Browsing by Author "WENG, PK"

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A REVOLVING RETRO-REFLECTIVE MARKER FOR AN OPTICAL TACHOMETER
(1990-09-01)
WENG, PK
;
SHIE, JS
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
A new tachometric marker with a surface consisting of right-angle V grooves has been made by the silicon micromachining technique. Anisotropic etching on a (001) silicon surface by three conventional recipes has been adopted. The results of the etched qualities are compared; hydrazine hydrate and potassium hydroxide-isopropanol-water solutions can give good quality right-angle V grooves. The revolving retro-reflection effect associated with this marker is described. When placed on a rotating plane, it can be utilized for wide-angle and remote tachometric measurements, where proximity measurements are either impossible or dangerous.
DESIGN CONSIDERATIONS OF METAL-FILM BOLOMETER WITH MICROMACHINED FLOATING MEMBRANE
(1992-06-01)
SHIE, JS
;
WENG, PK
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
A metal-film microbolometer formed on a glass membrane suspended on a silicon substrate has been fabricated by the anisotropic etching technique. The rectangular glass membrane is supported by its four leads connected to the corners of an etched V-groove cavity. This structure allows flexible thermal management and sensitivity optimization of the bolometer for different kinds of application, with a trade-off between lead thermal impedance and device active area. Optimizations of the structure applied to both a focal-plane array and a single detector are interpreted. A thermal impedance as high as 4 x 10(5)-degrees-C/W with a response time of several milliseconds can be achieved. For a 320-mu-m x 320-mu-m detector, theoretical predictions give a responsivity and normalized detectivity of over 700 V/W and 10(9) cm square-root Hz/W, respectively. For dimensions of 128-mu-m x 128-mu-m, suitable for a focal-plane-array detector, theory predicts a D* of 5.5 x 10(8). A discrepancy exists between the experiment and the theory, which is also discussed.
MICRO-PIRANI VACUUM GAUGE
(1994-02-01)
WENG, PK
;
SHIE, JS
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
A Pirani vacuum sensor has been fabricated by the silicon micromachining technique. A square glass membrane was formed on (100) silicon substrate with a platinum-film resistor coated. The membrane is suspended by its four leads extended to the corners of an etched cavity. This structure can provide both low thermal loss through leads to the substrate and large active area for gaseous heat conduction. It thus can be used as a highly sensitive vacuum sensor. The fabricated sensor has shown a linear response of pressure from 8X10(-5) to 6 Torr with constant-temperature operation. It is found that the low-pressure limit of the vacuum sensor was caused by the noise of the instrument used in the experiment. A new terminology called ''noise equivalent pressure'' thus is definable due to this finding. The physical limit of the noise equivalent pressure is analyzed. Optimization of the device structure and the noise equivalent pressure are also discussed in detail. A new method of ambient-temperature compensation is also proposed and analyzed here.
SELF-DIRECTIONING WITH THE REVOLVING RETROREFLECTION TECHNIQUE
(1992-08-01)
WENG, PK
;
SHIE, JS
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
We have developed a method for giving direction and/or position information in an optical guidance system based on the pulse position modulation property of a reflected light pulse train from a revolving retroreflector. The principle and theoretical analysis are described. Experimental verification of the one-axis, closed-loop tracking system is presented, which resulted in a static angular resolution as low as 22-mu-rad. This method suggests some potential applications to coordinate determinations or line-of-sight guidance systems.