Ophthalmic laser system and method of operation thereof

Abstract

A laser beam delivery system for an ophthalmic laser system uses a single multi-purpose beam sampler to generate three sampled laser beams, including two for redundant laser energy monitoring and one for laser focal depth measurement. The beam sampler is preferably a transparent plate with parallel front and rear faces. The front face reflects a portion of the incident beam to form a first sampled beam toward an energy monitoring detector. The rear face reflects another portion of the beam to form a second sampled beam that exits the front face toward another energy monitoring detector. An objective lens focuses the transmitted beam onto a target and collects light reflected or scattered back from the target to form a return beam. The rear face of the beam sampler reflects a portion of the return beam to form a third sampled beam toward a third detector.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 63 / 081,081, filed September 21, 2020, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present invention relates to ophthalmic laser surgery systems, and more particularly to laser beam delivery systems for ophthalmic laser surgery systems. [Background technology]

[0003] 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, a portion of the laser beam is tapped off at two locations and sent to two independent detectors to monitor the laser energy, or power.

[0004] Some ophthalmic laser surgery systems use a beam splitter to direct a small portion of the returning laser beam to a light intensity detector for the purpose of calibrating and measuring the depth position of the laser focus. The returning laser beam refers to the laser beam that is focused by the objective lens onto a target (e.g., an eye or other target), reflected or scattered back by the target, and collected by the objective lens to travel back along the laser beam path. One such laser system is described in commonly 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 [Means for solving the problem]

[0005] In an ophthalmic laser system that requires three sampled beams to be formed (two for separate laser energy monitoring detectors and one for the depth measurement detector), using three separate beam samplers in the main laser beam path would result in significant light loss and wavefront distortion.

[0006] Accordingly, the present invention relates to a laser beam delivery system for an ophthalmic laser system that uses a single versatile beam sampler to form three sampled beams. Such a system substantially obviates one or more problems due to limitations and drawbacks of the related art.

[0007] It is an object of the present invention to provide a laser beam delivery system with a simpler structure, reduced alignment complexity, reduced optical losses and reduced wavefront distortion.

[0008] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the detailed description and claims hereof, as well as the appended drawings.

[0009] To achieve the above object, the present invention provides a beam sampler comprising a plate made of a transparent material having a front surface and a rear surface, the beam sampler being configured to receive a laser beam at the front surface, reflect a first portion of the laser beam by the front surface to form a first sampled beam, reflect a second portion of the laser beam by the rear surface to form a second sampled beam, the second sampled beam exiting the front surface, and transmit a portion of the laser beam through the rear surface; and a beam sampler configured to receive the first sampled beam and the second sampled beam, respectively. An ophthalmic laser system is provided, comprising: a first photodetector and a second photodetector, which are arranged to emit and detect light and are independent of each other; an objective lens arranged to receive a laser beam transmitted through a beam sampler and focus the laser beam to a focal point within a target, the objective lens being further configured to receive laser light reflected or scattered from the target and form a return beam toward a rear face of the beam sampler, the beam sampler being further configured to form a third sampled beam by reflecting a portion of the return beam by the rear face; and a third photodetector arranged to receive the third sampled beam.

[0010] In another aspect, the invention is a method practiced 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 at the front surface by the beam sampler to form a first sampled beam; reflecting a second portion of the laser beam at the back surface by the beam sampler to form a second sampled beam exiting the front surface; transmitting a portion of the laser beam through the back surface by the beam sampler; and detecting the first sampled beam through a first photodetector. receiving the laser beam transmitted through the beam sampler with an objective lens and focusing the laser beam to a focal point within the target; receiving the laser light reflected or scattered from the target with the objective lens and forming a return beam toward the rear facet of the beam sampler; reflecting a portion of the return beam by the rear facet of the beam sampler to form a third sampled beam; and receiving and detecting the third sampled beam with a third photodetector.

