Dual-Laser Projector Polarization Control for Stable Beam Intensity

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Solution Overview

Problem

Existing laser projection devices lack the ability to maintain consistent laser beam intensity and continuous operation in case of diode failure, and do not allow for dynamic adjustment of intensity for enhanced visibility and safety.

Innovation Solution

A device utilizing two laser diodes with perpendicular linear polarizations combined by a polarization combiner, with an intensity-measuring arrangement and control unit to adjust and maintain beam intensity, ensuring continuous operation and dynamic intensity control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single laser diode is used for projection, then the device structure is simple, but the operation is interrupted when the laser diode fails or performance degrades

Engineering Contradiction:
Improvecontinuous operationVSAvoidlaser source structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines two laser diodes with different wavelengths (red and green) into a single projection system. Both laser diodes are coupled to a common beam combining element that merges their beams into a single combined beam for projection, enabling continuous operation even if one diode fails.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The laser source is segmented into two independent laser diodes (red and green wavelengths) that can operate separately. Each diode can be independently controlled and monitored, allowing the system to maintain operation with one diode if the other fails or requires maintenance.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If laser diode intensity is fixed, then the device structure is simple, but the projection intensity cannot be adjusted for different applications or safety requirements

Engineering Contradiction:
Improveprojection intensity adjustmentVSAvoidcontrol system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system implements dynamic intensity control by independently adjusting the drive currents of the red and green laser diodes. The control unit can vary the intensity of each diode based on application requirements, safety considerations, or detected performance degradation, enabling flexible adaptation to different projection needs.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters (drive currents) of the laser diodes to control output intensity. By adjusting the current supplied to each diode, the system can optimize projection brightness, respond to safety requirements, or compensate for aging effects without mechanical adjustments.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If one laser diode fails, then the other diode can compensate, but the system requires complex monitoring and control mechanisms

Engineering Contradiction:
Improvefault toleranceVSAvoidintensity control automation
Core Design Contradiction:
ReliabilityVSExtent of automation

Solution Approach 1:

The system incorporates feedback mechanisms where the control unit monitors the performance and intensity of each laser diode. Based on this feedback, the control unit automatically adjusts the drive currents to maintain optimal combined beam intensity, detect failures, and enable seamless switching or compensation when one diode underperforms or fails.

Inventive Principle:
Principle #23Feedback

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

Ensures consistent laser beam intensity and continuous operation even with diode failure, and allows for dynamic intensity adjustments for improved visibility and safety in industrial applications.

Implementation Method 1

The beams of the laser diodes are each linearly polarized, with the polarization axes or directions being in pairs perpendicular to one another. A polarization combiner is also provided, which combines the incident beams of the laser diodes into a combined beam with circular or elliptical polarization.

Methodology Applied
Scientific EffectPolarization: Polarisation

Data Source

PatentEP3930320B1Laser projector with two laser diodes
Publication Date: 2026.05.06 LAP GMBH LASER APPLIKATIONEN
  • EP3930320B1 patent drawingFigure 1
  • EP3930320B1 patent drawingFigure 2

AI summary

Device (10) for laser projection comprising: • two laser diodes (12, 14) of the same wavelength, whose beam is linearly (20, 28) polarized and whose polarization axes are perpendicular to each other, • a polarization combiner (24) which combines the beams of the laser diodes (12, 14) into a combined beam (26) with circular or elliptical polarization, • a measuring arrangement (25) which measures an intensity of the combined laser beam (26) and • a control unit to which the measured intensity of the combined laser beam is applied as an input signal and which sets an intensity of at least one of the laser diodes.