Four-Mirror Beam Deflection Device With Orthogonal Pivot Axes

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Solution Overview

Problem

Existing light beam shifting devices with four rotary mirrors often introduce a permanent lateral offset of the deflected light beam relative to the incident optical axis, requiring additional mirrors or compensation for accurate scanning.

Innovation Solution

The device aligns the pivot axes of the rotary mirrors such that the plane containing the third and fourth pivot axes is orthogonal to the first pivot axis, allowing the deflected light beam to remain on the optical axis without additional offsets, enabling efficient two-dimensional scanning with minimized lateral displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional beam tilting units with two rotary mirrors per direction are used, then the light beam can be deflected in two directions, but a permanent lateral offset is introduced between the incident and deflected optical axes

Engineering Contradiction:
Improvebeam deflection capabilityVSAvoidoptical axis alignment
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The device divides the beam deflection function into four separate rotary mirrors, each with its own pivot axis, rather than using two mirrors per direction. This segmentation allows independent control of each mirror's pivot axis orientation to eliminate lateral offset

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses asymmetric pivot axis configurations where the pivot axes of the four rotary mirrors are not arranged symmetrically as in conventional designs. Specifically, the pivot axes are positioned such that their plane is orthogonal to the first pivot axis, creating an asymmetric arrangement that cancels lateral offset

Inventive Principle:
Principle #4Asymmetry

2Manufacturing precision

If additional mirrors are added to compensate for lateral offset, then optical axis alignment is improved, but device complexity increases

Engineering Contradiction:
Improveoptical axis alignmentVSAvoidnumber of mirrors
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the need for additional compensation mirrors by properly configuring the pivot axes of the four rotary mirrors from the outset. The lateral offset compensation function is integrated into the basic mirror arrangement rather than being added as a separate component

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The four rotary mirrors serve multiple functions simultaneously: they deflect the beam in two directions and also compensate for lateral offset through their specific pivot axis configuration. This multi-functionality eliminates the need for separate compensation mirrors

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If more mirrors are used to achieve precise scanning, then scanning accuracy is improved, but scanning speed decreases

Engineering Contradiction:
Improvescanning accuracyVSAvoidscanning speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The invention merges the beam deflection function and lateral offset compensation function into a single integrated system of four rotary mirrors. This combination achieves both high scanning accuracy and high scanning speed without requiring additional mirrors that would slow down the scanning process

Inventive Principle:
Principle #5Merging (Combining)

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 configuration allows for precise, high-speed scanning with reduced complexity and offset compensation, achieving a higher maximum scanning speed with fewer mirrors and minimizing the distance between the device and downstream optics.

Implementation Method 1

four rotary mirrors which successively deflect the light beam by reflection on their mirror surfaces

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3312656B1Device for relocating a light beam impacting an optical axis
Publication Date: 2019.12.18 ABBERIOR INSTR GMBH
  • EP3312656B1 patent drawingFigure 1~2
  • EP3312656B1 patent drawingFigure 3~4
  • EP3312656B1 patent drawingFigure 5~6

AI summary

A device (1) for redirecting a light beam incident on an optical axis (11) has four rotating mirrors (2 to 5) which deflect the light beam successively by reflection at their mirror surfaces. One (5) of the four rotating mirrors (2 to 5) is pivotable about a first pivot axis (10) that is parallel to its mirror surface and orthogonal to the optical axis (11). Another (4) of the four rotating mirrors (2 to 5) is pivotable about a second pivot axis (9) that is parallel to its mirror surface and parallel to the first pivot axis (10). A further (3) of the four rotating mirrors (2 to 5) is pivotable about a third pivot axis (8) that is parallel to its mirror surface; and a remaining (2) of the four rotating mirrors (2 to 5) is pivotable about a fourth pivot axis (7) that is parallel to its mirror surface and lies in a plane (14) together with the third pivot axis (8).In a pivoted position of the four rotating mirrors (2 to 5) about their four pivot axes (7 to 10), the light beam (13) deflected by all four rotating mirrors (2 to 5) again travels along the optical axis (11). For this purpose, the plane (14) is orthogonal to the first pivot axis (10); and the fourth pivot axis (7) runs at an acute angle of no more than 80° to the optical axis (11), so that pivoting the further (3) of the four rotating mirrors (2 to 5) and the remaining (2) of the four rotating mirrors (2 to 5) deflects the light beam both in the direction of the first pivot axis (10) relative to the plane (14) and along the plane (14), and pivoting one (5) of the four rotating mirrors (2 to 5) and the other (4) of the four rotating mirrors (2 to 5) deflects the light beam along the plane (14).