Foundations of millimeter-wave frequency acoustic microscopy

This work discusses the advancements in the field of millimeter-wave superfluid helium acoustic microscopy.; The superfluid helium acoustic microscope operating at a center frequency of 8 GHz at temperatures less than 0.2 K has been shown to have a resolution of at least 200A. In order to increase the operating frequency, and hence the resolution, of the acoustic microscope nearly all the components of the 8 GHz microscope had to be redesigned. Instead of the single layer ZnO acoustic transducers used below 10 GHz, multilayer ZnO acoustic transducer have been used to generate sufficient power at frequencies above 24 GHz. These multilayer ZnO transducers have been used to generate approximately 28 GHz sound with two-way conversion losses as low as 27 dB. Multilayer transducers have also been fabricated for operation at frequencies as high as 100 GHz, where the two-way conversion loss is approximately 50 dB. These ZnO multilayer transducers represent the highest operating frequency of any ZnO transducer and the highest conversion efficiencies for any type of transducer in this frequency range. The theoretical aspects of multilayer transducers are explored along with experimental verification of some theoretical predictions. The possibility of generating sound at frequencies as high as 300 GHz is explored.; A piezoelectric mechanical scanning system has been designed for operation at temperatures as low as 100 milliKelvin. The scanner is able to overcome the loss in travel of the piezoelectric elements at low temperatures by using lever arms to magnify the piezoelectric motion. The resolution, frequency characteristics, and heat dissipation properties of the scanner are presented. The possibility of using superconducting bolometers for incoherent signal detection of millimeter-wave frequency acoustic waves is investigated. Several different configurations for using bolometers in conjunction with multilayer acoustic transducers are described.; Image processing algorithms for automatically correcting phase delays and single point and single line scan errors which occur in many different types of scanning microscopy are presented. The usefulness of several types of two-dimensional image interpolation techniques is evaluated using data obtained from the Scanning Tunneling Microscope (STM). STM images of various single component liquid crystals and liquid crystal mixtures are presented and the technological applications discussed.