We show how a student may construct simple and versatile optical tweezers to manipulate micron-sized particles. The tweezers apparatus is used to set birefringent calcite particles into rotation using circularly polarized light. This demonstrates the mechanical transfer of the angular momentum associated with circularly polarized light from the laser beam to the trapped particle. This offers the student a method for performing Beth’s experiment qualitatively in the undergraduate laboratory.
REFERENCES
1.
J. H.
Poynting
, “The Wave Motion of a Revolving Shaft, and a Suggestion as to the Angular Momentum in a Beam of Circularly Polarized Light
,” Proc. R. Soc. London, Ser. A
85
, 560
–567
(1909
).2.
R. A.
Beth
, “Mechanical Detection and Measurement of the Angular Momentum of Light
,” Phys. Rev.
50
, 115
–125
(1936
).3.
A.
Ashkin
, J. M.
Dziedzic
, J. E.
Bjorkholm
, and S.
Chu
, “Observation of a single-beam gradient force optical trap for dielectric particles
,” Opt. Lett.
11
, 288
–290
(1986
).4.
M. E. J.
Friese
, T. A.
Nieminen
, N. R.
Heckenberg
, and H.
Rubinstein-Dunlop
, “Optical alignment and spinning of laser-trapped microscopic particles
,” Nature (London)
394
, 348
–350
(1998
).5.
S.
Sato
and H.
Inaba
, “Optical trapping and manipulation of microscopic particles and biological cells by laser beams
,” Opt. Quantum Electron.
28
, 1
–16
(1996
).6.
S. P.
Smith
, S. R.
Bhalotra
, A.
Brody
, B.
Brown
, E. K.
Boyd
, and M.
Prentiss
, “Inexpensive optical tweezers for undergraduate laboratories
,” Am. J. Phys.
67
, 26
–35
(1999
).7.
K.
MacAdam
, A.
Steinbach
, and C.
Wieman
, “A narrow band tunable diode-laser system with grating feedback and a saturated absorption spectrometer for Cs and Rb
,” Am. J. Phys.
60
, 1098
–1111
(1992
).8.
Bangs laboratories, Inc., Technology Drive, Fishers, IN 46038-2886.
9.
J. W. Simmons and M. J. Guttmann, STATES, WAVES AND PHOTONS: A Modern Introduction to Light (Addison–Wesley, Reading, MA, 1970).
This content is only available via PDF.
© 2001 American Association of Physics Teachers.
2001
American Association of Physics Teachers
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.
