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Analysis of depth profiling data obtained by confocal Raman microspectroscopy
J Vyörykkä1, J Paaso, M Tenhunen
1Helsinki University of Technology, Laboratory of Forest Products Chemistry, P.O. Box 6300, FIN-02015 HUT, Finland.
Applied Spectroscopy
|November 13, 2003
Summary
Confocal Raman microscopy depth resolution is improved by using immersion objectives and index matching oils. This method determines the instrument
Area of Science:
- Optics and Photonics
- Materials Science
- Spectroscopy
Background:
- Confocal Raman microscopy offers micrometer-level depth resolution.
- Light refraction at sample surfaces often degrades this resolution.
- Immersion objectives and index-matching oils can mitigate refraction effects.
Purpose of the Study:
- To determine the instrument's point-spread function (PSF) in confocal Raman microscopy.
- To investigate methods for improving depth resolution and analyzing sample structures.
- To establish a technique for measuring sample thickness.
Main Methods:
- Utilized an immersion objective and index-matching oils to minimize refractive index mismatch.
- Determined the instrument PSF by measuring a depth profile and calculating its first derivative.
- Employed the first-derivative method to ascertain sample thickness.
- Applied convolution and deconvolution techniques using the determined PSF.
Main Results:
- The PSF was successfully determined using the first-derivative method.
- Sample thickness was accurately measured using the same method.
- Convolution allowed simulation of instrument behavior with various sample functions.
- Deconvolution was shown to reduce blurring and enhance depth resolution.
Conclusions:
- The immersion sampling technique, combined with convolution, effectively determines the instrument PSF.
- This approach enables accurate sample thickness determination.
- Deconvolution using the PSF significantly improves depth resolution and aids in surface and layer analysis.