Disk Laser Pump Light Arrangement with Radial Image Reversal

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Solution Overview

Problem

Disk lasers face inefficiencies due to low absorption of pump light by the laser-active medium, leading to imaging errors and beam expansion, which limits the number of multiple passes and results in clipping effects, especially when using high beam quality pump sources become costly.

Innovation Solution

A pumped light arrangement with a deflection device that performs at least half of the total deflections between two ring areas with radial image reversal, compensating for imaging errors by swapping the inner and outer ray bundles and alternating between radial and azimuthal deflections to maintain beam focus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If multiple passes of pump radiation through the laser-active medium are implemented to increase absorption efficiency, then the laser power and efficiency are improved, but imaging errors and beam expansion occur due to repeated focusing via the concave mirror, which limits the number of multiple passes

Engineering Contradiction:
Improvepump light absorption efficiencyVSAvoidbeam collimation quality
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The reflection surface of the focusing device is divided into multiple discrete reflection areas arranged in different ring areas at different radial distances from the central axis. The deflection arrangement directs the pump light beam to sequentially pass through different reflection areas, enabling multiple passes through the laser-active medium while distributing the focusing operations across segmented zones to manage and compensate imaging errors

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes changes in radial distance as a key parameter by arranging reflection areas at different radial positions from the central axis of the focusing device. By varying the radial distance of reflection areas, the system exploits the relationship between radial position and imaging error characteristics to compensate for accumulated beam expansion and collimation degradation across multiple passes

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the number of ring areas is increased to enable more deflections and multiple passes, then the pump light absorption is improved, but imaging errors increase sharply for radially outermost ring areas, leading to beam widening and clipping effects

Engineering Contradiction:
Improvenumber of multiple passesVSAvoidbeam focus accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

Different ring areas with reflection areas at different radial distances are assigned specific functions in the multiple-pass sequence. The system strategically selects and alternates between inner and outer ring areas to balance the number of passes enabled by outer areas against the imaging error tolerance of inner areas, optimizing the overall beam quality maintenance across all passes

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If pump light sources with high beam quality are used to reduce beam expansion, then the imaging errors are minimized, but the system cost increases significantly

Engineering Contradiction:
Improvebeam qualityVSAvoidsystem cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The system uses standard, cost-effective pump light sources and allows the optical arrangement itself to compensate for beam quality degradation. The alternating deflection pattern between inner and outer ring areas creates self-compensation of imaging errors, eliminating the need for expensive high beam quality pump sources while maintaining acceptable beam focus accuracy

Inventive Principle:
Principle #25Self-service

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 arrangement effectively compensates for imaging errors, reducing beam expansion and clipping effects, thereby increasing the efficiency of the laser system and allowing more passes through the laser-active medium without excessive losses.

Implementation Method 1

a focusing device, in particular a concave mirror, with a reflection surface for focusing a pumped light beam onto a laser-active medium

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a deflection arrangement for deflecting the pumped light beam between reflection areas formed on the reflection surface

Methodology Applied
Scientific EffectTotal Internal Reflection: Total Internal Reflection

Data Source

PatentEP3240124B1Pump light arrangement, disc laser using the same and method for pumping a laser-active medium
Publication Date: 2019.03.27 TRUMPF LASER GMBH CO KG
  • EP3240124B1 patent drawingFigure 1~2
  • EP3240124B1 patent drawingFigure 3a~4
  • EP3240124B1 patent drawingFigure 5~6

AI summary

The invention relates to a pump light arrangement for a disk laser, comprising: a focusing device, in particular a concave mirror, with a reflective surface for focusing a pump light beam onto a laser-active medium, and a deflection arrangement (15) for deflecting the pump light beam between reflection areas (B1 to B36) formed on the reflective surface, which are arranged at different angular ranges around a central axis of the reflective surface in at least a first ring area (RB1) and a second ring area (RB2), wherein the deflection arrangement (15) is configured to perform at least one deflection of the pump light beam between two reflection areas (B8, B9; B16, B17; B24, B25) of the first ring area (RB1) and at least one deflection between two reflection areas (B4, B5; B12, B13; B20, B21) of the second ring area (RB2).The deflection arrangement (15) is also configured to perform a number (NR) of deflections between two reflection areas (B2 to B28) of the two ring areas (RB1, RB2) with an image reversal of the pump light beam (8) in the radial direction to the central axis, which corresponds to at least one third, preferably at least half, of the total number (NR + NA) of deflections between two reflection areas (B2 to B28) of the two ring areas (RB1, RB2). The invention also relates to a disk laser with such a pump light arrangement and an associated method for pumping a laser-active medium.