Multi-Focal Laser Scribing With TAG Lens Focal Control

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Solution Overview

Problem

Traditional multi-focal laser processing techniques lack flexibility and response rate, limiting their ability to dynamically adjust focal positions and efficiently allocate laser energy to multiple locations, which restricts their application in high-throughput processing of transparent materials.

Innovation Solution

The use of a tunable acoustic gradient of index (TAG) lens to shape a pulsed laser beam into multiple focal points along an axial axis without mechanically moving optics, allowing for synchronous or asynchronous operation to achieve quasi-simultaneous multi-focal laser processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional diffractive or refractive optics are used to generate multi-focal beam patterns, then multiple focal points can be achieved, but the system lacks dynamic adjustability and has low response rate (less than 100 Hz)

Engineering Contradiction:

Improvedynamic adjustability of focal positionsVSAvoidresponse rate

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent employs a spatial light modulator (SLM) that can dynamically change the phase profile of the laser beam in real-time, allowing the multi-focal pattern to be reconfigured on demand. This dynamic control enables rapid adjustment of focal positions and numbers without mechanical movement, achieving response rates significantly faster than traditional optics.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention replaces mechanical focusing systems (such as moving lenses or mirrors) with a purely optical/phased-array approach using SLM. By modulating the phase of light across different regions of the beam, the system achieves focal point control without any mechanical components, thereby eliminating mechanical inertia and achieving high-speed response.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If fixed multi-focal optical systems are used, then laser energy can be delivered to multiple locations, but the system complexity and fabrication difficulty increase

Engineering Contradiction:

Improvethroughput of laser processingVSAvoidoptical system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The spatial light modulator serves as a universal beam shaping device that can generate any desired multi-focal pattern through software control. A single SLM device can replace multiple fixed optical elements, providing the same functionality with reduced physical complexity and easier reconfiguration for different processing requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system controls the number, position, and intensity distribution of focal points by changing the phase parameters programmed into the SLM. This software-based parameter control allows rapid adaptation to different processing tasks without physical reconfiguration, simplifying the overall system design while maintaining high productivity.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional single-focal laser processing is used, then the system is simple to operate, but the processing speed and throughput are limited

Engineering Contradiction:

Improvemicromachining speedVSAvoidoperational simplicity

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The laser beam is segmented into multiple independent focal spots using the SLM, allowing simultaneous processing at multiple locations. This segmentation of the beam enables parallel processing operations, dramatically increasing throughput while maintaining the simplicity of a single laser source and basic optical path.

Inventive Principle:

Principle #1Segmentation

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 enables high-throughput multi-focal processing with a response rate at the hundreds of kHz scale, matching emerging ultrafast pulsed lasers, and allows for efficient allocation of laser energy to desired locations, enhancing processing techniques like dicing, scribing, and marking of transparent materials.

Implementation Method 1

using a tunable acoustic gradient of index (TAG) lens to shape the pulsed laser beam pulse-by-pulse into a plurality of focal points along an axial axis

Methodology Applied

Scientific EffectAcoustic gradient of index (TAG) lens effect: Acoustic Lens

Data Source

PatentUS20240246171A1Multi-focal laser marking, dicing, and scribing

Publication Date: 2024.07.25 THE TRUSTEES OF PRINCETON UNIV

AI summary

Disclosed herein is an ultrafast, variable multi-focal technique using a laser (such as a picosecond laser or a femtosecond laser) to generate a pulsed laser beam, and a tunable acoustic gradient of index (TAG) lens ahead of an objective lens to achieve multi-focal laser scribing by shaping the pulsed laser beam pulse-by-pulse into a plurality of focal points along an axial axis of the laser beam at one or more selected positions without mechanically moving any optics or sample repositioning. The location of the focal points can be customized and even varied during processing.