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The demand for increasing optical data storage densities is ever present and there are currently many methods being researched, which address this problem. In order to achieve these densities many techniques, based upon near-field optical recording, will most certainly super-cede the far-field recording technique, in which the classical diffraction limit constrains recording density. A near-field recording technique based upon a Solid Immersion Lens (SIL) has proved to be a probable solution to this. In order to increase the resolution, the wavelength can be reduced or the numerical aperture (NA) increased. The downside of this is the reduction in the depth of focus, which places more demands on the optical system. The increase in resolution for SIL, compared to a conventional head is by a factor of 1/n as first introduced by Mansfield and Kino, where n is the refractive index of the SIL lens. SIL has continued to be of interest in the data storage community and has the potential to compete with other technologies to achieve the high data storage capacities desired in the current and future market.
The system to be developed is to be based on an existing Scanning Laser Microscope, which will be adapted to incorporate a PZT positioning structure to control the SIL to sample gap height, and also the SIL's attitude. This is required in order for the collimated beam to focus through the SIL to a spot on the sample and achieve the required resolution. After the structure is complete, SIL's (firstly, hemisperical SILs ) of varying sizes will be used to form the investigation into the SIL structure, material, size and the affect this has on the system build and the materials being imaged. A variety of SIL configurations will be used to study this. The results obtained will be verified using a magnetic force microscope.
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