Optical Trepanning Head With Rotating Diffraction Grating

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Solution Overview

Problem

Current optical trepanning heads for laser machining are bulky and inflexible, limiting the control of draft angles and speed, especially when machining parts with high height/diameter ratios and varying materials with different thermal diffusion properties.

Innovation Solution

A compact optical trepanning device with a rotating diffraction grating and a picosecond or femtosecond pulsed laser source, utilizing a rotating diffraction grating and variable focal length lenses to control draft angles and achieve high precision machining, suitable for parts with large height/diameter ratios and various materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If refractive optical components such as prisms are used in optical trepanning heads, then the laser beam can be directed onto the workpiece, but the device becomes bulky and limits compactness and movement

Engineering Contradiction:

Improvelaser beam direction controlVSAvoidoptical trepanning head size

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The patent replaces traditional refractive optical components (prisms, mirrors) with a rotating diffraction grating that uses diffraction physics to direct the laser beam. This substitution eliminates bulky mechanical optical elements while maintaining beam direction control capability, enabling a compact optical trepanning head design that can move freely along multiple axes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters by using ultrashort pulsed lasers (femtosecond or picosecond duration) instead of continuous wave lasers, and combines this with a rotating diffraction grating operating at high rotational speeds (180,000-200,000 RPM). This parameter change enables precise draft angle control through rotational speed modulation while keeping the device compact.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional laser drilling methods are used, then the process is simple, but draft angles cannot be controlled and machining precision is limited

Engineering Contradiction:

Improvedrilling process simplicityVSAvoiddraft angle control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic control by rotating the diffraction grating at precisely controlled speeds (180,000-200,000 RPM) and adjusting the angle of incidence of the laser beam. This dynamic approach allows real-time control of draft angles during the drilling process, transforming a static simple drilling operation into a dynamically controllable precision machining process.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs periodic action through the rotation of the diffraction grating, which periodically modulates the laser beam direction as it rotates. This periodic modulation, synchronized with the laser pulsing, enables precise control over the drilling trajectory and draft angle while maintaining a relatively simple overall process structure.

Inventive Principle:

Principle #19Periodic action

3Productivity

If high rotational speed is used for the rotating diffraction grating, then machining speed increases, but the complexity of controlling the system increases

Engineering Contradiction:

Improvemachining speedVSAvoidsystem control complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent makes the rotating diffraction grating system multi-functional by using it for both beam direction control and draft angle regulation simultaneously. The single rotating component performs multiple functions (deflection, focusing, and draft angle control) that would otherwise require separate mechanisms, thereby increasing machining speed without proportionally increasing system control complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables precise control of draft angles, increased machining speed, and adaptability to diverse materials, allowing for high-quality micromachining of holes with diameters from 50 micrometers to 1 millimeter, while maintaining a compact design that facilitates movement and orientation along multiple axes.

Implementation Method 1

The rotating device of the opto-mechanical system comprises a rotating diffraction grating, which may be of circular geometry. The diffractions of order 1 and −1 are mainly exploited through the rotating diffraction grating.

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

a picosecond or femtosecond pulsed laser source

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS20220305590A1Laser machining device

Publication Date: 2022.09.29 HAUTE ECOLE ARC

AI summary

Machining device comprising an optical trepanation head (1), comprising an opto-mechanical system having a head body (21) provided with a rotating device (22), a picosecond or femtosecond pulsed laser source (3), and at least one optical fiber (4) wherein the rotation device (22) of the opto-mechanical system (2) comprises a rotative diffraction grating (R1). Machining process by means of optical trepanation using such a device.