Optical trapping is an increasingly important technique for manipulating and probing matter ranging from nanometers to millimeters. In this paper, the theories of optical trapping to date are reviewed briefly. The typical conventional far field trapping design is introduced. A 5-micron yeast cell is trapped and manipulated with a 1.25 numerical aperture (NA) oil-immersion, 100X magnification objective by a 780 nm trapping beam at 16 mW in our experiment. Furthermore, the development of near-field optical trapping associated with evanescent wave is also discussed. Several proposed near-field trapping schemes, respectively using laser-illuminated metal tip, metal-coated fiber probe in the scanning near-field optical microscopy (SNOM) and focused evanescent wave, are also described.
© 2005 Chinese Optics LettersPDF Article