Mark A. Meier

Converted-wave resolution

Seismic-resolution theory used in survey design applies to P- and S-wave reflection seismology but is not readily applicable to converted waves. We rederived the theory with sufficient generality to include converted waves explicitly. Generalization of the theory requires that the inherent converted-wave properties of mode change and finite scattering angle be accommodated. The significance of amplitude fidelity in modern seismic applications also affects the resolution description. We considered resolution in the context of a single recorded trace (trace resolution) and an image derived from many traces (image resolution). Trace resolution is governed by wavelet width, which results in a minimum bandwidth requirement, depending on scattering angle and local propagation velocities of incident and scattered modes. Image resolution is governed additionally by the migration acceptance angle and results in minimum aperture and sampling requirements. The requirements for converted-wave surveys generally differ...

Low frequency pressure modulation of indium antimonide

A lumped parameter resonator capable of generating megapascal pressures at low frequency (kilohertz) is described. Accelerometers are used to determine the applied pressure, and are calibrated with a piezoelectric sample. A laser diagnostic was also developed to measure the pressure in semiconductor samples through the band gap pressure dependence. In addition, the laser diagnostic has been used to measure the attenuation coefficient α of commercially available indium antimonide (InSb) wafers. The resonator and laser diagnostic have been used with InSb samples to verify the pressure response.

Resonant transducers for solid-state plasma density modulation

We have developed transducers capable of modulating the plasma density and plasma density gradients in indium antimonide. These transducers make use of piezoelectric drivers to excite acoustic pressure resonance at 3λ/2, generating large amplitude standing waves and plasma density modulations. The plasma density has been directly measured using a laser diagnostic. A layered media model shows good agreement with the experimental measurements.

Density modulation of a solid-state plasma using acoustic pressure

We are studying the plasma density response with pressure in indium antimonide (InSb), with the goal of developing a solid-state pressure gradient transducer [1]. We use intrinsic InSb, where the free carrier concentration depends only on the energy band gap and temperature. We have developed two techniques to apply pressure modulation to an InSb sample. One method, which we call a Lumped Parameter Resonator (LPR), applies pressure at low frequency (~2 kHz) with no spatial dependence. The second method uses higher frequency (~200 kHz) in a resonant structure to generate a standing wave. We have also developed a laser plasma diagnostic to directly measure the plasma density.

Converted‐wave survey design

Converted-wave reflection seismology, such as PS, provides information about the subsurface different from that privoded by conventional longitudinal-wave (PP) reflection seismology. Added independent information, in principle, can be used to ascertain subsurface characteristics otherwise unobtainable. Interestingly, the business objectives that motivate PS surveys are often derived from problems with data from previous PP surveys. The data prove inadequate at providing needed information because of local conditions that are problematic for the PP method. The PS method is pursued if it is anticipated that it can overcome those conditions.