METHOD FOR PROVIDING CONTROL DATA OF A LASER DEVICE FOR THE NON-DESTRUCTIVE LASER-INDUCED PROPERTY CHANGE OF A POLYMER STRUCTURE

Abstract

The invention relates to a method for providing control data of a laser device (10) for the non-destructive laser-induced property change of a polymer structure (14). As steps, the method includes ascertaining (S10) a respective irradiation parameter range for preset irradiation parameters of the laser device (10) by means of an irradiation model, wherein a property change model is provided in the irradiation model, in which a caused property change of the polymer structure (14) is modelled depending on the irradiation parameters, wherein a destruction threshold value model is provided in the irradiation model, in which at least one threshold value for a laser-induced optical breakthrough of the polymer structure is modelled depending on the irradiation parameters, and wherein the caused property change from the property change model is optimized while limiting by the threshold value from the destruction threshold value model for ascertaining the irradiation parameter ranges.

Claims

1. A method for providing control data of a laser device for the non-destructive laser-induced property change of a polymer structure, comprising: ascertaining a respective irradiation parameter range for preset irradiation parameters of the laser device by means of an irradiation model; wherein a property change model is provided in the irradiation model, in which a caused property change of the polymer structure is modelled depending on the irradiation parameters; wherein a destruction threshold value model is provided in the irradiation model, in which at least one threshold value for a laser-induced damage of the polymer structure is modelled depending on the irradiation parameters; and wherein the caused property change from the property change model is optimized while being limited by the threshold value from the destruction threshold value model for ascertaining the irradiation parameter ranges; and providing the control data for the laser device, which includes the ascertained irradiation parameter ranges.

2. The method according to claim 1, wherein the control data is provided for a laser-induced refractive index change (LIRIC) of the polymer structure and/or a cross-linking method of the polymer structure.

3. The method according to claim 1, wherein the control data is provided for a solid-state laser, in particular a fiber laser or crystal laser.

4. The method according to claim 1, wherein for a laser-induced refractive index change (LIRIC), an irradiation parameter range of a numerical aperture between 0.15 and 0.35, in particular between 0.2 and 0.3; of a pulse length between 10 fs and 90 fs, in particular between 30 fs and 75 fs; of an energy between 5 nJ and 95 nJ, in particular between 20 nJ and 80 nJ; of a wavelength between 300 nm and 1450 nm, in particular between 900 nm and 1100 nm; and of a repetition frequency between 100 kHz and 100 MHz, in particular between 5 MHz and 75 MHz is provided as the control data.

5. The method according to claim 1, wherein a pulse distance along a scanning direction between 1 nm and 10 μm, in particular between 10 nm and 1 μm, is provided for the control data.

6. The method according to claim 1, wherein a pulse path distance of respectively adjacent laser pulse paths between 10 nm and 50 μm, in particular between 50 nm and 5 μm, is provided for the control data.

7. The method according to claim 1, wherein the irradiation parameters are delimited from the threshold value by a preset factor in ascertaining the irradiation parameter ranges.

8. The method according to claim 1, wherein the control data is provided for a property change of a biopolymer, in particular of a cornea of a human or animal eye.

9. The method according to claim 1, wherein the control data is provided for a property change of a plastic polymer, in particular for generating artificial lenses.

10. The method according to claim 1, wherein an energy and/or a laser pulse distance for the generation of the property change of the polymer structure are provided by a variably changeable value within the respective irradiation parameter range in the control data, wherein the further irradiation parameters are kept constant within their irradiation parameter ranges.

11. A method for controlling a laser device for a non-destructive laser-induced refractive index change (LIRIC) of a polymer structure, comprising: controlling the laser device by means of a control device such that it emits pulsed laser pulses in a shot sequence in a preset pattern into the polymer structure, wherein the laser pulses are emitted for non-destructive refractive index change of the polymer structure with a numerical aperture between 0.15 and 0.35, a pulse length between 10 fs and 90 fs, an energy between 5 nJ and 95 nJ, a wavelength between 300 nm and 1500 nm, and a repetition frequency between 100 kHz and 100 MHz.

