM>, sensor <NUM> may mistakenly determine the presence of illumination beam <NUM>. For example, the placement of sensor <NUM> in surgical laser system <NUM> is such that it may receive some of the scattered light from the diffracted treatment beams 210a-d and incorrectly detect the presence of illumination beam <NUM>.

<FIG> illustrates an example DOE <NUM> having three segments <NUM>, <NUM>, and <NUM>. DOE <NUM> is similar to DOEs <NUM> and <NUM> in terms of the number of segments it has. As shown, a beam <NUM> is diffracted by segment <NUM> into one beam while the same beam <NUM> is diffracted by segment <NUM> into four beams. Segment <NUM> diffracts beam <NUM> into two beams.

A user, such as a surgeon, may select a desired number of beams to be propagated from a probe. For example, the surgeon may select four treatment beams to be propagated from the probe. The surgeon's selection is received at the surgical laser system (e.g., surgical laser system <NUM>, <NUM>, or <NUM>) as input into the system's central processing unit (CPU). The CPU may then be configured to execute a certain set of instructions that are stored in the system's memory, which cause the system to position the system's DOE(s) based on the surgeon's selection. In the example of DOEs <NUM> and <NUM>, the processor may cause an electromechanical motor to move a carriage on which DOEs <NUM> and <NUM> are mounted to ensure that aiming beam <NUM> and treatment beam <NUM> are aligned with segments of DOEs <NUM> and <NUM>, respectively, that are configured to diffract the beams into four diffracted beams.

Claim 1:
A surgical laser system (<NUM>), comprising:
a first laser source (<NUM>) configured to emit a first laser beam (<NUM>) with a first wavelength;
a second laser source (<NUM>) configured to emit a second laser beam (<NUM>) with a second wavelength;
a first diffraction optical element, DOE, (<NUM>) tuned to the first wavelength, wherein the first DOE is configured to diffract the first laser beam into one or more first diffracted beams at a diffraction angle;
a second DOE (<NUM>) tuned to the second wavelength, wherein the second DOE is configured to diffract the second laser beam into one or more second diffracted beams at the diffraction angle;
a first beam splitter (<NUM>) configured to reflect the one or more first diffracted beams onto a lens (<NUM>) and a second beam splitter (<NUM>) configured to reflect the one or more second diffracted beams onto the lens (<NUM>); and
the lens (<NUM>) configured to focus the one or more first diffracted beams and the one or more second diffracted beams onto an interface plane of a proximal end of a cable (<NUM>) coupled to the surgical laser system, wherein a distal end of the cable is configured to project the one or more first diffracted beams and the one or more second diffracted beams onto a target surface; and
further comprising
a light source (<NUM>) configured to emit an illumination beam (<NUM>) onto the lens (<NUM>), wherein once emitted by the light source the illumination beam passes through the first beam splitter (<NUM>) and the second beam splitter (<NUM>); and
wherein the lens (<NUM>) is configured to focus the illumination beam onto the interface plane.