In this paper, a tilting micromirror device that can achieve designed angle is proposed. A lever structure, driven by electrostatic actuators, was used to enlarge tilting angle. To obtain precise deflecting angle, the lever structure is constrained by the substrate. By applying a voltage, the electrostatic actuators drive the lever down to the substrate such that the micromirror device on the opposite side of the lever structure could be lifted. PolyMUMPs process was used to fabricate proposed micromirror devices. The actuators are simulated to investigate characteristics of the micromirror devices. Experimental results had indicated that the micromirror device could reach 10-degree tilting angle with 80V driving signal with 6.4% relative error compared to designed model.
In this paper, a back-to-back micromirror device fabricated through surface-micromachining and flip chip packaging technologies is developed for optical add/drop multiplexer applications. Pre-stressed beams were designed to elevate micromirror devices after the release and thermal heat-treatment processes. Torsion flexure structure design provides a reliable rotation degree of freedom for micromirror devices. A mechanical stopper was bonded using flip chip packaging on the top of micromirror devices to constrain the popped-up micromirror to obtain precise deflecting angle. Preliminary experiments had demonstrated the feasibility of the micromirror devices.
In this paper, the configuration of combining holographic gratings and micromirror devices for optical add/drop functions is proposed for constructing OADM. Based on this architecture, a MEMS based vibrating micromirror device that is driven by electrostatic force in executing add/drop functions is designed and fabricated. Preliminary experiments had demonstrated the feasibility of the proposed system.
This paper describes the development of a novel, flexible, with appropriate accuracy dynamic characteristics measurement system for optical scanning micromirror. With the system, we can measure dynamic behavior such as transient response, scan speed, scan angle, scan repeatability, and scan non-linearity of the canning micromirror devices. Moreover, the optical system performances such as scan spot size and even scan spot intensity can also be obtained.
KEYWORDS: Micromirrors, Actuators, Mirrors, Microelectromechanical systems, Surface micromachining, Oxides, Signal processing, Digital micromirror devices, Lithium, Control systems
A newly developed micromirror device that possesses two rotational and one displacement degrees of freedom has been designed and fabricated by using surface micromachining technology. The device consists of a micromirror, four vertical thermal-actuator arrays and four torsion bars that connect the mirror and the actuator. The vertical thermal actuator has the capability to elevate from its origin position. To demonstrate the feasibility of the vertical thermal actuator, various layouts and sizes has been designed. The present device was fabricated through the Multi-User MEMS process. When the controlled signal is applied to any two adjacent thermal-actuator arrays of the device, the remaining two thermal actuator arrays and torsion bars will act as the supporting beams that allow the micromirror to experience rolling or pitching motion. On the other hand, by applying controlled signals to all four thermal-actuator arrays synchronously , the micromirror would elevate vertically. Note that different rolling or pitching angle of the micromirror can be archived by designing the locations of the torsion bars with vertical thermal actuators. Through the process, a compact, extremely light in weight, potentially low cost, and operating in very low voltage micromirror device with various applications can be obtained.
Segmentation is a fundamental step in many quantitative analysis tasks for clinical ultrasound images. However, due to the speckle noises and the ill-defined edges of the object of interest, the classic image segmentation techniques are frequently ineffective in segmenting ultrasound images. It is either difficult to identify the actual edges or the derived boundaries are disconnected in the images. In this paper, we present a novel algorithm for segmentation of general ultrasound images, which is composed of two major techniques, namely the early vision model and the discrete snake model. By simulating human early vision, the early vision model can highlight the edges and, at the same time, suppress the speckle noises in an ultrasound image. The discrete snake model carries out energy minimization on the distance map rather than performing snake deformation on the original image as other snake models did. Moreover, instead of searching the next position for a snaxel along its searching path pixel by pixel, the discrete model only consider the local maxima as the searching space. The new segmentation algorithm has been verified on clinical ultrasound images and the derived boundaries of the object of interest are quite consistent with those specified by medical doctors.
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