Contact structure for a tunable liquid crystal optical device

#The present invention relates to the field of tunable liquid crystal optical devices and their manufacture. More particularly, the invention is directed to a contact structure for a tunable liquid crystal optical device and to a method for manufacturing tunable liquid crystal optical devices with such a contact structure.

#As is well known in the art, the successful implementation of intelligent (self-adjustable) optical imaging systems requires devices capable of controllably changing their optical properties. One of the most important optical functions required to be adjustable is the focusing capacity and the focusing distance. Those properties are essential, for example, for the manufacturing of high quality cell phone cameras, storage/reading systems and adjustable glass of vision systems.

#In modern high performance optical imaging systems, the optical zoom is obtained by the use of a mechanical movement. As a result, such imaging systems are of a relatively large size (in order to accommodate a motor, for example), heavy and generally have a slow zoom time (in the order of seconds). Several approaches to replacing the electro-mechanical zoom have been explored, including the use of liquid crystal (LC) technology. It is well known that LCs may provide huge electrically controlled refractive index changes. However, the focus tuning (which is required for optical zoom) requires the generation of spatially varying refractive index changes in the LCs, which in turn usually requires either a spatially non-uniform LC layer (e.g. a lens that is submerged in the LC cell) or a spatially varying electric field.

#The invention will be better understood by way of the following non-limiting detailed description of examples of implementation of the invention, with reference to the appended drawings, in which:

#FIGS. 1A and 1B illustrate the basic structure of one half of an exemplary prior art tunable liquid crystal device (hereinafter “TLCL”) in cross-section and plan view, respectively;

#FIGS. 2A, 2B, 2C and 2D illustrate one half of an exemplary prior art TLCL juxtaposed with the second half of the TLCL, where the second half (shown in FIGS. 2C and 2D) has been rotated in the plane of the device by 90 degrees;

#The present invention is directed to a contact structure for a liquid crystal optical device that allows for reliable electrical connections to be made to the conductive layers of the device in an inexpensive manner, in the context of wafer scale manufacturing of such a device.

#FIGS. 1A and 1B illustrate cross-section and plan views, respectively, of a prior art example of the basic structure of one half of a tunable liquid crystal device (TLCL). A complete or full TLCL is composed of two of these half TLCLs, as will be shown in the following example. Other variations of this basic TLCL structure exist and the invention disclosed herein may apply equally to those variations.

#The half TLCL is composed of two main layers: the liquid crystal (LC) layer and the lens structure layer. These layers are bounded by two additional layers consisting of substrates with conductive electrodes. An optional central substrate may serve as a dividing layer between the LC layer and lens structure layer. The plan view of FIG. 1B shows one additional feature of the half TLCL, notably that the LC layer has a unique orientation along one direction. Because of this property of the LC, a half TLCL only effects one polarization (half of the light) passing through the device. In order for all of the light passing through the device to be affected by the LC, a second half TLCL, with its polarization rotated by 90 degrees, must also be used.