Modular Multi-Axis Differential Interferometer Design
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Solution Overview
Problem
Existing multi-axis differential interferometers for measuring displacement and rotation are costly and difficult to assemble due to the need for large optical elements and complex configurations, limiting their effectiveness and manufacturability.
Innovation Solution
A modular multi-axis differential interferometer design using three separate optical modules, each emitting a measurement and reference beam, which are stacked and aligned for compactness and ease of assembly, allowing for the measurement of displacement and rotation in three degrees of freedom with smaller, more manageable optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single beam splitter unit is used to split three coherent beams into measurement and reference beams, then the interferometer remains compact, but the dimensions of the beam splitter unit must be relatively large increasing cost
Solution Approach 1:
The patent divides the single beam splitter function into three separate optical modules, each handling one coherent beam. This segmentation allows each beam splitter to be smaller and less expensive, while collectively they achieve the same functionality as a single large beam splitter unit.
2Ease of manufacture
If three separate optical modules are used for each beam pair, then the optical elements become smaller and cheaper, but the device complexity increases
Solution Approach 1:
The system is segmented into three independent optical modules that can be manufactured separately and then assembled. This modular approach reduces the complexity of manufacturing each individual module while maintaining overall system functionality.
Solution Approach 2:
The three optical modules are arranged in a stacked configuration, with one module positioned above another, creating a compact nested structure that minimizes the overall volume while accommodating multiple independent optical paths.
3Volume of moving object
If optical modules are stacked side-by-side, then the interferometer volume is reduced, but alignment precision becomes more difficult to achieve
Solution Approach 1:
The optical modules are stacked vertically one above another in a nested arrangement, which reduces the horizontal footprint while maintaining manageable alignment requirements through the vertical stacking geometry.
Solution Approach 2:
Alignment features and adjustment mechanisms are built into each optical module during manufacturing, allowing preliminary alignment to be performed at the module level before final assembly, thereby simplifying the overall alignment process.
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
The modular design reduces the size and cost of optical elements, simplifies assembly, and enhances manufacturability while maintaining accurate measurements of displacement and rotation, making it suitable for use in lithography systems with reduced volume and operational complexity.
Implementation Method 1
a beam splitter unit adapted for splitting said three beams into respective pairs of measurement beams and associated reference beams
Implementation Method 2
a beam splitter unit adapted for splitting said three beams into respective pairs of measurement beams and associated reference beams
Implementation Method 3
at least one beam combiner for combining each reflected measurement beam with its associated reflected reference beam to a combined beam
Implementation Method 4
three beam receivers, wherein each combined beam is projected onto a corresponding detector
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
The invention relates to a multi-axis differential interferometer (1) for measuring a displacement and/or rotation between a first reflective surface (21, 321) and a second reflective surface (81, 381), wherein said measuring is carried out using at least two pairs of beams, wherein each pair is formed by a measurement beam (Mb) to be emitted onto a first one (21, 321) of said reflective surfaces, and a reference beam (Rb) to be emitted onto another one (81, 381) of said reflective surfaces, said interferometer (1) comprising: a first optical module (20) and a second optical module (40), wherein each optical module (20, 40) is configured for receiving a respective coherent beam and for creating one of said pairs therefrom. The invention further relates to a lithography system comprising such an interferometer and to a method for assembling such a multi-axis differential interferometer.