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82 3 Optical Tweezers

Fig. 3.1. The tail of Halley’s comet is directed along the direction of the solar light.
This photograph was taken on March 21, 1986 at Nobeyama near Tokyo, Japan
Exit
photocell Vacuum chamber
To
C
oscillograph
Exit Beam
splitter Entrance
photocell
Vane 2
Laser
C E BB
To
Scale oscillograph
mirror
Light source Vane 1
Lens
Filter
Entrance beam splitter Lens
Collimator

Scale
Fig. 3.2. Top view of two-vane torsion pendulum for measuring optical pressure
force. Reprinted from [3.1] with permission by American Institute of Physics, Copy-
right Clearance Center License Number: 1273781240969

Table 3.1. Physical characteristics of optical pressure measurement [3.1]
item value
moment of inertia, I 7.75 g cm 2
torque constant, k 1.0 × 10 −2 dyne cm rad −1
distance between vane centers, 2r 7.40 cm
distance of scale from suspention, D 200 cm
transmissivity of window, T 0.92
reflectivity of vane, R 0.75
mass of suspension, M 0.98 g