| This thesis reports work on a new device to detect changes in spatially nonuniform intensity distributions, and shows how this device can be applied to the particular problem of optical vibration detection.; The phase of optical radiation is very sensitive to any disturbance of the light frequency, the index of refraction of the medium it traverses, or the optical path length. At the same time, any optical wavefront other than an infinite plane wave leads to some spatial nonuniformity in the intensity distribution in a given detection plane. A slight change in a number of physical conditions can therefore lead to detectable changes in this nonuniform intensity distribution.; The ability to detect variations in nonuniform optical intensity distributions therefore enables a variety of measurements. Interference, diffraction or laser speckle patterns are of particular interest in this context. One such area of application is the optical detection of surface vibrations.; The new method proposed in this work is based on multiple simultaneous four-point measurements of photoconductance. This approach is compared to established techniques, and the expected performance of the new method is given. Details of the design and fabrication of a prototype are provided. Results of vibration detection experiments are provided, including interferometric and referenceless detection, both on specularly reflecting and scattering surfaces. Shortcomings of the prototype are discussed, and finally an improved device design is suggested.; While the specific prototype fabricated and tested here has a limited bandwidth, the new method in general is found to have advantages over conventional detection techniques under certain circumstances. In particular, the approach proposed here allows for good spatial resolution and low-power operation. |
