Tunable transmission grating based on dielectric elastomer actuators

Optical gratings are used for light steering, wavelength separation, and filtering. So far, tunable diffraction gratings were based on relatively stiff materials allowing only a limited spatial tuning range. In this paper, we describe a technology for the implementation of shape changing, electrically adjustable, transmissive optical elements. To achieve large shape changes, soft optical materials and dielectric elastomer actuators (DEAs) are combined. The discussed optical transmission gratings operate with high transmission (> 90%), good optical quality, high damage threshold (> 93 kW/cm(2)), are polarization independent, and achieve very large, continuous changes in their main optical properties (7.5% in-plane compression of the active optical region). Further, the excellent properties of the novel optical components are highlighted by the implementation of a low cost, objective launched, total internal reflection fluorescence (TIRF) microscope that can be switched from epifluorescence operation to TIRF mode by simply applying a voltage to a DEA tuned diffractive transmission grating.