De-Ying Zhang

Fluidic adaptive lens with high focal length tunability

Fluidic adaptive lenses with an adjustable focal length over a wide range were demonstrated in this letter. The focal length adjustment was achieved by changing the shape of the fluidic lens without any mechanical moving parts. The shortest focal length demonstrated in such devices is 41 mm, which corresponds to a large numerical aperture of 0.24 and a small F number of 2.05. The highest resolution measured using a positive standard is 25.39 lp/mm in this fluidic adaptive lens.

Integrated fluidic adaptive zoom lens

An integrated fluidic adaptive zoom lens is demonstrated for what is believed to be the first time. A zoom lens was fabricated using an UV lithographic-galvanic-like process involving soft lithography and wafer bonding. The zooming capability of such a lens was achieved by varying the focal length instead of the distance between the lenses. A zoom ratio of greater than 2 was obtained for devices that are 8 mm thick and have a 20-mm lens diameter. Including the 30-mm image distance, the total physical length of the fluidic zoom lens was less than 43 mm. More-compact systems with a higher zoom ratio can be obtained by reduction of the aperture size.

Fluidic adaptive lens of transformable lens type

Fluidic adaptive lenses with a transformable lens type were demonstrated. By adjusting the fluidic pressure, not only can the lens properties, such as the focal distance and numerical aperture, be tuned dynamically but also different lens types, such as planoconvex, planoconcave, biconvex, biconcave, positive meniscus, and negative meniscus lenses, can be formed. The shortest focal length for a 20 mm aperture adaptive lens is 14.3 mm when the device is transformed into a positive lens, and −6.3 mm when transformed into a negative lens. The maximum resolution of the fluidic lens is better than 40 line pairs/mm.

High-performance fluidic adaptive lenses

High-performance fluidic lenses with an adjustable focal length spanning a very wide range (30 mm to infinite) are demonstrated. We show that the focal length, F-number, and numerical aperture can be dynamically controlled by changing the shape of the fluidic adaptive lens without moving the lens position mechanically. The shortest focal length demonstrated is less than 30 mm for a 20-mm lens aperture. The fluidic adaptive lens has a nearly perfect spherical profile and shows a resolution better than 40 line pairs/mm in a plano-convex structure and 57 line pairs/mm in a biconvex structure.

Integrated fluidic lenses and optic systems

Functionally integrated fluidic lenses and lens systems were demonstrated. Fluidic optic lenses can function as lenses with tunable focal distance, lens doublets with variable and convertible lens type, zoom lenses, and a lens system possessing both telephoto and reverse telephoto functions. High lens power and broad tuning range were achieved in a single 20-mm aperture device that can be tuned to have a convex or concave shape, with the respective tunable focal distance from 14.3 mm to infinity and from -6.1 mm to negative infinity. For fluidic adaptive zoom-lens-on-a-chip, a zoom ratio of 2.14 was achieved for 20-mm lens aperture, and a zoom ratio of 2.83 for 5-mm lens aperture. For the latter device, a tunable field-of-view from 10/spl deg/ to 80/spl deg/ was demonstrated, suggesting that the functions of telephoto and reverse telephoto systems can be achieved in a single zoom lens chip. Finally, the fluidic devices including the microfluidic pumps can be integrated with the lenses. All these integrated fluidic lenses and lens systems were microfabricated using a modified UV-LIGA process.

Fluidic zoom-lens-on-a-chip with wide field-of-view tuning range

Integrated fluidic zoom-lens-on-a-chip with 5-mm lens aperture and less than 18-mm optical system physical length was demonstrated. The device was fabricated using standard microfabrication process. The zooming capability was achieved via focal length tuning instead of varying the lens distance. Zoom lens, telephoto, and reverse telephoto optical systems can be functionally integrated into one system on a chip without any additional hardware. The device shows a zoom ratio large than 2.83 and has a wide tuning range in its field-of-view from 10/spl deg/ to 80/spl deg/.

Integrated dynamic fluidic lens system for in vivo biological imaging

We have developed an integrated dynamic lens system for in vivo optical imaging. Bioinspired dynamic microfluidic lenses allow for real-time dynamic manipulation of the lens focal length via microfluidic injection into a PDMS membrane-capped chamber. A piezoelectrically actuated micropump is integrated with with the lens to provide highspeed, accurate lens tunability. The 5mm dynamic lens has demonstrated focal length tunability from 8.5mm to 23mm, numerical aperture values from 0.39 to 0.77, and resolution of 40 linepairs/mm. The micropump operates at 5 kHz and achieved a flow rate of /spl sim/2.4 mL/min. This system can be applied to optical probe techniques to improve diagnosis with real-time depth resolution and variable numerical aperture.

Integrated dynamic fluidic lens actuation

We have demonstrated a dynamic, adaptable fluidic lens system with integrated piezoelectric actuation capable of fast, accurate optical imaging. Our compact and integrated dynamic lens control allows for miniaturized, inexpensive optical systems.

Fluidic zoom-lens-system-on-a-chip

This paper demonstrates for the first time, fluidic zoom-lens-system-on-a-chip. The device is fabricated using standard microfabrication process. Including 10 mm image distance, the entire system is less than 18 mm long. Above all, the zooming function, telephoto function, and reverse telephoto function can all be achieved in the same device. The zooming capability is achieved via focal length tuning instead of changing the lens distance. A zoom ratio larger than 2.83 has been demonstrated on such device. The device shows a wide tunable range in its field of view from 10 to 80 degrees, which is a particularly attractive property to be incorporated, with the zooming capability, into cameras in such devices as cell phones, PDAs, notebook computers, and miniaturized inspection and surveillance systems.

A novel technology for fabricating gratings of any chirp characteristics by design

Summary form only given. We demonstrated that, by using the elastomer PDMS (polydimethylsiloxane), one can form gratings of any desired chirp characteristics by simply designing the geometric profile of the material. Using two kinds of linearly tapered geometries as examples, one can generate non-linear (/spl sim/1/x) and quasi-linear chirped grating profiles. Following the design concept, we can achieve any kind of chirp profile by properly choosing the geometry of the device and the magnitude of the stretching force along the grating axis. Furthermore, the chirp profile can be dynamically changed by tuning the stretching force. This simple and low cost device technology holds promise for WDM and sensing applications. We further focus on incorporating the chirped grating into PDMS waveguide structures consisting of different compositions of PDMS pre-polymer and curing agent to create a refractive index difference between the core and cladding layers.