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Order-sorting filters for a grating spectrometer and multichannel detection system: application to real-time
1Department of Chemistry and Atomic-scale Surface Science Research Center, Yonsei University, Seoul, Korea.
Analytical Chemistry
|June 8, 2011
Summary
Novel optical and numerical filters eliminate overlapping spectral orders in grating spectrometers, improving rapid spectroscopic ellipsometry measurements. This technique corrects for spectral overlap, enhancing data accuracy in optical characterization.
Area of Science:
- Optics and Photonics
- Materials Science
- Spectroscopy
Background:
- Grating spectrometers are valuable for dispersing light in spectroscopic ellipsometry.
- Overlapping spectral orders are a significant limitation in grating spectrometer performance.
- Accurate spectroscopic ellipsometry requires precise spectral data without order overlap.
Purpose of the Study:
- To develop and implement novel techniques for eliminating overlapping spectral orders from reflection gratings.
- To enhance the accuracy and reliability of rapid spectroscopic ellipsometry measurements.
- To correct for second-order reflection artifacts in real-time spectroellipsograms.
Main Methods:
- Utilized a multichannel detection system with a grating spectrometer.
- Developed a two-pronged filtering approach: an optical filter and a numerical filter.
- Employed a monochromatic source to quantify spectral overlap as irradiance ratios.
- Applied numerical filtering to correct for overlapping irradiance based on measured ratios.
Main Results:
- Quantified the irradiance ratio of second- to first-order diffraction, indicating spectral overlap.
- Observed increasing overlap ratios from 5% to 11% in the 1.5–2.5 eV spectral region.
- Successfully corrected second-order reflection in real-time rotating element spectroellipsograms using the developed filters.
Conclusions:
- The developed optical and numerical filtering techniques effectively eliminate overlapping spectral orders in grating spectrometers.
- This method significantly improves the accuracy of rapid spectroscopic ellipsometry data.
- The findings enable more reliable optical characterization of materials using spectroscopic ellipsometry.
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