Performance of varifocal lenses using KTa 1 − x Nb x O 3 crystals with response times faster than 2 μs

A varifocal lens (previously reported by the authors) made of a single crystal of potassium tantalite niobate (KTa 1− x Nb x O 3 , KTN) is characterised by its fast responses and large apertures (∼ 3 mm). Presented is a report on the focus shift performance of this varifocal lens with response times of < 2 μs. To investigate this quick response, a strobe technique was introduced. It was confirmed that the KTN lens changed its lens power in 2 μs as predicted by the theory stating that the lens power is proportional to the square of the applied voltage. The lens power can be controlled from 0 to 0.8 m −1 at a wavelength of 1.06 μm.