Interferometer Compensation Device for Moving Specimen Measurement
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Solution Overview
Problem
Existing interferometric measurement devices struggle to accurately measure the surface of a moving specimen with movement components parallel to the sensitivity vector, leading to reduced interference contrast or falsified measurement results due to changes in optical path length.
Innovation Solution
A device and method that adjust the optical path length difference between the object and reference paths using a compensation device, controlled by a measuring device and control system, to maintain constant phase difference and compensate for movements parallel to the sensitivity vector, allowing for accurate measurement of surfaces moving in any direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the test object moves in a direction parallel to the sensitivity vector, then the measurement can capture dynamic surface changes, but the optical path length changes causing phase shifts that reduce interference contrast and distort measurement results
Solution Approach 1:
The patent applies dynamics by making the optical path length adjustable and controllable during measurement. The compensation device dynamically adjusts the optical path length in the reference arm to match changes caused by specimen movement, allowing the interferometer to maintain accurate measurements of moving surfaces while preserving interference contrast
Solution Approach 2:
The patent changes the parameter of optical path length dynamically. By controlling the optical path length difference between the two arms to follow the specimen's movement, the system compensates for phase shifts and maintains measurement accuracy for moving surfaces
2Measurement precision
If the optical path length difference is kept constant, then interference contrast is maintained, but the system cannot compensate for movements of the test specimen parallel to the sensitivity vector
Solution Approach 1:
The system transitions from a static optical path length to a dynamic one. The compensation device enables real-time adjustment of the optical path length difference, allowing the system to adapt to specimen movement while maintaining interference contrast through active control
Solution Approach 2:
The control device receives measurement signals containing velocity information and uses this feedback to adjust the optical path length difference. This closed-loop feedback mechanism ensures the optical path length continuously compensates for specimen movement, maintaining both interference contrast and measurement accuracy
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
Enables accurate interferometric measurement of surfaces moving with arbitrary directions and speeds by compensating for path length changes, maintaining interference contrast and ensuring reliable measurement results even when movement components are parallel to the sensitivity vector.
Implementation Method 1
an interferometer (2) having an object path (7) and a reference path (8)... measuring a shape of a surface (15) of the test object (10)
Data Source
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AI summary
The present invention relates to a device for the interferometric measurement of the surface of a moving test object using an interferometer. In contrast to the prior art, the object of the present invention is to provide a device and a method for the interferometric measurement of the surface of a test object moved in a targeted manner in any direction, where the path of movement does not need to be measured and where the path of movement can also be considerably larger than the wavelength of light. To solve at least one of these problems, it is proposed to design the aforementioned device such that the device includes a compensation device which is designed and configured such that the optical path length difference between an object path and a reference path of the interferometer can be variably adjusted with the compensation device, and with a control device,wherein the control device is effectively connected to the compensation device in such a way that the path length difference between the object path and the reference path is adjustable and controllable, wherein the control device is set up and designed in such a way that, in operation of the device, the control device controls the compensation device such that a change in the path length difference between the object path and the reference path caused by the compensation device is equal to a change in the path length difference resulting from a velocity of the surface of the test specimen in a direction parallel to the sensitivity vector.