The new construction of LC cell useful for a study both simple twist deformation and 3D structures in liquid crystals induced by boundaries and electric fields is proposed. One of the main advantages of the cell is a very high sensitivity of optical response to the small variations of the twist angle. It is possible to create homogeneous "in plane" electric field under special choice of dimensions of a rectangular channel filled with a liquid crystal. The new LC cell provides good perspectives for measurements of practically important viscous and elastic properties of liquid crystals including a rotational viscosity coefficient. The cell can be also used for. a study of static and dynamic properties of liquid crystals at weak anchoring.