Femtosecond laser operation flat-topped beam shaping optical system

Abstract

The invention discloses a femtosecond laser operation flat-topped beam shaping optical system which comprises a laser, a beam expander, a DOE shaping module and a focusing scanning module. The laser is used for outputting a femtosecond Gaussian laser beam, and the femtosecond Gaussian laser beam sequentially passes through the beam expander, the DOE shaping module and the focusing scanning module and then acts on an operation area; the beam expander is used for expanding the diameter of the femtosecond Gaussian laser beam to the beam diameter used for cutting the light path; the DOE shaping module comprises a DOE diffractive optical element; the DOE diffractive optical element is arranged on a path of the femtosecond Gaussian laser beam and is used for converting an incident Gaussian beam into a flat-topped beam with uniformly distributed energy through phase modulation; the flat-topped light beam has no local energy peak value, thermal damage and excessive ionization of traditional Gaussian laser to normal tissues of eyes are avoided, postoperative inflammatory response is light, the tissue recovery speed is increased, and the risk of operative complications is reduced.

Description

Technical Field

[0001] This invention relates to the field of laser surgery technology, and in particular to a femtosecond laser surgery flat-top beam shaping optical system. Background Technology

[0002] Femtosecond laser surgery, with its ultra-short pulse and ultra-high peak power, has become the core technology of ophthalmic refractive surgery. It achieves precise and minimally invasive cutting of corneal and ocular tissues through the nonlinear ionization effect of laser and biological tissues. Compared with traditional mechanical surgery, it has significant advantages such as less trauma, faster recovery and higher precision.

[0003] Currently, conventional femtosecond laser surgery optical systems mostly output Gaussian beams. These beams exhibit a normal energy distribution with a strong center and weak edges, which presents several technical drawbacks in clinical applications: First, excessively high energy at the center of the Gaussian beam can lead to over-ionization of tissue in the surgical area, causing corneal stromal thermal damage and cell apoptosis, increasing postoperative inflammation and recovery time. Second, insufficient energy at the beam edges results in irregular tissue cutting edges and rough incisions, affecting the closure of the surgical incision and postoperative visual quality. Third, uneven energy distribution makes it difficult to precisely control the laser cutting depth and range, significantly increasing surgical risks for patients with thin corneas and high refractive errors. Summary of the Invention

[0004] According to an embodiment of the present invention, a femtosecond laser surgery flat-top beam shaping optical system is provided, comprising: a laser, a beam expander, a DOE shaping module, and a focusing scanning module; The laser is used to output a femtosecond Gaussian laser beam, which is applied to the surgical area after passing through a beam expander, a DOE shaping module and a focusing scanning module in sequence. The beam expander is used to expand the diameter of the femtosecond Gaussian laser beam to the diameter of the beam used in the cutting optical path; The DOE shaping module includes: DOE diffraction optical elements; The DOE diffraction optical element is placed in the path of the femtosecond Gaussian laser beam and is used to convert the incident Gaussian beam into a flat-top beam with uniform energy distribution through phase modulation. The focusing scanning module is used to focus the flat-top beam onto the surgical area.

[0005] Furthermore, the femtosecond Gaussian laser beam has a pulse width of 10fs to 500fs and a wavelength of 980nm to 1080nm, and the femtosecond Gaussian laser beam is a parallel beam with a spot diameter of 1mm to 20mm.

[0006] Furthermore, the DOE diffractive optical element has a flat-top beam conversion efficiency of ≥90% and an energy uniformity error of ≤5%.

[0007] Furthermore, the surface of the DOE diffractive optical element is coated with an antireflection film, the wavelength of which is adapted to the output wavelength of the laser, and the transmittance of the antireflection film is ≥95%.

[0008] Furthermore, the DOE shaping module also includes: a fixing bracket and an adjustment mechanism; The adjustment mechanism is mounted on a fixed support, and its output end is connected to the DOE diffraction optical element to adjust the incident angle of the DOE diffraction optical element.

[0009] Furthermore, the angle adjustment accuracy of the adjustment mechanism is <1°, enabling bidirectional fine adjustment of the DOE diffraction optical element around the X and Y axes.

[0010] Furthermore, the light spot of the flat-top beam in the surgical area is circular, and the diameter of the light spot is less than 10 μm.

[0011] Furthermore, the light spot of the flat-top beam in the surgical area is square, and the width of the light spot is less than 10 μm.

[0012] Furthermore, the focusing scanning module includes: an X-ray galvanometer, a relay system, a Y-ray galvanometer, a scanning optical path, and a focusing objective lens; The flat-top beam converted by the DOE diffraction optical element passes sequentially through an X-mirror, a relay system, a Y-mirror, a scanning optical path, and a focusing objective. The X-mirror is used to deflect the flat-top beam in the X direction. The relay system is used to accurately image the reflecting surface of the X-mirror onto the reflecting surface of the Y-mirror. The Y-mirror is used to deflect the flat-top beam in the Y direction. The scanning optical path is used to maintain a high degree of consistency in the beam size, shape, energy density, and incident angle. The focusing objective is used to focus the flat-top beam onto the surgical area.

[0013] Furthermore, a deflection optical path is provided between the scanning optical path and the focusing objective lens, and the deflection optical path is used to adjust the transmission path of the flat-top beam.

[0014] According to an embodiment of the present invention, a femtosecond laser surgery flat-top beam reshaping optical system outputs a raw Gaussian-distributed femtosecond laser beam. After being expanded by a beam expander, the parallel Gaussian beam is perpendicularly incident on a DOE diffraction optical element. The micro-nano phase structure on the surface of the DOE diffraction optical element modulates the wavefront phase of the beam. Through the diffraction effect of light, the Gaussian beam with concentrated energy at the center and attenuated energy at the edges is converted into a flat-top beam with uniform energy distribution and steep edges within the beam spot. The beam is precisely focused onto the corneal surgical area by a focusing scanning module, achieving uniform and precise minimally invasive ablation. Since the flat-top beam has no central peak energy, excessive damage to local tissues will not occur during the ablation process, resulting in neat incision edges and consistent ablation depth, significantly improving the quality and safety of the surgery.

[0015] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0016] Figure 1 This is a top view of a femtosecond laser surgery flat-top beam shaping optical system according to an embodiment of the present invention; Figure 2 This is a front view of a femtosecond laser surgery flat-top beam shaping optical system according to an embodiment of the present invention; Figure 3 This is a diagram of the shaping optical path of a DOE shaping module in a femtosecond laser surgery flat-top beam shaping optical system according to an embodiment of the present invention. Figure 4 This invention relates to a Gaussian beam intensity distribution in a femtosecond laser surgical flat-top beam shaping optical system according to an embodiment of the present invention. Figure 5 This is a light intensity distribution diagram of a femtosecond laser surgical flat-top beam shaping optical system according to an embodiment of the present invention.

[0017] In the figure, the following labels are used: 1 is the DOE diffraction optical element, 2 is the X-ray galvanometer, 3 is the relay system, 4 is the Y-ray galvanometer, 5 is the scanning optical path, 6 is the turning optical path, and 7 is the focusing objective. Detailed Implementation

[0018] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, further illustrating the present invention.

[0019] First, combine Figures 1-5 This invention describes a flat-top beam shaping optical system for femtosecond laser surgery, used for shaping a Gaussian beam during femtosecond laser surgery.

[0020] like Figures 1-5As shown, an embodiment of the present invention provides a femtosecond laser surgical flat-top beam shaping optical system, comprising: a laser, a beam expander, a DOE shaping module, and a focusing scanning module; The laser is used to output a femtosecond Gaussian laser beam, which is applied to the surgical area after passing through a beam expander, a DOE shaping module and a focusing scanning module in sequence. The beam expander is used to expand the diameter of the femtosecond Gaussian laser beam to the diameter of the beam used in the cutting optical path; The DOE shaping module includes: DOE diffraction optical element 1; The DOE diffraction optical element 1 is disposed in the path of the femtosecond Gaussian laser beam and is used to convert the incident Gaussian beam into a flat-top beam with uniform energy distribution through phase modulation. The focusing scanning module is used to focus the flat-top beam onto the surgical area.

[0021] The laser in this application outputs a raw Gaussian-distributed femtosecond laser beam, which is expanded by a beam expander and then incident perpendicularly onto the DOE diffractive optical element 1. The micro-nano phase structure on the surface of the DOE diffractive optical element 1 modulates the wavefront phase of the beam. Through the diffraction effect of light, the Gaussian beam with concentrated energy at the center and attenuated energy at the edges is converted into a flat-top beam with uniform energy distribution within the spot and steep edges. The beam is then precisely focused onto the corneal surgical area by a focusing scanning module, achieving uniform and precise minimally invasive ablation. Since the flat-top beam has no central peak energy, excessive damage to local tissues will not occur during the ablation process, resulting in neat incision edges and consistent ablation depth, significantly improving the quality and safety of the surgery.

[0022] The flat-top beam has no local energy peaks, avoiding thermal damage and excessive ionization of normal eye tissues caused by traditional Gaussian lasers. Postoperative inflammatory response is mild, tissue recovery is faster, and the risk of surgical complications is reduced.

