General electrooptical properties of Deformed Helix Ferroelectric (DHF) liquid crystal effect have been analyzed. This promising effect opens the door to continuous gray scale of diode active matrix displays, the most low electric voltage amplitude in comparison with any other type of liquid crystal cells can drive DHF displays cells. On the contrary, high voltage and high frequency mode of DHF effect provides the response time about 1.5 micrometers in a very broad temperature range. The electrically controlled birefringence of DHF cells could be applied in adaptive optics.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.