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Amplitude and phase microscopy for sizing of spherical particles
Nicolas B E Sawyer1, Stephen P Morgan, Michael G Somekh
1University of Nottingham, School of Electrical and Electronic Engineering, University Park, Nottingham NG7 2RD, United Kingdom. nicholas.sawyer@nottingham.ac.uk
Applied Optics
|August 15, 2003
Summary
A new numerical model accurately simulates imaging spherical particles using various microscopes. This advanced model enables subwavelength particle sizing, with phase imaging proving superior for detecting smaller particles.
Area of Science:
- Optical microscopy
- Computational electromagnetics
- Nanoparticle characterization
Background:
- Accurate modeling of light scattering from nanoparticles is crucial for microscopy.
- Existing models may not fully capture the complexities of imaging subwavelength particles.
- Interference microscopy offers potential for enhanced particle sizing beyond traditional amplitude measurements.
Purpose of the Study:
- To develop a numerical vector diffraction model based on Mie theory for imaging spherical particles.
- To accurately simulate light interference in copolarization transmission microscopy.
- To demonstrate subwavelength particle sizing capabilities using amplitude and phase imaging.
Main Methods:
- Development of a numerical vector diffraction model incorporating Mie theory.
- Simulation of light scattering and interference for various microscopy techniques (bright-field, confocal, interferometric).
- Validation of the model through experimental measurements.
Main Results:
- The model correctly scales scattered and incident fields for accurate simulation of copolarization transmission microscopy.
- Demonstration that interferometric microscopy enables subwavelength particle sizing using both amplitude and phase information.
- The phase channel of interferometric microscopy significantly improves the ability to size smaller particles compared to amplitude-only measurements.
Conclusions:
- The developed numerical model provides a robust tool for simulating nanoparticle imaging.
- Interferometric microscopy, particularly its phase channel, offers enhanced capabilities for subwavelength particle sizing.
- Experimental validation confirms the model's accuracy and utility in optical microscopy applications.