Multipurpose beam sampler in laser beam delivery path of ophthalmic laser system

Abstract

In a laser beam delivery system for an ophthalmic laser system, a single multipurpose beam sampler is employed to form three sampled laser beams, including two sampled laser beams for redundant laser energy monitoring and one sampled laser beam for laser focal point depth measurement. The beam sampler is a transparent plate having preferably parallel front and back surfaces. The front surface reflects a portion of an incident beam to form a first sampled beam toward an energy monitoring detector. The back surface reflects another portion of the beam to form a second sampled beam from the front surface rearward toward another energy monitoring detector. An objective lens focuses a transmitted beam onto a target and collects back-reflected or scattered light from the target to form a return beam. The back surface of the beam sampler reflects a portion of the return beam to form a third sampled beam toward a third detector.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 63 / 081,081, filed on September 21, 2020, which is incorporated herein by reference in its entirety. Background Art Technical Field

[0004] The present invention relates to ophthalmic laser surgical systems, and in particular, it relates to laser beam delivery systems for ophthalmic laser surgical systems.

[0005] Related technologies

[0006] In ophthalmic laser surgery systems, to meet relevant safety requirements, energy monitoring components must function redundantly to monitor the laser power delivered to the surgical target. In a typical ophthalmic laser surgery system, small portions of the laser beam are picked up at two locations and sent toward two separate detectors to monitor the laser energy or power.

[0007] In some ophthalmic laser surgery systems, a beam splitter is used to direct a small portion of the return laser beam to a light intensity detector for the purpose of calibrating and measuring the depth position of the laser focus. The return laser beam refers to the laser beam that has been focused on a target (e.g., an eye or other target) by an objective lens, reflected or scattered back by the target, and collected by the objective lens to travel backward along the laser beam path. One such laser system is described in co-owned U.S. Patent Application Publication No. 2020 / 0064622, entitled “Detection of Optical Surface of Patient Interface for Ophthalmic Laser Applications Using a Non-Confocal Configuration.” Summary of the Invention

[0008] In an ophthalmic laser system that needs to form three sampling beams (two sampling beams for independent laser energy monitoring detectors and one sampling beam for a depth measurement detector), using three independent beam samplers in the main laser beam path will result in significant optical losses and wavefront distortion.

[0009] Accordingly, the present invention is directed to a laser beam delivery system for an ophthalmic laser system that employs a single multipurpose beam sampler to form three sampling beams. Such a system substantially obviates one or more problems due to limitations and disadvantages of the related art.

[0010] An object of the present invention is to provide a laser beam delivery system having a simpler structure, reduced alignment complexity, and reduced optical losses and wavefront distortion.

[0011] Additional features and advantages of the present invention will be set forth in the following description, and in part will be apparent from the description, or may be learned through practice of the present invention. The purposes and other advantages of the present invention will be realized and obtained through the structures particularly pointed out in the written description, claims, and drawings.

[0012] To achieve the above-mentioned object, the present invention provides an ophthalmic laser system, the ophthalmic laser system comprising: a beam sampler, the beam sampler comprising a plate made of a transparent material having a front surface and a rear surface, wherein the beam sampler is configured to: receive a laser beam at the front surface; form a first sampling beam by reflecting a first portion of the laser beam by the front surface; form a second sampling beam by reflecting a second portion of the laser beam by the rear surface, the second sampling beam leaving the front surface; and transmit a portion of the laser beam out of the rear surface; a first light detector and a second light detector, the first light detector and the second light detector The first photodetector and the second photodetector are respectively configured to receive and detect the first sampling beam and the second sampling beam, the first photodetector and the second photodetector being independent of each other; an objective lens configured to receive the laser beam transmitted through the beam sampler and focus the laser beam to a focal point in a target, wherein the objective lens is further configured to receive laser light reflected or scattered from the target to form a return beam toward the rear surface of the beam sampler, wherein the beam sampler is further configured to form a third sampling beam by reflecting a portion of the return beam by the rear surface; and a third photodetector configured to receive the third sampling beam.

