ABSTRACT
This chapter gives an overview of the use of liquid crystals (LCs) and the various geometries of electrically variable LC lenses (EVLCLs) for applications in optical cameras. However, it is important to justify our choice of EVLCL technology before discussing the design and performance details of optical cameras. Mobile cameras impose draconian requirements on the cost, size, performance, and reliability of their components. EVLCLs are based on very mature LC display (LCD) technology. This enables the simultaneous (wafer-level) fabrication of several thousand EVLCLs, which provides a unit cost that is significantly less than one dollar, simple scalability of volume production, and the promise of using a reflow process in the camera assembly. Indeed, their reliability is very similar to that of LCD products, which are proven to be very good (no moving parts). Their sizes may be very small; currently, the size of commercialized EVLCLs is 4.5 × 4.5 × 0.5 mm. The next generation of EVLCLs will have their thicknesses reduced from 0.5 mm down to 0.36 mm and EVLCL prototypes have already been demonstrated with <0.28 mm thickness. This is quite comparable with the voice coil motor (VCM) travel distance, needed for focusing at 10 cm. EVLCLs may be driven by ac voltages (1 kHz) as low as 3 V root mean square (RMS). Their power consumption can be <10 μW and they are very light (≈20 mg). Finally, they may combine AF and OIS functionalities in the same component. As will be seen in this chapter, their technical performances are quite comparable with other technologies; they have both advantages and drawbacks. However, I think that these factors are sufficient to warrant interest in EVLCL components.