[0011] In some embodiments, the beam sampler is a glass plate with uncoated parallel front and back surfaces.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 illustrates a schematic diagram of a laser beam delivery system for an ophthalmic laser surgery system using a single versatile beam sampler according to an embodiment of the present invention. [Figure 2]10 illustrates schematically another laser beam delivery system for an ophthalmic laser surgery system that uses multiple separate beam samplers. DETAILED DESCRIPTION OF THE INVENTION

[0014] FIG. 2 illustrates a schematic diagram of a laser beam delivery system for an ophthalmic laser surgery system using three separate beam samplers 21, 22, and 23. As shown in FIG. 2, a laser beam 20A generated by a laser source 24 passes sequentially 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 off the front surfaces of the first beam sampler 21 and the second beam sampler 22, respectively, and directed to two independent energy monitoring detectors (i.e., photodiodes) 25 and 26, respectively. Detectors 25 and 26 provide redundant energy monitoring functionality. After passing through the third beam sampler 23 (reflections from this beam sampler are not shown), laser beam 20A is focused by an objective lens 27 onto a target (e.g., the eye, a patient interface device, or other target not shown in FIG. 2). The laser beam reflected and / or scattered from the target is collected by the objective lens as a return beam 20D, a portion of which 20E is reflected at the rear face of the third beam sampler 23 towards a light intensity detector (i.e., photodiode) 28 for the depth-of-focus measurement function. The transmitted portion of the return beam is not shown in the drawings. Other optical components of the laser beam delivery system, such as shutters, mirrors, scanners, etc., are not shown in the drawings.

[0015] The beam sampler is a transparent plate. In this optical system, there are six optical surfaces (front and rear surfaces of each beam sampler) that contribute to light loss and wavefront distortion. Furthermore, this configuration makes the alignment of the optical system very complicated and has associated costs.

[0016] 1 shows a schematic diagram of a laser beam delivery system for an ophthalmic laser surgery system according to one embodiment of the present invention. The system uses a single beam sampler optic 11, preferably a transparent plate with two optical surfaces, to form three sampled beams.

[0017] 1, when laser beam 10A generated by laser source 14 enters beam sampler 11, a portion of the beam is reflected off the front surface of the beam sampler toward a first energy monitoring detector (i.e., photodiode) 15 as a first sampled beam 10B. After traveling through the interior of the beam sampler, another portion of the beam is reflected off the back surface of the beam sampler, travels back through the interior of the beam sampler, and exits the front surface as a second sampled beam 10C toward a second energy monitoring detector (i.e., photodiode) 16. Detectors 15 and 16 are independent of each other, providing redundant energy monitoring capabilities.

[0018] After exiting the rear facet of the beam sampler 11 (and passing through any other optical components not shown in FIG. 1 ), 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). 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 from the rear facet of the beam sampler 11 as a third sampled beam 10E toward a light intensity detector (i.e., a photodiode) 18 for the focal depth measurement function. The transmitted portion of the return beam is not shown in the drawings. Note that the return beam 10D is shown schematically offset relative to the incident beam 10A for ease of illustration, although in reality the two beams overlap. The principles of focal depth measurement using a sampled return beam are described in the aforementioned U.S. Patent Application Publication No. 2020 / 0064622.

[0019] In preferred embodiments, the beam sampler is a glass plate with parallel front and rear surfaces and no coatings on either surface. The reflectivity of an uncoated air-glass interface is a function of the refractive index of the glass and is very stable over time. Such surfaces typically have 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 at an angle close to the Brewster angle (e.g., within ±12 degrees of the Brewster angle) with respect to the incident laser beam 10A, and the incident laser beam is p-polarized. Therefore, the intensities of both the first sampled beam 10B and the second sampled beam 10C are very low, e.g., both only about 0.6% (or more commonly 0.4%-0.8%) of the intensity of the incident laser beam.

[0020] For 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 systems, the return beam reflected by the target has approximately the same polarization as the incident laser beam, and therefore the reflectivity of the return beam at the back surface is also approximately 0.6%. In alternative embodiments, the return beam may have a different polarization than the incident laser beam, and therefore 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, for example, when cutting ocular tissue with the laser beam, the return beam will have a different polarization than the incident laser beam. In such a situation, the reflectivity of the return beam at the back surface of the beam sampler will be higher, for example, approximately 6-8%. This higher reflectivity is desirable for detecting weak backscattered light.

[0021] In some alternative embodiments, the beam sampler may be a glass plate having a coated surface, including an anti-reflective coating, a dichroic coating, a metallic coating, or other type of suitable coating.

[0022] In a preferred embodiment, the beam sampler 11 has parallel front and rear surfaces and a sufficient thickness so that the first sampled beam 10B and the second sampled beam 110C are sufficiently spatially separated to allow them to impinge on two separate detectors 15 and 16. In one example, the beam sampler 11 is 10 mm thick. With a glass plate refractive index of 1.45 and an angle of incidence of 45 degrees, this thickness provides a 3.15 mm lateral deviation between the incident and transmitted laser beams, resulting in a 7.6 mm separation between the parallel first sampled beam 10B and second sampled beam 10C. The first energy monitoring detector 15 and the second energy monitoring detector 16 are appropriately sized and positioned to separately receive the first sampled beam and the second sampled beam, respectively. More generally, the beam sampler 11 may be 10 mm to 20 mm thick.

