ABSTRACT
In this paper, we present the design and fabrication of a 1D beam steering device based on planar electro-optic thermal-plastic prisms and a collimator lens array. With the elimination of moving parts, the proposed device is able to overcome the mechanical limitations of present scanning devices, such as fatigue and low operating frequency, while maintaining a small system footprint (~0.5mm×0.5mm). From experimental data, our prototype device is able to achieve a maximum deflection angle of 5.6° for a single stage prism design and 29.2° for a cascaded three prisms stage design. The lens array shows a 4µm collimated beam diameter.
ABSTRACT
Our research team has developed a 2D micro image display device that can potentially overcome the size reduction limits while maintaining the high-image resolution and field of view obtained by mirror-based display systems. The basic design of the optical scanner includes a microfabricated SU-8 cantilever waveguide that is electromechanically deflected by a piezoelectric actuator. From the distal tip of the cantilever waveguide, a light beam is emitted and the direction of propagation is displaced along two orthogonal directions. The waveforms for the actuator and the LED light modulation are generated and controlled using a field programmable gate array. Our recent study is an update to the previously-reported mechanical scanner, replacing the hand-built PZT scanner and fiber waveguide with a microfabricated system incorporating aerosol-deposited PZT thin film and a polymeric SU-8 wave guide. In this article, we report on the design and fabrication of a prototype miniaturized 2D scanner, discuss optical and mechanical the modeling of the system's properties and present the experimental results.
ABSTRACT
Our research team has developed a MEMS based on a 2D micro image display device that can potentially overcome the size reduction limits while maintaining the high image resolution and field of view obtained by mirror based display systems. The basic design of the optical scanner includes a micro-fabricated polymer based cantilever waveguide that is electromechanically deflected by a 2D piezoelectric actuator. From the distal tip of the cantilever waveguide, a light beam is emitted and the direction of propagation is displaced along two orthogonal directions. The waveforms for the X-Y actuators and the LED light modulation are controlled using a field programmable gate array (FPGA). In this paper we will extend our display development by reporting more recent integration of components including actuators and light sources with a controller. Here we will describe the design, fabrication of the latest polymeric waveguide cantilever beam steering device driven by 2-D piezoelectric actuator using aerosol deposited PZT thick film actuators. The mechanical and optical design for the microresonating scanner will be discussed. In addition, the mechanical and optical performance of the 2-D scanner will be presented.
ABSTRACT
BACKGROUND: Blunt abdominal trauma (BAT) is a diagnostic challenge to the emergency physician (EP). The introduction of bedside ultrasound provides another diagnostic tool for the EP to detect intra-abdominal injuries. AIMS: To evaluate the performance of EP in a local emergency department in Hong Kong to perform the 'focused abdominal sonography for trauma' (FAST) in BAT patients. METHODS: This was a retrospective cohort study including all the trauma team cases in a 36-month period in the emergency department of a public hospital in Hong Kong. The results of FAST scans were analyzed and compared with CT scans when the FAST was positive or followed by a period of clinical observation when the FAST was negative. Descriptive statistics and sensitivity, specificity, and predictive values were calculated. RESULTS: There was a total of 273 cases, and FAST scans were performed in 242 cases. The sensitivity and specificity were 86% and 99%, respectively. The negative predictive value was 0.98, while the positive predictive value was 0.94. The overall accuracy was 97%. CONCLUSIONS: The performance of the EP in using FAST scans in BAT patients was encouraging. The high specificity (99%), positive predictive value (0.98), and likelihood ratio for positive tests (86) make it a good 'rule in' tool for BAT patients. The high negative predictive value also makes the FAST scan a useful screening tool. However, ultrasound examination is operator dependent, and FAST scan has its own limitations. For negative FAST scan cases, we recommend a period of monitoring, serial FAST scans, or further investigations, such as CT scan or peritoneal lavage.
