Heterodyne Holography with full control of both signal and reference arms

Heterodyne holography is a variant of phase shifting holography in which reference and signal arms are controlled by acousto optic modulators. In this review paper, we will briefy describe the method and its properties, and we will illustrate its advantages in experimental applications

Use of near field acoustic levitation sliding contact

This paper presents an investigation into producing self-levitation effect using piezo-electric actuators (PZT). Self-levitation has been demonstrated and results are presented and discussed. A relationship between the levitation distance and weight of the levitating sample has been found. In addition the orientation and position of the PZTs has been found to affect the levitation distance. Modal shapes of the vibration plates used have been produced through modelling annd found to accurately correlate with the experimental results found. Additional evidence suggests that the type of vibration plate material affects the separation distance, possibly due to the material's properties of acoustic reflection

Non-contact Microelectronic Device Inspection Systems And Methods

Non-contact microelectronic device inspection systems and methods are discussed and provided. Some embodiments include a method of generating a virtual reference device (or chip). This approach uses a statistics to find devices in a sample set that are most similar and then averages their time domain signals to generate the virtual reference. Signals associated with the virtual reference can then be correlated with time domain signals obtained from the packages under inspection to obtain a quality signature. Defective and non-defective devices are separated by estimating a beta distribution that fits a quality signature histogram of inspected packages and determining a cutoff threshold for an acceptable quality signature. Other aspects, features, and embodiments are also claimed and described.Georgia Tech Research Corporatio

High temperature measuring device

Ultrasonic pulse technique for measuring average gas temperature in nuclear rocket engine - sound propagation and environmental studie

A parametric study for the design of an optimized ultrasonic-percussive planetary drill tool

Traditional rotary drilling for planetary rock sampling, in situ analysis, and sample return are challenging because the axial force and holding torque requirements are not necessarily compatible with lightweight spacecraft architectures in low-gravity environments. This paper seeks to optimize an ultrasonic percussive drill tool to achieve rock penetration with lower reacted force requirements, with a strategic view toward building an ultrasonic planetary core drill (UPCD) device. The UPCD is a descendant of the ultrasonic/sonic driller/corer technique. In these concepts, a transducer and horn (typically resonant at around 20 kHz) are used to excite a toroidal free mass that oscillates chaotically between the horn tip and drill base at lower frequencies (generally between 10 Hz and 1 kHz). This creates a series of stress pulses that is transferred through the drill bit to the rock surface, and while the stress at the drill-bit tip/rock interface exceeds the compressive strength of the rock, it causes fractures that result in fragmentation of the rock. This facilitates augering and downward progress. In order to ensure that the drill-bit tip delivers the greatest effective impulse (the time integral of the drill-bit tip/rock pressure curve exceeding the strength of the rock), parameters such as the spring rates and the mass of the free mass, the drill bit and transducer have been varied and compared in both computer simulation and practical experiment. The most interesting findings and those of particular relevance to deep drilling indicate that increasing the mass of the drill bit has a limited (or even positive) influence on the rate of effective impulse delivered

Bioinspired low-frequency material characterisation

New-coded signals, transmitted by high-sensitivity broadband transducers in the 40–200 kHz range, allow subwavelength material discrimination and thickness determination of polypropylene, polyvinylchloride, and brass samples. Frequency domain spectra enable simultaneous measurement of material properties including longitudinal sound velocity and the attenuation constant as well as thickness measurements. Laboratory test measurements agree well with model results, with sound velocity prediction errors of less than 1%, and thickness discrimination of at least wavelength/15. The resolution of these measurements has only been matched in the past through methods that utilise higher frequencies. The ability to obtain the same resolution using low frequencies has many advantages, particularly when dealing with highly attenuating materials. This approach differs significantly from past biomimetic approaches where actual or simulated animal signals have been used and consequently has the potential for application in a range of fields where both improved penetration and high resolution are required, such as nondestructive testing and evaluation, geophysics, and medical physics

The acousto-ultrasonic approach

The nature and underlying rationale of the acousto-ultrasonic approach is reviewed, needed advanced signal analysis and evaluation methods suggested, and application potentials discussed. Acousto-ultrasonics is an NDE technique combining aspects of acoustic emission methodology with ultrasonic simulation of stress waves. This approach uses analysis of simulated stress waves for detecting and mapping variations of mechanical properties. Unlike most NDE, acousto-ultrasonics is less concerned with flaw detection than with the assessment of the collective effects of various flaws and material anomalies. Acousto-ultrasonics has been applied chiefly to laminated and filament-wound fiber reinforced composites. It has been used to assess the significant strength and toughness reducing effects that can be wrought by combinations of essentially minor flaws and diffuse flaw populations. Acousto-ultrasonics assesses integrated defect states and the resultant variations in properties such as tensile, shear, and flexural strengths and fracture resistance. Matrix cure state, porosity, fiber orientation, fiber volume fraction, fiber-matrix bonding, and interlaminar bond quality are underlying factors

Sensors for ceramic components in advanced propulsion systems: Summary of literature survey and concept analysis, task 3 report

The results of a literature survey and concept analysis related to sensing techniques for measuring of surface temperature, strain, and heat flux for (non-specific) ceramic materials exposed to elevated temperatures (to 2200 K) are summarized. Concepts capable of functioning in a gas turbine hot section environment are favored but others are reviewed also. Recommendation are made for sensor development in each of the three areas