Near-field scanning optical microscope with a high Q-factor piezoelectric sensing element
US6515274B1 · kind B1 · utility
Inventors
Key dates
| Filing date | Jul 20, 2000 |
| Grant date | Feb 4, 2003 |
| Priority date | — |
| Expiry date | Oct 27, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S977/862
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A perpendicular-mode near-field scanning optical microscope (NSOM) utilizing a piezoelectric micro tuning fork as its height-sensing element is described. The present invention provides a method and apparatus for modifying and attaching an optical fiber to the tuning fork that allows the assembly to retain Q-factors up to 9000, substantially higher than those described so far in the literature for tuning-fork-based instruments. The method involves reducing the diameter of the cladding of the optical fiber down to the 17-25 &mgr;m using several chemical etching steps, before the fiber is attached to the tuning fork. A sharp upturn in the Q-factor is observed when the fiber diameter d drops below ˜25 &mgr;m. An analysis, which shows that the stretching force constant of a bent fiber is proportional to d4, is used to account for the great sensitivity of the Q-factor to the fiber diameter. The high Q-factors resulted in improved force sensitivity and allowed us to construct a perpendicular mode instrument without the use of additional dithering piezoelements. An improved NSOM operating in the sear force mode is also provided by thinning the optical fiber length running down the le…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.