Free-Beam Laser Focus Adjustment for Transparent Material Cutting

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Solution Overview

Problem

Existing methods for producing three-dimensional cut surfaces parallel to the optical axis, such as in cataract surgery, face challenges with rapid focus adjustment and the use of optical fibers, which can cause vibrations and thermal stress, and require complex optics with large image fields.

Innovation Solution

A processing device that adjusts the focus position transversely to the optical axis along a curved trajectory, allowing for slower axial focus adjustments and reducing the need for rapid image field adjustments, using a combination of scanners and free-beam optics to maintain focus precision without parallel beam paths, enabling the creation of cut surfaces that are essentially parallel to the optical axis with minimal effort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical fiber is used to guide laser radiation to the handpiece, then the laser can be delivered to the treatment site, but vibrations and thermal stress occur due to rapid focus adjustment requirements

Engineering Contradiction:
Improvefocus adjustment stabilityVSAvoidvibrations and thermal stress
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical/optical fiber-based focus adjustment system with a free-beam optical system. Instead of using an optical fiber that requires mechanical coupling and rapid collimator adjustment, the invention uses free-propagating laser beams with galvanometric scanners to achieve focus positioning. This substitution eliminates the mechanical vibrations and thermal stress associated with rapid optical fiber connector adjustments while maintaining precise focus control capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If rapid image field adjustment is performed to create three-dimensional cut surfaces, then cutting speed is improved, but device complexity and mechanical stress increase

Engineering Contradiction:
Improvecutting speedVSAvoidoptics complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic focus adjustment through galvanometric scanners that can rapidly change the angular position of reflective mirrors. This dynamic system allows the focus to be repositioned in three-dimensional space without mechanical movement of the entire optical train or handpiece. The scanners enable rapid image field adjustment by changing beam direction electronically, achieving high cutting speeds while reducing mechanical complexity compared to physically moving optical components.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention adds angular dimension control through galvanometric scanners, transforming the traditional linear focus adjustment into a multi-dimensional beam steering system. By controlling the angular position of mirrors in two orthogonal directions, the system can rapidly reposition the focus point in three-dimensional space without mechanical displacement of optical components, thereby reducing device complexity while maintaining high productivity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If collimator is mechanically adjusted for focus position, then focus depth can be changed, but rapid movement causes vibrations and thermal stress on the handpiece

Engineering Contradiction:
Improvefocus position precisionVSAvoidfocus adjustment speed
Core Design Contradiction:
Manufacturing precisionVSSpeed

Solution Approach 1:

The patent replaces the mechanical collimator adjustment system with an electronic beam steering system using galvanometric scanners. Instead of mechanically moving the collimator to change focus depth, the invention uses angular deflection of reflective mirrors to redirect the laser beam and achieve focus repositioning. This substitution eliminates mechanical vibrations and thermal stress while maintaining precise focus control, enabling rapid focus adjustment without the limitations of mechanical systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

This approach allows for efficient and precise creation of cut surfaces, including cylindrical shapes, with reduced optical complexity and minimal axial adjustments, enhancing the speed and accuracy of procedures like cataract surgery while avoiding undesirable vibrations and thermal issues.

Implementation Method 1

having an optic that focuses optical radiation along an optical axis into a focus located in the material

Methodology Applied
Scientific EffectOptical focusing: Focusing

Implementation Method 2

Normally, non-linear processes are used which require the focusing of processing radiation, usually pulsed laser radiation, into the material

Methodology Applied
Scientific EffectNonlinear optical processes:

Implementation Method 3

the control device controls the laser device such that its device for adjusting the position of the focus shifts the position of the focus of the optical radiation in the material along a trajectory curve

Methodology Applied
Scientific EffectFocus shifting:

Data Source

PatentEP4101426B1Producing cut surfaces in a transparent material by means of optical radiation
Publication Date: 2024.06.12 CARL ZEISS MEDITEC AG
  • EP4101426B1 patent drawingFigure 1~3
  • EP4101426B1 patent drawingFigure 4~5
  • EP4101426B1 patent drawingFigure 6~7

AI summary

A processing device for producing a cut surface in a transparent material (7, 8), comprising a laser device (L) configured to effect a separation within the transparent material (7, 8) by means of optical radiation (2), and comprising optics (O) that focus optical radiation along an optical axis (OA) into a focus (6) located in the material and has an image field (B) in the material (7, 8) in which the focus (6) lies and which has an image field size; a device for adjusting the position of the focus (6) transversely to the optical axis (OA) and along the optical axis (OA); a control device (S) which is connected to the laser device (L) and controls the laser device (L) such that its device for adjusting the position of the focus (6) displaces the position of the focus (6) of the optical radiation (2) in the material (7, 8) along a trajectory (10), wherein the control device (S) controls the laser device (L) in such a way thatthat the cut surface (10) extends at least sectionally substantially parallel or inclined to the optical axis (OA) and follows a curve (K) transversely to the optical axis (OA), and the control device (S) along the optical axis (OA) during movement on the curve (K) specifies a multiply oscillating adjustment of the position of the focus (6) between an upper axial focus position (z1) and a lower axial focus position (z2), wherein the device for adjusting the position of the focus (6) transversely to the optical axis (OA) causes a displacement of the image field (B) transversely to the optical axis (OA) and is designed in two stages for adjusting the position of the focus (6) along the optical axis (OA) with one stage for slow large-stroke adjustment and one stage for fast short-stroke adjustment, and the control device (S) controls the laser device (L) such that the cut surface (9) transversely to the optical axis (OA) has a maximum extent,which is larger than the image field size, and for the device for adjusting the position of the focus (6) transversely to the optical axis (OA) specifies a movement of the position of the focus (6) along the curve (K).