12. A laser device with a control device, which is configured to perform a method according to claim 1.

13. The laser device according to claim 12, wherein the laser device a solid-state laser, in particular a fiber laser.

14. The laser device according to claim 12, wherein the laser device is suitable to emit laser pulses in a wavelength range between 300 nm and 1500 nm, preferably between 900 nm and 1100 nm, at a respective pulse duration between 10 fs and 90 fs, preferably between 30 fs and 75 fs, and a repetition frequency of greater than 10 kHz, preferably between 100 kHz and 100 MHz.

15. The laser device according to claim 12, wherein the control device: comprises at least one storage device for at least temporary storage of at least one control dataset, wherein the control dataset or datasets include(s) control data for positioning and/or for focusing and/or for irradiation parameter adjustment of individual laser pulses; and includes at least one beam device for beam guidance and/or beam shaping and/or beam deflection and/or beam focusing of a laser beam of the laser device.

16. A computer program including commands, which cause a laser device according to claim 12 with a control device to execute a method according to claim 1.

17. A non-transitory computer-readable medium, on which the computer program according to claim 16 is stored.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further features of the invention are apparent from the claims, the figures and the description of figures. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of figures and/or shown in the figures alone are usable not only in the respectively specified combination, but also in other combinations without departing from the scope of the invention. Thus, implementations are also to be considered as encompassed and disclosed by the invention, which are not explicitly shown in the figures and explained, but arise from and can be generated by separated feature combinations from the explained implementations. Implementations and feature combinations are also to be considered as disclosed, which thus do not comprise all of the features of an originally formulated independent claim. Moreover, implementations and feature combinations are to be considered as disclosed, in particular by the implementations set out above, which extend beyond or deviate from the feature combinations set out in the relations of the claims.

[0030] FIG. 1 depicts a schematic representation of a laser device according to an exemplary embodiment.

[0031] FIG. 2 depicts a schematic method diagram according to an exemplary embodiment.

[0032] In the figures, identical or functionally identical elements are provided with the same reference characters.

DETAILED DESCRIPTION

[0033] FIG. 1 shows a schematic representation of a laser device 10 with a laser 12, in particular a solid-state laser, for the non-destructive laser-induced property change of a polymer structure 14. In this embodiment, the polymer structure 14 can be a biopolymer, in particular an area of a cornea 14 of a human or animal eye 16, and the property change can be a laser-induced refractive index change (LIRIC) of the cornea 14. A laser pulse sequence, a laser pulse distribution and irradiation parameters for refractive index change of the cornea 14 can be provided in the form of control data by a control device 18, such that the laser 12 emits pulsed laser pulses in laser pulse positions preset by the control data with irradiation parameters provided by the control data to achieve the refractive index change. Alternatively, the control device 18 can be a control device 18 external with respect to the laser device 10.

[0034] Furthermore, FIG. 1 shows that the laser beam 20 generated by the laser 12 can be deflected towards the eye 16 by means of a beam deflection device 22, namely a beam deflection apparatus such as for example a rotation scanner, to generate the refractive index change in the cornea 14. The beam deflection apparatus 22 can also be controlled by the control device 18.

[0035] Preferably, the illustrated laser 12 can be a fiber laser, which is at least formed to emit laser pulses in a wavelength range between 300 nanometers and 1500 nanometers, preferably between 900 nanometers and 1100 nanometers, at a respective pulse duration between 10 femtoseconds and 90 femtoseconds, preferably between 30 femtoseconds and 75 femtoseconds, and a repetition frequency of greater than 10 kilohertz, preferably between 100 kilohertz and 100 megahertz.

[0036] Optionally, the control device 18 additionally comprises a storage device (not illustrated) for at least temporary storage of at least one control dataset, wherein the control dataset or datasets include(s) control data for irradiation parameter adjustment, positioning and/or focusing of individual laser pulses in the eye 16.

[0037] In a laser-induced refractive index change, but also in other non-surgical methods for property change of the polymer structure 14, such as for example the cross-linking method, it is provided to achieve a maximized effect of the property change per laser pulse without therein damaging the polymer structure 14. In particular with a too high energy density, cavitation bubbles can arise, which is to be avoided. In order to obtain the optimum irradiation parameters, the control device 18 can therefore perform the method shown in FIG. 2.

[0038] In FIG. 2, a schematic method diagram for providing control data for the laser device 10 for non-destructive laser-induced property change of a polymer structure is illustrated, wherein the polymer structure can be a cornea 14 of an eye 16 in this embodiment and the property change can be a laser-induced refractive index change (LIRIC).

