S.t. Lagerwall S.a.r.l.

S.a.r.l. S T Lagerwall

Bengt Stebler

Sven T Lagerwall

Gunnar Andersson

Ingolf Dahl

Kent Skarp

Kurt Flatischler

Kent Sharp

Wojciech Kuczynski

A device for influencing light has a polarizer, a ferroelectric or electroclinic response type liquid crystal halfwave plate whose liquid crystals are in the smectic phase with bookshelf geometry and have molecular axes which are rotatable around a first direction corresponding to the direction of incoming light in response to an electric field applied across the electrodes on either side of the halfwave plate, a quarter wave retarder plate, and a mirror. The polarizer, plates and mirror are arranged such that incoming light is passed from the polarizer through the liquid crystal plate and the retarder plate, and is reflected by the mirror in a second direction opposite to the first direction back through the retarder and the liquid crystal plate so as to provide a reflected polarized light plane to the polarizer. The polarizer has a first polarization direction set parallel to one electrically selectable molecular axis direction of the liquid crystal molecules, which is selected in response to a first electric field level. The retarder plate has its slow axis inclined either 45.degree. or 135.degree. relative to the optic axis of the liquid crystal. The liquid crystal, furthermore, is of a material which produces an angular difference 2.theta. in optic axis direction in response to a second electric field level whose polarity is opposite that of the first electric field level. This allows the device to rotate the reflected polarized light plane by an angle of 8.theta. in response to the second electric field level.

Liquid crystal devices using a linear electro-optic effect

Chiral nematic liquid crystal device with linear electroclinic effect

A new liquid crystal electro-optic device similar to the SSFLC device is described. It uses the same kind of polar chiral smectics and the same geometry as the SSFLC device (thin sample in the 'book-shelf' layer arrangement) but instead of using a tilted smectic phase like the C* phase, it utilizes the above-lying, essentially non-ferroelectric A phase. The achievable optical intensity modulation is considerably lower than for the SSFLC device, but the device is about one hundred times faster. It is thus appropriate for modulator rather than for display applications. Sample fabrication is simpler and, finally, the device is insensitive to polarization compensation from external charges. The electro-optic switching at moderate applied voltages can be detected through the full range of the A phase.

Device for submicrosecond electro-optic modulation in the liquid crystal

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Goteborg, Sweden

Bengt Stebler