Interferometer Line Focus for Rotation Measurement
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Solution Overview
Problem
Existing interferometric measurement systems face limitations in measuring large eccentric movements and flexibility due to punctiform focusing, which restricts the maximum measurable eccentricity and requires complex calibration routines, especially in applications like crystallographic investigations where submicrometer accuracy is needed.
Innovation Solution
The use of a linearly focused measuring beam instead of a punctiform beam, achieved through cylindrical lenses, allows for increased angle tolerance and larger measurable eccentricities, along with a compact, fiber-optically separated interferometer head suitable for vacuum and cryogenic environments, enhancing alignment efficiency and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a punctiform focused measuring beam is used in interferometric measurement, then measurement precision can be maintained, but the maximum measurable eccentricity is restricted and alignment complexity increases
Solution Approach 1:
The patent transforms the measuring beam from a punctiform (point) focus to a line focus by using cylindrical lenses. This dimensional change from 0D point to 1D line allows the beam to accommodate larger angular deviations and eccentric movements while maintaining interferometric measurement capability, thereby resolving the contradiction between precision and measurable eccentricity range
2Measurement precision
If a punctiform focused measuring beam is used, then optical path precision is maintained, but alignment effort and device complexity increase
Solution Approach 1:
By changing the focal geometry from point to line using cylindrical lenses, the system becomes more tolerant to misalignments in the direction perpendicular to the line focus. This reduces the precision required for alignment procedures while maintaining measurement precision along the measurement axis, thereby reducing device complexity and alignment effort
3Ease of operation
If the interferometer head is integrated and compact, then ease of operation in vacuum/cryogenic environments is improved, but thermal interference may increase
Solution Approach 1:
The patent segments the interferometer into separate components: the compact interferometer head containing only passive optical elements (beam splitter, cylindrical lenses, mirrors) can be placed in vacuum/cryogenic environments, while the active components (laser source, photodetectors, control electronics) are located externally. This segmentation eliminates thermal interference from active components while maintaining ease of operation in challenging environments
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 significantly reduces alignment efforts, increases flexibility, and improves measurement accuracy by allowing larger wobble movements and eccentricities to be measured, while maintaining high resolution and minimizing thermal interference in challenging environments.
Implementation Method 1
a beam splitter (14) which divides the laser beam (11) into a reference beam (13) and a measuring beam (15)
Implementation Method 2
the measuring beam (15) is focused by a cylindrical lens (17) to form a first focal line (15') which runs transversely to the axis of rotation (5)
Implementation Method 3
recombines the light beams, lets the light beams interfere with each other to generate interference light, the interference light opto-electrically into an optical frequency and measures
Implementation Method 4
a reflection plane (18) which is perpendicular to the axis of rotation (5) and which reflects the measuring beam (15) impinging thereon
Data Source
Figure 1~2B
Figure 3~4
Figure 5
AI summary
The present invention relates to a device and a method for interferometric measurement and in particular a device for measuring a rotation of a body about an axis of rotation, a positioning system with such a device and a method for measuring a rotation of a body about an axis of rotation, with an interferometer and optics.To avoid or at least reduce the recognized disadvantages of known solutions, particularly with regard to alignment effort and limited flexibility, the invention provides a device for measuring the rotation of a body (18) about an axis of rotation (5) with an interferometer (11, 12, 14, 16, 19) and an optic (17, 17a), wherein the optic (17, 17a) is configured to focus at least one measuring beam (15) of the interferometer to a first focus line which runs transversely to the axis of rotation (5), and to supply at least a part of a reflection of the first focus line from the body (18) to the interferometer, wherein the device is configured to carry out the measurement using the interferometer and the reflection.