[0039] In a step S10, an optimum irradiation parameter range for a respective irradiation parameter can be determined by the control device 18, wherein irradiation parameters can for example be a numerical aperture, a pulse length, an energy, a wavelength, a repetition frequency, a pulse distance and/or a pulse path distance. For determining the optimum irradiation parameter ranges, an irradiation model can be used, in which a property change model and a destruction threshold value model are provided. In this embodiment, the property change model can be a LIRIC model, which describes an induced phase change by laser irradiation. In particular, the phase change can be determined by means of the formula

Δϕ=γ.Math.P.sub.avg.sup.m.Math.NA.sup.2(m−2).Math.m.sup.m−2.Math.υ.sup.1−m.Math.τ.sup.1−m.Math.λ.sub.write.sup.3−2m.Math.λ.sub.read.sup.−1.Math.S.sup.−1.Math.t.sup.−1

wherein ΔΦ is the induced phase change, γ is a material constant, P.sub.avg is the average power of the laser, NA is the numerical aperture of the laser device 10, m is the order of the multi-photon absorption, v is the repetition frequency of the laser 12, τ is the pulse duration, λ.sub.read is the wavelength of the laser radiation 20, λ.sub.write is the wavelength, for which the phase change is to be provided, S is a scanning speed and t is a pulse path distance.

[0040] The destruction threshold value model, which describes a threshold value for a laser-induced damage of the polymer structure, can be a modelling of an optical breakthrough in this embodiment, wherein the model of the optical breakthrough can be given by the formula

E.sub.Th∝√.sup.3τ.Math.λ.Math.√m.Math.M2.sup.2.Math.NA.sup.−2

wherein E.sub.TH represents the pulse energy threshold value for the optical breakthrough and M2 represents a beam quality. Alternatively or additionally, further destruction threshold value models can be taken into account, which describe a damage of the polymer structure, such as for example thermal models.

[0041] In order to ascertain the optimum irradiation parameter ranges from this irradiation model, it is preferably provided to maximize the phase change without initiating the optical breakthrough.

[0042] As a step S12, the control data thus ascertained can then be provided for the laser device 10, by means of which the control device 18 for example can control the laser 12 and the beam deflection device 22 for refractive index change. For the laser-induced refractive index change, an irradiation parameter range of a numerical aperture between 0.15 and 0.35, in particular between 0.2 and 0.3, of a pulse length between 10 femtoseconds and 90 femtoseconds, in particular between 30 femtoseconds and 75 femtoseconds, of an energy between 5 nanojoules and 95 nanojoules, in particular between 20 nanojoules and 80 nanojoules, of a wavelength between 300 nanometers and 1,500 nanometers, in particular between 900 nanometers and 1,100 nanometers, and of a repetition frequency between 100 kilohertz and 100 megahertz, in particular between 5 megahertz and 75 megahertz, can preferably be provided in the control data for controlling the laser device 10. Furthermore, a pulse distance along a scanning direction between 1 nanometer and 10 micrometers, in particular between 10 nanometers and 1 micrometer, and a pulse path distance of respectively adjacent laser pulse paths between 10 nanometers and 50 micrometers, in particular between 50 nanometers and 5 micrometers, can preferably be provided by means of the beam deflection device 22.

[0043] For the suitable control of the laser device 10, for example to achieve a refractive index change, it can preferably be provided that only the energy and/or a laser pulse distance are changed within the respective irradiation parameter ranges depending on an irradiation position in the cornea 14 in the control data, wherein a value is respectively selected from the further irradiation parameter ranges and kept constant. Thus, the suitable refractive index change can be obtained at each location of the cornea 14 without generating cavitation bubbles.

[0044] The previously shown embodiment is only one of multiple examples, in which a property change, in particular a laser-induced refractive index change, in a biopolymer, in particular the cornea 14, can be generated. Alternatively or additionally, a cross-linking method can also be performed as the property change, wherein the property change model can for example be adapted hereto. Furthermore, the polymer structure can also be a plastic polymer, in particular for generating artificial lenses.

[0045] Overall, the examples show, how optimized irradiation parameters for a non-surgical method can be provided by the invention.