Interferometric Surface Control for Laser Secondary Source Stability

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Solution Overview

Problem

Current devices for controlling the orientation and position of a surface in movement, used to generate secondary beams through laser-material interaction, suffer from instabilities in beam position and orientation, leading to inefficiencies in high-repetition rate operations due to surface destruction and the need for continuous regeneration.

Innovation Solution

A device utilizing interferometric measurements with a control laser beam and motorized actuators to precisely control the orientation and position of a moving surface, generating interference fringes analyzed by a camera and processed for real-time feedback to maintain surface stability and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a disk-shaped target with rotational movement is used to regenerate the interaction surface between laser shots, then the repetition rate of the secondary source can be equal to that of the primary source, but instabilities occur in the position and orientation of the secondary source

Engineering Contradiction:

Improverepetition rateVSAvoidstability of secondary source position and orientation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback control system using interferometric measurement. A control laser beam is split into reference and analysis beams, which interfere to generate fringes captured by a camera. The fringe analysis provides real-time information about surface position and orientation, which feeds back to actuators that adjust the target surface to maintain stability despite rotational movement.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces direct mechanical control of the rotating target with an optical measurement and control system. Instead of mechanically ensuring perfect stability during rotation, the system uses optical interferometry to measure deviations and applies corrective forces through actuators, substituting mechanical precision with optical feedback control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Duration of action of stationary object

If the target surface is moved to present a fresh region to each laser pulse, then surface destruction is avoided and high repetition rate operation is enabled, but the position and orientation of the secondary source become unstable

Engineering Contradiction:

Improvetarget surface longevityVSAvoidprecision of beam position and orientation

Core Design Contradiction:

Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

The feedback control system continuously monitors the target surface position and orientation using interferometric fringes and applies real-time corrections through actuators. This allows the surface to be moved for regeneration while maintaining precise control over the interaction point, ensuring stable secondary source characteristics despite surface movement.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary control system between the moving target surface and the laser interaction. The interferometric measurement system acts as a mediator that decouples the mechanical movement of the target from the optical interaction requirements, allowing surface regeneration while maintaining interaction precision through the intermediary feedback loop.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution stabilizes the secondary source's position and orientation, enhancing the precision and efficiency of beam generation, allowing for higher repetition rates without surface damage, and maintaining high precision in beam alignment.

Implementation Method 1

means for making said reference and analysis beams interfere so as to generate interference fringes

Methodology Applied

Scientific EffectInterference: Interference

Implementation Method 2

the other of which is a mobile analysis beam reflected by the surface in movement

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS8654344B2Device for generating a secondary source by laser-material interaction comprising an optical device for controlling the orientation and the position of a surface in movement

Publication Date: 2014.02.18 ECOLE POLYTECHNIQUE

AI summary

A device for generating a secondary source from a primary optical source emitting a first optical beam focused onto a surface in movement, with which said first beam interacts so as to generate a secondary beam, includes an optical device for controlling the orientation and position of said surface to determine the orientation and position of the emission point of said secondary source on said surface. The device comprises: a control laser beam split into two branches, a fixed reference beam and a mobile analysis beam reflected by the surface in movement; means for making said reference and analysis beams interfere to generate interference fringes; means for imaging the interference fringes carrying information about the orientation and position of said surface; means for analyzing said interference images; and means for generating a feedback loop for controlling the orientation and position of said surface in movement based on the analysis.