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In this paper, we demonstrate the first attempt of encapsulating a flexible micro battery into a contact lens to implement an eye-tracker. The paper discusses how to scale the battery to power various circuits embedded in the contact lens, such as ASIC, photodiodes, etc., as well as how to combine the battery with external harvested energy sources. The fabricated ring battery has a surface area of 0.75 cm2 yielding an areal capacity of 43 µAh·cm−2 at 20C. Based on simulated 0.35-µm CMOS ASIC power consumption, this value is large enough to allow powering the ASIC for 3 minutes. The functioning of the micro battery is demonstrated by powering an orange LED.

We propose to study the conditions for implementation of complex amplitude modulation on standard liquid-crystal spatial light modulators when illuminated by polarized light. The spatial light modulators are used in a conventional configuration, i.e., the voltage is applied parallel to the wave-front propagation direction. The most commonly used liquid-crystal materials are compared and their usefulness in some general applications discussed. Their specificities with respect to different modulation types and application requirements are briefly described. Typical characteristics such as response time, modulation range, and wavelength insensitivity are also discussed. Finally, as an illustration, a first attempt at nomenclature is proposed for the case of a linearly polarized light.

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A new compact optical refractometer is presented to improve the measurement of the refractive index of seawater. These measurements are useful in oceanography to calculate density and salinity of oceans from empirical relations. This refractometer shows a lower temperature dependence and obtains a better absolute accuracy on salinity compared to the conductivity sensors which are used nowadays to assess seawater salinity. Tests and calibrations have been made in a temperature-stabilized seawater tank. They show that the prototype is capable of measuring seawater refractive index with a resolution of about ±4 × 10−7, equivalent to a salinity resolution of ±2 × 10−3 g kg−1.