[0023] In this embodiment, the beam expander can eliminate the individual differences in the output beam diameter caused by the processing error of the laser itself, so that the entire cutting optical path can fully utilize the expected optical system aperture, resulting in the smallest laser spot diameter at the laser output window position.

[0024] The femtosecond Gaussian laser beam has a pulse width of 10fs to 500fs and a wavelength of 980nm to 1080nm. The femtosecond Gaussian laser beam is a parallel beam with a spot diameter of 1mm to 20mm.

[0025] The DOE diffractive optical element 1 has a flat-top beam conversion efficiency of ≥90% and an energy uniformity error of ≤5%.

[0026] The surface of the DOE diffractive optical element 1 is coated with an antireflection film, the wavelength of which is adapted to the output wavelength of the laser, and the transmittance of the antireflection film is ≥95%.

[0027] The femtosecond laser Gaussian beam is precisely converted into a flat-top beam using a dedicated DOE diffraction optical element 1, achieving an energy uniformity of ≥95%. This eliminates the defects of an excessively strong center and weak edges in the Gaussian beam, resulting in uniform tissue stress in the cutting area, smooth and regular incisions, and higher cutting precision. The DOE diffraction optical element 1 is coated with a dedicated antireflection film, achieving a light transmittance of ≥99% and a beam conversion efficiency of ≥90%, reducing laser energy waste and ensuring effective power output of the surgical laser.

[0028] The DOE shaping module also includes: a fixing bracket and an adjustment mechanism; The adjustment mechanism is mounted on a fixed support, and its output end is connected to the DOE diffraction optical element 1 to adjust the incident angle of the DOE diffraction optical element 1.

[0029] The angle adjustment accuracy of the adjustment mechanism is <1°, which enables bidirectional fine adjustment of the DOE diffraction optical element 1 around the X-axis and Y-axis.

[0030] The DOE diffractive optical element 1 is installed using a fixed bracket and a high-precision angle adjustment mechanism. It is easy to debug and can quickly complete optical path calibration, meeting the high-efficiency operation requirements of clinical surgery.

[0031] The DOE plastic surgery module has a compact structure and can be directly integrated into the optical path of existing femtosecond laser surgical equipment without modifying the main structure of the equipment. The adjustment mechanism can be adapted to the optical path parameters of different types of surgical lasers, making it highly versatile.

[0032] This application does not impose any limitations on the structure of the fixed support and the adjustment mechanism. Both the fixed support and the adjustment mechanism are existing structures in the prior art. The adjustment mechanism only needs to meet the requirement of adjusting the incident angle of the DOE diffraction optical element 1.

[0033] The light spot of the flat-top beam in the surgical area is circular, and the diameter of the light spot is less than 10 μm.

[0034] The light spot of the flat-top beam in the surgical area is square, and the width of the light spot is less than 10 μm.

[0035] The focusing scanning module includes: an X-ray galvanometer 2, a relay system 3, a Y-ray galvanometer 4, a scanning optical path 5, and a focusing objective lens 7; The flat-top beam converted by the DOE diffraction optical element 1 passes sequentially through the X-mirror 2, the relay system 3, the Y-mirror 4, the scanning optical path 5, and the focusing objective 7. The X-mirror 2 is used to deflect the flat-top beam in the X direction. The relay system 3 is used to accurately image the reflecting surface of the X-mirror 2 onto the reflecting surface of the Y-mirror 4. The Y-mirror 4 is used to deflect the flat-top beam in the Y direction. The scanning optical path 5 is used to maintain a high degree of consistency in the beam size, shape, energy density, and incident angle. The focusing objective 7 is used to focus the flat-top beam onto the surgical area.

[0036] The relay system 3, scanning optical path 5, and focusing objective lens 7 in this application are all devices in the prior art.

[0037] A deflection optical path 6 is provided between the scanning optical path 5 and the focusing objective lens 7. The deflection optical path 6 is used to adjust the transmission path of the flat-top beam.

[0038] In this embodiment, the DOE diffraction optical element 1 is placed after the beam expander. After beam expansion, the divergence angle of the laser beam is smaller and the transmitted wavefront is smoother. At this time, the diffraction efficiency of the DOE diffraction optical element 1 is higher. However, a larger aperture is required. If the aperture of the DOE diffraction optical element 1 is limited, the DOE diffraction optical element 1 can also be placed in front of the beam expander.

