Material and biological response of femtosecond photo-modification in hydrogel and cornea
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Publication Number
US-12304164-B2
Publication Date
2025-05-20
Expiration Date
Abstract
Systems and methods for optimizing laser damage threshold and induced phase change range in a method of writing phase change structures in a hydrogel material with a femtosecond laser writing system focusing a laser beam into the hydrogel material. A laser pulse width and a laser effective NA are selected for a given focused laser average power range to increase the laser damage threshold relative to use of laser pulse widths shorter than the selected laser pulse width and/or use of laser effective NAs greater than the selected laser effective NA. In a particular embodiment, the focused laser average power is from 1 to 5000 mW, the selected laser pulse width is greater than about 165 fs, and the selected laser effective NA is less than 0.50. Applications of the techniques described include laser induced refractive index change (LIRIC) customization of contact lenses, intra-ocular lenses, and other ophthalmic materials.
Core Innovation
The invention relates to a method for optimizing laser damage threshold and induced phase change range in a method of writing phase change structures in a hydrogel material with a femtosecond laser writing system focusing a laser beam into the hydrogel material. The method selects a laser pulse width and a laser effective NA for a given focused laser average power range to increase the laser damage threshold and the induced phase change range relative to using laser pulse widths shorter than the selected laser pulse width and/or laser effective NAs greater than the selected laser effective NA. The focused laser average power range is from 1 to 5000 mW, the selected laser pulse width is greater than about 165 fs, and the selected laser effective NA is less than 0.50.
The optimized femtosecond photo-modification is used to write phase change structures in hydrogels and related ocular polymers in a way that expands the achievable phase change range before damage. The selection of longer laser pulse widths and smaller laser effective NAs increases the phase change achievable prior to damage, and the induced phase change range is further expanded by combinations of fill factor and scan speed. The writing results are supported by a design of experiments and metrology.
The disclosed system and characterization address stability and measurement of the refractive index change. Mach-Zehnder interferometry and differential interference contrast microscopy are used to measure phase change structures and refractive index change, with findings that the induced phase change is polarization independent and exhibits long-term phase stability.
Claims Coverage
Independent claim clm-00001 covers optimizing femtosecond-laser writing of phase change structures in a hydrogel by selecting laser pulse width and laser effective NA for a given focused laser average power range. The dependent claims mainly tighten quantitative bounds on the selected parameters and specify related writing, system, and application features.
Optimizing laser damage threshold and induced phase change range by selecting pulse width and effective NA
Select a laser pulse width and a laser effective NA for a given focused laser average power range to increase the laser damage threshold and induced phase change range relative to use of laser pulse widths shorter than the selected laser pulse width and/or use of laser effective NAs greater than the selected laser effective NA, wherein the focused laser average power is from 1 to 5000 mW, the selected laser pulse width is greater than about 165 fs, and the selected laser effective NA is less than 0.50.
Tightened pulse width limits
Further specify the selected laser pulse width to be greater than or equal to about 180 fs and/or less than or equal to about 500 fs.
Tightened effective NA limits
Further specify the selected laser effective NA to be less than or equal to about 0.20.
Writing phase change pattern by scanning a pulsed focused laser beam
Write a desired phase change pattern in a hydrogel by scanning a pulsed focused laser beam to produce one or more refractive-index changes at a selected laser pulse width and selected effective NA for a given focused laser average power range.
Ophthalmic device hydrogel application
Use the hydrogel material as an ophthalmic device selected from contact lenses, intraocular lenses, or corneal implants.
Overall claim coverage centers on using selected laser pulse width greater than about 165 fs and selected laser effective NA less than 0.50 for a given focused laser average power range of 1 to 5000 mW to increase both laser damage threshold and induced phase change range, with dependent refinements narrowing pulse-width and effective-NA limits, defining writing via scanning to form refractive-index changes, and restricting hydrogel use to ophthalmic devices.
Stated Advantages
Increases the laser damage threshold and the induced phase change range relative to using shorter pulse widths and/or greater laser effective NAs.
Expands the achievable phase change range before damage.
Provides polarization independent induced phase change.
Provides long-term phase stability for the induced phase change.
Documented Applications
Ophthalmic applications using the hydrogel material in devices including contact lenses, intraocular lenses, and corneal implants.
Use of the femtosecond laser writing system to write phase change structures or desired phase change patterns in a hydrogel material.
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