Pockels Cell Crystal Vibration Damping via Compensation Pulses

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Solution Overview

Problem

Pockels cells used for polarization adjustment of electromagnetic radiation experience mechanical vibrations due to piezoelectric effects, leading to unstable switching behavior and potential mechanical damage, especially when operated near resonance frequencies.

Innovation Solution

A method involving the application of compensation pulses that counteract mechanical oscillations caused by use voltage pulses, with specific voltage profiles and timing to induce destructive interference and prevent resonance excitations, allowing for high-voltage switching near resonance frequencies without causing mechanical damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If high voltage pulses are applied to induce birefringence for polarization setting, then the polarization control function is achieved, but mechanical vibrations and resonances are excited in the crystal

Engineering Contradiction:

Improvepolarization controlVSAvoidmechanical stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by introducing compensation voltage pulses that generate mechanical vibrations opposite in phase to those caused by the use voltage pulses. These compensation pulses are timed to counteract the piezoelectrically induced vibrations before they can cause harmful resonances, thereby maintaining both polarization control and mechanical stability.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful mechanical vibrations caused by piezoelectric effects into a beneficial phenomenon by using the same piezoelectric effect to generate compensation vibrations. The harmful vibrations are transformed into useful counter-vibrations that actively cancel out the detrimental resonances, turning a negative effect into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Speed

If voltage switching is performed near resonance frequencies, then faster polarization switching is achieved, but mechanical damage to the crystal may occur

Engineering Contradiction:

Improvevoltage switching speedVSAvoidcrystal integrity

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The patent applies preliminary action by preparing and applying compensation voltage pulses immediately following the use voltage pulses. These compensation pulses are pre-timed to arrive at critical moments when resonance vibrations would otherwise build up to damaging levels, preventing mechanical damage before it occurs while maintaining fast switching speeds.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If damping foils and special holders are used to reduce mechanical vibrations, then mechanical stability is improved, but device complexity increases

Engineering Contradiction:

Improvemechanical stabilityVSAvoidmounting structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical damping system (damping foils and special holders) with an electrical control system. Instead of using mechanical elements to absorb and dissipate vibrations, the invention uses electronically generated compensation voltage pulses that create counter-vibrations through the piezoelectric effect, thereby maintaining mechanical stability while reducing structural complexity.

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 creates a stable polarization window by reducing or eliminating mechanical vibrations, preventing resonance excitations and ensuring stable operation of Pockels cells, even when operated near resonance frequencies, thus maintaining the quality of the polarization state and preventing mechanical damage.

Implementation Method 1

The high voltage applied causes an electrical polarization in the crystal via the electro-optical effect, which, for example, leads to a desired birefringence of the crystal

Methodology Applied

Scientific EffectElectro-optical effect: Electro-Optic Effects

Implementation Method 2

switching the voltage that fast can be accompanied by mechanical oscillations of the crystal caused by a piezoelectric effect occurring at the same time as the electro-optical effect

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS10931076B2Exciting a crystal of a pockels cell

Publication Date: 2021.02.23 TRUMPF SCI LASERS GMBHCO KG

AI summary

A Pockels cell utilizes high-voltage pulses for a polarization adjustment of electromagnetic radiation passing through the crystal, in particular laser radiation. The polarization adjustment involves applying a sequence of useful voltage pulses (N) to the crystal, each having a useful period duration (TP, N) and a useful pulse width (TN), and induces birefringence of the crystal via electric polarization in the crystal for polarization adjustment of the electromagnetic radiation. A sequence of compensation pulses (K, K1, K2) are applied to the crystal, each having a voltage curve, wherein the sequence is temporally overlaid by the sequence of useful voltage pulses (N) so that the voltage curves of the compensation pulses (K, K1, K2) counteract the inducing of a mechanical vibration in the crystal of the Pockels cell by the useful voltage pulses (N).