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Terahertz continuous wave system using phase shift interferometry for measuring the thickness of sub-100-μm-thick
Optics Express
|June 6, 2019
Summary
This study presents a terahertz continuous wave system for precise thickness measurement. The novel Gouy phase shift interferometry method accurately determines sub-100-μm sample thicknesses without frequency sweeping.
Area of Science:
- Physics
- Optics
- Metrology
Background:
- Accurate thickness measurement is crucial in various scientific and industrial applications.
- Traditional methods may lack precision or require complex setups for thin samples.
Purpose of the Study:
- To demonstrate a terahertz continuous wave system for non-contact thickness measurement.
- To utilize Gouy phase shift interferometry without frequency sweep for enhanced simplicity and accuracy.
Main Methods:
- A terahertz continuous wave interferometer was developed.
- One arm used a collimated wave (reference), the other a focused beam (sample).
- Gouy phase shift interferometry was employed to analyze interference patterns and determine optical path difference.
Main Results:
- The system successfully measured thicknesses of sub-100-μm samples at 625 GHz.
- Destructive interference was observed at zero optical path difference.
- Minimizing the difference between measured and calculated signals allowed for precise thickness determination.
Conclusions:
- The demonstrated terahertz system offers a viable method for accurate thickness measurement of thin samples.
- Gouy phase shift interferometry without frequency sweep simplifies the measurement process.
- This technique holds potential for quality control and material characterization.
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