Publications

An ultrasonic rangefinder has a working range of 30 mm to 450 mm and operates at a 375 Hz maximum sampling rate. The random noise increases with distance and equals 1.3 mm at the maximum range. The range measurement principle is based on pulse-echo time-of-flight measurement using a single transducer for transmit and receive. The transducer consists of a piezoelectric AlN membrane with 400 µm diameter, which was fabricated using a low-temperature process compatible with processed CMOS wafers. The performance of the system exceeds the performance of other micromechanical rangefinders.

Oriented zinc-oxide layers have been combined with NMOS planar technology and silicon micromachining to produce integrated sensors empolying the pyroelectric effect in thin deposited films. Several fully integrated sensors have been designed and fabricated to detect differential temperatures as small as 18uK (and up to 2K) that arise in response to physical or chemical variables being sensed. The following fully-integrated pyroelectric sensors have been designed, fabricated, and tested: infrared detector array, gas-flow sensor, and chemical-reaction sensor. These sensors have been...

Numerous analytical instruments require a sensor to detect small quantities of electric charge. The techniques of scanning tunneling microscopy and ballistic electron emission microscopy require tiny currents to be sensed, on the order of a few picoamperes. In a mass spectrometer, the analysis of a sample requires a measurement of the current resulting from ions passing through a mass filter. In a technique known as chargedetection mass spectrometry, used to measure the mass of large molecules such as DNA molecules or virus particles, the resolution of the mass determination is limited in...

This dissertation discusses the fundamental limits of scanning mirror design, focusing on the limitations due to the interaction between mechanical properties
(mirror flatness and dynamic deformation), and optical properties (beam divergence and optical resolution). The performance criteria for both resonant scanning mirrors and steady-state, beampositioning mirrors are related to the mirror geometries, desired optical resolution, material properties, and mechanical resonant frequencies. The optical resolution of the scanning mirror is linearly dependent on the mirror length, so longer...