Subsurface Laser Machining With Tilt and Aberration Correction
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Solution Overview
Problem
Laser machining within materials, particularly high refractive index materials like diamond gemstones, faces challenges due to aberrations caused by refraction and tilt of the sample surface, leading to loss of resolution and control over focusing.
Innovation Solution
A laser system that includes a tilt measurement device and a drive mechanism to correct for coma aberration by adjusting the sample holder or optical elements, combined with optical elements to correct for spherical aberration, ensuring precise focusing and marking capabilities within the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high numerical aperture optics are used to obtain high resolution, then manufacturing precision is improved, but spherical aberration increases due to refractive index mismatch
Solution Approach 1:
The patent applies preliminary anti-action by introducing an aberration correction element that pre-compensates for spherical aberration before the laser beam enters the high refractive index material. The correction element applies an equal and opposite phase correction to counteract the expected spherical aberration from refractive index mismatch, enabling high NA focusing without the detrimental effects of spherical aberration.
Solution Approach 2:
The patent introduces an aberration correction element as an intermediary component between the objective lens and the sample. This intermediary element modifies the wavefront of the laser beam to compensate for spherical aberration, acting as a mediator that enables high resolution focusing through the interface between different refractive index media.
2Ease of operation
If the sample surface is tilted relative to the optical axis, then ease of operation is improved, but coma aberration increases leading to loss of focusing precision
Solution Approach 1:
The patent implements feedback by using a tilt measurement device to detect the actual orientation of the sample surface relative to the optical axis. The measured tilt information is fed back to the control system, which then adjusts the aberration correction element or sample holder to compensate for coma aberration, maintaining focusing precision despite surface tilt.
Solution Approach 2:
The patent applies dynamics by making the aberration correction element adjustable and reconfigurable in real-time. The system dynamically adapts to different sample orientations and tilt angles by modifying the correction applied to the laser beam, allowing flexible operation while maintaining precision through active compensation.
3Manufacturing precision
If aberration correction elements are added to correct spherical and coma aberration, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing an aberration correction element that can simultaneously correct for multiple types of aberrations (spherical and coma) and accommodate various sample types and orientations. This multi-functional approach consolidates multiple correction functions into a single adjustable element, reducing overall system complexity while maintaining high precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables efficient and precise sub-surface machining with high numerical aperture, allowing for the creation of small and large marks at various depths, including security markings that are visible under different magnifications, thereby improving the control and accuracy of laser machining in diamond gemstones.
Implementation Method 1
a laser light source configured to provide laser light
Implementation Method 2
one or more optical elements configured to direct the laser light from the laser light source into the sample... wherein the one or more optical elements includes a component configured to correct for spherical aberration caused by mismatch in refractive index
Implementation Method 3
a tilt measurement device configured to measure a tilt angle of the surface of the sample relative to an optical axis of the laser light entering through the surface
Data Source
AI summary
A laser system for modification of a sample to form a modified region at a target location within the sample, the target location being disposed below a surface of the sample, the laser system comprising: a laser light source configured to provide laser light; a sample holder for supporting the sample; one or more optical elements configured to direct the laser light from the laser light source into the sample when the sample is supported by the sample holder, wherein the one or more optical elements are configured to focus the laser light into the sample, and wherein the one or more optical elements includes a component configured to correct for spherical aberration caused by mismatch in refractive index at the surface of the sample through which the laser light enters the sample such that the laser light is focused at the target location within the sample, a tilt measurement device configured to measure a tilt angle of the surface of the sample relative to an optical axis of the laser light entering through the surface, and a drive mechanism for moving the sample holder and/or one or more of the optical elements based on the measured tilt angle to correct for coma aberration caused by the tilt angle.