Dynamic axial-position control of a laser-trapped particle by wave-front modification.
The axial position of a laser-trapped particle has been controlled by modification of the wave front by means of a membrane deformable mirror. The mirror gives wave-front modulation in terms of Zernike polynomials. By modulation of the Zernike defocus term we can modulate the particle position under conditions of laser trapping. A polystyrene particle of 1-microm diameter was moved along the optical axis direction for a distance of 2370 nm in minimum steps of 55.4 nm. We also demonstrated particle oscillation along the optical axis by changing the focal position in a sinusoidal manner. From the frequency dependency of the amplitude of particle oscillation we determined the spring constant as 91.7 nN/m.
Ota
Taisuke
T
Department of Applied Physics, Osaka University, Suita, Osaka 565-0871, Japan. ota@ap.eng.osaka-u.ac.jp
Kawata
Satoshi
S
Sugiura
Tadao
T
Booth
Martin J
MJ
Neil
Mark A A
MA
Juskaitis
Rimas
R
Wilson
Tony
T