[0013] In another aspect, the present invention provides a method implemented in an ophthalmic laser system, the method comprising: receiving a laser beam at a front surface by a beam sampler, the beam sampler being a plate made of a transparent material having a front surface and a back surface; reflecting a first portion of the laser beam by the beam sampler through the front surface to form a first sampling beam; reflecting a second portion of the laser beam by the beam sampler through the back surface to form a second sampling beam exiting the front surface; transmitting a portion of the laser beam out of the back surface by the beam sampler; receiving the first sampling beam by a first photodetector; receiving the second sampling beam by a second photodetector independent of the first photodetector; receiving the laser beam transmitted through the beam sampler by an objective lens and focusing the laser beam to a focal point in a target; receiving laser light reflected or scattered from the target by the objective lens to form a return beam toward the back surface of the beam sampler; reflecting a portion of the return beam by the beam sampler through the back surface to form a third sampling beam; and receiving and detecting the third sampling beam by a third photodetector.

[0014] In some embodiments, the beam sampler is a glass plate having uncoated parallel front and back surfaces.

[0015] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A laser beam delivery system for an ophthalmic laser surgery system employing a single multipurpose beam sampler is schematically illustrated according to an embodiment of the present invention.

[0017] Figure 2 Another laser beam delivery system for an ophthalmic laser surgery system employing multiple independent beam samplers is schematically shown. DETAILED DESCRIPTION

[0018] Figure 2 The laser beam delivery system for an ophthalmic laser surgery system is schematically shown, which employs three independent beam samplers 21, 22 and 23. Figure 2As shown, a laser beam 20A generated by a laser source 24 sequentially passes through a first beam sampler 21, a second beam sampler 22, and a third beam sampler 23. Portions 20B and 20C of the beam are reflected at the front surfaces of the first beam sampler 21 and the second beam sampler 22, respectively, toward two separate energy monitoring detectors (i.e., photodiodes) 25 and 26, respectively. The detectors 25 and 26 provide redundant energy monitoring functionality. After passing through the third beam sampler 23 (reflection from this beam sampler is not shown), the laser beam 20A is focused by an objective lens 27 onto a target (e.g., an eye, or a patient interface device, or other target, in FIG. 2 ). Figure 2 (not shown in the figure). The laser beam reflected and / or scattered from the target is collected by the objective lens as a return beam 20D, a portion 20E of which is reflected at the rear surface of the third beam sampler 23 toward a light intensity detector (i.e., a photodiode) 28 for a focus depth measurement function. The transmitted portion of the return beam is not shown in the figure. Other optical components of the laser beam delivery system (such as a shutter, a reflector, a scanner, etc.) are not shown in the figure.

[0019] The beam sampler is a transparent plate. In this optical system, there are six optical surfaces—the front and back surfaces of each beam sampler—which contribute to optical losses and wavefront distortion. In addition, this configuration has significant optical system alignment complexity and associated costs.

[0020] Figure 1 A laser beam delivery system for an ophthalmic laser surgery system according to an embodiment of the present invention is schematically shown.The system employs a single beam sampler optical element 11 (preferably a transparent plate with two optical surfaces) to form three sampling beams.

[0021] like Figure 1 As shown, when a laser beam 10A generated by a laser source 14 enters the beam sampler 11, a portion of the beam is reflected at the front surface of the beam sampler as a first sampling beam 10B toward a first energy monitoring detector (i.e., a photodiode) 15. After traveling through the interior of the beam sampler, another portion of the beam is reflected at the rear surface of the beam sampler, travels back through the interior of the beam sampler, and exits the front surface as a second sampling beam 10C toward a second energy monitoring detector (i.e., a photodiode) 16. Detectors 15 and 16 are independent of each other and provide redundant energy monitoring functionality.

[0022] After leaving the rear surface of the beam sampler (and passing through Figure 1After being transmitted through the optical fiber of the optical fiber sampling device 11 and the incident beam 10A, the laser beam 10A is focused by the objective lens 17 onto a target (e.g., an eye, or a patient interface device, or other target, not shown in the figure). The laser beam reflected and / or scattered from the target is collected by the objective lens 17 as a return beam 10D. A portion of the return beam is reflected at the rear surface of the beam sampler 11 (as a third sampling beam 10E) toward a light intensity detector (i.e., a photodiode) 18 for a depth of focus measurement function. The transmitted portion of the return beam is not shown in the figure. Note here that for ease of illustration, the return beam 10D is schematically shown in a manner offset relative to the incident beam 10A, but the two beams actually overlap with each other. The principle of depth of focus measurement using a sampled return beam is described in the above-mentioned U.S. Patent Application Publication No. 2020 / 0064622.

[0023] In a preferred embodiment, the beam sampler is a glass plate having parallel front and back surfaces with no coating on either surface. The reflectivity of the uncoated air-glass interface is a function of the refractive index of the glass, which is very stable over time. Such a surface typically has a weak reflectivity, e.g., a few percent, which also depends on the angle of incidence and polarization of the incident light. In some preferred embodiments, the beam sampler is positioned close to the Brewster angle (e.g., within ±12 degrees of the Brewster angle) relative to the incident laser beam 10A, and the incident laser beam is p-polarized, so that the intensity of both the first sampling beam 10B and the second sampling beam 10C is very low, e.g., both are only about 0.6% of the intensity of the incident laser beam (or more generally, between 0.4% and 0.8%).

[0024] With respect to the return beam, in some preferred embodiments, the optical components between the beam sampler 11 and the objective lens 17 are such that they do not substantially change the polarization of the laser light. In such a system, the return beam that has been reflected from the target will have approximately the same polarization as the incident laser beam, so the reflectivity of the return beam at the back surface will also be about 0.6%. In alternative embodiments, the return beam may have a different polarization than the incident laser beam, so the reflectivity of the return beam at the back surface may be different. When the laser light is scattered (as opposed to reflected) by the target, such as when the laser beam is used to cut eye tissue, the return beam will have a different polarization than the incident laser beam. In this case, the reflectivity of the return beam at the back surface of the beam sampler will be higher, such as about 6%-8%. This higher reflectivity is desirable for detecting weak backscattered light.

[0025] In some alternative embodiments, the beam sampler can be a glass plate having a coated surface including an antireflective coating, a dichroic coating, a metallic coating, or other type of suitable coating.

[0026] In a preferred embodiment, beam sampler 11 has parallel front and back surfaces and sufficient thickness to spatially separate first and second sampling beams 10B, 10C sufficiently to allow them to be incident on two independent detectors 15 and 16. In one example, the thickness of beam sampler 11 is 10 mm. When the glass sheet has a refractive index of 1.45 and the angle of incidence is 45 degrees, this thickness provides a lateral deviation between the incident and transmitted laser beams of 3.15 mm, and a distance between the parallel first and second sampling beams 10B, 10C of 7.6 mm. First and second energy monitoring detectors 15, 16 are appropriately sized and positioned to separately receive the first and second sampling beams, respectively. More generally, the thickness of beam sampler 11 can be 10 mm to 20 mm.

[0027] In some alternative embodiments, the beam sampler can be a plate with two non-parallel surfaces. In such an embodiment, the first sampling beam and the second sampling beam will not be parallel to each other, and the positions of the first energy monitoring detector 15 and the second energy monitoring detector 16 and the depth measurement detector 18 should be adjusted accordingly.

[0028] One or more filters 19 (i.e., color filters, polarization filters, etc.) may be provided in the paths of the first sampling beam 10B and the second sampling beam 10C. Other optical components of the laser beam delivery system (such as shutters, mirrors, scanners, etc.) are not shown in the figure. These components may be located between the laser source 14 and the beam sampler 11 and / or between the beam sampler and the objective lens 17.

[0029] In summary, embodiments of the present invention employ a single beam sampler with two optical surfaces in the laser beam delivery path of an ophthalmic laser system to form three sampling beams, two for redundant laser energy monitoring and one for focus depth measurement. Figure 2 Compared to the system shown, which uses three independent beam samplers with six optical surfaces, only two optical surfaces are present in the optical path to perform the beam sampling function. Optical losses and wavefront distortion are reduced by a factor of three. Furthermore, the system is more robust because the laser alignment complexity is also reduced by a factor of three. This design also reduces costs.

