An example fighting device has a luminaire and a driver circuit. The luminaire includes a variable electrokinetic optic that includes an electrokinetic fluid between a transparent substrate and a diffuser. The electrokinetic fluid includes a carrier fluid mixed with charged particles. The variable electrokinetic optic further includes a transparent substrate electrode and a diffuser electrode configured to generate an electric field in the electrokinetic fluid in response to a control voltage applied across the transparent substrate electrode and the transparent diffuser electrode. The electric field attracts the charged particles to adjust an effective birefringence of the variable electrokinetic optic. Increasing the effective birefringence increases an output beam angle of the emitted illumination lighting relative to an input beam angle. The driver circuit selectively controls the applied control voltage.