Parallel Beam Position Detection for Stable Out-of-Plane Displacement
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Solution Overview
Problem
Current position detection methods using interferometers face challenges in measuring microscopic objects without contact, as they require precise optical alignment and are limited by spatial resolution and measurable area, making them unstable for out-of-plane displacement measurements, especially when alignment deviations occur.
Innovation Solution
A position detection apparatus that employs a beam splitter to separate and recombine light beams from a reference surface and a measurement target surface at an angle, generating signals based on phase differences to achieve stable interference measurements, even with large out-of-plane displacements, by using a cat's eye optical system to maintain alignment and increase the measurable area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is focused on the measurement target surface to achieve high spatial resolution, then measurement precision is improved, but the measurable area is limited to several tens of μm and alignment deviation becomes critical
Solution Approach 1:
The patent changes the beam configuration parameter from focused to parallel, which fundamentally alters the measurement characteristics. By using parallel light beams instead of focused beams, the system achieves both high measurement precision and large measurable area (millimeter scale) simultaneously, resolving the contradiction between spatial resolution and measurable area
Solution Approach 2:
The patent introduces angular dimension by incidenting parallel beams at an angle θ to the normal of the measurement target surface. This angular incidence combined with parallel beam configuration creates a measurement system that is insensitive to alignment deviations while maintaining high precision and enabling millimeter-scale measurement area
2Reliability
If light is focused on the measurement target to stabilize interference state, then reliability is improved, but the system becomes sensitive to alignment deviation and measurable area is limited
Solution Approach 1:
The patent changes the beam configuration from focused to parallel, which fundamentally improves alignment tolerance. Parallel beams maintain their configuration over large distances and areas, making the system robust against alignment deviations while keeping the interference state stable and reliable
Solution Approach 2:
The parallel beam configuration inherently provides self-alignment characteristics. The system automatically maintains stable interference without requiring precise manual alignment adjustments, as the parallel beam geometry naturally compensates for minor misalignments across millimeter-scale measurement areas
3Reliability
If a cube corner reflector is used to maintain optical alignment, then measurement stability is improved, but the device cannot be attached to microscopic locations
Solution Approach 1:
The patent extracts and eliminates the cube corner reflector component from the measurement system. By using parallel beam incidence directly on the measurement target surface without requiring cube corner reflectors, the system achieves optical alignment stability while being applicable to microscopic locations where cube corner reflectors cannot be attached
Solution Approach 2:
The patent introduces parallel beam configuration as an intermediary mechanism that replaces the cube corner reflector's alignment-maintaining function. The parallel beams incident at an angle θ to the surface normal provide inherent alignment stability without requiring additional optical components, enabling measurement on microscopic surfaces
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 approach allows for high-resolution, stable out-of-plane displacement measurements on a millimeter scale, unaffected by alignment deviations, without the need for cube corner reflectors, enabling a compact and easily maneuverable optical system with enhanced spatial resolution and measurement area.
Implementation Method 1
a beam splitter arranged to separate an incident parallel beam and to supply separated beams to a reference surface and a measurement target surface respectively
Implementation Method 2
a beam splitter arranged to separate an incident parallel beam and to supply separated beams to a reference surface and a measurement target surface respectively
Implementation Method 3
generation means that generates a signal corresponding to a phase difference of the separated beams by interfering a returning beam that has been supplied from the reflection unit
Data Source
AI summary
Position detection apparatus comprises: an incident unit that forms a parallel beam from a light beam of a light source and supplies the parallel beam to a beam splitter in a way that the separated beams, obtained from the parallel beam by the beam splitter, are respectively incident upon the reference surface and the measurement target surface at an angle; and a reflection unit that reflects the separated beams, which have been reflected by the reference surface and the measurement target surface and integrated to a light path by the beam splitter, to be supplied to the beam splitter as a parallel beam along the light path, and generates a signal corresponding to a phase difference of the separated beams by interfering a light beam that has been supplied from the reflection unit, separated by the beam splitter, reflected by the reference surface and the measurement target surface, and integrated again to a light path by the beam splitter.