Figure 5. Requirement of simultaneous blue and green light for oscillation.

(a) Plot of the calculated deflection angle versus time of F-azo film during exposure to 157 mW cm⁻² green (530 nm) LED light and simultaneously to blue (405 nm) light of the intensity depicted in the graph, derived from frame-by-frame video analysis. (b) Storage modulus of the polymer film as a function of time during illumination to 157 mW cm⁻² green (green line), 318.8 mW cm⁻² blue (blue line), and both blue and green LEDs simultaneously (dark cyan line).