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Pressure driven optical switch and aperture

Pressure driven optical switch and aperture

Chair: Physics of Complex Fluids

Optical switches and controlled diaphragm (apertures) have great potential in various areas of application, such as communication, microscopy and lab-on-a-chip. Traditionally, such switches and apertures are controlled mechanically. However the operation of small-scale mechanical parts is not attractive. An interesting alternative is the application of liquid droplets in tunable lenses, beam steering devices and displays. The optical isotropy and high transmittance of droples combine very well with these applications, with the additional advantage that switching or diaphragm setting can be done by simply tuning the pressure. This does not involve any moving parts!

In this project we look forward to design a liquid based optical switch and aperture which will be controlled just by an external pressure. The droplet shape can then be tuned by using the competition between a mechanical pressure that tends to inflate the droplet, and the surface tension that tends to minimize its surface area.

Within this project you will learn how to build a pressure driven optical switch and tunable diaphragm (aperture). The basic design of the device has been realized within our research group; however your imagination and the experimental skills can improve this design. You will determine the response time of this optical switch, and characterize diaphragm diameter as function of wetting properties of substrate.

Figure 1: Schematic presentation of the pressure driven optical switch and diaphragm (aperture). Top panel presents the optical switch in the off state, since the water meniscus is not touching the bottom surface. Bottom panel present the optical switch in the on state, since the water meniscus touches the bottom surface creating a tunnel through which light can pass. Typical size of the aperture will be 1 mm.