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Topography characterization of a deep grating using near-field imaging
Niels Gregersen1, Bjarne Tromborg, Valentyn S Volkov
1Research Center COM, NanoDTU, Technical University of Denmark, Building 345V, DK-2800 Kgs. Lyngby, Denmark. ngr@com.dtu.dk
Applied Optics
|January 21, 2006
Summary
Researchers used near-field optical microscopy to image light patterns above a glass grating. An inversion method successfully extracted the grating
Area of Science:
- Optics and Photonics
- Materials Science
- Nanotechnology
Background:
- Total internal reflection (TIR) is crucial for optical phenomena.
- Near-field optical microscopy (NSOM) offers high-resolution imaging.
- Characterizing nanostructures requires precise metrology.
Purpose of the Study:
- To image light intensity distributions above a glass grating using NSOM.
- To numerically model these intensity distributions.
- To develop an inversion method for extracting grating geometry from optical data.
Main Methods:
- Utilized near-field optical microscopy at a 633 nm wavelength.
- Illuminated a glass grating (2-microm-deep, 1-microm-period) from below under TIR.
- Employed numerical modeling and a least-squares-fit optimization for data inversion.
Main Results:
- Successfully imaged light intensity distributions at various heights above the grating.
- Numerical modeling accurately represented the observed intensity patterns.
- The inversion procedure effectively retrieved the grating's geometric parameters.
Conclusions:
- Near-field optical microscopy combined with numerical inversion is a viable technique for nanostructure metrology.
- The method allows for non-destructive characterization of grating geometries.
- This approach has potential applications in fabricating and analyzing optical devices.
