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Full-field heterodyne interference microscope with spatially incoherent illumination
Mark C Pitter1, Chung W See, Michael G Somekh
1Applied Optics Group, School of Electrical and Electronic Engineering, University of Nottingham, Nottingham NG7 2RD, UK. mark.pitter@nottingham.ac.uk
Optics Letters
|June 24, 2004
Summary
This study introduces a novel heterodyne interference microscope using laser speckle for enhanced imaging. The system achieves high surface height precision, suppressing noise for clearer microscopy results.
Area of Science:
- Optical microscopy
- Interferometry
- Surface metrology
Background:
- Coherent full-field microscopy often suffers from coherence noise.
- Traditional setups may require complex alignment and expensive components.
- Achieving high-resolution surface imaging demands precise optical arrangements.
Purpose of the Study:
- To develop a heterodyne interference microscope for full-field imaging.
- To suppress coherence noise in microscopy using speckle illumination.
- To demonstrate high-precision surface height measurement.
Main Methods:
- Utilizing a heterodyne interference microscope with time-varying laser speckle patterns for object and reference beams.
- Implementing temporal averaging to mitigate coherence noise.
- Employing a Linnik-type microscope configuration with high-numerical-aperture objectives.
Main Results:
- The speckle illumination provides a confocal transfer function.
- Temporal averaging effectively suppressed coherence noise.
- Demonstrated full-field surface height precision of 1 nm root mean square (rms).
Conclusions:
- The described heterodyne interference microscope offers a robust method for high-precision surface imaging.
- The use of laser speckle illumination simplifies the system and reduces cost.
- This technique advances coherent microscopy by improving image quality and measurement accuracy.