The traditional method of monitoring cameras is employed in robot vision, surveillance cameras, and so on. However, it cannot track as fast as expected due to the large inertia of the camera and mechanical pan-tilt. It also decreases the optical resolution because of the digital zoom on the interest area. Therefore, we proposed high-speed zooming and tracking optics that consists of an optical zooming unit and an active tracking unit. The two units are designed with coaxial optical paths by a beam splitter. The zooming unit is built with three liquid lenses, one glass lens, and a high-speed camera. It can continuously change the magnification from 1x to 2x. By controlling the optical powers of three liquid lenses, the focal length of the zooming unit can be changed from 40 to 80 mm within milliseconds. The tracking unit composed of a high-speed mirror-based gaze controller, a high-speed camera, and pupil shift optics, can track the object and keep it in the center of both views. In addition, the zooming unit provides a compensation algorithm for the zooming unit to achieve adaptive zoom accurately. The experiment shows that the zooming unit performs adaptive optical zoom, and the tracking unit recognizes the object by adaptive tracking algorithm within 6 milliseconds.
We propose an optical switch with a circular tunable aperture based on electrowetting effect. The device is composed of two immiscible liquids. One liquid is dye-doped and conductive, while the other is transparent and insulating. The dye-doped water droplet is placed in the center of the bottom substrate, surrounded by transparent oil. In our experiment, in the voltage-off state, the light beam cannot pass through the aperture. When the voltage is applied, the black liquid expands in the radial direction because of the effect of electric field force and a circular aperture appears in the center of the device. Therefore, the device can achieve the function of light-on and light-off. Our device can provide a reasonable attenuation (∼582 ∶ 1). The aperture can be tuned from ∼0 to ∼5.8 mm. It requires ∼260 ms and ∼2.4 s for the device to switch on and off, respectively. Potential applications of this tunable optical switch are wide, for example, in adaptive irises, light shutters, and optical beam controls.
In this paper, two holographic zoom systems are proposed based on the programmability of spatial light modulator (SLM) and zoom characteristics of liquid lens. An active optical zoom system is proposed in which the zoom module is composed of a liquid lens and an SLM. By controlling the focal lengths of the liquid lens and the encoded digital lens on the SLM, we can change the magnification of an image without mechanical moving parts and keep the output plane stationary. Then a color holographic zoom system based on a liquid lens is proposed. The system processes the color separation of the original object for red, green, and blue components and generated three holograms respectively. A new hologram with specific reconstructed distance can be generated by combing the hologram of the digital lens with the hologram of the image. By controlling the focal lengths of the liquid lens and the encoded digital lens on the SLM, we can change the magnification of the reconstructed image.
In this paper, we propose an ultrathin zoom lens system based on liquid lenses. The proposed system consists of an annular folded lens and three electrowetting liquid lenses. The annular folded lens has several concentric surfaces. The annular folded lens is used to get the main power and correct aberrations. The three liquid lenses are used to change the focal length and correct aberration. An analysis of the proposed system is presented along with the design, fabrication, and testing of a prototype. All the elements in the proposed system are very thin, so the system is an ultrathin zoom lens system, which has potential application as lightweight, thin, high-quality imagers for aerospace, consumer, and military applications.
An adaptive liquid iris for an optical switch based on electrowetting is demonstrated. The device consists of a clear conductive liquid and an opaque insulate oil. In the voltage-off state, the dome of the clear liquid touches the top substrate, and an iris-like opening is formed in its central area, and the aperture of the opening is at its largest. When a voltage is applied to the device, the shape of the conductive liquid is deformed due to the electrowetting effect. As a result, the diameter of the opening is reduced. Our results show that the aperture of the device can be tuned from ∼6.4 mm to 0 as the applied voltage is changed from 0 to ∼60 V. The device can obtain a high optical attenuation (∼872∶1). The response time was measured to be ∼117 ms (shrinking time is ∼25 ms, and relaxing time is ∼92 ms) with turnaround speed of 55 mm/s. Our device has potential applications in light shutters, variable optical attenuators, adaptive irises, and displays.
We propose a liquid prism based on electrowetting for wide-angle beam tracking and steering. Two transparent cubic cells which are filled with two immiscible liquids are stacked together to form the device. The two cubic cells function as two optical prisms. Via eletrowetting, we successfully control the liquid–liquid interface by changing the applied voltage on the opposite sidewalls. The device is capable of wide-angle beam tracking and steering. The experiment shows that the device can deflect and steer the light through an angle of ∼19.9 deg (+10.4 deg to −9.5 deg), and the total response time is ∼202 ms. The proposed liquid prism has a potential application such as free-space optical communications and laser detection electrowetting solar cells.
This paper proposes a zoom lens system based on liquid lenses. The system design consists of a fixed lens and four two-chamber liquid lenses. The chambers are filled with different liquids. The design principle is analyzed. Optimization method is used to get the optimal solution. With the solution, the proposed zoom lens system can obtain achromatic and spherical aberration corrected images in a particular zooming range, and no moving element is needed in the proposed zoom lens system. By choosing proper liquids, it can be designed to work within particular working regions with improved optical performance. We give the detailed simulation examples. The results indicate that the proposed design can help to improve the optical performances of zoom lens systems.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.