CMOS-based Integrated Wavefront Sensor

This thesis addresses the design, implementation and performance of an integrated Hartmann-Shack wavefront sensor suitable for real-time operation and compatible with a standard technology. A wavefront sensor can be used for the detection of distortions in the profile of a light beam or of an optical component.With such a sensor, one can, for instance, estimate the distortions of a human-eye lens or the distortions present in a light beam after this has propagated through a turbulent atmosphere. Moreover, the wavefront sensor can be coupled to a deformable mirror such that this combination can compensatedistortions in a laser beam. This kind of adaptive system finds more and more applications in astronomy, industry andrecently in medicine. We propose the implementation of a Hartmann wavefront sensor that uses a matrix of integrated position-sensitive detectors which are compatible with standard Complementary Metal-Oxide-Semiconductor technology (CMOS). A wavefront is sampled into a number of light spots, whose displacements are proportional to local tilts of the wavefront. The idea is to have one position-sensitive detector per sampled spot, such that direct information about the spot-centroid position is available. This scheme renders faster operation than when a conventional imager is used because it circumvents the image-processing step. The developed wavefront sensor proved to meet all the initially proposed prerequisites: it is capable of real-time operation, compact, simple and compatible with a standard technology. In terms of performance, each particular application has its own requirements and the developed sensor, which should be used with light sources in the visible spectrum, shall perform well for applications involving enough light (> 0.5-mW beams) and there where lower-order wavefront aberrations are expected (< 30 Zernike terms). The sensor can be modified in a variety of ways to attend to particular applications.Information Technology and System

Feasibility Study of Analogue and Digital Temperature Sensors in Nanoscale CMOS Technologies

The downscaling of CMOS technology gives rise to a myriad of nanoscale effects. At the same time, power density and thus heat generation increases. The aim of this paper is to evaluate the feasibility of both analogue and digital temperature sensors in nanoscale CMOS using the Berkeley Predictive Technology Model (BPTM) for 65nm. For the oscillator-based digital sensor presented, a sensitivity of 1.86MHz/{degree sign}C is achieved. The analogue sensor achieves a sensitivity of 1.7mV/{degree sign}C.Electrical Engineering, Mathematics and Computer Scienc

Coupling of a CMOS Optical Sensor to a Micromachined Deformable Mirror with an Adaline Neural Method

We report on the preliminary results of an Adaline neural method for the coupling of a custom CMOS wavefront sensor to a micromachined adaptive mirror. The algorithm does not rely on a fixed basis matrix -as opposed to traditional methods-, offers excellent immunity to round-off errors and admits real-time input adaptability to speed up computations.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc

Silicon micro-optics for smart light control

We present an overview of the results of our recent research in the field of adaptive optical components based on silicon microtechnologies, including membrane deformable mirrors, spatial light modulators, liquid-crystal correctors, wavefront sensors, and both spherical and aspherical micro-optical components. We aim at the realization of adaptive optical systems using standard-technology solutions.Electronic Instrumentation LaboratoryElectrical Engineering, Mathematics and Computer Scienc