Stacked Stage Positioning System with Decoupled Out-of-Plane Accuracy

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Solution Overview

Problem

Traditional optical measurement systems for freeform surfaces face challenges in achieving high accuracy and compactness due to the accumulation of positioning errors in stacked stage systems, leading to the need for expensive and heavy metrology systems with low out-of-plane positioning errors.

Innovation Solution

A positioning system with a stacked stage system where the main stage is supported directly on a reference surface via a support bearing, decoupling its out-of-plane positional accuracy from the underlying stages, allowing for the use of less expensive and compact stages while maintaining high accuracy through a rotary drive system and pre-loading subsystems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional stacked stage systems are used for positioning, then positioning functionality is achieved, but positioning error accumulates and system complexity increases

Engineering Contradiction:

Improvepositioning accuracyVSAvoidstacked stage system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The positioning system is divided into independent functional modules: a first stage for in-plane translation, a second stage for out-of-plane translation, and a rotary stage for rotation. Each stage operates independently with its own drive system, allowing precise control of positioning errors without accumulation across the entire stack.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A reference surface is introduced as an intermediary element between the stacked stages and the object being positioned. The reference surface provides a stable baseline that decouples the positioning error accumulation of individual stages from the overall positioning accuracy, allowing each stage to be optimized independently.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If air-bearing supported stages are used to reduce positioning error, then positioning accuracy improves, but system size and cost increase

Engineering Contradiction:

Improveout-of-plane positioning errorVSAvoidmetrology system weight

Core Design Contradiction:

Measurement precisionVSWeight of moving object

Solution Approach 1:

Different bearing types are used for different positioning requirements: air-bearing supported stages are used only where out-of-plane positioning accuracy is critical, while simpler roller bearings are used for in-plane positioning. This localized application of high-precision components reduces overall system weight and cost while maintaining necessary accuracy.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system uses cost-effective roller bearings for in-plane positioning where extreme precision is not required, reserving expensive air-bearing supported stages only for out-of-plane positioning where nanometer-level accuracy is necessary. This selective approach reduces overall system cost and weight.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If multiple high-precision stages are stacked, then positioning capability is achieved, but system compactness deteriorates

Engineering Contradiction:

Improvepositioning accuracyVSAvoidmetrology system volume

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from a purely vertical stacked configuration to a multi-dimensional arrangement where stages are positioned at different heights and orientations. The rotary stage is oriented perpendicular to the reference surface, and the second stage extends in the out-of-plane direction, creating a compact three-dimensional configuration that reduces overall system volume.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 reduces the dependency on high-precision stages, enabling a more compact and efficient optics measurement system with improved in-plane and out-of-plane positioning accuracy, suitable for high-precision applications like freeform optical elements.

Implementation Method 1

the main stage is movable with respect to the first stage in the out-of-plane direction and wherein the main stage further comprises a support bearing arranged to movably support the main stage on the reference surface in said out-of-plane direction

Methodology Applied

Scientific EffectAir bearing: Air Lubrication

Data Source

PatentUS12044520B2Positioning system for positioning an object

Publication Date: 2024.07.23 DUTCH UNITED INSTR BV

AI summary

A positioning system for positioning an object includes a stacked stage system movable on a reference surface. The stacked stage system includes a driving system for driving the stacked stage system; a first stage driven along a driving plane parallel to the plane of the reference surface; and a main stage for supporting the object, the main stage arranged on the driven first stage for moving the main stage along the driving plane. The main stage includes a rotary drive system for rotating the main stage with respect to the first stage around an axis parallel to an out-of-plane direction perpendicular to the driving plane. The main stage is movable with respect to the first stage in the out-of-plane direction and further includes a support bearing to movably support the main stage on the reference surface in said out-of-plane direction.