We report on the laser and sunlight driven, fast and large oscillation of cantilevers composed of photoresponsive liquid crystal polymer materials. The oscillation frequency, driven with a focused 100 mW laser of multiple wavelengths (457, 488, 514 nm), is as high as 270 Hz and is shown to be strongly correlated to the physical dimensions of the cantilever. The experimental frequency response is accurately described by the calculated natural resonant frequency for a non-damped cantilever. To further understand the conversion efficiency of light energy to mechanical work in the system, the oscillatory behavior of a 2.7 mm × 0.7 mm × 0.04 mm cantilever was examined at pressures ranging from 1 atm to 0.03 atm. A large increase in amplitude from 110° at STP to 250° at low pressure was observed. A first approximation of the system efficiency was calculated at 0.1%. The large increase in amplitude at low pressure indicates strong hydrodynamic loss and thus, the material efficiency is potentially much greater. Using a simple optical setup, oscillatory behavior was also demonstrated using sunlight. This work indicates the potential for remotely triggered photoactuation of photoresponsive polymer cantilevers from long distances with lasers or focused sunlight.
An adaptive liquid lens actuated by a photo-polymer is demonstrated. The lens cell consists of a top glass substrate and a bottom plastic slab with two holes: reservoir hole and lens hole, which are sealed with elastic membranes. A photo-sensitive polymer is attached to the membrane of the reservoir hole. Under blue light irradiation, the polymer is bent which exerts a pressure to regulate the curvature of the membrane on the lens hole and then change the focal length of the plano-convex lens. The focal length is tunable from infinity to 21.2 mm in seconds. Non-mechanical driving, easy integration with other optical components and compact system are the key features of this lens.
We present new lenses – waveplate lenses created in liquid crystal and liquid crystal polymer materials. Using an electrically-switchable liquid-crystal half-wave retarder we realized switching between focused and defocused beams by the waveplate lens. A combination of two such lenses allowed the collimation of a laser beam as well as the change of focal length of optical system.
Vector vortex waveplates (VVWs) open the door to new techniques in stellar coronagraphy and optical communications, but the performance of currently available liquid-crystal-polymer-based VVWs tends to be limited by defects in the axial region of the vortex pattern. As described here, several steps allow for a reduction in the size of such axial defects, including the use of photoalignment materials with high photosensitivity and reversible response, and a reduction in exposure energy. Moreover, redistributing the writing beam’s intensity from the axial region to its periphery (using a VVW) allows the production of large area VVWs with a small defect area. Finally, using VVWs as linear to axial polarization converters allows producing VVWs of higher topological charge, while also reducing the photoalignment time to a few minutes. These steps have allowed the fabrication of VVWs with topological charges of 1 and 2 with central defect sizes below 3 μm.