[0023] In some alternative embodiments, the beam sampler may be a plate with two non-parallel surfaces. In such embodiments, the first and second sampled beams are non-parallel to each other, and the positions of the first and second energy-monitoring detectors 15, 16 and the depth-measuring detector 18 should be adjusted accordingly.

[0024] One or more filters 19 (i.e., color filters, polarizing filters, etc.) may be provided on the paths of the first sampled beam 10B and the second sampled beam 10C. Other optical components of the laser beam delivery system, such as shutters, mirrors, scanners, etc., are not shown in the drawings. 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.

[0025] In summary, an embodiment of the present invention uses a single beam sampler with two optical surfaces in the laser beam delivery path of an ophthalmic laser system to form three sampled beams: two for redundant laser energy monitoring and one for focal depth measurement. Compared to using three separate beam samplers with six optical surfaces in the system shown in Figure 2, only two optical surfaces are present in the optical path to achieve the beam sampling function. Light loss and wavefront distortion are reduced by a factor of three. Furthermore, the complexity of laser alignment is also reduced by a factor of three, making the system more robust. This design also reduces costs.

[0026] It will be apparent to those skilled in the art that various modifications and variations can be made to the ophthalmic laser beam delivery system of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[0027] [Embodiment] (1) An ophthalmic laser system, comprising: a beam sampler comprising a plate made of a transparent material having a front surface and a rear surface, the beam sampler configured to receive a laser beam at the front surface; form a first sampled beam by reflecting a first portion of the laser beam by the front surface; form a second sampled beam by reflecting a second portion of the laser beam by the rear surface, the second sampled beam exiting the front surface; and transmit a portion of the laser beam out the rear surface; a first photodetector and a second photodetector, independent of each other, positioned to receive and detect the first sampled beam and the second sampled beam, respectively; an objective lens positioned to receive the laser beam transmitted through the beam sampler and focus the laser beam to a focal point within a target, the objective lens being further configured to receive laser light reflected or scattered from the target and form a return beam toward the rear facet of the beam sampler; an objective lens, the beam sampler further configured to form a third sampled beam by reflecting a portion of the return beam by the rear facet; a third photodetector positioned to receive the third sampled beam. (2) An ophthalmic laser system as described in embodiment 1, wherein the beam sampler is a transparent plate. (3) An ophthalmic laser system as described in embodiment 1, wherein the beam sampler is a glass plate having uncoated front and rear surfaces. (4) An ophthalmic laser system as described in embodiment 3, wherein the front and rear surfaces of the beam sampler are parallel to each other. (5) An ophthalmic laser system as described in embodiment 4, wherein the beam sampler is positioned within ±12 degrees of Brewster's angle with respect to the received laser beam.

[0028] (6) An ophthalmic laser system as described in embodiment 1, wherein the front and rear surfaces of the beam sampler are parallel to each other and the thickness of the beam sampler is 10 to 20 mm. (7) An ophthalmic laser system as described in embodiment 1, wherein the beam sampler is a glass plate having coated front and rear surfaces. (8) An ophthalmic laser system as described in embodiment 1, wherein the first photodetector, the second photodetector, and the third photodetector are photodiodes. (9) An ophthalmic laser system as described in embodiment 1, further comprising one or more filters positioned between the front surface of the beam sampler and the first photodetector and the second photodetector. (10) An ophthalmic laser system as described in embodiment 1, further comprising a laser source configured to generate the laser beam.

[0029] (11) A method practiced in an ophthalmic laser system, the method comprising: receiving the laser beam at a front surface with a beam sampler, the beam sampler being a plate made of a transparent material having a front surface and a rear surface; reflecting, by the beam sampler, a first portion of the laser beam by the front surface to form a first sampled beam; reflecting a second portion of the laser beam by the rear facet with the beam sampler to form a second sampled beam exiting the front facet; transmitting a portion of the laser beam through the rear surface by the beam sampler; receiving the first sampled beam with a first photodetector; receiving the second sampled beam with a second photodetector independent of the first photodetector; receiving the laser beam transmitted through the beam sampler with an objective lens and focusing the laser beam to a focal point within a target; receiving, by the objective lens, laser light reflected or scattered from the target and forming a return beam directed toward the rear facet of the beam sampler; reflecting a portion of the return beam by the rear facet with the beam sampler to form a third sampled beam; receiving and detecting the third sampled beam with a third photodetector. (12) The method of embodiment 11, wherein the beam sampler is a transparent plate. 13. The method of claim 11, wherein the beam sampler is a glass plate having uncoated front and rear surfaces. (14) The method of embodiment 13, wherein the front and rear surfaces of the beam sampler are parallel to each other. (15) The method of embodiment 14, wherein the beam sampler is positioned within ±12 degrees of Brewster's angle with respect to the received laser beam.

