| 摘要 |
PURPOSE:To obtain a variable focus optical system which can change freely the focal length without changing the magnification of the optical system neither adjusting finely the optical system mechanically, by providing the optical system including a lens system and a variable refractive index plate and constituting this variable refractive index plate with plural light-transmissive plates, a transparent ferroelectric element whose refractive index is changed in accordance with an impressed voltage, and transparent electrode plates. CONSTITUTION:A lens system 1, a variable refractive index plate 2, and a variable AC power source 7 are provided to constitute the optical system, and the variable refractive index plate 2 consists of a plane glass plate 3 as the light-transmissive plate, a transparent ferroelectric element 4, transparent electrode plates 5 and 5' on both sides of this element 4, and a polarizing plate 6 as the light-transmissive plate. The ferroelectric element 4 consists of ADP (ammonium diphosphate) or a liquid crystal, and the optical property of its crystal is changed because of double refraction due to the voltage when the voltage is impressed to the crystal. |
