OPTICAL MICROSCOPY WITH IMPROVED RESOLUTION USING TWO-BEAM INTERFERENCE OF LOW-COHERENCE LIGHT |
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| Tomohiro Takada, Shin Usuki, Kenjiro T. Miura |
- Abstract:
- In recent years, high-resolution microscopy using structured illumination has been practically applied for fluorescent bio-imaging. However, there is a large amount of speckle noise in reflected- and scattered-light images, because structured illumination is typically generated by laser-beam interference. Hence, this high-resolution imaging technique cannot be effectively used in industrial applications. In this study, we attempted to generate structured illumination using two-beam interference of low-coherence light, and to develop a high-resolution and low-speckle imaging technique for industrial applications. First, we constructed an optical system consisting of a Michelson interferometer configured in such a manner that it achieved zero optical path-length difference and allowed the interference fringes to be manipulated. Second, we observed a sample pattern of 0.2-µm-sized dots to confirm the generation of interference fringes under structured illumination. Then, we endeavored to observe other sample dotted patterns with several types of pitches. In one case, the pattern pitch of 0.4 µm was beyond the diffraction limit of 0.5 µm. In this experiment, we could obtain an image and observe the fringe patterns corresponding to features of low-coherence interference. The patterns show a moiré effect due to the combination of the periodic sample patterns and the structured illumination, and we confirmed that the moiré-pattern width corresponded to the coherence length of the light source. Finally, we reconstructed a resolution-improved image from an image stack resulting from spatial scanning of the generated structured illumination. As a result, the narrow pitch pattern of 0.4 µm was successfully resolved with relatively less speckle noise.
- Keywords:
- optical microscopy, structured illumination, two beam interference, low-coherence light
- Download:
- IMEKO-TC14-2014-51.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC14
- Event name:
- TC14 LMPMI Symposium 2014
- Title:
11th Symposium on Laser Metrology for Precision Measurement and Inspection in Industry
- Place:
- Tsukuba, JAPAN
- Time:
- 03 September 2014 - 05 September 2014