Coherence Scanning Interferometer Alignment Using Focusing Beam
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Solution Overview
Problem
Existing coherence raster interferometers require complex and laborious adjustments to set the measurement position, as the imaging depth of focus is significantly larger than the coherence length, making it difficult to align the object for interference pattern generation.
Innovation Solution
Incorporating a focusing light source with a smaller depth of field, allowing for initial alignment of the focusing beam to simplify the measurement position setup, followed by fine adjustments using interference signal maximization, and utilizing a second optical path length change unit for precise height data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coherence scanning interferometer is used for spatially resolved optical measurement, then height geometry data can be determined, but the adjustment to set the measurement position becomes complex and laborious
Solution Approach 1:
The patent introduces a focusing light source that projects a focusing beam onto the object with a smaller depth of field than the measuring beam. This preliminary focusing action allows the user to easily locate and set the measurement position by optimizing the focusing beam's focus before conducting the actual height measurement, thereby simplifying the operation without compromising measurement precision
Solution Approach 2:
The focusing light source acts as an intermediary tool between the user and the measurement system. By providing a visual feedback mechanism through the focusing beam with distinct depth of field characteristics, it mediates the complex alignment process, making it easier for users to set the measurement position accurately
2Area of stationary object
If the imaging depth of focus is made significantly larger than the coherence length, then a larger measurement area can be imaged, but the alignment of the object for interference pattern generation becomes difficult
Solution Approach 1:
Before conducting the actual interference measurement, the system performs a preliminary focusing operation using the focusing light source. This preliminary action establishes the correct measurement position by optimizing the focus of the focusing beam, making subsequent interference pattern generation straightforward even with a large measurement area
Solution Approach 2:
The patent separates the focusing function from the measurement function by using two distinct light sources: a focusing light source for alignment and a measuring light source for height measurement. This segmentation allows each function to be optimized independently, enabling large measurement areas while maintaining easy alignment
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
Significantly simplifies the process of finding and setting the measurement position, enabling easier alignment and reducing the effort required for initial setup, while maintaining precise height geometry data determination.
Implementation Method 1
an output beam generated by the measuring light source is split into a measuring beam and a reference beam. The measuring beam is projected onto an image plane of the measuring detector... the measurement beam, at least partially reflected and/or scattered by the object, is coupled back into the beam path of the interferometer and projected onto the detection surface of the camera with a depth of field
Implementation Method 2
Incorporating a focusing light source with a smaller depth of field, allowing for initial alignment of the focusing beam to simplify the measurement position setup
Data Source
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AI summary
The coherence scanning interferometer has an optical path length changing unit, a measurement light source (11), an interferometer and a measuring detector (10) with a detection surface. The detection surface has multiple spatially different photosensors. A focused light source (1) is designed to interact with the coherence scanning interferometer such that a focusing beam (19) is represented in an image plane of the focused light source with a focused depth of sharpness over a beam splitter (6). The focusing beam is emitted from the focused light source. An independent claim is included for a method for locating a measurement position of a coherence scanning interferometer.