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6 Answers, Hints and Solutions 221

F
F F
F a
(a) b 2 (b) 2
1.4
9
8 7 1.2 1
Optical torque 6 5 4 3 Optical torque 0.8
0.6

0.2
1 2 0.4
0 0
90 100 110 120 130 140 150 90 100 110 120
Angle a
Angle b 2
2
Fig. A.8. Relationship between optical torque and side wall angle β 2 (a), and side
wall angle α 2 (b), both simulated in two dimension for simplicity

◦
Fig. A.9. Improved shape of the three-wing shuttlecock rotor with β = 130 and
◦
α 2 = 100 for the rotor of n 2 =1.6,d =20 µm,t =10 µm,w =5 µm, and medium
n 1 =1.33
A4.2 See Fig. A.10.

900
800
Optical torque (pNmm) 600
700
500
400
300
200
100
0
0 10 20 30 40 50 60
Rotor diameter (mm)

Fig. A.10. Optical torque dependence on diameter of rotor with four wings