[0030] (16) The method described in embodiment 11, wherein the front and rear surfaces of the beam sampler are parallel to each other and the thickness of the beam sampler is 10 to 20 mm. 17. The method of claim 11, wherein the beam sampler is a glass plate having coated front and rear surfaces. (18) The method of embodiment 11, wherein the first photodetector, the second photodetector, and the third photodetector are photodiodes. (19) The method of embodiment 11, further comprising filtering the first sampled beam and the second sampled beam with one or more filters. (20) The method of claim 11, further comprising generating the laser beam with a laser source.

Claims

1. 1. An ophthalmic laser system, comprising: a beam sampler comprising a plate made of a transparent material having a front surface and a rear surface, the beam sampler configured to receive a laser beam at the front surface; form a first sampled beam by reflecting a first portion of the laser beam by the front surface; form a second sampled beam by reflecting a second portion of the laser beam by the rear surface, the second sampled beam exiting the front surface; and transmit a portion of the laser beam through the rear surface; a first photodetector and a second photodetector, independent of each other, positioned to receive and detect the first sampled beam and the second sampled beam, respectively; an objective lens positioned to receive the laser beam transmitted through the beam sampler and focus the laser beam to a focal point within a target, the objective lens being further configured to receive laser light reflected or scattered from the target and form a return beam toward the rear facet of the beam sampler; an objective lens, the beam sampler further configured to form a third sampled beam by reflecting a portion of the return beam by the rear facet; a third photodetector positioned to receive the third sampled beam.

2. The ophthalmic laser system of claim 1 , wherein the beam sampler is a transparent plate.

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

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

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

6. 2. The ophthalmic laser system of claim 1, wherein the front and back surfaces of the beam sampler are parallel to each other, and the thickness of the beam sampler is between 10 and 20 mm.

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

8. 2. The ophthalmic laser system of claim 1, wherein the first photodetector, the second photodetector, and the third photodetector are photodiodes.

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

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

11. 1. A method of operating an ophthalmic laser system, the method comprising: a beam sampler of the ophthalmic laser system, the beam sampler being a plate made of a transparent material having a front surface and a rear surface, receiving the laser beam at the front surface; the beam sampler reflecting a first portion of the laser beam by the front surface to form a first sampled beam; the beam sampler reflecting a second portion of the laser beam by the rear facet to form a second sampled beam exiting the front facet; the beam sampler transmitting a portion of the laser beam through the rear facet; a first photodetector of the ophthalmic laser system receiving the first sampled beam; a second photodetector of the ophthalmic laser system, independent of the first photodetector, receiving the second sampled beam; an objective lens of the ophthalmic laser system receiving the laser beam transmitted through the beam sampler to focus the laser beam to a focal point within a target; the objective lens receives laser light reflected or scattered from the target and forms a return beam directed toward the rear facet of the beam sampler; the beam sampler reflecting a portion of the return beam by the rear facet to form a third sampled beam; a third photodetector of the ophthalmic laser system receiving and detecting the third sampled beam.

12. The method of claim 11 , wherein the beam sampler is a transparent plate.

13. 12. The method of claim 11, wherein the beam sampler is a glass plate having uncoated front and back surfaces.

14. 14. The method of claim 13, wherein the front and back faces of the beam sampler are parallel to one another.

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

16. 12. The method of claim 11, wherein the front and back surfaces of the beam sampler are parallel to each other, and the thickness of the beam sampler is between 10 and 20 mm.

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

18. 12. The method of claim 11, wherein the first photodetector, the second photodetector, and the third photodetector are photodiodes.

19. A method of operating an ophthalmic laser system as described in claim 11, further comprising one or more filters of the ophthalmic laser system filtering the first sampled beam and the second sampled beam.

20. A method of operating an ophthalmic laser system as described in claim 11, further comprising a laser source of the ophthalmic laser system generating the laser beam.

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