An optically actuated surface scanning probe

Phillips, D., Gibson, G.M. , Bowman, R., Padgett, M.J. , Hanna, S., Carberry, D.M., Miles, M.J. and Simpson, S.H. (2012) An optically actuated surface scanning probe. Optics Express, 20(28), p. 29679. (doi: 10.1364/OE.20.029679)

Abstract

We demonstrate the use of an extended, optically trapped probe that is capable of imaging surface topography with nanometre precision, whilst applying ultra-low, femto-Newton sized forces. This degree of precision and sensitivity is acquired through three distinct strategies. First, the probe itself is shaped in such a way as to soften the trap along the sensing axis and stiffen it in transverse directions. Next, these characteristics are enhanced by selectively position clamping independent motions of the probe. Finally, force clamping is used to refine the surface contact response. Detailed analyses are presented for each of these mechanisms. To test our sensor, we scan it laterally over a calibration sample consisting of a series of graduated steps, and demonstrate a height resolution of ∼ 11 nm. Using equipartition theory, we estimate that an average force of only ∼ 140 fN is exerted on the sample during the scan, making this technique ideal for the investigation of delicate biological samples.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Gibson, Dr Graham and Bowman, Dr Richard and Phillips, Dr David and Padgett, Professor Miles
• Authors: Phillips, D., Gibson, G.M., Bowman, R., Padgett, M.J., Hanna, S., Carberry, D.M., Miles, M.J., and Simpson, S.H.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Optics Express
• Publisher: Optical Society of America
• ISSN: 1094-4087
• ISSN (Online): 1094-4087
• Copyright Holders: Copyright © 2012 OSA
• First Published: First published in Optics Express 20(28):29679
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher