We have developed a self-contained, liquid tunable microlens based on polyacrylate membranes integrated with compact on-chip thermo-pneumatic actuation fabricated using full-wafer processing. Silicone oil is used as the optical liquid, which is pushed or pulled into the lens cavity via an extended microfluidic channel structure without any pumps, valves or other mechanical means. The heat load generated by the thermal actuator is physically isolated from the lens chamber. The back focal length may be tuned from infinity to 4 mm with a maximum power consumption of 300 mW. The principal application is fine tuning of the back focal length, for which tuning time constants as small as 100 ms are suitable.

An integrated tunable microlens, whose focal length may be varied over a range of 3 to 15 mm with total power consumption below 250 mW, is presented. Using thermo-pneumatic actuation, this adaptive optical microsystem is completely integrated and requires no external pressure controllers for operation. The lens system consists of a liquid-filled cavity bounded by a distensible polydimethyl-siloxane membrane and a separate thermal cavity with actuation and sensing elements, all fabricated using silicon, glass and polymers. Due to the physical separation of thermal actuators and lens body, temperature gradients in the lens optical aperture were below 4 °C in the vertical and 0.2 °C in the lateral directions. Optical characterization showed that the cutoff frequency of the optical transfer function, using a reference contrast of 0.2, varied from 30 lines/mm to 65 lines/mm over the tuning range, and a change in the numerical aperture from 0.067 to 0.333. Stable control of the focal length over a long time period using a simple electronic stabilization circuit was demonstrated.

Pathologic microvasculature plays a crucial role in innumerable diseases causing death and major organ impairment. A major clinical challenge is the development of selective therapies to remove these diseased microvessels without damaging surrounding tissue. This report describes our development of novel photo-mediated ultrasound therapy (PUT) technology for precisely removing choroidal blood vessels in the eye. PUT selectively removes microvessels by concurrently applying nanosecond laser pulses with ultrasound bursts. In PUT experiments on rabbit eyes in vivo, we applied 55–75 mJ/cm2 of light fluence at the retinochoroidal surface at 532-nm and 0.5 MPa of ultrasound pressure at 0.5 MHz. PUT resulted in significantly reduced blood perfusion in the choroidal layer which persisted to four weeks without causing collateral tissue damage, demonstrating that PUT is capable of removing choroidal microvasculature safely and effectively. With its unique advantages, PUT holds potential for the clinical management of eye diseases associated with microvessels and neovascularization.

Mirror symmetry breaking and restoration within mmsized polymer particles in optofluidic media by pumping circularly polarised light3

An ultra-wideband fiber optic acoustic sensor based on graphene diaphragm with a thickness of 10nm has been proposed and experimentally demonstrated. The two reflectors of the extrinsic Fabry-Perot interferometer is consist of fiber endface and graphene diaphragm, and the cavity is like a horn-shape. The radius of the effective area of the ultrathin graphene diaphragm is 1mm. Attributed to the strong van der Waals force between the diaphragm and the ceramic ferrule, the sensor head can be applied not only in the air but also underwater. Experimental results illustrate that ultra-wideband frequency response is from 5Hz to 0.8MHz, covering the range from infrasound to ultrasound. The noise-limited minimum detectable pressure level of 0.77Pa/Hz@5Hz and 33.97μPa/Hz@10kHz can be achieved, and the applied sound pressure is 114dB and 65.8dB, respectively. The fiber optic acoustic sensor may have a great potential in seismic wave monitoring, photoacoustic spectroscopy and photoacoustic imaging application due to its compact structure, simple manufacturing, and low cost.