[0039] The DOE diffractive optical element 1 adopts a Wiener structure. When the characteristic size of the DOE diffractive optical element 1 is close to the laser wavelength scale, geometric optics theory will no longer be applicable. In this case, wave optics theory is required for optical field modulation. The incident laser from the laser passes through the DOE diffractive optical element 1, and the transmitted wave propagates forward in different diffraction directions to achieve the purpose of modulating the incident Gaussian distributed optical field. The DOE diffractive optical element 1 can be a continuous relief structure or a multi-level relief structure. Above, refer to Figures 1-5 This invention describes a femtosecond laser surgery flat-top beam reshaping optical system according to an embodiment of the present invention. The laser outputs a raw Gaussian-distributed femtosecond laser beam, which is expanded by a beam expander and then incident perpendicularly onto a DOE diffraction optical element 1. The micro-nano phase structure on the surface of the DOE diffraction optical element 1 modulates the wavefront phase of the beam. Through the diffraction effect of light, the Gaussian beam with concentrated energy at the center and attenuated energy at the edges is converted into a flat-top beam with uniform energy distribution within the spot and steep edges. The beam is then precisely focused onto the corneal surgical area by a focusing scanning module, achieving uniform and precise minimally invasive ablation. Since the flat-top beam has no central peak energy, excessive damage to local tissues will not occur during the ablation process, resulting in neat incision edges and consistent ablation depth, significantly improving the quality and safety of the surgery.

[0040] It should be noted that, in this specification, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0041] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A femtosecond laser surgical flat-top beam shaping optical system, characterized in that, include: Laser, beam expander, DOE shaping module, and focusing scanning module; The laser is used to output a femtosecond Gaussian laser beam, which is applied to the surgical area after passing through a beam expander, a DOE shaping module and a focusing scanning module in sequence. The beam expander is used to expand the diameter of the femtosecond Gaussian laser beam to the diameter of the beam used in the cutting optical path; The DOE shaping module includes: DOE diffraction optical elements; The DOE diffraction optical element is placed in the path of the femtosecond Gaussian laser beam and is used to convert the incident Gaussian beam into a flat-top beam with uniform energy distribution through phase modulation. The focusing scanning module is used to focus the flat-top beam onto the surgical area.

2. The femtosecond laser surgery flat-top beam reshaping optical system as described in claim 1, characterized in that, The femtosecond Gaussian laser beam has a pulse width of 10fs to 500fs and a wavelength of 980nm to 1080nm. The femtosecond Gaussian laser beam is a parallel beam with a spot diameter of 1mm to 20mm.

3. The femtosecond laser surgery flat-top beam reshaping optical system as described in claim 1, characterized in that, The DOE diffractive optical element has a flat-top beam conversion efficiency of ≥90% and an energy uniformity error of ≤5%.

4. The femtosecond laser surgical flat-top beam reshaping optical system as described in claim 1, characterized in that, The surface of the DOE diffractive optical element is coated with an antireflection film, the wavelength of which is adapted to the output wavelength of the laser, and the transmittance of the antireflection film is ≥95%.

5. The femtosecond laser surgical flat-top beam reshaping optical system as described in claim 1, characterized in that, The DOE shaping module also includes: a fixing bracket and an adjustment mechanism; The adjustment mechanism is mounted on a fixed support, and its output end is connected to the DOE diffraction optical element to adjust the incident angle of the DOE diffraction optical element.

6. The femtosecond laser surgery flat-top beam reshaping optical system as described in claim 5, characterized in that, The adjustment mechanism has an angle adjustment accuracy of <1°, enabling bidirectional fine adjustment of the DOE diffraction optical element around the X and Y axes.

7. The femtosecond laser surgery flat-top beam shaping optical system as described in claim 1, characterized in that, The light spot of the flat-top beam in the surgical area is circular, and the diameter of the light spot is less than 10 μm.

8. The femtosecond laser surgery flat-top beam reshaping optical system as described in claim 1, characterized in that, The light spot of the flat-top beam in the surgical area is square, and the width of the light spot is less than 10 μm.

9. The femtosecond laser surgery flat-top beam reshaping optical system as described in claim 1, characterized in that, The focusing scanning module includes: an X-ray galvanometer, a relay system, a Y-ray galvanometer, a scanning optical path, and a focusing objective lens; The flat-top beam converted by the DOE diffraction optical element passes sequentially through an X-mirror, a relay system, a Y-mirror, a scanning optical path, and a focusing objective. The X-mirror is used to deflect the flat-top beam in the X direction. The relay system is used to accurately image the reflecting surface of the X-mirror onto the reflecting surface of the Y-mirror. The Y-mirror is used to deflect the flat-top beam in the Y direction. The scanning optical path is used to maintain a high degree of consistency in the beam size, shape, energy density, and incident angle. The focusing objective is used to focus the flat-top beam onto the surgical area.

10. The femtosecond laser surgery flat-top beam reshaping optical system as described in claim 9, characterized in that, A deflection optical path is provided between the scanning optical path and the focusing objective lens, and the deflection optical path is used to adjust the transmission path of the flat-top beam.

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