[0030] It will be apparent to those skilled in the art that various modifications and variations can be made in the ophthalmic laser beam delivery system of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Claims

1. An ophthalmic laser system comprising: a beam sampler comprising a plate made of a transparent material having a front surface and a back surface, wherein the beam sampler is configured to: receive a laser beam at the front surface; form a first sampling beam by reflecting a first portion of the laser beam by the front surface; and form a second sampling beam by reflecting a second portion of the laser beam by the back surface, the second sampling beam exiting the front surface; and transmitting a portion of the laser beam out of the rear surface; a first light detector and a second light detector, wherein the first light detector and the second light detector are respectively configured to receive and detect the first sampling light beam and the second sampling light beam, and the first light detector and the second light detector are independent of each other; an objective lens configured to receive the laser beam transmitted through the beam sampler and focus the laser beam to a focal point in a target, wherein the objective lens is further configured to receive laser light reflected or scattered from the target to form a return beam toward the rear surface of the beam sampler, wherein the beam sampler is further configured to form a third sampling beam by reflecting a portion of the return beam by the rear surface; and A third light detector is configured to receive the third sampling light beam.

2. The ophthalmic laser system according to claim 1, wherein: The beam sampler is a transparent plate.

3. The ophthalmic laser system of claim 1 , wherein: The beam sampler is a glass plate with uncoated front and back surfaces.

4. The ophthalmic laser system of claim 3, wherein: The front surface and the rear surface of the beam sampler are parallel to each other.

5. The ophthalmic laser system of claim 4, wherein: The beam sampler is positioned within ±12 degrees of the Brewster angle relative to the received laser beam.

6. The ophthalmic laser system of claim 1 , wherein: The front surface and the rear surface of the beam sampler are parallel to each other and the beam sampler has a thickness of 10 mm to 20 mm.

7. The ophthalmic laser system of claim 1 , wherein: The beam sampler is a glass plate having coated front and back surfaces.

8. The ophthalmic laser system of claim 1 , wherein: The first light detector, the second light detector, and the third light detector are photodiodes.

9. The ophthalmic laser system of claim 1, further comprising one or more filters disposed between the front surface of the beam sampler and the first and second light detectors.

10. The ophthalmic laser system of claim 1, further comprising a laser source configured to generate the laser beam.

11. A method implemented in an ophthalmic laser system, the method comprising: receiving the laser beam at the front surface by a beam sampler, the beam sampler being a plate made of a transparent material having the front surface and a rear surface; reflecting a first portion of the laser beam by the beam sampler through the front surface to form a first sampling beam; reflecting a second portion of the laser beam by the beam sampler through the rear surface to form a second sampling beam exiting the front surface; transmitting a portion of the laser beam out of the rear surface by the beam sampler; receiving the first sampling light beam by a first light detector; receiving the second sampling beam by a second light detector independent of the first light detector; receiving, by an objective lens, the laser beam transmitted through the beam sampler and focusing the laser beam to a focal point in a target; receiving, by the objective lens, laser light reflected or scattered from the target to form a return beam toward the rear surface of the beam sampler; reflecting a portion of the return beam by the beam sampler through the rear surface to form a third sampling beam; and The third sampling light beam is received and detected by a third light detector.

12. The method according to claim 11, wherein The beam sampler is a transparent plate.

13. The method according to claim 11, wherein The beam sampler is a glass plate with uncoated front and back surfaces.

14. The method according to claim 13, wherein: The front surface and the rear surface of the beam sampler are parallel to each other.

15. The method according to claim 14, wherein The beam sampler is positioned within ±12 degrees of the Brewster angle relative to the received laser beam.

16. The method according to claim 11, wherein The front surface and the rear surface of the beam sampler are parallel to each other and the beam sampler has a thickness of 10 mm to 20 mm.

17. The method according to claim 11, wherein The beam sampler is a glass plate having coated front and back surfaces.

18. The method according to claim 11, wherein The first light detector, the second light detector, and the third light detector are photodiodes.

19. The method according to claim 11, further comprising: The first sampling beam and the second sampling beam are filtered by one or more filters.

20. The method of claim 11, further comprising: The laser beam is generated by a laser source.

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