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116 3 Optical Tweezers

Polarization Photodetector A
Volts = (A-B)/(A+B)
and
Normalizing
Polarizing differential
beam-splitting amplifier
cube
Photodetector B

l/4 plate
diffraction-limited
laser spots
Wollaston
prism
Lens
Specimen
Interferometer
Lens x-y piezo Volts input-output
stage relationship
Wollaston
prism 200 400
d (nm)
Polarized laser light
Fig. 3.41. Direct observation of kinesin stepping by optical trapping interferometry
[3.25]

Halogen lamp
Prism

Green laser
Stage Objective

Galvano DM
scanner
He-Ne laser
Frosted glass
filter
DM
YAG Laser PBS DM SIT camera
DM

APD
4D-PD Filter Filter

Fig. 3.42. Simultaneous measurement of individual ATPase and mechanical re-
actions of single myosin molecules. Reprinted from [3.26] with permission by
T. Yanagida, Osaka University, Japan